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Age and origin of the Turnagain Alaskan-type intrusion and associated Ni-sulphide mineralization, north-central.. 2007

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A G E A N D O R I G I N O F T H E T U R N A G A I N A L A S K A N - T Y P E I N T R U S I O N A N D A S S O C I A T E D N I - S U L P f f l D E M I N E R A L I Z A T I O N , N O R T H - C E N T R A L B R I T I S H C O L U M B I A , C A N A D A by J . E R I K S C H E E L B . S c . H . Un ive r s i t y o f Alber ta , 2004 A T H E S I S S U B M I T T E D F O R P A R T I A L F U L F I L M E N T O F T H E R E Q U I R E M E N T S F O R T H E D E G R E E O F M A S T E R O F S C I E N C E in T H E F A C U L T Y O F G R A D U A T E S T U D I E S ( G E O L O G I C A L S C I E N C E S ) T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A M a y 2007 © J . E r i k Scheel , 2007 ABSTRACT The Turnagain Alaskan- type intrusion i n north-central B r i t i s h C o l u m b i a consists o f ultramafic to dior i t ic rocks and contains significant magmatic sulphide mineral iza t ion. The age o f the intrusion is constrained by U - P b and A r - A r geochronology to be 1 9 0 ± 1 M a and the m i n i m u m deposi t ional age o f the youngest host rocks (volcanic wacke) is 301 M a . W h o l e rock N d isotopic composi t ions are characteristic o f Pa leozo ic arc-derived mafic rocks i n the northern Canadian C o r d i l l e r a (£Nd(i90) = +4 to +6), but indicat ive o f variable crustal contaminat ion in some samples (ENd(i90) = +2 down to -3.3). The age and tectonic characteristics of the Turnagain intrusion and its host rocks constrain the terrane it intrudes to be either Y u k o n - Tanana or Quesne l l ia , but not Ances t ra l Nor th A m e r i c a . The Turnagain parent magmas were hydrous, arc-derived, i n equ i l ib r ium wi th mantle peridotite, and ankaramitic . Cross-cut t ing and geochemical relationships define the crysta l l izat ion and emplacement sequence o f the Turnagain intrusion to be: dunite (~For,i) —> wehrli te (~Fog 7 ) —> o l iv ine c l inopyroxeni te ( ~ F o 8 5, M g # c p x = 0.92) —• hornblende c l inopyroxeni te ( M g # c p x = 0.81, M g # h D i = 0.65) —> hornblendite (Mg#ht>i = 0.60) —> diorite. M i n e r a l and whole- rock geochemistry indicate that al l ultramafic l i thologies are genetically related and relative depletion in the H F S E , specif ical ly N b and T a , are consistent wi th an arc mantle source for the parent magmas. Var ia t ions in spinel chemistry i n the Turnagain intrusion are ma in ly a function o f post-crystal l izat ion re- equi l ibrat ion and oxida t ion . P r imary (unmodified) chromite composi t ions , observed in chromit i te samples, are C r - r i c h ( C r / ( C r + A l ) = 0.86-0.90) and F e 3 + - p o o r ( F e 3 + / ( F e 3 + + C r + A l ) < 0 . 1 ) , indica t ing their crysta l l izat ion f rom a magma wi th relat ively l ow JO2 ( A F M Q < 0), w h i c h is substantially lower than for other Alaskan- type intrusions. A t these 2 2 re la t ively reduced condi t ions , S was d isso lved as sulphide (S ") rather than sulphate (SO4 ")• Sulphur ( 8 3 4 S = -9.7 to +1.4%o) and lead isotopic composi t ions o f sulphide from the ultramafic rocks indicate that upper crustal sulphur and lead were added to the parent magmas by ass imila t ion o f graphitic, pyr i t ic metasedimentary inclus ions ( 8 3 4 S = -17.9%o), wh ich are found on ly in the sulphide-minera l ized zones. Thus , addi t ion o f crustal carbon and sulphur reduced the Turnagain magmas and increased total S, w h i c h lead to early sulphide saturation. TABLE OF CONTENTS ABSTRACT ii TABLE OF CONTENTS iii LIST OF TABLES vi LIST OF FIGURES vii LIST OF APPENDICES ix ACKNOWLEDGEMENTS x CHAPTER 1: GEOLOGICAL CONTEXT AND EXPLORATION HISTORY OF THE TURNAGAIN ALASKAN-TYPE INTRUSION, NORTH-CENTRAL BRITISH COLUMBIA 1 1.1 INTRODUCTION 2 1.2 EXPLORATION HISTORY OF THE TURNAGAIN INTRUSION 5 1.3 OVERVIEW OF THE THESIS 6 1.4 REFERENCES 9 CHAPTER 2: GEOCHRONOLOGY OF THE TURNAGAIN ALASKAN-TYPE INTRUSION, NORTH-CENTRAL BRITISH COLUMBIA, WITH IMPLICATIONS FOR THE TECTONIC EVOLUTION OF THE NORTHERN CANADIAN CORDILLERA 12 2.1 INTRODUCTION 13 2.2 GEOLOGICAL SETTING OF THE TURNAGAIN INTRUSION 14 2.3 GEOLOGY OF THE TURNAGAIN INTRUSION 19 2.4 SAMPLE DESCRIPTIONS AND ANALYTICAL TECHNIQUES 21 2.4.1 U-Pb zircon/titanite 21 2.4.2 Ar-Ar phlogopite/amphibole 24 2.4.3 Neodymium isotopes 25 2.5 RESULTS 26 2.5.1 U-Pb geochronology 26 2.5.1.1 Mela-diorite 26 2.5.1.2 Leuco-diorite 27 2.5.1.3 Volcanic wacke 30 2.5.1.4 Hornblendite 30 2.5.2 Ar-Ar geochronology 32 2.5.2.1 Hornblendite 32 2.5.2.2 Wehrlite 32 2.5.3 Rare earth elements and Nd isotopes 36 2.6 DISCUSSION 36 2.6.1 Age and source of the Turnagain intrusion 36 2.6.2 Age comparison with other Alaskan-type intrusions 43 2.6.3 Tectonic implications for northern British Columbia 47 2.7 CONCLUSION 49 2.8 ACKNOWLEDGEMENTS 50 2.9 REFERENCES 51 CHAPTER 3: CHROMITE CHEMISTRY OF THE TURNAGAIN INTRUSION, NORTHERN BRITISH COLUMBIA, AND THE REDOX STATES OF ALASKAN- TYPE PARENTAL MAGMAS 58 3.1 INTRODUCTION 59 3.2 REGIONAL GEOLOGY 60 3.3 GEOLOGY AND SPINEL CONTENT OF THE TURNAGAIN INTRUSION 60 3.3.1 Dunite 62 3.3.2 Wehrlite 65 3.3.3 Olivine clinopyroxenite 65 3.3.4 Hornblende clinopyroxenite and hornblendite 67 3.4 ANALYTICAL TECHNIQUES 67 3.5 RESULTS 69 3.5.1 Chromitite 72 3.5.2 Dunite 72 3.5.3 Wehrlite 72 3.5.4 Olivine clinopyroxenite 75 3.4.1 Hornblende clinopyroxenite .. 75 3.6 DISCUSSION 77 3.6.1 Primary spinel compositions 77 3.6.2 Reequilibration trends 79 3.6.3 Compositional effects of serpentinization on spinel chemistry 80 3.6.4 Implications for the redox state of the Turnagain intrusion 80 3.7 CONCLUSIONS 83 3.8 ACKNOWLEDGEMENTS 84 3.9 REFERENCES 85 CHAPTER 4: PETROLOGY AND METALLOGENY OF TURNAGAIN ALASKAN- TYPE INTRUSION AND ITS ASSOCIATED NI-SULPHIDE MINERALIZATION 89 4.1 INTRODUCTION 90 4.2 GEOLOGY OF THE TURNAGAIN INTRUSION 91 4.2.1 Regional geology 91 4.2.2 Ultramafic rocks 94 4.2.2.1 Dunite and chromitite ; 94 4.2.2.2 Wehrlite 99 4.2.2.3 Olivine clinopyroxenite and clinopyroxenite 100 4.2.2.4 Hornblende clinopyroxenite 101 4.2.2.5 Hornblendite 102 4.2.3 Other rocks 102 4.2.3.1 Diorite 102 4.2.3.2 Hornfels 103 4.2.4 Sulphide 103 4.2.5 Inclusions 106 4.3 ANALYTICAL TECHNIQUES 107 4.3.1 Mineral chemistry 107 4.3.2 Major and trace elements 110 4.3.3 Platinum group elements 118 4.3.4 Sulphur isotopes - sulphide 121 4.3.5 Lead isotopes - sulphide 121 4.4 RESULTS 125 4.4.1 Olivine chemistry 125 4.4.2 Clinopyroxene chemistry 127 4.4.3 Amphibole and biotite chemistry 127 4.4.4 Major and trace element chemistry 129 4.4.4.1 High-Mg olivine-rich rocks 129 4.4.4.2 Intermediate-Mg clinopyroxene-rich rocks 133 4.4.4.3 Hornblendites 133 4.4.4.4 Dioritic rocks 134 4.4.5 Platinum group elements 134 4.4.6 Sulphur isotopic compositions 137 4.4.7 Lead isotopic compositions 137 4.5 DISCUSSION 137 4.5.1 Parent magma characteristics 137 4.5.2 Sequence of crystallization 140 4.5.3 Implications for associated volcanic rocks 141 4.5.4 Origin of sulphide mineralization in the Turnagain intrusion 142 4.5.5 Petrogenesis the Turnagain intrusion and associated Ni-sulphide mineralization 144 4.6 CONCLUSIONS 145 4.7 ACKNOWLEDGEMENTS 147 4.8 REFERENCES 148 CHAPTER 5: SUMMARY AND CONCLUSIONS 153 5.1 SUMMARY AND CONCLUSIONS 154 5.2 REFERENCES 157 L I S T O F T A B L E S Table 2.1: U-Pb TIMS analytical data from zircon and titanite grains separated from samples from the Turnagain intrusion 28 Table 2.2: 4 0 Ar/ 3 9 Ar step-heating results of mineral separates from ultramafic rocks of the Turnagain intrusion 34 Table 2.3: Major (wt. % oxide) and trace element abundances (ppm) in whole rock samples from the Turnagain intrusion 37 Table 2.4: Nd isotopic compositions of whole rock samples from the Turnagain intrusion 39 Table 2.5: Ages of Alaskan-type intrusions in B.C. and Alaska 44 Table 3.1: Representative spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion 70 Table 4.1: Representative olivine compositions from olivine-bearing ultramafic lithologies in the Turnagain intrusion I l l Table 4.2: Representative clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies in the Turnagain intrusion 113 Table 4.3: Amphibole compositions from ultramafic rocks of the Turnagain intrusion 115 Table 4.4: Biotite compositions from biotite-bearing ultramafic lithologies in the Turnagain intrusion... 117 Table 4.5: Major (wt. % oxide) trace element abundances (ppm) in mafic-ultramafic rocks of the Turnagain intrusion 119 Table 4.6: PGE concentrations of representative ultramafic rocks from the Turnagain intrusion 122 Table 4.7: Sulphur isotopic compositions of sulphide from the Turnagain intrusion and surrounding lithologies 123 Table 4.8: Pb isotopic compositions of selected sulphide fractions from the Turnagain intrusion and surrounding lithologies 124 vi L I S T O F F I G U R E S Figure 1.1: Simplified geological map of the Turnagain Alaskan-type intrusion, modified from Clark (1975) 3 Figure 2.1: Terrane map of British Columbia, modified from Colpron & Nelson (2004) 15 Figure 2.2: Regional geological map of the area immediately surrounding the Turnagain intrusion, extracted and modified from Massey et al. (2005) 16 Figure 2.3: Geologic map of the Turnagain intrusion 18 Figure 2.4: Photomicrographs of zircon and titanite separates from the Turnagain intrusion 22 Figure 2.5: Concordia plots for U-Pb data from analyzed zircon fractions for diorite samples from the Turnagain intrusion 29 Figure 2.6: Concordia plots for U-Pb data from analyzed zircon fractions from a volcanic wacke sample from the Turnagain intrusion (04ES-00-07-02) 31 Figure 2.7: Concordia plots for U-Pb data from analyzed titanite fractions separated from a hornblendite dike (04ES-00-07-04) in the northwestern region of the Turnagain intrusion 33 Figure 2.8: 4 0Ar/ 3 9Ar incremental-heating age spectra and 4 0 Ar/ 3 9 Ar inverse isochron diagrams for mineral separates from the Turnagain intrusion 35 Figure 2.9: Chondrite-normalized rare earth element diagram for whole rock samples from the Turnagain intrusion, and whole rock samples from Erdmer et al. (2005) 38 Figure 2.10: Nd isotopic geochemistry of whole rock samples from the Turnagain intrusion 40 Figure 2.11: Ages of Alaskan-type intrusions in B.C. and Alaska 45 Figure 3.1: Simplified geological map of the Turnagain Alaskan-type intrusion 61 Figure 3.2: Photographs of chromitite in outcrop from the Turnagain intrusion 63 Figure 3.3. Photomicrographs of chromite textures from chromitite and dunite 64 Figure 3.4: Photomicrographs of chromite textures from wehrlite and olivine clinopyroxenite in the Turnagain intrusion 66 Figure 3.5: Photomicrographs of magnetite textures from sample DDH04-47-7-49, a hornblende clinopyroxenite from the western zone of the Turnagain intrusion 68 Figure 3.6: Chromite compositional ternary diagrams, represented by sample number 73 Figure 3.7: Binary plots of spinel compositions from the Turnagain intrusion. A) divalent vs. trivalent cation plot. B) Fe# vs. Cr/Cr+Al 74 Figure 3.8: Binary plots of spinel compositions from the Turnagain intrusion. A) Fe3+/(Fe3++Cr+AI) vs. Ti0 2 . B) Ti vs. V 76 Figure 3.9: Expanded trivalent cation (Fe3+-Cr-Al) plot of Turnagain spinel compositions, focusing on those compositions nearest end-member chromite 78 Figure 3.10: Expanded trivalent cation (Fe3+-Cr-Al) plot of Turnagain spinel compositions with the data density maxima for other Alaskan-type intrusions from Barnes & Roeder (2001) 82 Figure 4.1: Geological map of the Turnagain intrusion showing sample locations chosen for whole rock geochemistry and sulphide sulphur and lead isotopic compositions 92 Figure 4.2: Photographs of dunite exposures in the Turnagain intrusion 93 Figure 4.3a: Photographs of outcrop-scale features from olivine cumulate lithologies in the Turnagain intrusion 95 Figure 4.3b: Photographs of outcrop-scale features in olivine-clinopyroxene cumulate lithologies in the Turnagain intrusion 96 Figure 4.4a: Photomicrographs (transmitted light, crossed-polars) of silicate mineral textures in the Turnagain intrusion from dunite and wehrlite 97 Figure 4.4b: Photomicrographs (transmitted light, crossed-polars) of silicate mineral textures in the Turnagain intrusion from olivine clinopyroxenite, hornblendite, and diorite 98 Figure 4.5: Photomicrographs of sulphide textures in the Turnagain intrusion 105 Figure 4.6: Photographs of sedimentary xenoliths in NQ size drillcore from the Turnagain intrusion 108 Figure 4.7: Olivine mineral chemistry 126 Figure 4.8: Clinopyroxene mineral chemistry 128 Figure 4.9: Select major element oxides and Mg# vs. MgO for whole rock samples and mineral analyses from the Turnagain intrusion 130 Figure 4.10: Compatible trace element geochemistry vs. MgO 131 Figure 4.11: Chondrite-normalized rare earth element diagrams for whole rocks from the Turnagain intrusion and whole rock samples from Erdmer et al. (2006) 132 Figure 4.12: PGE compositional variations for whole rocks from the Turnagain intrusion 135 Figure 4.13: Primitive-mantle normalized platinum group element diagrams for whole rocks from the Turnagain intrusion 136 Figure 4.14: Sulphur isotopic composition of sulphide vs. lithology in the Turnagain intrusion 138 Figure 4.15: Lead isotopic compositions (206Pb/204Pb vs. 2 0 7Pb/2 0 4Pb) of sulphide from the Turnagain intrusion 139 Figure 4.16: The effects of oxygen fugacity on sulphur speciation and saturation, after Jugo et al. (2004; 2005) 143 viii L I S T O F A P P E N D I C E S Appendix I: Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion 160 Appendix II: Olivine compositions from olivine-bearing ultramafic rocks of the Turnagain intrusion 179 Appendix III: Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion 189 Appendix IV: Garnet compositions from a serpentine vein in dunite from the Turnagain intrusion 195 Appendix V: List of X-ray lines and mineral standards for E P M A 196 Appendix VI: Blind duplicate analyses from whole-rock geochemical samples 198 Appendix VII: Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion 200 ix A C K N O W L E D G E M E N T S There are many people w h o have contributed in some part to the development and comple t ion of this thesis. I w o u l d never have written this thesis without the advice and support o f m y supervisors James Scoates and G r a h a m N i x o n , who have taught me so m u c h since I first arr ived at U B C . James was a lways w i l l i n g to answer questions that I had about everything thesis-related or otherwise, regardless of his o w n work load . James also spent significant amounts o f t ime edi t ing various draft sections o f this thesis, and for that I am extremely grateful. G r a h a m introduced me to the Turnagain property and imparted his experiences o f w o r k i n g on Alaskan- type intrusions on me wi th s k i l l and precis ion. H e must also be thanked for he lp ing me set-up necessary f ie ld gear, maps, air photographs, and lodg ing when I v is i ted h i m in V i c t o r i a . R i c h F r i edman , Janet Gabites , B r u n o Kief fe r , Thomas U l l r i c h , and M a t i Raudsepp are thanked for their analyt ical work and advice dur ing the research phase o f this thesis. A l s o R i c h Fr iedman , D o m i n i q u e W e i s , and J i m Mortensen o f the P C I G R are thanked for consultations dur ing data interpretation and the impl ica t ions thereof. I also thank A n d r e w Greene, Caro l ine Emmanue l l e -Mor i s se t , and R o b i n M a c k i e for sharing their thoughts on ultramafic rocks wi th me. H a r d Creek N i c k e l Corpora t ion , its president M a r k Jarvis , and its past and present employees T o n y Hi t ch ins , Chr i s B a l d y s , B ruce Northcote, and L e s l i e Y o u n g are al l thanked for the ideas, support, and seasonal employment dur ing the duration o f this thesis as we l l as for funding the research project. Other past and present H a r d Creek N i c k e l employees, i nc lud ing Jeff K y b a , T y l e r K u h n , M a r k Greenhalgh, and G r e g Ross , must also be thanked for mak ing summer w o r k a great experience. J i m and Sharon R e e d at Pac i f i c Western Hel icopters must be thanked for transport dur ing the numerous summers spent i n the Turnagain camp. Thanks to John Schussler, the first dr i l le r on the Turnagain property and former owner of D J D r i l l i n g , for lodg ing i n B o u l d e r C i t y i n 2004 and 2005. F i n a l l y , I l ike to thank m y fami ly for their help and support dur ing the last 7 years o f m y academic career. I w o u l d l ike to thank T o m C h a c k o , B o b L u t h , L a r r y Heaman , Sarah Gleeson , and Jeremy Richards at the Un ive r s i t y o f Albe r t a for he lp ing me f ind m y ca l l i ng in geology, and for m a k i n g the undergraduate program there one o f the best i n the continent. M a n y thanks to a l l m y friends at U B C and i n Vancouver , because without them I w o u l d not have made it this far. x C H A P T E R 1 GEOLOGICAL CONTEXT AND EXPLORATION HISTORY OF THE TURNAGAIN ALASKAN-TYPE INTRUSION, NORTH-CENTRAL BRITISH COLUMBIA 1.1 INTRODUCTION This study focuses on the Turnagain Alaskan-type mafic-ultramafic intrusion, wh ich is located 70 k m east o f Dease Lake , Br i t i sh Columbia , Canada. The Turnagain intrusion is a 24 k m 2 pluton that is dominantly composed o f ultramafic cumulate rocks and minor dioritic phases and that contains appreciable nickeliferrous sulphide mineralization (Figure 1.1). G loba l ly , Alaskan-type intrusions are characteristically sulphide-poor and no other intrusion found to date contains significant concentrations o f magmatic Ni-bear ing sulphide. The main goal o f this thesis is to assess the or igin and petrogenesis o f the Turnagain intrusion and to constrain the mechamism o f sulphide mineralization by combined field mapping and dril lcore logging, geochemistry (mineral chemistry, major and trace elements, N d - S - P b isotopes) and geochronology (U-Pb , A r - A r ) . The Turnagain intrusion is situated wi th in greenschist facies metasedimentary rocks currently assigned to the Ancestral Nor th Amer ican miogeocline (Gabrielse, 1998). The intrusion is entirely fault-bounded on al l margins, and is situated 1.5 k m northeast o f the Kutcho Fault, wh ich is a major tectonic structure separating the miogeocline to the east from felsic plutons and mafic volcanics o f the Quesnel accreted terrane to the west. The term "Alaskan-type," synonymous wi th "Uralian-type", "Ural ian-Alaskan-type", and "zoned ultramafic", was first used by Taylor & Nob le (1960) and Nob le & Taylor (1960) and original ly referred to mafic-ultramafic intrusions found in the A la skan Panhandle and in the U r a l Mountains, Russia (e.g. Duke Island, Irvine, 1962; N i z h n i i - T a g i l , Krause et al, 2006). These two belts, along with other occurrences o f Alaskan-type intrusions, are typical ly found in paleo-arc environments. The subduction zone or arc setting o f these intrusions has been qualified in a large number o f studies (e.g. Irvine, 1974; Tis t l et al, 1994; Green et al., 2004; Batanova et al., 2005) by association wi th other arc rocks, mineralogy, and geochemistry. Despite the fact that many more o f these bodies have been found throughout the wor ld , the term "Alaskan-type" is sti l l retained. "Zoned ultramafic" refers to the observation that many o f these intrusions are zoned from the core outwards, from more mafic (or ultramafic) to less mafic rocks. This zonation can be perfectly concentric, or completely absent, and is a common, although not a diagnostic, trait o f Alaskan-type intrusions. It has long been known that Alaskan-type intrusions can be spatially associated wi th basaltic volcanic rocks (Findlay, 1969; Irvine, 1974), and a genetic l ink between Alaskan-type intrusions and arc-derived ankaramitic/picritic magmas and lavas has recently been established (Mossman et al., 2000). Intrusion Centre: X 58°29'N, 128°52'W Horsetrail Zone 1 km | Dunite, with minor wehrlite Wehrlite, with minor dunite and olivine clinopyroxenite Olivine clinopyroxenite and clinopyroxenite, undivided Hornblende clinopyroxenite, with minor clinopyroxenite Hornblendite and clinopyroxene hornblendite, undivided Diorite, quartz diorite, and granodiorite, undivided Homfels, sedimentary or volcanic protolith Reverse fault, observed Normal fault, inferred —^ Fault (relative sense of motion indicated) Figure 1.1: Simplified geological map of the Turnagain Alaskan-type intrusion, with its location in British Columbia shown as an inset in the upper right comer (also indicated are the locations of other major Alaskan- type intrusions in B.C. and Alaska), modified from Clark (1975). The lithologies of the intrusion are shown in the legend; some units are composites (e.g. olivine clinopyroxenite and clinopyroxenite). The intrusion is entirely fault-bounded, and the large area of hornblende-rich lithologies with associated felsic rocks in the west is mostly interpreted from both airborne and ground geophysics, as well as information from drill holes. Major mineralized zones are indicated with white ovals, as is the Discovery Showing. The DJ/DB zone is a hydrothermal Pt-Pd zone, whereas all other zones contain Ni-sulphide mineralization. Arc-der ived ankaramites are composed o f o l iv ine- and clinopyroxene-porphyritic basalt containing groundmass amphibole and plagioclase. Ankaramite dikes, typical ly found cross- cutting certain Alaskan-type intrusions (e.g. Greenhil ls , Spandler et al., 2003), are commonly zoned from the interior to the margin, suggesting that the observed zonation in Alaskan-type intrusions may be the result o f common petrogenetic processes. The mineralogy and crystallization sequence o f ankaramite and Alaskan-type intrusions is also nearly identical and the chemical signatures o f both rock types indicates their common origin from the mantle (e.g. Green et al, 2004). The defining characteristic o f Alaskan-type intrusions is their mineralogy. Their typical order o f crystallization is olivine+chromite —> diopside —*• magnetite —> hornblende+calcic plagioclase. Chromite is an early (high temperature) crystal l izing phase in Alaskan-type intrusions and typical ly ceases to crystallize shortly after clinopyroxene saturation (Irvine, 1965). In general, mafic-ultramafic intrusions rarely contain primary magmatic hornblende, but primary hornblende is a common mineral in evolved rocks wi th in many Alaskan-type intrusions. Orthopyroxene is typical ly absent, save a few isolated examples (e.g. Salt Chuck, A l a s k a , Loney & Himmelberg , 1992; Gabbro A k a r e m , Egypt , H e l m y & E l M a h a l a w i , 2003), indicating that the parental magmas to these bodies were silica-undersaturated (Irvine, 1965). Plagioclase is generally absent as an early cumulus phase, and crystallizes after clinopyroxene or hornblende. The suppression o f early plagioclase crystall ization is due to the relatively high water contents o f the magmas as elevated water contents in silicate magmas are known to suppress the crystallization o f plagioclase to l ow temperatures (e.g. Irvine, 1965; Gaetani et al., 1993). The presence o f small amounts o f primary phlogopite in the most ultramafic parts o f intrusions is also a diagnostic feature, and may reflect the alkaline to subalkaline chemical characteristics o f primit ive Alaskan-type magmas (Findlay, 1969; Irvine, 1974; N i x o n et al., 1997). M a n y intrusions have lode and associated placer Pt (± Pd) mineral deposits (e.g. Tulameen, B . C . , F indlay, 1969; A l t o Condoto, Columbia , T is t l , 1994; N i z h n i i Tag i l , Russia , Johan, 2002) and they are commonly explored for platinum-group metals ( P G M ) . The majority o f these P G M are found in chromitite as PtsFe (isoferroplatinum) (e.g. N i x o n et al., 1990; Johan et ah, 2000), however there are also occurrences o f Os-Ir alloys (e.g. Garuti et al., 2003) and possible alloys, such as Pt2CuFe (tulameenite, N i x o n et al., 1990), o f hydrothermal origin. T w o Alaskan-type intrusions contain significant sulphide (Salt Chuck and Turnagain), each wi th a distinctive sulphide mineralogy and l i thologic association. The Salt Chuck intrusion contains Pd-r ich, bornite-bearing clinopyroxenite and gabbro (Loney & Himmelberg , 1992). In contrast, the Turnagain intrusion contains disseminated to semi-massive pyrrhotite and pentlandite wi th minor secondary phases, but also contains a late-stage, hydrothermal Pt- P d zone associated wi th a C u soi l geochemical anomaly (Figure 1.1). Thirty-five o f the 39 known Alaskan-type intrusions (e.g. Duke Island; Irvine, 1962) in southeastern A l a s k a occur in a 560 k m long by 50 k m wide belt (Taylor, 1967). The other four occurrences (e.g. Salt Chuck; Loney et ah, 1987) are to the west o f this belt, are older, and have different petrological characteristics (e.g. more plagioclase, trace orthopyroxene). Simi lar large belts occur in the U r a l Mountains (15 large bodies; Taylor , 1967; Krause, 2006), wh ich is approximately 1000 k m long and 60 k m wide; the Kamchatka Peninsula, Far East Russia (Batanova et al., 2005; and references therein), wh ich contains over 20 Alaskan-type intrusions; and Br i t i sh Columbia , wh ich has 9 known occurrences (e.g. Tulameen; F indlay , 1969; Turnagain; Clark , 1980; N i x o n et al., 1997). Alaskan-type intrusions in Co lumbia and Ecuador (Tist l , 1994; Tis t l et al., 1994) may belong to a larger belt that currently remains unconstrained and relatively unexplored. A tectonically dismembered belt that existed prior to the Miocene opening o f the Sea o f Japan has been proposed to l ink Alaskan-type intrusions in Japan, northeastern China , and Far East Russia (Ishiwatari & Ichiyama, 2004). There are also a number o f other Alaskan-type intrusions that occur as either single intrusions (e.g. Papua N e w Guinea; Johan et al, 2000; Greenhil ls; Mossman et al., 2000) or as small groups o f intrusions (e.g. F i f i e ld , Austral ia; Johan, 2002). 1.2 EXPLORATION HISTORY OF THE TURNAGAIN INTRUSION Sulphide mineralization in the Turnagain intrusion was discovered along the banks o f the Turnagain R ive r ca. 1956, and this semi-massive sulphide showing has henceforth been called the Discovery showing (Figure 1.1). Falconbridge N i c k e l M i n e s L t d . , interested in the n icke l potential o f the semi-massive sulphide, owned and explored the Turnagain property between 1966 and 1973 and dri l led the major sulphide showings (Northwest, Horsetrail , F i sh ing Rock , Discovery, Ha tz l ; Figure 1) wi th small , portable "packsack" dri l ls . Ai rborne magnetic surveys were also f lown across the entire intrusion. A P h . D . thesis on the geology and petrography o f the intrusion was completed by T o m Cla rk in 1975 at Queens Univers i ty (Clark, 1975), fo l lowed by several publications derived from the thesis (Clark, 1978; Clark , 1980). Interest in the platinum-group element ( P G E ) potential o f Alaskan-type intrusions in Br i t i sh Co lumbia during the 1980s resulted in significant government survey mapping and associated geochemical studies (especially P G E ) o f these intrusions across the province (N ixon etal, 1989; 1990; 1997). Interest in the nickel potential o f the intrusion was renewed when B r e n - M a r L t d . acquired the property in 1996 (Bren-Mar L t d . became Canadian Metals Explorat ion L t d . in 2002, and then became Hard Creek N i c k e l Corp. in 2004). Contour-defined and grid soi l sampling was conducted over the entire intrusion to constrain existing n icke l targets and to find covered targets (the intrusion is only - 3 0 % exposed). A zone o f hydrothermal P t -Pd -Cu mineralization was discovered as a result o f extensive soi l sampling in the summer o f 2004. Sulphide mineralogical and chemical studies have been carried out by D r . Harry K u c h a at the Univers i ty o f K r a k o w , Poland (Hard Creek N i c k e l internal reports), and are ongoing. Recent air photographs, and airborne and ground geophysics (magnetic, electromagnetic), were acquired in late 2005. To date, Hard Creek N i c k e l Corp . has dr i l led ~50 k m o f B Q and N Q drillcore in - 1 7 0 holes, and has outlined a N i resource o f 429 M t (measured and indicated) containing 0.17% sulphide N i (see http://www.hardcreeknickel.com). The author spent 8 weeks in the summer o f 2004 at the Turnagain property as part o f his field work, during which time detailed mapping and sampling o f outcrops wi th in and around the Turnagain intrusion were conducted. In the summer o f 2005, the author conducted two weeks o f drillcore sampling from the Turnagain intrusion for sulphides o f various textures and tenors, and sulphide from the wal l rocks where the contact had been penetrated by dr i l l ing . The author also sampled for chromitite and whole-rock geochemical samples. Fo r the remainder o f the summer, the author was involved in the summer exploration program o f Hard Creek N i c k e l Corp. , wh ich involved logging core and in - f i l l mapping. The current map o f the Turnagain intrusion, based on the map o f Cla rk (1975), was created as a joint effort by the author and Bruce Northcote (formerly o f Hard Creek N i c k e l Corp.) . 1.3 O V E R V I E W O F T H E S I S There are three complimentary studies on the Turnagain intrusion presented in this thesis. Pr ior to this study, there was no geochronological data for the Turnagain intrusion, nor were there any whole rock trace element or isotopic compositions. The main objectives o f this thesis were 1) to determine the age and tectonic significance o f the intrusion and its host rocks, 2) to characterize the lithologies and magmatic evolution o f the Turnagain intrusion using mineral and whole rock chemistry, and 3) to ultimately constrain the or igin o f the anomalous sulphide mineralization in the intrusion. Chapters 2, 3, and 4 were prepared in manuscript format for submission to appropriate scientific journals, and as such they contain some similar introductory figures and geologic backgrounds, although only information relevant to each specific study is reported in each chapter. Chapter 2 describes the geochronology and tectonic setting o f the Turnagain intrusion. The age o f the intrusion is determined by the dating o f four ultramafic and mafic samples using both U - P b and A r - A r geochronological techniques. A fifth sample, representing the stratigraphically-highest wallrocks to the Turnagain intrusion, was also dated using detrital z i rcon U - P b geochronology. The N d isotopic compositions o f eight whole rock samples were determined to help constrain the source o f the Turnagain intrusion and to ascertain the relative degree o f crustal contamination. Addi t iona l ly , available age data from other Alaskan-type intrusions in B . C . and southeastern A l a s k a were compiled in an effort to constrain the temporal evolution o f their respective arc systems. The results from this study place important constraints on the source o f the Turnagain intrusion, terrane assessment, and the temporal evolution o f the host rocks to the intrusion. Mine ra l separation (zircon, titanite, phlogopite, hornblende) was performed by the author, R i c h Friedman, H a i L i n , and T o m U l l r i c h at U B C . G w e n Wi l l i ams , Bruno Keiffer , and Jane Bar l ing were responsible for aquiring the N d isotopic compositions (sample dissolution, column chemistry, and mass spectrometry), and U - P b and A r - A r goechonologic analyses were carried out by R i c h Friedman and T o m U l l r i c h , respectively. Chapter 3 documents the chemistry o f chromite in the Turnagain intrusion wi th emphasis on the or ig in and significance o f compositional variations. Spinel grains from sixteen samples were analyzed by electron microprobe (a total o f 320 point analyses). F r o m these analyses, a primary spinel composit ion for the Turnagain intrusion has been defined. The intrasample chemical trends present in the analyzed chromite grains are used to discriminate reequilibration wi th ol iv ine , clinopyroxene, interstitial l iquid , and the effects o f ox id iz ing and serpentinizing fluids. Establishment o f primary chromite compositions also provides constraints on the relative oxygen fugacity o f the parental magmas, wh ich is cri t ical for understanding the or igin o f the nickeliferrous sulphide mineralization in the Turnagain intrusion. A l l analytical work was carried out by the author wi th supervision by M a t i Raudsepp. Chapter 4 involves a detailed petrological study o f the ultramafic and mafic rocks in the Turnagain intrusion based on silicate mineral chemistry, whole rock major/trace element geochemistry, platinum-group element chemistry, and sulphur and lead isotopes o f sulphides. The forsterite contents o f ol ivine confirm the primit ive nature o f the Turnagain parent magmas (up to F092.5 in ol ivine that has not reequilibrated wi th chromitite) and the N i contents o f ol ivine provide a clear signal o f sulphide l iquid saturation during formation o f some o f the dunites, wehrlites, and ol ivine clinopyroxenites. The major element geochemistry o f 23 whole rock samples was used in tandem wi th ol iv ine , clinopyroxene, and amphibole mineral chemistry to constrain the chemical relationships o f whole rock samples relative to their mineralogy. These results have important implications for the crystallization sequence and emplacement history o f the magmas that formed the Turnagain intrusion. Trace element chemistry from the whole rock suite further constrains the genetic relationship between al l lithologies present in the Turnagain intrusion and al lows for recognition o f an arc affinity. Twenty-seven sulphur isotopic compositions and 14 lead isotopic compositions o f sulphide separates from hand samples and drillcore samples are used evaluate the extent o f crustal contamination involved in sulphide saturation in the Turnagain intrusion, wh ich is important for understanding the formation o f nickeliferrous magmatic sulphide deposits in Alaskan-type intrusions. A l l microprobe analyses were carried out by the auther under the supervision o f M a t i Raudsepp at U B C . The author also produced the sulphide separates for Pb and S isotopic anaysis, and Janet Gabites at U B C processed the sulphides for chemistry and perfomed the Pb- isotopic analyses. F ina l ly , the appendices contain the full datasets for spinel, ol ivine, clinopyroxene, and garnet microprobe analyses, the X - r a y lines and standards for a l l microprobe analyses, and the comparison between whole rock geochemical samples and respective b l ind duplicates. Addi t iona l ly , the U T M coordinates for al l samples relevant to this thesis are listed in the final appendix. 1.4 REFERENCES Batanova, V . G . , Pertsev, A . N . , Kamenetsky, V . S . , A r i s k i n , A . A . , Mocha lov , A . G . , & Sobolev, A . V . (2005). Crustal evolution o f island-arc ultramafic magma: Galmoenan pyroxenite- dunite plutonic complex, K o r y a k High land (Far East Russia). Journal of Petrology 46, 1345-1366 Clark , T. (1975). Geology o f an ultramafic complex on the Turnagain River , northwestern Br i t i sh Columbia . Unpublished P h . D . dissertation, Queens University, 453p Clark , T. (1978). Oxide minerals in the Turnagain ultramafic complex, northwestern Br i t i sh Columbia . Canadian Journal of Earth Sciences 15 (12), 1893-1903 Clark , T. (1980). Petrology o f the Turnagain ultramafic complex, northwestern Br i t i sh Columbia . Canadian Journal of Earth Sciences 17, 744-757 Findlay, D . C . (1969). Or ig in o f the Tulameen ultramafic-gabbro complex, southern Br i t i sh Columbia . Canadian Journal of Earth Sciences 6, 399-425 Gabrielse, H . (1998). Geology o f C r y Lake and Dease Lake map areas, north-central Br i t i sh Co lumbia ; Geological Survey of Canada, Bu l le t in 504, 147p Gaetani, G . A . , Grove, T . L . , Bryan , W . B . (1993). The influence o f water on the petrogenesis o f subduction-related igneous rocks. Nature 365, 332-334 Garuti , G . , Pushkarew, E . V . , Zaccar ini , F . , Cabel la , R . , and A n i k i n a , E . (2003). Chromite composit ion and platinum-group mineral assemblage in the Uktus Ural ian-Alaskan-type complex (Central Urals , Russia). Mineralium Deposita 38, 312-326 Green, D . H . , Schmidt, M . W . , & Hibberson, W . O . (2004). Island-arc ankaramites: Pr imit ive melts from fluxed refractory lherzolit ic mantle. Journal of Petrology 45, 391-403 H e l m y , H . M . , E l M a h a l l a w i , M . M . (2003). Gabbro A k a r e m mafic-ultramafic complex, Eastern Desert, Egypt : A late Precambrian analogue o f Alaskan-type complexes. Mineralogy and Petrology 11, 85-108 Irvine, T . N . (1962). Minera logy and petrology o f the ultramafic complex at Duke Island, S .E . A l a s k a . American Mineralogist 47, 193 Irvine, T . N . (1965). Chromian spinel as a petrogenetic indicator. Part 1. Theory. Canadian Journal of Earth Sciences 2, 648-672 Irvine, T . N . (1974). Petrology o f the Duke Island ultramafic complex, southeastern A l a s k a . Geological Society of America - Memoir 138, 240p Ishiwatari, A . , & Ichiyama, Y . (2004). Alaskan-type plutons and ultramafic lavas in Far East Russia, northeast China , and Japan. International Geology Review 46, 316-331 Johan, Z . , Slansky, E . , & K e l l y , D . A . (2000). Plat inum nuggets from the K o m p i a m area, Enga Province, Papua N e w Guinea: Evidence for an Alaskan-type complex. Mineralogy and Petrology 68, 159-176 Johan, Z . (2002). Alaskan-types complexes and their platinum-group element mineralization. In: Cabr i , L . J . (ed.) The Geology, Geochemistry, Mineralogy and Mineral Benefwiation of Platinum-Group Elements. Canadian Institute o f M i n i n g , Meta l lurgy and Petroleum, Special V o l u m e 54, 669-719 Krause, J . , Brugmann, G . E . , Pushkarev, E . V . (2007). Accessory and rock forming minerals monitoring the evolution o f zoned mafic-ultramafic complexes in the Central U r a l Mountains . Lithos 95, 19-42 Loney , R . A . , Himmelberg , G . R . , Shaw, N . B . (1987). Salt Chuck palladium-bearing ultramafic body, Prince o f Wales Island. U.S. Geological Survey Circular Report C 0998, 126-127 Loney , R . A . , Himmelberg , G . R . (1992). Petrogenesis o f the Pd-r ich intrusion at Salt Chuck, Prince o f Wales Island: A n Ear ly Paleozoic Alaskan-type ultramafic body. Canadian Mineralogist 30, 1005-1022 Mossman, D . J . , Coombs, D . S . , K a w a c h i , Y . , & Reay, A . (2000). H i g h - M g arc ankaramitic dikes, Greenhills Complex , Southland, N e w Zealand. Canadian Mineralogist 38, 191-216 N i x o n , G . T . , A s h , C . H . , Connel ly , J . N . , Case, G . (1989). Geology and noble metal geochemistry o f the Turnagain ultramafic complex, northern Br i t i sh Co lumbia . B.C. Ministry of Energy, Mines, and Petroleum Resources, Open F i l e 1989-18 N i x o n , G .T . , Cabr i , L . J . , & Laf lamme, J . H . G . (1990). Platinum-group-element mineralization in lode and placer deposits associated wi th the Tulameen Alaskan-type complex, Br i t i sh Co lumbia . Canadian Mineralogist 28, 503-535 N i x o n , G . T . , Hammack, J . L . , A s h , C . H . , Cabr i , L . J . , Case, G . , Connel ly , J . N . , Heaman, L . M . , Laf lamme, J . H . G . , Nut ta l l , C , Paterson, W . P . E . , & W o n g , R . H . (1997). Geology and platinum-group-element mineralization o f Alaskan-type ultramafic-mafic complexes in Br i t i sh Columbia . B.C. Ministry of Employment and Investment, Bu l le t in 93, 141p Nob le , J . A . , & Taylor , H . P . , Jr. (1960). Correlation o f the ultramafic complexes o f southeastern A l a s k a wi th those o f other parts o f Nor th A m e r i c a and the W o r l d . 2f' International Geological Progress Report Part XIII, 188-197 Spandler, C.J., Arculus, R.J., Eggins, S.M., Maurogenes, J.A., Price, R.C., & Reay, A.J. (2003). Petrogenesis of the Greenhills Complex, Southland, New Zealand: Magmatic differentiation and cumulate formation at the roots of a Permian island-arc volcano. Contributions to Mineralogy and Petrology 144, 703-721 Taylor, H.P., Jr., & Noble, J.A. (1960). Origin of the ultramafic complexes in southeastern Alaska. 21st International Geological Progress Report Part XIII, 175-187 Taylor, H.P., Jr. (1967). The zoned ultramafic complexes of southeastern Alaska. In: Wyllie, P.J. (ed.) Ultramafic and Related Rocks. New York: John Wiley and Sons, 97-121 Tistl, M . (1994). Geochemistry of platinum-group elements of the zoned ultramafic Alto Condoto complex, northwest Columbia. Economic Geology 89, 158-167 Tistl, M . , Burgath, K.P., Hoehndorf, A., Kreuzer, H., Munox, R., & Salinas, R. (1994). Origin and emplacement of Tertiary ultramafic complexes in northwest Columbia: Evidence from geochemistry and K-Ar, Sm-Nd, and Rb-Sr isotopes. Earth and Planetary Science Letters 126,41-59 CHAPTER 2 GEOCHRONOLOGY OF THE TURNAGAIN ALASKAN-TYPE INTRUSION, NORTH-CENTRAL BRITISH COLUMBIA, WITH IMPLICATIONS FOR THE TECTONIC EVOLUTION OF THE NORTHERN CANADIAN CORDILLERA 2.1 INTRODUCTION Alaskan-type intrusions, synonymous wi th Uralian-type and zoned ultramafic intrusions (e.g. Taylor & Noble , 1960), are predominantly composed o f ultramafic cumulate rocks (e.g. dunite, wehrlite, hornblendite) wi th minor diorit ic phases. The majority o f Alaskan-type intrusions occur wi th in paleo-arcs (e.g. Quesnel terrane, B . C . , N i x o n et al, 1997; Alexander terrane, A la ska , Himmelberg & Loney , 1995) that are island or continental in nature, and a few occur in cratonic environments (e.g. K o n d y o r Complex , Russia , Johan, 2002). A number o f Alaskan-type intrusions have been studied wi th respect to their platinum-group-element potential in lode and associated placer deposits (e.g. U r a l Mountains, Russia, Garuti et al, 2003). In general, few precise ages o f crystallization are available for Alaskan-type intrusions, w h i c h is cri t ical for understanding their tectonic setting and proposed relationships to contemporaneous intrusive rocks or volcanic sequences. The Turnagain intrusion, situated in north-central Br i t i sh Columbia , is distinct from other Alaskan-type intrusions in that it contains unusually high, and perhaps economic, concentrations o f Ni-sulphide mineralization. The current resource estimate (measured and indicated) is 428 M t grading 0.17% N i (http://www.hardcreeknickel.com). The age and tectonic history o f the Turnagain intrusion, as w e l l as the or igin o f the magmas, are important for understanding the evolution o f the northern Canadian Cordi l lera . N i x o n (1998) proposed two contrasting interpretations for the tectonic setting o f the Turnagain intrusion. The first interpretation is that the Turnagain intrusion was emplaced into miogeocl inal metasedimentary rocks o f Ancestral Nor th A m e r i c a in a subduction zone environment. The second interpretation is that the Turnagain intrusion lies wi th in a series o f northeast-verging imbricated thrusts. This study presents new U - P b and A r - A r geochronologic data, coupled wi th whole-rock N d isotopic compositions, to constrain the age and or ig in o f the Turnagain intrusion and its host rocks. Determining the precise age o f crystallization o f ultramafic rocks in Alaskan-type intrusions is typical ly difficult as abundances o f U-bearing (e.g. z i rcon, baddeleyite) accessory minerals are relatively low to absent, and primary K-bear ing (e.g. biotite, feldspar) phases tend to be altered. The results from this study have implications for the significance o f Alaskan-type intrusions and tectonic evolution o f a portion o f the northern Canadian Cordi l lera . 2.2 GEOLOGICAL SETTING OF THE TURNAGAIN INTRUSION The Turnagain Alaskan-type intrusion is located approximately 70 k m east o f the town o f Dease Lake , in north-central Br i t i sh Co lumbia (Figure 2.1). The intrusion is fault-bounded and proximal to the Kutcho Fault, wh ich is a major tectonic structure that is interpreted to separate intrusive and volcanic sequences o f the accreted Quesnel terrane from passive margin sedimentary rocks and post-accretionary Cretaceous granitoids o f Ancestral Nor th A m e r i c a (Gabrielse, 1998). The Quesnel terrane is part o f the Intermontane Bel t , a composite o f terraries that extend south into Washington State and north into Y u k o n Territory (Figure 2.1). Seven Alaskan-type intrusions have been identified in the Quesnel terrane, including the Polaris intrusion and the Tulameen intrusion, wh ich is the largest Alaskan-type intrusion in the wor ld and is associated wi th concentrations o f placer platinum-group metals in both lode and placer occurrences (Findlay, 1963; N i x o n et al., 1990) (Figure 2.1). The Tulameen is one o f the three precisely dated (U-Pb zircon) Alaskan-type intrusions in B . C . (Rublee, 1994; N i x o n et al., 1997). The Alaskan-type intrusions o f Quesnell ia are typical ly associated wi th diorit ic plutons o f Triassic-Jurassic age and mafic volcanics, specifically the Late Triassic Takla , N i c o l a , and Stuhini groups. These mafic volcanics have been considered to be genetically associated wi th Alaskan-type intrusions (e.g. F indlay , 1969; Irvine, 1974; N i x o n et al., 1997), and the Turnagain intrusion is 20 k m northwest o f an exposure o f Tak la volcanics (Figure 2.2), although their genetic association wi th the intrusion remains to be evaluated. Numerous Alaskan-type intrusions o f Cretaceous age occur wi th in the Alexander terrane in southeastern Alaska , including the Duke Island intrusion (Irvine, 1967; Irvine, 1974; Loney & Himmelberg , 1992). Four other intrusions located to the west o f the Cretaceous intrusions are Paleozoic in age and include the Salt Chuck intrusion, wh ich exhibits extensive Pd-enriched Cu-sulphide mineralization at a major l i thological boundary (Loney et al., 1987; Loney & Himmelberg , 1992; Watkinson & M e l l i n g , 1992). Pelagic sedimentary rocks o f the Road R ive r and Earn Groups ( -Ord iv i c i an - Mississ ippian) were mapped by Gabrielse (1998) to occur along the northern and eastern edges o f the Turnagain intrusion (Figure 2.2). The R o a d R ive r and Earn Groups have been interpreted to represent ocean basin sediments deposited on the margin o f Ancestral Nor th A m e r i c a (Gabrielse, 1998; Erdmer et al., 2005). The l i thological ly diverse Road R ive r Formation in the M c D a m e locality has a type thickness o f 95 m (Gabrielse, 1998) and varies from a lower member o f black, graptolitic, local ly calcareous shale, a middle member o f mid-Triassic to Jurassic Alaskan-type intrusions Turnagain intrusion Lunar Creek intrusion Polaris intrusion Tulameen intrusion mid-Cretaceous Alaskan-type intrusions O Duke Island Salt Chuck intrusion (Paleozoic) Ancestral North America Stikinia Kootenay/Miogeocline (ANA) Cache Creek Klinkit/Harper Ranch Yukon-Tanana Quesnellia • Coast Plutonic Complex Methow Bridge River Cadwallader Harrison Shuksan Slide Mountain Figure 2.1: Terrane map of British Columbia, modified from Colpron & Nelson (2004), showing the locations of the major Alaskan-type intrusions in British Columbia and southeastern Alaska. The region outlined by the white box is the area displayed in Figure 2.2. Note that the Turnagain intrusion is situated on the western edge of Ancestral North America. Ancestral North America Cache Creek up|g Ingenika Group Quesne l l ia DPHq Nizi Formation CPgb Carboniferous to Permian gabbro "RJTk Takla Group DMEa Earn Group CPrum Carboniferous to Permian ultramafic complexes "Kgd Triassic granodiorite ODRo Road River Group MJCc Cache Creek Complex EJum Turnagain Alaskan-type ultramafic intrusion €OKe Kechika Group Stikinia EJgd Eaglehead Pluton and equivalents €At Atan Group uTS Stuhini Group, Mosley and Mount Moore Formations Quaternary Cover | Kutcho Formation, Sillika Assemblage ImJLffl Laberge Group MJdg monzodiorite Late Intrusive/Extrusive rocks EKgr Cassiar Batholith: granitoid [_TQT Tuya Formation Figure 2.2: Regional geological setting of the area immediately surrounding the Turnagain intrusion, extracted and modified after Massey et al. (2005). Note that the western, northern, and eastern margins of the Turnagain intrusion are flanked by the Road River/Earn groups. The Kutcho Fault separates Ancestral North America from Quesnellia and Cache Creek. The white box represents the study area (shown in more detail in Figure 2.3) and the white oval represents the general study area of Erdmer et al. (2005). 16 laminated dolomite, and an upper member o f calcareous siltstone and shale. The entire package ranges in biostratigraphic age from Ear ly Ord iv ic ian to M i d d l e Si lur ian (Gabrielse, 1998). The Earn Group also exhibits extreme l i thological diversity depending on where it is observed. In general, the Earn Group is a darkly coloured slate to siltstone that is local ly pyri t ic and ranges in thickness from 50 to 1000 m in northern B . C . (Gabrielse, 1998). It is has been biostratigraphically dated to be Devonian to Miss iss ippian in age. However , the age o f the phylli te to the north and east o f the Turnagain intrusion has not been determined and is currently assigned to the undivided Road R ive r and Earn Groups based on l i thological similarities wi th these two sedimentary packages (Gabrielse, 1998). Constrastingly, the Sandpile, Ramhorn, and M c D a m e formations, wh ich are observed between the R o a d R ive r Formation and the Earn Group elsewhere in B . C . , are not observed in the v ic in i ty o f the Turnagain intrusion. Due to these discrepancies, the greenschist-facies pelagic sediments proximal to the Turnagain intrusion are referred to as "graphitic phyl l i te" in this manuscript. Graphitic pre-Devonian sediments are also associated wi th the Yukon-Tanana terrane (Mortensen, 1992; Simard et al., 2003; Ne l son & Friedman, 2004) and have been observed stratigraphically below the L a y Range Assemblage (Ferri & M e l v i l l e , 1990), wh ich is a volcano-sedimentary, arc-derived, package o f rocks observed in Quesnell ia. The graphitic phyll i te to the north and east o f the Turnagain intrusion, possibly part o f the Road R ive r Formation and Earn Groups, is composed o f unfossiliferous, graphitic, and pyri t ic slates and phyllites containing interbeds o f tuff, calcareous phyll i te, and rare quartzite (Gabrielse, 1998; Erdmer et al., 2005; Scheel et ah, 2005). The graphitic phyll i te is typical ly recessive- weathering and crops out along the Turnagain R ive r to the north and southeast o f the intrusion, as w e l l as in alpine areas to the east o f the Turnagain R ive r (Figure 2.2). These rocks generally have a steeply-dipping cleavage and may be complexly folded (Erdmer et al., 2005; Scheel et al., 2005). The graphitic phyllites, and a metasedimentary inclusion in the northwestern part o f the Turnagain intrusion (Figure 2.3), commonly contain 1 cm to 1 m-thick quartz veins that do not cross-cut the Turnagain intrusion. The few exposures o f the metasedimentary unit to the south o f the Turnagain intrusion have been interpreted by Massey et al. (2005) as the N i z i Formation, and referred to by Gabrielse (1998) as "uncorrelative". These metasediments are a grey-green, banded wacke, and appear similar to the hornfelsed unit that crops out in the northwestern portion o f the intrusion (Figure 2.3). This unit (herein referred to as volcanic wacke) is described by Erdmer 04ES-00-07-04 £Nd: +1.9 Ar-Ar age (hornblende):| 189.9 +/-1.4Ma U-Pb age (titanite): 190.3 +/-4.6 04ES-09-02-02 ENd: -3.9 04ES-00-07-02 ENd: +1.1 Depositional Age (U-Pb): -300 Ma Max Inheritance: -2100 Ma A DDH04-57-12-89.2 ENd: +4.4 U-Pb age (zircon): 185.2 +/- 0.34 Ma 04ES-00-07-01 U-Pb age (zircon): 189.2+/-0.6 Ma Intrusion Centre: X 58°29'N, 128°52'W 04ES-00-07-03 Ar-Ar age (phlogopite) 189.9+/- 1.3 Ma 05ES-03-01-01 | 1 k m ENd: +2.3 | Dunite, with minor wehrlite Wehrlite, with minor dunite and olivine clinopyroxenite Olivine clinopyroxenite and clinopyroxenite, undivided Hornblende clinopyroxenite, with minor clinopyroxenite Hornblendite and clinopyroxene hornblendite, undivided | Diorite, quartz diorite, and granodiorite, undivided Hornfels, sedimentary or volcanic protolith Reverse fault, observed Normal fault, inferred Fault (relative sense of motion indicated) Neodymium isotope sample locality Geochronological sample locality* Figure 2.3: Generalized geologic map of the Turnagain intrusion, modified after Clark (1975). Note that some lithological units are composites at this scale. The inset in the upper right corner shows the location of the Turnagain intrusion in British Columbia, as well as other major Alaskan-type intrusions. The main nickeliferous sulphide zones are marked with white ovals (from west to east: Northwest Zone, Horsetrail Zone, Hatzl Zone). The geochronological sample localities are marked as yellow stars and U-Pb and Ar-Ar ages, and initial eNd values (for geochronological samples) are indicated as yellow stars. Other whole rock sample localities for Nd isotopic compositions are marked as blue stars. et al. (2005) as a "tuffeaceous phylli te wi th minor wacke" and is observed to conformably overlie "Road R i v e r " strata. However , Gabrielse (1998) proposed that this metasedimentary unit was separated from "Road R i v e r " strata by a fault. A westward extension o f this fault was postulated to merge into the north-bounding and east-bounding faults bounding the Turnagain intrusion, creating a small nappe. Because o f the inferred ages o f the volcanic wacke and the Turnagain intrusion (both considered to be Late Triassic), Gabrielse (1998) associated this apparently "fault-bounded" package o f rocks wi th the Quesnel terrane. However , recent geochronological studies o f Erdmer et al. (2005) indicate that the metasedimentary package, coupled wi th its conformable nature to the underlying graphitic phylli tes, is Miss iss ippian in age. The graphitic phyll i te is also observed to be intruded by an Ear ly Jurassic "granodiorite" pluton (Erdmer et al., 2005), a relationship that is not observed in "bona fide" Ancestral Nor th Amer ican lithologies ( J .K. Mortensen, pers. comm., 2006). Addi t iona l ly , relatively small (0.5- 20 m) inclusions o f metamorphosed graphitic phyll i te (containing graphite, quartz, and pyrrhotite bands) and volcanic wacke are observed in dril lcore from the sulphide-mineralized zones wi th in the Turnagain intrusion. 2.3 G E O L O G Y OF T H E T U R N A G A I N INTRUSION The 3.5 k m x 8 k m Turnagain Alaskan-type intrusion was the subject o f a P h . D . dissertation by T o m Clark (1975) and subsequent publications (Clark, 1978; 1980). It is a crudely zoned mafic-ultramafic pluton that ranges from dunite to a hornblende-rich diorite in the west-central portion (Figure 2.3). The central dunite is considered to represent the base o f the intrusion, whereas the hornblende-rich central portion o f the intrusion is considered to represent part o f the roof zone. Dunite in the Turnagain intrusion contains M g - r i c h cumulus ol ivine (F089-F093) (Chapter 4), disseminated cumulus chromite, minor intercumulus clinopyroxene and rare interstitial phlogopite. L o c a l accumulations o f chromite are observed as thin layers, rare beds, pods, schleiren, and wispy concentrations (see Chapter 3). In many Alaskan-type intrusions, these chromitites are prospective for platinum-group element mineralization. Wehrli te in the Turnagain intrusion occurs as either ol ivine cumulates or ol ivine-cl inopyroxene cumulates (ol ivine: Fogs to F090). Disseminated sulphide reaches ~0.5 v o l . % in most lithologies o f the Turnagain intrusion. In the sulphide-mineralized Horsetrail Zone (Figure 2.3), both dunite and wehrlite can contain significant abundances o f sulphide (typically 5 v o l . % , but up to 50 v o l . % local ly) . Ol iv ine clinopyroxenite is a relatively uncommon li thology and is typical ly an olivine-clinopyroxene cumulate wi th ol ivine compositions ranging from F083 to F089. Hornblende clinopyroxenite wi th local cumulus magnetite is rarely exposed and is typical ly observed in dril lcore from the east-central part o f the intrusion. Hornblende clinopyroxenite is typical ly composed o f cumulus clinopyroxene and intercumulus amphibole; as such it commonly grades into clinopyroxene hornblendite and vice versa. Hornblendite is a recessive li thology and is also rarely exposed. A fine-grained (<1 mm) hornblendite dike, 30 to 50 c m in width, in the northwestern part o f the intrusion (Figure 2.3) contains abundant igneous amphibole (magnesiohastingsite) and accessory titanite. The crystallization sequence o f the Turnagain intrusion, from dunite —» wehrlite —• ol ivine clinopyroxenite —* hornblende clinopyroxenite —* hornblendite —• diorite, is constrained by cross-cutting and gradational contact relationships, as w e l l as by systematic mineral and whole rock geochemical trends (see Chapter 4). The intrusion is fault-bounded on its northern and eastern margins margins (observed on surface, in dril lcore, and inferred from aeromagnetic data) against graphitic phyll i te and on its western and southern margins by volcanic wacke. The entire intrusion is interpreted to represent a small kl ippe, however based on the results o f this study and others (Chapters 3 and 4), this kl ippe was not significantly displaced. The metasedimentary rocks in the northwest (Figure 2.3) are relatively coarse-grained (-1-2 mm) compared to similar rocks south o f the Turnagain intrusion (<1 mm). The metasedimentary inclusion in the northwest is composed o f hornfelsed volcanic wacke that contains abundant detrital z i rcon. The volcanic wacke appears to represent an inclusion o f wal l rock wi th in the Turnagain intrusion in contrast to the lower-grade, finer-grained, metasediments observed to the south o f the intrusion. This inclusion does not appear to be fault-bounded, but is in igneous contact wi th the ultramafic lithologies. Smal l pods (1-5 cm wide) o f amphibole-bearing two-mica granite, interpreted as partial melt, were observed by the author in this inclusion, but not in the metasedimentary rocks to the south. Melanocrat ic to leucocratic dioritic rocks in the Turnagain intrusion have gradational contacts wi th , or cross-cut, ultramafic rocks and represent the youngest intrusive phases. Dior i t i c rocks are the only zircon-bearing li thology present in the Turnagain intrusion. The largest diorite occurrence is located in the central part o f the intrusion (Figure 2.3). The margins o f this pluton are melanocratic (85 v o l . % amphibole, 14 v o l . % plagioclase) and fine- to medium-grained (1-5 m m grain sizes), whereas the central part o f the pluton (as observed from surface exposures) is dominantly composed of plagioclase and quartz. Texturally and mineralogically similar mafic diorite is also observed in drillcore as 4 cm to 1 m-wide dikes that intrude the hornblende-rich central portion of the intrusion and the adjacent dunite to the east. Leucocratic diorite dikes, predominantly composed of plagioclase and quartz, are commonly found cross-cutting the hornblende-bearing lithologies, however these felsic dikes are rarely found cutting ultramafic rocks elsewhere in the intrusion. 2.4 S A M P L E D E S C R I P T I O N S A N D A N A L Y T I C A L T E C H N I Q U E S 2.4.1 U-Pb Zircon/Titanite Four samples were selected for U-Pb geochronology (see sample locations on Figure 2.3). Zircon (ZrSi0 4) was separated from three samples (04ES-00-07-01, DDH04-57-12, 04ES-00- 07-02) and titanite (CaTiSi0 5) from a fourth sample (04ES-00-07-04). Sample 04ES-00-07-01 is a green-black, medium-grained diorite with relatively abundant (10-15 vol.%) large plagioclase crystals (subsequently referred to as mela-diorite) and occurs at the north-central margin of the large felsic body. At this location no ultramafic inclusions in the diorite were observed, however a similar lithology intersected in NQ drillcore in the north-central part of the intrusion locally contains abundant (10-70 vol.%) ultramafic xenoliths. Sample DDH04- 57-12 is a green-and-white, coarse-grained hornblende diorite with 20 vol.% euhedral amphibole (3 cm long), and 1 cm-wide euhedral plagioclase (subsequently referred to as leuco- diorite). The sample was obtained from NQ drillcore from the west-central part of the Turnagain intrusion (see Figure 4.6: G,H, Chapter 4). The interval from which this sample was taken is gradational into hornblendite over a distance of 10 cm. Sample 04ES-00-07-02 is a hornfelsed volcanic wacke (epidote + plagioclase ± amphibole ± biotite ± quartz) from the northwestern part of the intrusion, and based on contact relationships (intruded by hornblendite) and degree of metamorphism (the mineral assemblage is indicative of epidote- amphibole hornfels facies) it is interpreted to represent an inclusion of wallrock. Sample 04ES-00-07-04 is a black, fine-grained equigranular hornblendite dike (-30 cm wide) that contains accessory titanite (1-2 vol.%), abundant wall-rock inclusions, and intruded rocks equivalent to the previous sample (volcanic wacke) (Figure 2.3). The morphologies of some of the zircon and titanite separates are exhibited in Figure 2.4. A l l sample preparation, geochemical separation and mass spectrometry were done at the Pacific Centre for Isotopic and Geochemical Research in the Department of Earth and 21 Figure 2.4: Photomicrographs of zircon and titanite separates from the Turnagain intrusion. The scale bar in each photo is 200 um. A) Mela-diorite (04ES-00-07-01); large, clear, broken grains, one of which is fraction F. B) Mela-diorite (04ES-00-07-01), fraction A; large equant, slightly elongate zircon grains. Note their similar size. C) Mela-diorite (04ES-00-07-01), fraction D; large zircon laths, some with minute inclusions. D) Leuco-diorite (DDH04-57-12), fraction H; slightly rounded, broken, prismatic grains of medium size. E) Volcanic wacke (04ES-00-07-02), fractions D, F, G (pre-separation); intermediate zircon laths, clear and relatively inclusion-free. F) Hornblendite (04ES-00-07-04); colourless to slightly yellow titanite grains. 22 Ocean Sciences, Univers i ty o f Br i t i sh Co lumbia . Z i r con and titanite were separated from the rocks using conventional crushing, grinding, and Wi l f l ey table techniques. F ina l concentration incorporated the use o f heavy liquids and a magnetic separator. Z i r con and titanite fractions were selected for analysis based on magnetic susceptibility, grain quality, size, and morphology. U s i n g the technique o f K r o g h (1982), a l l z i rcon fractions were air-abraded prior to dissolution to min imize the effects o f post-crystallization Pb-loss. Titanite grains were dissolved on a hotplate in 7 m L screwtop P F A beakers for at least 48 hours at ~ 1 3 0 ° C . Z i r con grains were dissolved in sub-boiled 4 8 % H F and 14 M H N O 3 (ratio o f - 1 0 : 1 , respectively) in the presence o f a mixed 2 3 3 - 2 3 5 t j - 2 0 5 P b tracer for 40 hours at 2 4 0 ° C in 300 u L P T F E or P F A microcapsules contained in high-pressure vessels ( P a r r ™ acid digestion vessels wi th 125 m L P T F E liners). Sample solutions were then dried to salts at ~ 1 3 0 ° C . Z i r con residues were redissolved in - 1 0 0 u L o f sub-boiled 3.1 M H C I for 12 hours at 2 1 0 ° C in high-pressure vessels and titanite residues were redissolved on a hotplate in -1 m L o f sub-boiled 6.2 M H C I in the same 7 m L screwtop P F A beakers for at least 24 hours at ~ 1 3 0 ° C . Titanite solutions were again dried to salts and were again redissolved on a hotplate, in the same beakers, in 1 m L o f sub-boiled 3.1 M H C I at ~ 1 3 0 ° C for at least 24 hours. Fo r z i rcon fractions o f about 10 ug or less, 3.1 M H C I was transferred to 7 m L P F A beakers, dried to a small droplet after addition o f 2 u L o f 1 M phosphoric acid (H3PO4), and loaded directly onto Re filaments for analysis, as described below (referred to as the "no chemistry" method). Fo r larger fractions o f both minerals, separation and purification o f Pb and U employed ion exchange column techniques modified slightly from those described by Parrish et al. (1987). Pb and U were sequentially, eluted into a single beaker; U from titanite solutions was purified by passing through columns a second time. Elutants were dried in 7 m L screwtop P F A beakers on a hotplate at ~ 1 2 0 ° C in the presence o f 2 u L o f ultrapure 1 M H3PO4. Samples were then loaded on single, degassed zone-refined R e filaments in 5 u L o f a s i l ica gel ( S i C l 4 ) phosphoric acid emitter. Isotopic ratios were measured using a modified single collector V G - 5 4 R thermal ionization mass spectrometer equipped wi th an analogue D a l y photomultiplier. Measurements were done in peak-switching mode on the D a l y detector. Ana ly t i ca l blanks were <1 pg for U and for 1-3 pg Pb for the "no chemistry" fractions. Fo r dissolved z i rcon and titanite that passed through ion exchange columns, a blank o f 2-10 pg Pb was used. Pb isotopic ratios were corrected for fractionation o f 0.32-0.37 %/amu, based on replicate analyses o f the N B S - 9 8 2 Pb standard reference material and the values recommended by T h i r l w a l l (2000), and U 23 fractionation was determined directly on individual runs using the " U tracer. Reported precisions for Pb/U and Pb/Pb dates were determined by numerically propagating all analytical uncertainties through the entire age calculation using the technique of Roddick (1987). Standard concordia diagrams were constructed and regression intercepts calculated with Isoplot 3.09 (Ludwig, 2003). Unless otherwise noted, all errors are quoted at the 2a level. 2.4.2 Ar-Ar Phlogopite/Amphibole Two samples (04ES-00-07-03, 04ES-00-07-04) were selected for Ar-Ar geochronology. Sample 04ES-00-07-03, a black, medium-grained wehrlite located in the far southeastern corner of the Turnagain intrusion (Figure 2.3), was chosen because it contained 1-2 vol.% interstitial phlogopite. Amphibole was separated from sample 04ES-00-07-04, the hornblendite dike described above. The samples were crushed using a steel jaw crusher and sieved to obtain fragments ranging in size from 0.25 to 1.0 mm. The sieved fractions were washed in deionized water and then air-dried at room temperature after magnetite and metallic crusher fragments were removed with a hand magnet. The amphibole and phlogopite separates were hand-picked using a binocular microscope, wrapped in aluminum foil and stacked in an irradiation capsule with similar-aged samples, neutron flux monitors (Fish Canyon Tuff sanidine, 28.02 Ma; Renne et ah, 1998), optical grade CaF2 and potassium glass. The samples were irradiated with cadmium shielding on April 25-27, 2005 at the McMaster Nuclear Reactor in Hamilton, Ontario, for 84 MWH, with a neutron flux of approximately 3xl0 1 6 neutrons/cm . Total fusion analyses (n=72) of 21 neutron flux monitor positions produced errors of <0.5% in the J value. The samples were analyzed on June 3 and 6, 2005, at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. Using a defocused beam of a 10W CO2 laser (New Wave Research MIR10), the mineral separates were step-heated at incrementally higher powers until fused. A VG5400 mass spectrometer, equipped with an ion-counting electron multiplier, analyzed the gas evolved from each step. A l l measurements were corrected for mass discrimination, mass spectrometer sensitivity, total system blank, radioactive decay during and subsequent to irradiation, and interfering Ar from atmospheric contamination and the irradiation of Ca, CI and K. Isotope production ratios were: (4 0Ar/3 9Ar)K=0.0005±0.00006, ( 3 7Ar/ 3 9Ar) C a=l048±0.9, ( 3 6Ar/ 3 9Ar)C a=0.3542±0.0008, Ca/K= 1.83±0.01 ( 3 7 Ar C a / 3 9 Ar K ) . The plateau and correlation ages were calculated using Isoplot 3.09 ( L u d w i g , 2003). Errors are quoted at the 2 a (95% confidence) level and are propagated from al l sources except mass spectrometer sensitivity and age o f the flux monitor. The best statistically-justified plateau and plateau ages for both samples were p icked based on the fo l lowing criteria: (1) three or more contiguous steps comprising more than 50% o f the 3 9 A r ; (2) a probabili ty o f fit o f the weighted mean age greater than 5%; (3) a slope o f the error-weighted line through the plateau ages equals zero at 5% confidence; (4) the ages o f the two outermost steps on a plateau are not significantly different from the weighted-mean plateau age (at 1.8a six or more steps only); and (5) the outermost two steps on either side o f a plateau must not have non-zero slopes wi th the same sign (at 1.8a nine or more steps only) . 2.4.3 Neodymium Isotopes A total o f eight samples were selected for neodymium isotopic composit ion measurements and were chosen to reflect the l i thological range o f the Turnagain intrusion. Dunites were excluded from analysis due to their extremely low N d concentrations (<0.1-0.4 ppm). Samarium and neodymium concentrations, as w e l l as major elements and other incompatible trace elements, were determined by I C P - M S at Act iva t ion Laboratories L t d . (Actlabs) in Ancaster, Ontario (see complete analytical techniques description in Chapter 4). The accuracy o f the suite o f elements analyzed was determined by the use o f U S G S reference materials ranging in composit ion from basalt to granite and by various in-house standard materials. Relat ive standard deviations from three duplicated analyses are typical ly less than 5% for most elements. L o w concentrations o f S m and N d in one duplicate (sample 05ES-05-06-01, a hornblende clinopyroxenite) resulted in higher standard deviations; however when concentrations o f S m and N d are an order o f magnitude higher than their respective detection limits (04ES-00-07-04) the standard deviation drops to below 5% relative. The N d isotopic compositions o f samples from the Turnagain intrusion were measured at the Pacif ic Centre for Isotopic and Geochemical Research, Univers i ty o f Br i t i sh Co lumbia . The volcanic wacke and leuco-diorite samples (04ES-00-07-02 and D D H 0 4 - 5 7 - 1 2 , respectively) were digested in Tef lon bombs enclosed in metallic bombs (modified K r o g h design) and placed for 120 hrs in H F - H N O 3 - H C I O 4 (7:1:1) and 24 hrs in H C I in an oven at 190°C. A l l other samples were dissolved in Savil lex™ and subject to the above digestion procedure. The N d isotopic ratios were measured using a Thermo Finnigan Tri ton-TI thermal ionization mass spectrometer ( T I M S ) in static mode wi th relay matrix rotation. The measured composit ion o f each sample is the average o f 125-130 separate analyses. The L a Jo l la N d standard was measured once g iv ing a value o f 1 4 3 N d / 1 4 4 N d = 0.511858 ± 0.000008 (2a) and the Rennes N d standard was measured 48 times wi th in one week g iv ing a mean value o f 1 4 3 N d / 1 4 4 N d = 0.511960 ± 0.000008 (2a). The N d isotopic compositions o f procedural duplicates o f three samples (04ES-09-02-02, 05ES-05-06-02, 04ES-00-07-02) are wi th in the 2 a error (less than 0.001% relative). A l l measurements were corrected using 1 4 6 N d / 1 4 4 N d = 0.7219 for internal mass fractionation. The U S G S G S P - 2 reference material was also analyzed for its N d isotopic composition, and the results are wi th in the 2 a analytical error o f previously reported results (Weis et al., 2006). 2.5 RESULTS Three dates from two ultramafic samples (wehrlite and hornblendite) were obtained from the Turnagain intrusion using A r - A r and U - P b geochronological techniques. The two A r - A r samples are from opposite corners o f the intrusion (~8 k m apart) (Figure 2.3). Add i t iona l U - P b (zircon) dates were determined from a mela-diorite, a leuco-diorite, and the hosted volcanic wacke inclusion. N e o d y m i u m isotopic compositions were analyzed from the three geochronological samples, and five additional ultramafic samples. 2.5.1 U-Pb Geochronology 2.5.1.1 04ES-00-07-01 - Mela-diori te The mela-diorite was sampled from the north-central margin o f the large diori t ic body that intruded, and/or is gradational wi th , the central part o f the Turnagain intrusion (Figure 2.3). The margin o f the diorite is hornblende-rich, local ly resembling hornblendite elsewhere in the Turnagain intrusion. However , this hornblende-rich outer phase grades inwardly to a more felsic diorite over a distance o f - 1 0 0 m on surface. The presence o f euhedral (cumulus) plagioclase (~1 c m in diameter) helps discriminate this l i thology from feldspathic hornblendite elsewhere in the Turnagain intrusion. The least magnetic fraction o f sample 04ES-00-07-01 yielded abundant (>500) zi rcon grains typical ly 150-250 um in length. The z i rcon grains exhibit either equant (3:1 to 2:1) (Figure 2 .4B) or lath (length/width 6:1 to 4:1) (Figure 2.4C) morphology and range in colour from clear to pale ye l low. A distinct population o f grains exhibit inherited cores (not analyzed), some o f wh ich are metamict. Each analyzed fraction contained 2-18 grains wi th the exception o f Fraction F (Figure 2 .4A) , wh ich is represented by a single grain o f z i rcon. Uran ium concentrations range from 123-283 ppm and T h / U ratios from 0.32 to 0.79 (Table 2.1). The U - P b data from the analyzed fractions y i e ld similar 2 0 6 p b / 2 3 8 T J a g e s > r a n g i n g f r o m 186 .3±0.4 M a to 189 .2±0.6 M a , the latter o f wh ich (Fraction B , seven 75-100 pm equant grains) has the highest 2 0 6 P b / 2 3 8 U and 2 0 7 P b / 2 3 5 U and is interpreted to be the m i n i m u m age o f crystallization o f the mela-diorite. Each o f the error ellipses (2a) for each o f the five fractions overlap concordia (Figure 2.5 A ) , however their distribution suggests that z i rcon from a l l fractions may have undergone Pb-loss. A free-fit discordia line through al l fractions ( M S W D =0.17) yields an upper intercept wi th concordia o f 190 .5±6.6 M a (and a poorly constrained lower intercept o f 7 0 5 ± 2 5 0 0 M a ) (Figure 2 .5A) . Alternat ively, a fixed regression (lower intercept at 0 M a ) yields an older upper intercept o f 199 .2±6.6 M a . Neither the upper intercept age o f 190.5 +6.6/-1.9 M a from the free-fit regression (lower error combined wi th the error o f the oldest fraction), nor the fixed regression age o f 199 .2±6 .6 M a are considered to represent the true crystallization age o f the mela-diorite, because the calculated upper intercept ages have relatively large 2 a errors due to the relatively small dispersion o f points along the fitted discordia lines. The better constrained m i n i m u m age o f 189.2±0.6 M a o f fraction B is interpreted to be the min imum age o f the Turnagain intrusion. These results are consistent wi th the A r - A r geochronological results (see below). 2.5.1.2 D D H 0 4 - 5 7 - 1 2 - Leuco-diori te This sample, taken from a dri l lhole in the south-central portion o f the intrusion (Figure 2.3), is a coarse-grained leucocratic hornblende diorite composed o f euhedral, cumulus plagioclase and amphibole. Mul t i p l e 10-50 cm-wide l i thological variations were observed in dril lcore along the 9 m-thick interval (e.g. amphibole-rich phases, quartz-rich phases). Fewer than 200 z i rcon grains, 20-200 pm in length, were present in the least magnetic fraction. Broken lath (length/width 2:1 to 1.5:1) and some intact lath (length/width 4:1 to 3:1) morphologies are exhibited by most z i rcon grains, and al l grains are generally colourless (Figure 2.4). O f the four fractions analyzed, two were single grains (Fractions B and F ) , whereas fractions E and H (Figure 2.4D) contained 2 and 7 grains, respectively. Uran ium concentrations range from 183- 582 ppm and T h / U ratios range from 0.17 to 0.39 (Table 2.1). The U - P b data from the four analyzed fractions are concordant and y ie ld similar Pb/ U dates from 183.6±0.6 to Table 2.1: U-Pb TIMS analytical data from zircon and titanite grains separated from samples from the Turnagain intrusion Fraction1 Wt U 2 Pb*3 2 0 6 Pb 4 Pb5 Th/U6 Isotopic ratios (1CT,%) 7 Apparent ages (2o,Ma)7 discordance (mg) (ppm) (ppm) 2 0 4Pb (pg) 2 0 6 Pb/ 2 3 8 U 2 0 7Pb/ 2 3 5U 2 0 7Pb/ 2 0 6Pb 2 «Pb/ 2 3 8 U 2 0 7Pb/ 2 3 5U 2 0 7Pb/2 0 6Pb to origin (%) 04ES-00-07-01 - mela-diorite A, 2 35 229 6.8 4179 3.5 0.41 0.02946 (0.08) 0.2036 (0.24) 0.05011 (0.21) 187.2 (0.3) 188.1 (0.8) 200.2 (9.5) 6.6 B, 7 32 145 4.2 1557 5.5 0.28 0.02979(0.17) 0.2058 (0.63) 0.05012 (0.58) 189.2 (0.6) 190.1 (2.2) 201 (27) 5.7 C, 18 38 123 3.7 3324 3.1 0.40 0.02965 (0.11) 0.2045 (0.34) 0.05002 (0.31) 188.4 (0.4) 188.9 (1.2) 196 (14) 4.0 D, 5 19 254 8.3 2207 4.0 0.79 0.02932 (0.11) 0.2029 (0.42) 0.05020 (0.38) 186.3 (0.4) 187.6(1.4) 204(18) 8.9 F, 1 41 283 8.3 1580 13.6 0.32 0.02961 (0.14) 0.2038 (0.57) 0.04992 (0.53) 188.1 (0.5) 188.3(2.0) 191 (24/25) 1.7 DDH04-57-12-89 - leuco-diorite B*, 1 9 183 5.0 1248 2.4 0.17 0.02890 (0.16) 0.1984 (0.72) 0.04979 (0.67) 183.6 (0.6) 183.7(2.4) 185 (31/32) 0.8 E*, 2 3 276 7.9 379 4.1 0.30 0.02921 (0.32) 0.2022 (2.20) 0.05020 (2.1) 185.6(1.2) 187.0 (7.5) 204 (93/98) 9.3 F, 1 14 213 6.0 422 13.9 0.26 0.02911 (0.17) 0.1998 (1.94) 0.04979(1.86) 185.0(0.6) 185.0(6.6) 185(84/89) 0.0 H, 7 17 582 17.2 1520 11.9 0.39 0.02915(0.09) 0.2004 (0.23) 0.04986 (0.18) 185.2 (0.3) 185.5(0.8) 188.4 (8.3) 1.7 04ESOO-07-04 - hornblendite dike T1.20 188 8.7 0.5 45.4 112 3.90 0.02983 (1.75) 0.2108 (7.2) 0.05124(6.32) 189.5(6.6) 194(25) 252 (267/320) 25.0 T2, 20 156 9.4 0.5 46.4 97.2 3.20 0.03009 (1.68) 0.2163 (7.61) 0.05216 (6.77) 191.1 (6.3) 199 (28) 292 (283/343) 35.1 04ES-00-07-02 - volcanic wacke A, 2 25 202 62.4 23000 4.0 0.35 0.29220 (0.11) 5.2136 (0.15) 0.12941 (0.07) 1652.5 (3.3) 1854.5(2.5) 2089.9 (2.5) 23.7 B, 5 30 152 11.2 5004 4.0 0.31 0.07265 (0.16) 0.7948 (0.18) 0.07935 (0.16) 452.1 (1.4) 593.9(1.6) 1180.9(6.2) 63.9 C, 5 5 175 14.6 580 7.5 0.51 0.07845 (0.30) 0.9486 (0.50) 0.07845 (0.30) 486.9 (2.8) 677.4 (5.0) 1375.7 (16.3) 67.0 D, 3 13 97.1 15.6 891 3.5 0.34 0.03863 (0.20) 0.2805 (0.80) 0.03863 (0.20) 244.4 (1.0) 251.0(3.5) 314 (33/34) 22.6 E, 12 8 260 16.9 1316 6.1 0.46 0.06179 (0.22) 0.6855 (0.32) 0.08046 (0.24) 386.5 (1.6) 530.1 (2.7) 1208.2 (9.4) 70.0 F, 2 12 113 5.5 364 11.6 0.40 0.04786 (0.21) 0.3450 (2.29) 0.05228(2.18) 301.4 (1.2) 301 (12) 298(97/103) -1.3 G*, 5 4 271 13.1 776 4.2 0.41 0.04750 (0.26) 0.3533 (0.26) 0.05395 (1.17) 299.1 (1.5) 307.2 (6.7) 369 (52/54) 19.3 H,4 11 132 11.2 539 13.9 0.37 0.08063 (0.19) 1.3242 (0.62) 0.11911 (0.54) 499.9(1.9) 856.4 (7.2) 1943 (19) 77.1 1 All zircon grains selected for analysis were air-abraded prior to dissolution. Fraction ID (capital letter) followed by the number of grains: T1,12 for titanite fractions. Asterisk after fraction name signifies no chemistry samples. 2 U blank correction of 1 pf ± 20%; U fractionation corrections were measured for each run with a double 2 3 3 u- 2 3 5 U spike. 3 Radiogenic Pb. 4 Measured ratio corrected for spike and Pb fractionation of 0.0028-0.0033/Amu ± 20% (Daly collector), which was determined by repeated analysis of NBS 982 Pb standard reference material throughout the course of this study. 5 Total common Pb in analysis based on blank isotopic composition. 6 Model Th/U derived from radiogenic 2 0 8Pb and the 2 0 7Pb/ 2 0 6Pb age of fraction. 7 Blank and common Pb corrected; Pb procedural blanks were -2 pg (zircon), 14 pg (titanite) and U, 1 pg for zircon and titanite. Common Pb compositions are based on Stacey-Kramer model Pb at the interpreted age or the Pb/'^Pb age of the rock (Stacy and Kramers, 1975). 0.199 0.201 0.203 0.205 0.207 0.209 2 0 7 p b / 2 3 5 u 0.19 0.20 0.21 0.22 2°W35U Figure 2.5: Concordia plots for U-Pb data from analyzed zircon fractions for diorite samples from the Turnagain intrusion. Each ellipse (2CT error) represents the analysis of a single fraction; all fractions are labelled. A) Sample 04ES-00-07-01, a mela-diorite proximal to the ultramafic lithologies in the centre of the intrusion. B) Sample DDH04-57-12, leuco-diorite, sampled from a plagioclase-rich horizon in the hornblende-rich central region of the Turnagain intrusion. The shaded gray band is the decay constant error envelope of the concordia curve. 185.6±1.2 M a . The age o f the oldest fraction (fraction H , 185.6±1.2 M a ) , is interpreted as the min imum age o f crystallization o f the leuco-diorite (Figure 2 .5B). 2.5.1.3 04ES-00-07-02 - Vo lcan i c Wacke T o constrain the age o f the host rocks, the volcanic wacke was sampled from the hornfelsed sedimentary unit in the northwestern portion o f the intrusion (Figure 2.3), wi th in 50 m o f the hornblendite dike (04ES-00-07-04). Z i r con in the least magnetic fraction is relatively abundant (>300 grains) and ranges in colour from colourless to pale ye l low to dark red-brown. Three distinct z i rcon morphologies are present in this sample: (1) large lath-shaped fragments (aspect ratio 1.5:1), some >200 urn wide, (2) smaller laths (-200 um long, aspect ratio o f 4:1) (Figure 2.4E) commonly containing f luid inclusions and inherited cores, and (3) sub-equant grains (aspect ratio 2:1) ranging from <50 um to - 2 0 0 um in diameter, the largest o f wh ich are commonly dark in colour. A total o f eight fractions were analyzed comprising 2-12 z i rcon grains per fraction. Uran ium concentrations range from 97-260 ppm, wi th a range o f T h / U ratios between 0.31 and 0.51 (Table 2.1). The U - P b data from these analyzed fractions y ie ld an extremely large range o f Pb / U dates (244 M a to 1652 M a , Figure 2 .6A) . The results from two fractions (F and G ) plot on or near concordia at - 3 0 0 M a . Fract ion F is concordant wi th a 2 0 6 p b / 2 3 8 u a g e o f 3oi.4±i.2 M a (Figure 2 .6B) , wh ich is interpreted to be the max imum depositional age o f the volcanic wacke. Fraction D has a significantly younger Pb / U age (244 M a ) and is discordant, wh ich is attributed to Pb-loss from - 3 0 0 M a . Fract ion A (not shown on Figure 2.6) is highly discordant wi th a 2 0 6 P b / 2 3 8 U age o f 1652 M a and a 2 0 7 P b / 2 0 6 P b age o f - 2 0 9 0 M a . The o ld 2 0 7 P b / 2 0 6 P b ages o f fractions A , B , C , and E indicate the presence o f Ear ly Proterozoic z i rcon grains in the source o f the volcanic wacke. A regression line through the discordant and concordant grains (not including fraction D ) has an upper intercept wi th concordia o f - 2 1 0 0 M a , wh ich is considered to be the average age o f inheritance in the analyzed fractions. 2.5.1.4 04ES-00-07-04 - Hornblendite The fine-grained hornblendite was sampled from a 30 cm-wide dike that intrudes the volcanic wacke in the northwestern part o f the Turnagain intrusion discussed above (Figure 2.3). The heavy mineral separate yielded abundant (>100 grains) colourless to pale ye l low to pale brown titanite grains (Figure 2.4F). M o s t grains are anhedral and equant, wi th an aspect ratio o f - 1 : 1 . 00 CO CM 0.085 r 0.075 0.065 £ 0.055 to CM 0.045 0.035 0.025 i 1 1 • T T r i • A „ 1 1 [- 1 1 1 1 1 yi to 2100 Ma . 500 ' C o y B / / <=> ' H 400 / E - 300 1/ - 1 Fig. 2.6B ; / D 04ES-00-07-02 200 / volcanic wacke 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2 0 7 P B / 2 3 5 U 0.0482 0.0480 0.0478 00 CO CM ^ 0.0476 Q_ to o N 0.0474 0.0472 0.0470 B 04ES-00-07-02 Volcanic Wacke 0.32 0.33 0.34 0.35 0.36 0.37 2»W35U Figure 2.6: Concordia plots for U-Pb data from analyzed zircon fractions from a volcanic wacke sample from the northwestern part of the Turnagain intrusion (04ES-00-07-02). All fractions are labelled. A) All analyzed zircon grains except fraction A (7 fractions, n=36 grains). The discordia line has a lower intercept of -300 Ma and an upper intercept of -2.1 Ga. B) Expanded view showing the concordant to nearly concordant results at -300 Ma (fractions F and G). The shaded gray band is the decay constant error envelope of the concordia curve. Both o f the analyzed fractions contained 20 titanite grains each. U contents range from 7 to 9.4 ppm, wi th T h / U ratios o f ~3.9 (Table 2.1). The U - P b data o f the two titanite fractions are concordant and the z u o P b / " ° U ages are 189.5 M a and 191.1 M a , respectively. The weighted mean o f these two concordant and statistically identical results is 190.3 ± 4.6 M a (Figure 2.7), wh ich is interpreted to represent the min imum crystallization age o f the hornblendite when the rock cooled through the closure temperature to Pb diffusion in titanite (see Discussion). 2.5.2 Ar -Ar Geochronology 2.5.2.1 04ES-00-07-04 - Hornblendite This sample, also dated by the U - P b (titanite) method as documented above, yielded abundant, dark brown to black, l o w - K ( C a / K =10-32), amphibole crystals. The amount o f 4 0 A r is extremely high in the grain edge (up to 94%), however the range in 4 0 A r in the core o f the grain is small (1.6-4.2%) (Table 2.2). The first eight heating steps (155 M a to 1279 M a , 6% o f total A r released) y ie ld a distorted ini t ial age spectrum, however a well-defined plateau (189 .3±1 .4 M a ) is observed for the remainder o f the heating steps (94% o f al l A r released) (Figure 2 .8A) . A similar total gas age o f 190 .1±1.4 M a was also obtained. The inverse isochron age is 190.7±2.3 M a ( M S W D =0.14) (Figure 2 .8B) . The A r - A r results for this amphibole separate are consistent wi th the U - P b (titanite) age o f 190 .3±4.6 M a . The plateau age obtained above is considered to represent the m i n i m u m age o f the hornblendite dike when the rock cooled through the closure temperature to A r diffusion in hornblende (see Discussion). 2.5.2.2 04ES-00-07-03 - Wehrli te This sample comes from an outcrop in the far southeastern part o f the Turnagain intrusion, in the southern portion o f the Hatz l Zone (Figure 2.3). Al though phlogopite is not abundant in this sample (<2 vo l .%) , there were sufficient grains for A r - A r analysis. Phlogopite from this sample, wh ich has h i g h - K interiors ( C a / K between 0.2-2), displays a large range in 4 0 A r (3.4- 94.9%) relative to 04ES-00-07-04 (Table 2.2), but the flat plateau step analyses have a smaller range in 4 0 A r (3.7-48.9%). The age range in this sample is somewhat smaller than the previous sample (36-220 M a ) , wi th a younger total gas age o f 181±1 M a . The plateau age o f 189 .9±1 .3 M a (Figure 2.8C), wh ich represents 56% o f al l argon released during step heating analysis, is in agreement wi th the inverse isochron age o f 190 .2±1.8 M a ( M S W D =1.17, Figure 2 .8D). 0.16 0.18 0.20 0.22 0.24 0.26 2 0 7 Pb/ 2 3 5 U Figure 2.7: Concordia plot for U-Pb data from analyzed titanite fractions separated from a hornblendite dike (04ES-00-07-04) in the northwestern region of the Turnagain intrusion. Each ellipse (2a error) represents the analysis of a single fraction. The results from the two analyzed fractions are concordant and nearly identical and the age is calculated from the weighted mean of their 2 0 6Pb/ 2 3 8U ages. The shaded gray band is the decay constant error envelope of the concordia curve. Table 2.2: 40Ar/39Ar step-heating results of mineral separates from ultramafic rocks of the Turnagain intrusion Laser Power (%) < u Ar/"Ar 2<T "Ar/^Ar 2a "Ar/"Ar 2o " A r f A r 2o ""ArV'Ar 2o- '/cTAr* Age (Ma) 2o Ca/K Cl/K f a 3 Ar 04ES-00-07-03 - wehrlite (phlogopite separate) J = 0.009579±0.000012 Volume ' 3ArK = 681.36 Integrated Date = 181.08±0.99 2 167.703 0.020 0.122 0.081 0.736 0.034 0.546 0.036 8.559 5.177 94.91 142.2 82.7 7.40 0.001 0.46 2.2 20.646 0.012 0.027 0.099 0.277 0.022 0.064 0.036 2.121 0.652 89.74 36.3 11.0 2.78 0 2.89 2.4 14.667 0.013 0.021 0.049 0.122 0.022 0.037 0.038 3.852 0.427 73.78 65.4 7.1 1.22 0 4.49 2.6 11.511 0.012 0.018 0.073 0.070 0.030 0.019 0.055 5.897 0.322 48.87 99.1 5.3 0.700 0 3.95 2.8 13.320 0.015 0.014 0.066 0.034 0.040 0.007 0.085 11.413 0.251 14.52 187.2 3.9 0.343 0 9.38 3 12.567 0.016 0.013 0.046 0.028 0.024 0.003 0.064 11.664 0.199 7.40 191.1 3.1 0.284 0 10.96 3.2 12.982 0.006 0.014 0.046 0.022 0.029 0.005 0.067 11.603 0.123 10.83 190.1 1.9 0.218 0 11.84 3.4 12.007 0.005 0.013 0.040 0.019 0.023 0.002 0.097 11.586 0.070 3.73 189.9 1.1 0.194 0 24.26 3.5 12.698 0.005 0.013 0.039 0.019 0.031 0.002 0.088 12.294 0.073 3.41 200.8 1.1 0.195 0 19.59 3.6 13.514 0.006 0.012 0.056 0.025 0.028 0.002 0.219 13.025 0.142 3.85 212.1 2.2 0.258 0 7.89 3.8 14.475 0.008 0.014 0.062 0.074 0.020 0.007 0.152 12.445 0.336 14.23 203.2 5.2 0.754 0 3.27 4.1 17.217 0.012 0.015 0.207 0.120 0.054 0.013 0.245 13.599 0.934 21.21 220.9 14.3 1.22 0 1.02 04ES-00-07-04 - hornblendite (amphibole separate) J = 0.009575±0.000012 Volume J aArK = 510.3 Integrated Date = 190.92±1.36 2 1833.924 0.054 1.161 0.080 2.692 0.069 5.916 0.059 107.792 41.445 94.15 1279 352.3 23.8 0.01 0.06 2.2 697.442 0.038 0.481 0.137 2.625 0.059 2.140 0.051 73.620 22.806 89.50 962.5 223.8 23.2 0.016 0.09 2.4 262.083 0.054 0.190 0.112 2.984 0.060 0.812 0.069 25.934 10.879 90.16 400.2 150.5 26.4 0.006 0.16 2.6 99.042 0.019 0.085 0.223 2.069 0.056 0.304 0.086 10.938 7.627 89.00 179.7 119.3 18.3 0.003 0.26 2.8 62.693 0.027 0.055 0.199 1.794 0.035 0.190 0.069 7.632 3.653 87.87 127.2 58.8 15.9 0.001 0.44 3 50.628 0.015 0.026 0.477 1.414 0.039 0.133 0.055 12.213 2.122 75.96 199.5 32.8 12.5 -0.003 0.55 3.2 36.948 0.016 0.032 0.106 1.220 0.030 0.091 0.038 10.733 0.967 71.05 176.5 15.2 10.8 0 0.8 3.4 23.810 0.011 0.026 0.102 1.762 0.021 0.051 0.052 9.376 0.788 60.77 155.1 12.5 15.6 0 1.15 3.6 15.387 0.011 0.020 0.098 3.645 0.018 0.019 0.083 10.787 0.488 30.28 177.3 7.7 32.3 0.001 2.64 3.8 12.730 0.017 0.019 0.030 3.316 0.019 0.007 0.067 11.490 0.252 10.22 188.3 3.9 29.4 0.001 14.32 4 11.959 0.009 0.018 0.043 3.832 0.015 0.005 0.105 11.522 0.194 4.20 188.8 3.0 33.6 0.001 9.35 4.3 11.887 0.012 0.018 0.036 3.520 0.016 0.004 0.053 11.589 0.157 3.04 189.8 2.4 30.9 0.001 15.5 4.6 11.814 0.010 0.018 0.034 3.346 0.015 0.004 0.106 11.560 0.175 2.67 189.4 2.7 29.3 0.001 14.04 4.9 11.809 0.011 0.017 0.043 3.146 0.015 0.004 0.079 11.650 0.151 1.85 190.8 2.3 27.6 0.001 16.28 5.2 11.783 0.012 0.018 0.033 3.262 0.016 0.004 0.095 11.652 0.170 1.63 190.8 2.7 28.6 0.001 15.93 5.8 11.973 0.008 0.018 0.058 3.459 0.015 0.005 0.120 11.610 0.188 3.55 190.2 2.9 30.3 0.001 8.44 Measured values of , u Ar/"Ar, J°Ar/ 3 3Ar, "Arl"Ar, and ™ArV°Ar are shown for each increment of step-heating. All errors are absolute 'Indicates atmospheric argon Volumes are 1E-13 cm J NPT 4^ 400 i Amphibole 04ES-00-07-04: Hornblendite dike 300 (0 2 < 200 100 r Plateau age = 189.9 ± 1.4 Ma (2o, including J-error of .5%) MSWD = 0.41, probability=0.88 Includes 93.9% of the 3 9 Ar 20 40 60 80 3 9 Cumulative Ar Percent 100 0.0005 0.0004 0.0003 36 40 Ar. Ar 0.0002 0.0001 0.0000 i 1 1 1 1 1 1 1 1 1 1 r Amphibole 04ES-00-07-04: Hornblendite dike Age = 190.7 ± 2.3 Ma Initial ' V / ^Ar =256±82 MSWD = 0.14 0.075 0.077 0.079 0.081 0.083 0.085 0.087 W A r 300 | 200 < 100 Plateau age = 189.9 ± 1.3 Ma (2<T, including J-error of .5%) MSWD = 0.86, probability=0.46 Includes 56.4% of the 3 9 Ar 20 40 60 80 Cumulative Ar Percent 100 0.0005 0.0004 36 Ar °Ar 0.0003 0.0002 0.0000 - i 1 i r i i i i 1 i i i i i Biotite 04ES-00-07-03: Wehrlite Age = 190.2 ± 1.8 Ma Initial "Ar/^Ar =287±34 MSWD = 1.17 • 0.071 0.073 0.075 0.077 0.079 0.081 0.083 0.085 W A T Figure 2.8:40Ar/39Ar incremental-heating age spectra and 4 0Ar/ 3 9Ar inverse isochron diagrams for mineral separates from the Turnagain intrusion. A) Results for amphibole separated from a hornblendite dike (04ES-00-07-04) sampled from the northwestern part of the intrusion. B) Results for phlogopite separated from a wehrlite (04ES-00-07-03) sampled in the southeastern part of the Turnagain intrusion (southern Hatzl Zone). The plateau age obtained above is considered to represent the m i n i m u m crystallization age o f the wehrlite when the rock cooled through the closure temperature to A r diffusion in phlogopite (see Discussion). 2.5.3 Rare Earth Elements and Nd Isotopes The S m - N d isotopic compositions o f eight whole rock samples from the Turnagain intrusion were determined in this study. W i t h respect to rare earth element ( R E E ) concentrations (Table 2.3), the samples have broadly subparallel chondrite-normalized patterns wi th prominent L R E E - d e p l e t i o n for the ultramafic rocks (Figure 2 .9A) . The leuco-diorite and the volcanic wacke exhibit distinctive L R E E - e n r i c h e d chondrite-normalized patterns (Figure 2 .9B) . The volcanic wacke, as w e l l as the samples o f Erdmer et al. (2005), fall wi th in or bracket the R E E range established for the L a y Range Assemblage (Ferri, 1997) and K l i n k i t Group (Simard et al., 2003) (Figure 2 .9B). ( L a / Y b ) c n values in ultramafic rocks range from 0.27-2.0, wi th the volcanic wacke and hornblende diorite samples exhibit ing ( L a / Y b ) c n values o f 3.9 and 1.9, respectively. The samples analyzed for N d isotopes (Table 2.4) show a wide range o f concentrations (Sm = 0.6-6 ppm, N d = 1.3-18.5 ppm), variable S m / N d values (0.33-0.45), a wide range in 1 4 3 N d / 1 4 4 N d (measured) from 0.512440 to 0.512997, and do not exhibit an isochron relationship (Figure 2.1 OA) . The majority o f Turnagain samples have SNd(i90) values between +1.9 and +5.9 (05ES-05-04-01), whereas one sample (hornblende clinopyroxenite) exhibits a moderately negative £Nd(i90) at -3.4 (Figure 2 .10B). 2.6 DISCUSSION 2.6.1 Age and Source of the Turnagain Intrusion The Turnagain intrusion is a composite mafic-ultramafic pluton that contains a range o f lithologies from dunite to diorite (plagioclase + amphibole). F i e l d relationships, and mineral and whole rock geochemistry (see Chapter 4) indicate the fo l lowing general crystall ization sequence: dunite —> wehrlite —> ol ivine clinopyroxenite —* hornblende clinopyroxenite —* hornblendite —• diorite. The A r - A r phlogopite date from the wehrlite (189.9+1.3 M a ) from the mineralized Ha tz l Zone and the A r - A r hornblende date from the hornblendite (189.9+1.4 M a ) from the northwestern part o f the Turnagain intrusion are identical wi th in error and represent the ages o f closure to A r diffusion (i.e. cool ing ages) at ~ 4 5 0 ° C (phlogopite) and ~ 5 7 5 ° C (hornblende) (closure temperatures from Hodges, 2003; and references therein). Titanite from Table 2.3: Major (wt. % oxide) and trace (ppm) element abundances in whole rock samples from the Turnagain intrusion Rock Type: Olivine Cpxite Cpxite Cpxite Hbl Cpxite Hblite Hblite Wacke Diorite Sample Prefix: 05ES 05ES 05ES 04ES 05ES 04ES 04ES DDH04 Sample #: 05-01-01 05-04-01 03-01-02 09-02-02 05-06-02 00-07-04 00-07-02 57-12-89.2 Oxides (wt. %) S i 0 2 51.23 48.99 49.04 47.14 38.53 41.93 49.67 53.56 T i 0 2 0.20 0.38 0.29 0.75 2.32 2.16 0.80 0.29 A l 2 0 3 1.05 2.21 2.07 4.20 12.06 12.21 16.19 20.82 F e 2 0 3 * 7.45 7.65 8.55 11.64 15.51 14.30 10.01 4.14 MgO 22.45 18.65 20.30 16.46 12.99 11.95 4.86 3.60 MnO 0.13 0.15 0.19 0.16 0.21 0.26 0.20 0.09 CaO 17.26 19.12 15.25 16.04 13.85 11.62 9.82 7.68 N a 2 0 0.17 0.20 0.17 0.63 0.67 0.78 3.57 6.02 K 2 0 0.10 0.08 0.11 0.40 0.32 0.89 1.86 1.17 P 2 0 5 0.03 0.14 0.01 0.31 0.37 0.19 LOI 2.20 3.37 2.35 3.31 2.80 1.88 2.12 Total 99.34 99.65 99.36 99.92 99.78 99.20 99.23 99.68 S 0.42 0.04 0.33 1.08 0.14 0.35 0.31 0.10 Mg #: 0.857 0.829 0.825 0.737 0.624 0.624 0.491 0.633 Trace Elements (ppm) Co 98 59 56 151 85 66 30 15 Cr 3200 1480 2690 1320 38 404 79 11 Cu 292 292 47 249 133 84 101 12 Ni 511 173 56 130 132 136 20 9 Sc 55.4 68.1 41.8 68.8 69.3 73.7 36.1 12.9 V 81 147 265 343 645 492 291 110 Zn 18 20 57 49 69 99 74 29 Rb 3 12.0 28 11 Ba 1 12 36 35 69 422 700 1980 Th 0.29 0.17 0.10 0.36 1.54 0.07 U 0.16 0.08 0.06 0.12 0.21 0.09 Ta 0.1 0.2 0.3 0.1 Nb 0.3 0.5 1.8 1.6 3.9 4.1 2.3 La 0.19 0.52 1.56 4.47 2.11 6.61 10.50 1.50 Ce 0.8 2.0 3.8 14.5 7.0 20.5 21.6 3.4 Pb 5 13 34 36 12 5 Pr 0.18 0.41 0.64 2.57 1.40 3.35 2.65 0.52 Sr 35 71 60 62 336 284 949 2808 Nd 1.33 2.64 3.60 12.60 8.64 18.25 11.60 2.62 Zr 2 7 12 14 30 49 38 17 Hf 0.3 0.4 0.7 1.3 2.1 1.4 0.7 Sm 0.60 1.04 1.16 3.69 3.26 5.95 2.99 0.80 Eu 0.204 0.318 0.277 0.928 1.310 1.845 1.020 0.386 Gd 0.80 1.31 1.36 3.62 4.10 7.18 3.21 0.86 Tb 0.15 0.25 0.25 0.63 0.76 1.33 0.56 0.15 Dy 0.92 1.57 1.56 3.49 4.74 7.91 3.42 0.95 Ho 0.18 0.31 0.31 0.65 0.97 1.62 0.70 0.19 Er 0.49 0.86 0.90 1.84 2.79 4.54 2.13 0.57 Tm 0.07 0.12 0.13 0.26 0.39 0.65 0.31 0.09 Yb 0.44 0.74 0.81 1.49 2.25 3.82 1.82 0.53 Lu 0.053 0.100 0.108 0.193 0.310 0.530 0.287 0.073 Y 5 10 8 19 28 42 19 4 Note: Blank entries represent values that were below detection limits. Abbreviated rock types: cpxite (clinopyroxenite), hblite (hornblendite) Mg# = Mg/(Mg+Fe) assuming all iron as F e 2 + 100 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Y D LU 100 Ol Clinopyroxenite Hbl Clinopyroxenite -&-05ES-05-01-01 -«-04ES-09-02-02 -A-05ES-05-04-01 Hornblendite O-05ES-05-06-02 •-04ES-00-07-04 -05ES-03-01-02 O a. E CC 10 1 - r B Erdmer et al. (2005) - • - MM100-13-4/PE00-74 - • - MM100-13-13/PE00-74 - C — MM100-13-6/PE00-75 - • - MM100-13-11 /PE00-75 —i i i i i— Turnagain (this study) -04ES-00-07-02 (volcanic wacke) -DDH04-57-12-89.2 (hornblende diorite) La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Figure 2.9: Chondrite-normalized rare earth element diagrams for whole rock samples from the Turnagain intrusion, and whole rock samples of mafic to intermediate volcanics from Erdmer et al. (2005) for comparison (normalizing values from McDonough & Sun, 1995). Note the wide range in concentrations of the rare earth elements from olivine clinopyroxenite to hornblendite, the broadly sub-parallel patterns with prominent LREE- depletion for the ultramafic rocks, and the distinctive LREE-enriched pattern for the hornblende diorite and the volcanic wacke. Note also that the volcanic wacke and the Erdmer et al. (2005) samples plot in or near the range of the Lay Range Assemblage (after Ferri, 1997). Table 2.4: Nd isotopic compositions of whole-rock samples from the Turnagain intrusion Sample No. Rock Type Sm Nd 1 4 3 Nd 20 1 4 7 Sm 1 4 3 Nd £ N d (0) ^Nd TcHUR TDM (ppm) (ppm) 1 4 4 Nd 1 4 4 Nd 1 4 4 Nd (190 Ma) (190 Ma) (Ma) (Ma) 05ES-05-01-01 clinopyroxenite 0.175 0.41 0.512997 0.000008 0.2581 0.512676 7.0 5.5 891 05ES-05-04-01 clinopyroxenite 1.04 2.64 0.512993 0.000010 0.2382 0.512697 6.9 5.9 1300 - 05ES-03-01-02 clinopyroxenite 1.16 3.60 0.512754 0.000008 0.1948 0.512511 2.3 2.3 - 3175 04ES-09-02-02A (a) hbl clinopyroxenite 3.69 12.6 0.512442 0.000005 0.1770 0.512222 -3.8 -3.3 1522 2924 04ES-09-02-02A (b) hbl clinopyroxenite 3.69 12.6 0.512438 0.000007 0.1770 0.512218 -3.9 -3.4 1557 2942 05ES-05-06-02 (a) hornblendite 3.26 8.64 0.512892 0.000004 0.2281 0.512608 4.9 4.2 1225 - 05ES-05-06-02 (b) hornblendite 3.26 8.64 0.512900 0.000004 0.2281 0.512617 5.1 4.4 1266 - 04ES-00-07-04 hornblendite 5.95 18.3 0.512738 0.000005 0.1971 0.512493 1.9 1.9 - 3751 DDH04-57-12-89.2 diorite 0.800 2.62 0.512865 0.000007 0.1846 0.512641 4.4 4.8 - 1490 04ES-00-07-02 (a) volcanic wacke 2.99 11.6 0.512693 0.000008 0.1558 0.512499 1.1 2.1 - 1202 04ES-00-07-02 (b) volcanic wacke 2.99 11.6 0.512695 0.000006 0.1558 0.512501 1.1 2.1 - 1197 GSP-2 (n=14) reference 0.511374 0.000011 Hornblende has been abbrieviated to hbl Concentrations of Sm and Nd were measured by ICP-MS T C H uR and T D M ages with hyphens represent either negative ages or unreasonably large ages 0.5131 I I • • A 0.5129 5 + 0.5127 0.5125 0.5123 _i i i_ 0.13 0.15 0.17 0.19 0.21 0.23 0.25 0.27 1 4 7 Sm/ 1 4 4 Nd 10 -10 -15 -20 -25 -30 Turnagain (this study) A Clinopyroxenite • Hornblende clinopyroxenite • Hornblendite + Felsic Diorite X Volcanic wacke • A O O + x B X X A A Erdmer ef al. (2005) • Dark green tuff X Plagioclase porphyry Granodiorite dyke • 'Road River" phyllite A Boya Formation (quartzite) A Boya Formation (muscovite schist) • Quartz-potassium feldspar porphyry 10 -5 -10 -15 eNd (190 Ma) -20 -25 -30 Figure 2.10: Nd isotopic geochemistry of whole-rock samples from the Turnagain intrusion. A) 1 4 3 Nd/ 1 4 4 Nd vs. 1 4 7 Sm/ 1 4 4 Nd with a 190 Ma reference isochron. Symbol size is greater than the 2a error for each analysis. B) Initial eNd vs. rock type. The upper portion of the diagram illustrates the range in initial eN d in Turnagain lithologies and the lower portion shows results from Erdmer et al. (2005), recalculated at 190 Ma, for samples collected -10 km southeast of the Turnagain intrusion. The light blue field represents the range of eNd for mafic volcanic rocks from Yukon-Tanana (from Piercey et al, 2006). the same hornblendite sample yields a date o f 190.3±4.6 M a (Figure 2.7), wh ich represents the time o f closure to Pb diffusion in titanite (~650°C) (Cherniak, 1993; Frost et al, 2000). A l l three dates from the ultramafic rocks o f the Turnagain intrusion are identical wi th in error and correspond to a range o f closure temperatures for the respective minerals and isotopic systems from 650°C down to 450°C , wh ich is consistent wi th relatively rapid cool ing o f the Turnagain intrusion fo l lowing emplacement and crystallization. Based on these three dates, the age o f crystallization and cool ing o f ultramafic rocks from the Turnagain intrusion is 189 .9±0 .9 M a (n=3, weighted mean age, 2a). The mela-diorite sample (04ES-00-07-01) exhibits gradational contacts wi th hornblendite, but intrudes dunite (Figure 2.3). The closure temperature for Pb diffusion in z i rcon is > 9 0 0 ° C (Cherniak & Watson, 2000), w h i c h is l ike ly to be higher than the temperature o f the fractionated hydrous melt from wh ich the z i rcon in this sample precipitated; thus the U - Pb z i rcon date for this sample can be interpreted as a crystallization age. A s noted previously, a l l analyzed z i rcon in this sample appears to have lost Pb since the time o f crystall ization. Based on the oldest least discordant fraction (Fraction B ) , the mela-diorite has a m i n i m u m crystallization age o f 189.2±0.6 M a (Figure 2 .5A) , wh ich is identical wi th in error to the weighted mean A r - A r (phlogopite, hornblende) and U - P b (titanite) age noted above. The absolute crystallization age o f the Turnagain intrusion is inferred to be 189.4±0.5 M a based on a weighted mean o f Fraction B from the mela-diorite and the A r - A r and U - P b titanite ages referred to above. The 185.2±0.3 M a U - P b z i rcon age o f the leuco-diorite (DDH-04-57-12-89) is approximately 4.5 mi l l i on years younger than the crystallization age o f the Turnagain intrusion established above. This younger age can be interpreted as (1) the true crystallization age o f the leuco-diorite, thus imply ing an extended period o f magmatism in the formation o f the Turnagain intrusion; or (2) a function o f Pb loss from zi rcon in this sample. F i e l d and petrographic relations suggest that the leuco-diorite is an integral part o f the 190 M a ultramafic and mafic rocks o f the Turnagain intrusion. The first interpretation is consistent wi th the observation that late dioritic dikes are a common feature o f many Alaskan-type intrusions (e.g. Lunar Creek; N i x o n et al., 1997). In addition, a diorite to granodiorite composite pluton ~5 k m to the east-southeast o f the Turnagain intrusion (Figure 2.2), a body considered to be a small ultramafic ' R i n g Complex ' genetically related to the Turnagain intrusion (Clark, 1975), was recently dated by Erdmer et al. (2005) at 187 .5±2 .9 M a (U-Pb zircon). This age overlaps both 41 the ages o f the leuco-diorite and the ultramafic rocks o f the Turnagain intrusion. The composite R i n g Complex is described by Erdmer et al. (2005) as a "medium-grained hornblende granodiorite to tonalite-diorite," wh ich suggests that it may be a similar l i thology to the mela-diorite o f the Turnagain intrusion. The date o f the granodiorite is a lower intercept age wi th concordia based on three o f the five analyzed fractions (see F i g . 5 o f Erdmer et al., 2005). However , the oldest analyzed fraction (not used in the above regression) is concordant and yields a 2 0 6 P b / 2 3 8 U age o f 192 .4±0.8 M a , thus it is possible that this hornblende granodiorite may be several m i l l i o n years older that its proposed crystallization age o f 187 .5±2 .9 M a . The second interpretation o f the age o f the leuco-diorite from the Turnagain intrusion - Pb-loss from zi rcon after crystallization at ca. 190 M a - is based on the observation o f Pb-loss in a l l z i rcon fractions from the mela-diorite (sample 04ES-00-07-01) and the field and petrographic characteristics o f the leuco-diorite sample. The hornblende diorite contains coarse (up to 1 c m in width) euhedral crystals o f plagioclase and amphibole, interpreted to be cumulus phases that crystall ized from an evolved plagioclase-amphibole-saturated magma late in the crystallization history o f the Turnagain intrusion. The dril lcore from wh ich the sample was collected contains 9 metres o f alternating plagioclase-rich and amphibole-rich bands, perhaps representing a layered sequence o f cumulate rocks. These observations require the leuco-diorite to have crystall ized at the same time as the other dated samples, thus the obtained age o f 185 .2±0.3 M a is most l ike ly a function o f Pb-loss from zi rcon fo l lowing crysall ization. The M g - r i c h ol ivine (F092.5) o f some Turnagain dunites indicate that the Turnagain magmas equilibrated wi th peridotitic mantle (with respect to major elements). However , the N d isotopic composit ion o f a l l lithologies in the Turnagain intrusion (sNd(i90)= +5.9 to -3.3) indicates that the intrusion was variably contaminated wi th continental crust (depleted mantle SNd(i90Ma) = +9 to +10; DePaolo & Wasserburg, 1976). The most positive £Nd(i90) results are consistent wi th the range observed in Paleozoic mafic volcanic rocks in Yukon-Tanana (Piercey et al., 2006). The N d isotopic compositions o f the graphitic phyll i te (Erdmer et al., 2005) and the volcanic wacke (this study) both indicate (respectively) their or igin from, and contamination wi th , continental crust (Figure 2.10). The variable 8Nd(i90) o f the analyzed ultramafic samples may reflect heterogeneous assimilation o f the volcanic wacke and the graphitic phyll i te, both o f wh ich are found as partially digested inclusions in the Turnagain intrusion. 2.6.2 Age Comparison with other Alaskan-type Intrusions The mineralogy and mineral compositions o f Alaskan-type intrusions suggest that they form from relatively hydrous, alkal ic to subalkalic, primit ive picritic/ankaramitic magmas (Irvine, 1974; Hernandez, 2000; Mossman et al, 2000; Spandler et al, 2003; Green et al, 2004; Batanova et al, 2005) in arc settings. The ages o f Alaskan-type intrusions, therefore, are important for understanding the temporal evolution o f arc systems. This is particularly relevant to the Cordi l leran orogeny o f B . C . , Y u k o n , and southeastern Ala ska , wh ich consists o f numerous accreted allochthonous and parautochthonous terranes (e.g. Monge r et al, 1982; Schermer et al, 1984; Gabrielse & Yora th , 1991; Co lp ron et al, 2006) (Figure 2.1). The published and reported ages o f Alaskan-type intrusions in B . C . and southeastern A l a s k a are compiled in Table 2.5 and shown wi th respect to terranes in Figure 2.11. O f the 9 known Alaskan-type intrusions in B . C . and 39 in southeastern Ala ska , only 12 have been dated; mostly by the K - A r method during the 1960s. Pr ior to this study, the only precise U - P b z i rcon ages o f Alaskan-type intrusions in B . C . and A l a s k a were reported by Saleeby (1992), R u b i n & Saleeby (1992), Rublee (1994), and N i x o n et al. (1997) (Duke Island, U n i o n B a y , Tulameen, and Lunar Creek+Polaris, respectively). There are two important observations that can be made regarding the age distribution o f Alaskan-type intrusions (see Figure 2.1 for terrane locations). Firs t ly , there are four age groups: -435-400 M a , -240-205 M a , -195-185 M a , and -125-100 M a . The oldest (Silurian-Devonian) and youngest (Cretaceous) age groups are found in the Alexander terrane, whereas the intermediate age groups (Triassic-Jurassic) are found in St ik inia and Quesnell ia (Figure 2.1). Secondly, the -240-205 M a intrusions are observed in both St ik inia and Quesnellia, whereas the -195-185 M a intrusions are found only in Quesnellia. Alaskan-type intrusions in B . C . and southeastern A l a s k a also exhibit an age distribution relative to their host rocks. The oldest group o f intrusions (Salt Chuck, D a l l Island, and Sukkwan Island) intrude older gabbroic plutons as w e l l as the Descon Formation (lower Paleozoic metavolcanic and metasedimentary rocks; e.g. Rub in & Saleeby, 1992), wh ich is unconformably overlain by the Gravina (Upper Jurassic-Lower Cretaceous metavolcanic and metasedimentary rocks) and A l v a (upper Paleozoic- lower Mesozo i c metabasalt, marble, and argillite) sequences. The youngest age group is also dominantly hosted by the Descon Formation, however the U n i o n B a y intrusion is hosted by the over lying Gravina sequence (Rubin & Saleeby, 1992). This implies that the youngest age group o f intrusions were Table 2.S: Compilation of isotopic dates for Alaskan-type intrusions in British Columbia and southeastern Alask Terrane Intrusion Rock Type Method (Mineral) Age (Ma) Uncertainty (2o) Host Lithology Reference Quesnellia Turnagain Wehrlite Hornblendite dike Hornblendite dike Mela-diorite Leuco-diorite Ar-Ar (phlogopite) Ar-Ar (hornblende) U-Pb (titanite) U-Pb (zircon) U-Pb (zircon) 189.9 189.9 190.3 189.2 . 185.2 1.3 1.4 4.6 0.6 0.3 "Road River" phyllite, Lay Range Assemblage This study Ring Complex1 diorite U-Pb (zircon) 187.5 2.9 "Road River" phyllite Erdmeref al., 2005 Lunar Creek K-spar pegmatite Cross-cutting dike Cross-cutting dike U-Pb (zircon) K-Ar (hornblende) K-Ar (hornblende) 237 190 182 2 8 13 Takla Group Nixon etal., 1997 Gabrielse etal., 1980 Gabrielse et al., 1980 Wrede Creek Hornblende pegmatite Hornblende pegmatite K-Ar (hornblende) K-Ar (hornblende) 219 225 20 16 Takla Group Wong etal., 1985 Johansson Lake Coase hornblendite K-Ar (hornblende) 232 13 Takla Group Stevens etal., 1982 Polaris Qtz-hbl-plag pegmatite Peridotite Peridotite U-Pb (zircon) K-Ar (biotite) K-Ar (hornblende) 186 167 156 2 9 15 Lay Range Assemblage Nixon etal., 1997 Wanless etal., 1968 Wanless etal., 1968 Tulameen Syenodiorite Hornblende clinopyroxenite Hornblende clinopyroxenite U-Pb (zircon) K-Ar (hornblende) Ar-Ar (hornblende) 209.9 208 196 4.7 *20 *15 Nicola Group Rublee, 1994 Nixon et al., 1997 -refs therein Nixon et al., 1997 -refs therein Stikinia Gnat Lakes Hornblendite Hornblende clinopyroxenite K-Ar (hornblende) K-Ar (hornblende) 230 227 10 14 Stuhini Group Stevens etal., 1982 Alexander Duke Island Gabbro Hornblendite U-Pb (zircon) Ar-Ar (hornblende) 109.5 118.5 1.5 10 Descon Formation Saleeby, 1992 Meen etal., 1991 Union Bay Gabbro pod in hornblendite U-Pb (zircon) 101.9 0.6 2 Gravina Sequence Rubin & Saleeby, 1992 Salt Chuck Biotite clinopyroxenite K-Ar (biotite) 429 11 Descon Formation Loney etal., 1987 Dall Island3 401.1 *20 Descon Formation Himmelberg & Loney, 1995 -refs therein Sukkwan Island3 440.5 *20 Descon Formation Himmelberg & Loney, 1995 -refs therein 1 The Ring Complex, originally described by Clark (1975), was interpreted to be ultramafic in nature (based on aeromagnetic results). However subsequent mapping by Erdmer etal., 2005, and the principal author, showed that the Ring Complex is a diorite pluton that intruded phyllites of th< Road River Group. See Discussion for details 2 Conservative estimate of error o n 2 0 6 P b / 2 3 8 U age 3 Age of intrusion derived from a personally communicated age to the refered authors, such that no specific data are available * These uncertainties are conservative estimates - no uncertainties are given by the original authors 4^ 80 Quesnellia Turnagain phlogopite (wenrlite) hbl (hornblendite) - hornblendite - mela-diorite - leuco-diorite - Ring Complex - Lunar Creek K-spar pegmatite hbl (x-cutting dike) hbl (x-cutting dike) Wrede Creek hbl (pegmatite) hbl (pegmatite) Johanson Lake hbl (hornblendite) Polaris qtz-hbl-plag pegmatite biotite (hornblendite) hbl (hornblendite) Tulameen syenodiorite hornblende hornblende Stikinia Gnat Lakes hbl (hornblendite) hbl (hornblende cpxite) Alexander Duke Island gabbro hornblendite Union Bay gabbro Salt Chuck biotite (clinopyroxenite) Dall Island Sukkwan Island 105 - 1 — 130 - I — 155 — I — 180 l— 205 230 255 280 T T =1 Method • E 1 U-Pb (zircon) • -• D U-Pb (titanite) • z K-Ar • Ar-Ar • _ 380 405 I 430 -L -L 80 105 130 155 180 205 Age (Ma) 230 255 280 Figure 2.11: Compilation of ages of Alaskan-type intrusions in B.C. and southeastern Alaska arranged from north to south (top to bottom) with each bar representing the age with its associated analytical uncertainty (2a), its dating method and mineral dated. References for the above ages are found in Table 2.5. 45 emplaced through both the Descon Formation and the Gravina sequence, and that a second arc was built upon a preexisting, extinct, arc. The Triassic intrusions (-240-205 M a ) are typical ly hosted in the Tak la (Monger, 1977) and N i c o l a (e.g. Shau, 1970) Groups, wh ich are Triassic packages o f volcanic rocks that occur in Quesnell ia and St ikinia (Dostal et al., 1999). The Gnat Lakes Alaskan-type intrusion, however, is hosted in the Stuhini Group in Stikina, and Stuhini Group, Tak la Group, and N i c o l a Group are considered to be coeval (Dostal et al., 1999). The Jurassic (-195-185 M a ) group o f intrusions is represented by the Polaris and Turnagain intrusions, wh ich have similar crystallization ages ( 1 8 6 ± 2 M a , 190±1 M a , respectively) and host rocks. The Polaris intrusion is hosted in the L a y Range Assemblage, wh ich has been correlated wi th the Harper Ranch Subterrane and the K l i n k i t Group (e.g. Ferr i , 1997) and is proximal to the Upper Proterozoic Ingenika Group, whereas the Turnagain is hosted by graphitic phyllites (possibly the Road R ive r Formation and Earn Group) and volcanic wacke that possibly correlates to the L a y Range Assemblage (see next section). The apparent 10 m i l l i o n year gap, based on the few reliable U - P b dates, between the Late to M i d d l e Triassic and Ear ly Jurassic intrusions may be related to (1) a period o f quiescence in arc magmatism, or (2) an artifact o f the lack o f geochronological data. Monge r & Church (1977) constrain the biostratigraphic age o f the Tak la Group from late Carnian to early Nor i an (-220 to 230 M a using the time scale o f Okul i tch , 1999). In addition, a Late Triassic angular unconformity wi th the overlying Ear ly Jurassic Rossland Group, a package o f volcanic rocks (with lateral facies changes gradational wi th limestone and epiclastic rocks) that are texturally and mineralogically similar to the N i c o l a Group, is observed in southern Quesnell ia (Beatty et al., 2006). This succession is inferred to represent the uplift and erosion o f the N i c o l a Group fol lowed by eastward-shifted renewed arc magmatism (overlying Rossland Group) at - 195 M a (Parrish and Monger , 1992). The older biostratigraphic age o f the Tak la Group, in comparison to the Late Triassic Alaskan-type intrusions, may indicate that its top has been removed by erosion. The youngest Alaskan-type intrusions, found at the easternmost extent o f Quesnell ia (Figure 2.1), may corroborate the eastward shift o f arc magmatism in Quesnell ia during the Ear ly Jurassic. However , the number o f precisely-dated Alaskan-type intrusions in B . C . is small (n=4). The apparent time gap may therefore simply be related to the lack o f dated Alaskan-type intrusions in B . C . A 185-212 M a plutonic suite does occur in the Yukon-Tanana terrane (Mortensen, 1992), wi th whole-rock compositions similar to the Tak la Group (Nelson et al., 2006). Some plutons contain ultramafic rocks wi th Alaskan- 46 type-like lithologies but have not yet been defined as Alaskan-type bodies per se ( J .K. Mortensen, pers. comm., 2007). There is also an absence o f preserved Late Triassic or Ear ly Jurassic volcanic rocks, but there is no apparent age' gap o f early Mesozo ic plutonic rocks in Yukon-Tanana - presumably the basement to Quesnell ia (Nelson et al., 2006). 2.6.3 Tectonic Implications for Northern British Columbia The combined ages, host lithologies, and N d isotopic compositions o f the Turnagain intrusion have implications for its tectonic setting and relation to the accreted terranes o f the Canadian Cordi l lera . The two major host lithologies, graphitic phyll i te and latest Pennsylvanian/earliest Permian volcanic wacke, are both found as inclusions in the Turnagain intrusion and appear to represent the host rocks to this fault-bounded intrusion. Based on l imited fossil biochronology, the age o f the Road R ive r Formation sensu stricto is Ear ly Ord iv ic ian to M i d d l e Si lur ian elsewhere in B . C . , and the overlying the Earn Group is Upper Devonian to Miss iss ippian (Gabrielse, 1998). The undivided Road R ive r and Earn Groups (as mapped by Gabrielse (1998) in the study area) are conformably overlain by volcanic and volcanosedimentary rocks that contain abundant Proterozoic inherited z i rcon (Figure 2 .6A) and are intruded at their base by a 337 M a porphyritic dike (Erdmer et al., 2005). A gradational contact (interbedded over 5- 10 m) between the graphitic phylli te and the volcanic wacke was observed in dril lcore in late 2006. The age o f the phyll i te is uncertain, as only a few poorly preserved graptolites have been found in the Dease Lake map area (Gabrielse, 1998; and references therein). Accreted terranes wi th in the Canadian Cordi l lera , specifically the Quesnel, Stikine, and Yukon-Tanana terranes, have recently been argued to be genetically related (Nelson et al., 2006), partially based on l i thological similarities. Fo r example, Alaskan-type intrusions are known in St ik in ia and Quesnellia, and recent unpublished findings indicate their probable presence in Yukon-Tanana (J. Ne l son , pers. comm., 2007). The association between carbonaceous phyll i te and overlying volcanic/volcano-sedimentary rocks has been documented in both Quesnell ia and Yukon-Tanana (Ferri & M e l v i l l e , 1990; Mortensen, 1992; Ferr i , 1997; Simard et al., 2003; Ne l son & Friedman, 2004). In Quesnellia, such volcanic-volcaniclast ic rocks have been included either in the Mississ ippian-Permian L a y Range Assemblage or the Devonian-Middle Permian Harper Ranch Subterrane (Ferri & M e l v i l l e , 1990; Ferr i , 1997; Dostal etal., 1999). The L a y Range Assemblage (Ferri , 1997) contains (1) a M i d d l e Mississippian-late M i d d l e Pennsylvanian L o w e r Sedimentary d iv is ion, consisting 47 predominantly o f argillite and siltstone wi th lesser limestone, tuff, and volcanic sandstones; and (2) an Ear ly Permian Upper M a f i c Tuf f d iv is ion, consisting o f a variety o f tuffs, agglomerates, and lavas flows. The L a y Range Assemblage is considered correlative wi th the M i d d l e Miss iss ippian-Ear ly Permian K l i n k i t Group in Yukon-Tanana (Simard et al., 2003; Ne l son & Friedman, 2004). The K l i n k i t Group has been observed to tectonically overlie a succession o f phyllites, grits, and tuffs o f the Devonian-Middle Permian Swift R ive r succession (Simard et al., 2003; Ne l son & Friedman, 2004), whi le the base o f the L a y Range Assemblage has been observed in central B . C . by Ferr i & M e l v i l l e (1990) to conformably overlie carbonaceous phyll i te . The base o f the Harper Ranch Subterrane has not been observed (Dostal et al., 1999). Other similarities between Yukon-Tanana and Quesnell ia possibly include a shared Ancestral Nor th A m e r i c a basement source. Erdmer et al. (2002) documented 313-1058 M a detrital z i rcon in sedimentary rocks o f the Quesnell ian N i c o l a Horst in south- central B . C . and Untershutz et al. (2002) documented a mixture o f primit ive and evolved N d isotopic compositions in Triassic sandstones over lying the L a y Range Assemblage. Ferr i (1997) documented inherited Proterozoic z i rcon in Permian tuffs and lavas from the Upper M a f i c T u f f d iv is ion o f the L a y Range Assemblage. In summary, the "Earn Group 'VSnowcap Assemblage is overlain by the K l i n k i t Group /Lay Range Assemblage/Harper Ranch Subterrane, a l l o f wh ich contain detrital z i rcon o f Proterozoic age. The Turnagain intrusion is the first documented Alaskan-type intrusion to be hosted in both L a y Range-equivalent rocks and older graphitic phyll i te . The - 3 0 0 M a volcanic wacke, wi th inherited Proterozoic zircons and trace element characteristics ( R E E ) similar to samples o f the L a y Range Assemblage and the K l i n k i t Group (Ferri , 1997; Simard et al., 2003 - Figure 9 A ) (Figure 2 .9B) , is l ike ly a northern equivalent o f the L a y Range Assemblage. The "Road R i v e r " phyll i te, as assigned by Gabrielse (1998), is conformably overlain by the L a y Range Assemblage and therefore constitutes part o f the same crustal block. The conformable nature o f these two rock packages is broadly consistent wi th the first interpreted tectonic setting o f the Turnagain intrusion o f N i x o n (1998) as outlined in the introduction, however this l i thological succession cannot be part o f Ancestral Nor th Amer i ca . These lithologies are intruded by the Turnagain Alaskan-type intrusion, a composite mafic-ultramafic pluton o f arc affinity (see Chapter 4). N o conclusive terrane assignment can be made based on the presence o f L a y Range Assemblage-equivalent rocks, on the presence o f an Ear ly Jurassic arc-derived intrusion, or on the presence o f Precambrian inheritance. The 48 results of this study demonstrate that the succession of Cambrian(?) to Permian sedimentary rocks in this part of northern B.C., intruded by the Turnagain intrusion and the Ring Complex, was at the locus of arc magmatism during the Early Jurassic. If the assignment of the graphitic phyllite to the Road River/Earn Groups (Gabrielse, 1998) is correct, then the conclusions of Erdmer et al. (2005) - that an Early Jurassic subduction zone existed beneath Ancestral North America - are correct. However, if the graphitic phyllites are in fact part of the Snowcap assemblage or equivalents, then the lithologies around the study area are part of Yukon-Tanana or Quesnellia. 2.7 C O N C L U S I O N The principal results from this geochronological study of the Turnagain Alaskan-type intrusion and host rocks in north-central British Columbia are 1) the crystallization age of mafic and ultramafic phases in the Turnagain intrusion, as determined by U-Pb (zircon, titanite) and Ar- Ar (phlogopite, amphibole) geochronometry, is 190±1 Ma, 2) the range of whole rock Nd isotopic compositions from the Turnagain intrusion is £ N d ( i 9 0 ) = +6 to +2 with a hornblende clinopyroxenite sample extending to £Nd(i90) = -3, indicating variable amounts of crustal contamination of mantle-derived parental magmas in an arc setting, 3) the minimum depositional age of the youngest host rocks to the Turnagain intrusion is 301 Ma (U-Pb zircon), or latest Pennsylvanian-earliest Permian, and 4) the hosting volcanic wacke in the study area, based on its age, REE geochemistry, and lithological similarities with other rocks in B.C. and Yukon, is equivalent to the Lay Range Assemblage, which is considered to be the basement to the Quesnellia terrane. The Turnagain intrusion, which intrudes the volcanic wacke and graphitic phyllite, is indicative of the presence of an Early Jurassic subduction zone in the study area and constrains the terrane assessment of the study area to be either Quesnellia or Yukon-Tanana. The association of other Alaskan-type intrusions in Quesnellia with the Lay Range Assemblage/Harper Ranch Subterrane is well-established, and may indicate the presence of unidentified Alaskan-type intrusions in the Klinkit Group of Yukon-Tanana, which would further support the proposed genetic relationships between Yukon-Tanana and Quesnellia. 49 2.8 A C K N O W L E D G E M E N T S W e w o u l d l ike to thank a number o f individuals at the Pacif ic Centre for Isotopic and Geochemical Research, Univers i ty o f Br i t i sh-Columbia , Vancouver: R i c h Fr iedman for U - P b T I M S chemistry and analyses, and his continuous input into data interpretation for this manuscript; T o m U l l r i c h for A r - A r analyses; G w e n W i l l i a m s and Bruno Keiffer for sample preparation, digestion, and N d isotopic analyses; and Dominique Weis for assistance in the interpretation o f the N d isotopic results. J im Mortensen, L u k e Baranek, and Reza Tafti are thanked for sharing their opinions and ideas concerning northern B . C . tectonics, and Ka t r in Breitsprecher for her helpful comments on this manuscript. The authors are grateful to Hard Creek N i c k e l Corp . for continued field support for this project and to J i m Reed o f Pacif ic Western Helicopters for his exemplary logistical support in the field. Special thanks to Tony Hitchins , Bruce Northcote, Chris Baldys , and M a r k Jarvis (President) o f Hard Creek N i c k e l Corp . for their generous support and interactions throughout the period o f the principal author's M . S c . thesis at U B C . Funding for this project was provided by a research grant from Hard Creek N i c k e l Corp . (formerly Canadian Metals Explorat ion Ltd.) . 2.9 REFERENCES Batanova, V . G . , Pertsev, A . N . , Kamenetsky, V . S . , A r i s k i n , A . A . , Mocha lov , A . G . , & Sobolev, A . V . (2005). 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Geology in British Columbia, 1977-1981, 148-155 C H A P T E R 3 CHROMITE CHEMISTRY OF THE TURNAGAIN INTRUSION, NORTHERN BRITISH COLUMBIA, AND THE REDOX STATES OF ALASKAN-TYPE PARENTAL MAGMAS 3.1 INTRODUCTION Chromian spinel, or chromite ( F e C ^ C U wi th minor amounts o f M g , A l , and F e 3 + substitution), is found as an accessory mineral in a wide variety o f mafic and ultramafic rocks (e.g. Barnes & Roeder, 2001). It crystallizes from magmas that are broadly basaltic in composit ion and is typical ly one o f the earliest phases to saturate in a mafic melt (e.g. Roeder, 1994). The abundance o f chromite in many ultramafic and mafic rocks is generally l ow (1 vo l .%) , although large accumulations called chromitite do occur in a number o f layered mafic- ultramafic intrusions (e.g. Roach et al., 1998), ophiolites, and Alaskan-type intrusions (e.g. Garuti et al., 2003; Krause et al., 2006) wor ldwide . The composit ion o f chromite is extremely sensitive to its environment o f formation as we l l as post-magmatic processes and thus can be a powerful petrogenetic indicator in petrologic studies (e.g. Irvine, 1965; Irvine, 1967; D i c k & Bu l l en , 1984; Roeder & Campbel l , 1985; Sack & Ghiorso, 1991; Scowen etal, 1991; Poustovetov & Roeder, 2000; Power et al, 2000). Variat ions in chromite compositions may record changes in magma compositions and types o f co-precipitating phases (Roeder, 1994), oxygen fugacity (e.g. Poustovetov & Roeder, 2000), pressure (e.g. Roeder & Reynolds , 1991), and may also record the effects o f sub-solidus re-equilibration and serpentinization (e.g. Roeder & Campbel l , 1985). A recent compilat ion o f chromite compositions from mafic-ultramafic rocks worldwide (Barnes & Roeder, 2001) includes only seven referenced sources o f data for Alaskan-type intrusions. These intrusions are typical ly composed o f ultramafic cumulate rocks, consisting o f M g - r i c h ol iv ine , clinopyroxene, amphibole ± plagioclase, and they may be crudely to concentrically zoned. Alaskan-type intrusions occur mostly in subduction zone settings and are proposed to have formed from relatively water-rich magmas (Himmelberg & Loney , 1995; Mossman et al, 2000; Johan, 2002; Spandler et al, 2003; Ishiwatari & Ichiyama, 2004; Green et al, 2004; Batanova et al, 2005). Chromite is a common accessory mineral and is typical ly disseminated in the most magnesian lithologies (dunite and wehrlite). The earlier chromite compositional study o f Cla rk (1978) provided a good basis for this study, wh ich provides an •i overview o f spinel compositions from the Turnagain Alaskan-type intrusion in northwestern Br i t i sh Co lumbia (Canada) wi th the aims o f 1) significantly increasing the spinel compositional database for Alaskan-fype intrusions, 2) assessing the crystallization sequence and subsequent chemical modifications during cool ing and serpentinization using chromite compositional variabil i ty and, importantly, 3) constraining the relative oxygen fugacity o f the parental magmas for the Turnagain intrusion. The Turnagain Alaskan-type intrusion is unusual in that it contains zones wi th significant Ni-sulphide mineralization (428 M t - measured and indicated - @ 0.17% sulphide N i ; http://www.hardcreeknickel.com). G i v e n the proposed arc setting for Alaskan-type intrusions, they are considered to form from relatively oxidized parental magmas ( A F M Q = +1 to +3.5, e.g. Carmichael , 1991; Parkinson & Arcu lus , 1999) wi th sulphur dissolved as sulphate (SO42") rather than sulphide (S2~) (Jugo et al., 2004) and have thus traditionally been considered unfavourable environments for nickeliferrous ore deposits. 3.2 REGIONAL GEOLOGY Numerous Alaskan-type intrusions in Br i t i sh Co lumbia occur wi th in the Mesozo ic Quesnel accreted arc terrane, including the Tulameen (Findlay, 1969), Polaris (Foster, 1974), Lunar Creek, Wrede Creek, Johansson Lake (N ixon et al, 1997), and Turnagain (Clark, 1975; 1978; 1980; N i x o n , 1998) intrusions. The Turnagain intrusion is located in northwestern B . C . , approximately 70 k m east o f Dease Lake , to the east o f the Kutcho Fault, wh ich is a regional strike-slip fault that represents the terrane boundary between Ancestral Nor th A m e r i c a to the north and Quesnell ia to the south (Gabrielse, 1998). The 24 k m 2 Turnagain intrusion is completely fault-bounded, and during the Ear ly Jurassic was thrust onto graphitic and pyrit ic phyllites currently assigned to the undivided Ordiv ic ian-Devonian R o a d Rive r Formation/Earn Group, a deep marine facies o f paleo-passive margin sedimentary units o f Ancestral Nor th A m e r i c a (Gabrielse, 1998). Conformably overlying the phyll i te is a Devonian-Miss iss ippian volcanic to sedimentary unit (Erdmer et al, 2005) that may be correlative to the L a y Range Assemblage (see Chapter 2). The crystallization age o f the Turnagain intrusion is constrained to be 190 M a using U - P b and A r - A r geochronological techniques (see Chapter 2). I 3.3 GEOLOGY AND SPINEL CONTENT OF THE TURNAGAIN INTRUSION Rocks o f the Turnagain intrusion are predominantly ultramafic cumulate rocks wi th associated late dioritic phases and intrusions (Figure 3.1). The 3.5 k m x 8.5 k m Turnagain intrusion is elongate in a N W - S E direction and the apparent thickness o f the intrusion is estimated at approximately 450 m based on inverse model ing o f gravity data (C . Baldys , pers. comm., 2005). Exposures o f the intrusion are l imited to the northern and northeastern areas, wh ich are above treeline, and near the Ni -minera l ized zones (the Horsetrail Zone and satellite zones) in Intrusion Centre: X 58°29'N, 128°52'W 1 km Dunite, with minor wehrlite Wehrlite, with minor dunite and olivine clinopyroxenite Olivine clinopyroxenite and clinopyroxenite, undivided Hornblende clinopyroxenite, with minor clinopyroxenite Hornblendite and clinopyroxene hornblendite, undivided Diorite, quartz diorite, and granodiorite, undivided Hornfels, sedimentary or volcanic protolith -j Reverse fault, observed j Normal fault, inferred "^Z- Fault (relative sense of motion indicated) it Spinel sample locality 'White ovals indicate the mineralized zones (from W to E): Northwest Zone, Horsetrail Zone, Hatzl Zone. Figure 3.1: Simplified geological map of the Turnagain Alaskan-type intrusion, modified from Clark (1975), with its location in British Columbia shown as an inset in the upper right corner (also indicated are the locations of other major Alaskan-type intrusions in B.C. and Alaska). The lithologies of the intrusion are shown in the legend; some units are composites (e.g. olivine clinopyroxenite and clinopyroxenite). The intrusion is entirely fault-bounded, and the large area of hornblende-rich lithologies with associated felsic rocks in the west is mostly interpreted from both airborne and ground geophysics, as well as information from drill holes. The N i - sulphide-mineralized zones (Horsetrail and satellite zones) are outlined in white ovals. Sample locations with spinel chemistry discussed in this paper are indicated as white stars. the southeastern part o f the intrusion, both northwest and southeast o f the Turnagain R ive r (Figure 3.1). Chromite is common in the more magnesian ol iv ine-r ich cumulates and magnetite is typical o f the more evolved, clinopyroxene/hornblende-bearing lithologies that comprise the west-central portion o f the intrusion. This part is considered to represent the roof o f the intrusion and contains porphyritic, megacrystic, and pegmatoidal textured rocks and appears to intrude the underlying ol ivine cumulate rocks based on an interpretation o f aeromagnetic data and diamond dr i l l hole results (courtesy o f Hard Creek N i c k e l Corp.) . In the section below, the typical abundances and textures o f spinel in rocks o f the Turnagain intrusion are described. 3.3.1 Dunite Dunite, the most abundant rock type in the Turnagain intrusion, is pr imari ly composed o f cumulus ol ivine and chromite wi th minor interstitial clinopyroxene (<10 vo l .%) and rare phlogopite (0-1 vo l .%) . Equigranular ol ivine is typical o f most dunite; however, local post- crystallization deformation has produced dunite wi th porphyroclastic textures. O l iv ine grain- size ranges from 2 m m in fine-grained equigranular dunite to 10 m m in porphyroclastic dunite. K i n k bands, observed as discrete undulatory extinction bands in individual ol ivine grains, and irregular grain boundaries are also observed. Serpentinization o f ol ivine in dunite is common, ranging from none to nearly complete, although the average amount o f serpentinization is - 1 0 % . Secondary magnetite is common between ol ivine grains. Chromite in dunite can be found as chromitite schleiren, pods, lamellae, and rarely as layers (max. 5 c m thick) (Figure 3.2). Chromite grain sizes are typical ly the largest in chromitite (up to 3 mm) and slightly smaller in dunite (up to 2 mm), and grain shapes are equigranular to euhedral (Figure 3.3; A and B ) . Ol iv ine may be encased wi th in chromitite, but more commonly ol ivine grains are only partially surrounded by chromite and are present near the edge o f the chromitite. Dunite typical ly contains up to 4 v o l . % disseminated euhedral to subhedral chromite (Figure 3.3 C ) both included wi th in ol ivine and along grain boundaries between ol iv ine crystals, although 2 v o l . % is the typical abundance. Secondary alteration has resulted in the formation o f magnetite r ims (~30 um thick) as overgrowths on chromite, and in some cases a 'ferritchromit ' r im (Cr- r ich magnetite) has been produced (Figure 3.3D). Ferritchromit, wi th no directly defined composit ion (e.g. Kanaris-Sot i r iou et al., 1978; Zakrzewski , 1989; Takashi & A d a c h i , 1995), is a term broadly used for C r - and A l - r i c h Figure 3.2: Photographs of chromitite in outcrop from the north-central portion of the Turnagain intrusion. A) Chromitite schleiren, grading into dunite towards the lower part of the photograph. Cross-cutting veins are fdled with serpentine minerals. Pencil is approximately 12 cm long. B) Numerous chromitite schleiren, which may represent disrupted layers, within dunite. Hammer is approximately 50 cm long. 63 0 Srp „ 0 1 # , Figure 3.3: Photomicrographs of chromite textures from chromitite and dunite in the Turnagain intrusion. The white scale bar on each photo is 200 um in length. A) Reflected light, sample 05ES-01-01-01, cluster 5. The large central chromite grain lies within a thin chromitite seam enclosed in dunite consisting of olivine (01) and secondary serpentine (Srp). Note the polygonal shapes of the chromite grains. B) BSE (backscattered electron) image, sample 05ES-01-01-01, cluster 4. Massive chromitite showing equigranular grain shapes produced during slow cooling and recrystallization. A small chalcopyrite (Cpy) inclusion is found in a chromite grain in the bottom right of the photograph. C) BSE image, sample 04ES-10-05-01, cluster 2. This cluster, within a partially serpentinized dunite, shows the primary euhedral nature of the chromite grains as well as the initial development of a thin magnetite rim (bright material on edge of grains). D) Reflected light, sample 04ES-08-01-01. Note the sulphide inclusion in the centre of a chromite grain. The inclusion originally consisted of an immiscible sulphide liquid that crystallized into pyrrhotite (Po) and pentlandite (Pn); note that the habit of the sulphide inclusion is determined by its host chromite grain. The distinct rim around the chromite grain is 'ferritchromit' produced during serpentinization. 64 magnetite, or Fe -r ich chromite, r ims observed on cumulus chromite (and rarely as entire grains) in serpentinized ultramafic rocks, wh ich appear to be overgrowths rather than alteration products (Roeder et al., 2001). The thickness o f these rims appears to depend on factors such as posit ion wi th respect to ol ivine, cl inopyroxene, and degree o f serpentinization. Since clinopyroxene is only rarely affected by serpentinization, chromite grains wi th in or partially encased by clinopyroxene typical ly do not show secondary overgrowths/rims. 3.3.2 Wehrlite Cumulus ol ivine and interstitial clinopyroxene are the dominant phases in wehrlite from the Turnagain intrusion; however, rare cumulus diopsidic clinopyroxene may occur. O l iv ine grain size is comparable to that in dunite (2 mm), although equigranular textures are less common and only occur in clinopyroxene-poor rocks. Ol iv ine contained, either partially or entirely, wi th in large clinopyroxene oikocrysts is typical ly rounded. Porphyroclastic textures are rarely observed in wehrlite, and clinopyroxene is typical ly interstitial to ol ivine porphyroclasts and neoblasts. Cumulus clinopyroxene is commonly finer grained than neighbouring ol iv ine , wi th grain sizes ranging from 75 um in diameter up to 2 m m in some samples. Serpentine minerals replace only ol ivine in wehrlites, and secondary magnetite is common along silicate grain boundaries. Chromite, typical ly - 1 5 0 um in diameter, in wehrlite is ubiquitous, is always disseminated, and is less abundant than in dunite (Figure 3.4; A and B ) . Wehrlite-hosted chromite grains are typical ly concentrated in specific areas, or clusters, and chromite grains in wehrlite tend to exhibit subhedral and anhedral habits. The majority o f chromite grains are included in ol ivine or along ol ivine-ol ivine or ol ivine-cl inpyroxene grain boundaries, wi th rare examples included in interstitial clinopyroxene. Magnetite and ferritchromit rims are as common in wehrlite as those described in dunite. 3.3.3 Olivine Clinopyroxenite This l i thology is typical ly composed o f variable amounts o f cumulus ol iv ine and clinopyroxene, although a few samples contain significant oikocrystic clinopyroxene (Figure 3.4C). This latter type o f ol ivine clinopyroxenite commonly contains more chromite than ol ivine clinopyroxenite where both the silicate minerals are cumulus (see Discussion). O l iv ine grain size (-1 mm) is significantly smaller compared to ol ivine in wehrlite and dunite and Figure 3.4: Photomicrographs of chromite textures from wehrlite and olivine clinopyroxenite in the Turnagain intrusion. The scale bar on each photo is 200 urn in length. A) BSE image, sample 04ES-10-06-01, cluster 5. This strongly serpentinized wehrlite contains few chromite grains and those present show well-developed magnetite/ ferritchromit rims, as well as a magnetite aureole (localized, very fine-grained magnetite). B) BSE image, sample 04ES-15-01-05, cluster 1. Small, euhedral chromite grains between cumulus olivine grains with little to no magnetite rim. Note the presence of fine-grained magnetite along grain boundaries between cumulus minerals and within fractures. C) Reflected light, sample 04ES-01-04-01, cluster 5. Cumulus olivine with abundant interstitial clinopyroxene (olivine clinopyroxenite). D) BSE image, sample 05ES-05-01-01, cluster 7. This grain is one of only two grains found in the entire thin section, which is a common feature of many Alaskan-type olivine clinopyroxenites. This small chromite grain is entirely encased within cumulus clinopyroxene. 66 clinopyroxene grains reach up to 15 m m across. The size o f the two cumulus silicate phases in ol ivine clinopyroxenite appears to be directly proportional to their modal abundance (i.e. an ol ivine clinopyroxenite wi th 60 v o l . % clinopyroxene w i l l generally have an equigranular texture, whereas an ol ivine clinopyroxenite wi th 90 v o l . % clinopyroxene w i l l have significantly larger clinopyroxene and very small ol ivine) . O l iv ine in ol ivine-poor clinopyroxenite is typical ly strongly serpentinized. Chromite in ol ivine clinopyroxenite is typical ly found as inclusions wi th in cumulus clinopyroxene or ol ivine, is never interstitial to the silicate minerals, and rarely contains secondary magnetite rims (Figure 3.4; C , D ) . Gra in sizes are typical ly small , around 150 um, and chromite is commonly euhedral (Figure 3.4D). Chromite abundance is significantly reduced (<0.5 vo l .%) compared to wehrlite. Chromite in ol ivine clinopyroxenite wi th intercumulus clinopyroxene, or clinopyroxene oikocrysts, is commonly very similar in texture and size to chromite found in both dunite and wehrlite. 3.3.4 Hornblende Clinopyroxenite and Hornblendite Hornblende clinopyroxenite and hornblendite occur in two distinct settings wi th in the Turnagain intrusion. The first setting is as fine-grained dikes that are interpreted to represent evolved magma compositions. Some o f these hornblendite dikes intrude a pendant o f wal l rock in the northwestern part o f the intrusion (Figure 3.1). Hornblende-bearing rocks, some o f wh ich are cumulate, also occur in the west-central portion o f the intrusion. Hornblendite dikes commonly contain subhedral ilmenite, whereas hornblende-rich lithologies o f the western portion o f the Turnagain intrusion typical ly contain primary magnetite (Figure 3.5). Al though its occurrence is l imited, magnetite may be found as local accumulations in hornblende- clinopyroxene-rich lithologies wi th grains reaching up to 1 c m across. Magnetite is typical ly much larger than chromite (about 5 times larger), and is subhedral to anhedral. Some grains appear intergrown (Figure 3.5B) and ilmenite oxy-exsolution is common. 3.4 ANALYTICAL TECHNIQUES The spinel content o f each sample, textural relationships to other phases, and relative degree o f alteration were carefully scrutinized using both transmitted and reflected light microscopy prior to analysis. Samples were selected to represent the various rock types found in the Turnagain intrusion and the range o f spinel morphologies and spinel-silicate associations 67 Figure 3.5: Photomicrographs of magnetite textures from sample DDH04-47-7-49, a hornblende clinopyroxenite from the western zone of the Turnagain intrusion. The scale bar on each photo is 200 um in length. A) Cluster 3. This cluster contains large magnetite grains with oxy-exsolved lamellae of ilmenite (Ilm) and larger composite grains of ilmenite (internal and external) that are interpreted to represent granule exsolution. B) Cluster 7. Composite magnetite grain (at least 8 separate grains) with oxy-exsolved lamellae of ilmenite and larger composite granule exsolution blebs along grain boundaries. 68 described above. Some samples contained appreciable spinel, such that local accumulations o f larger spinel grains were referred to as "clusters". Chromite grains from three different clusters were analyzed in each thin section. A total o f 16 samples were selected for microprobe analysis, carbon-coated, and documented using a Phi l ips X L - 3 0 scanning electron microscope at the Univers i ty o f Br i t i sh Columbia , Vancouver , B C . Quantitative analyses were carried out in wavelength-dispersion mode using a Cameca S X - 5 0 electron microprobe wi th a beam diameter o f 10 um, an accelerating voltage o f 15 k e V , and a beam current o f 20 n A wi th 20 s peak count-time and 10 s background count-time. The N i contents o f chromite grains from chromitite samples were analyzed using a fixed matrix, a beam diameter o f 10 pm, an accelerating voltage o f 15 k e V , and a beam current o f 200 n A wi th peak count-time extended to 100 s and a background time to 50 s. Fo r the elements considered, the fo l lowing standards, X - r a y lines and crystals were used: synthetic rhodonite, MnKa, L I F ; diopside, CaKa, P E T , and SiKa, T A P ; synthetic spinel, AlKa, T A P ; synthetic fayalite, VeKa, L I F ; synthetic magnesiochromite, MgATa, T A P , and CrKa, L I F ; rutile, TiKa, P E T ; V metal, VKa, P E T ; synthetic N i 2 S i 0 4 , ~NiKa, L I F . Data reduction o f a l l analytical results was undertaken using the " P A P " <(>(pZ) procedure o f Pouchou & Pichoi r (1985). U s i n g the higher beam current and counting times for N i as described above results in an analytical precision o f <5% relative. A total o f 360 points were analyzed in this study, 25 o f wh ich were magnetite analyses. Individual grains, prior to analysis, had their selected point locations ordered from r im to core. In the case o f grains on the edge o f chromitite schlieren, the part o f the grain closest to a neighbouring silicate was analyzed first, as opposed to the grain boundary in contact wi th other chromite. A l l spinels were assumed to be stoichiometric (Kamperman et al., 1996) and cation abundances and ferrous/ferric iron were calculated using the method o f Barnes and Roeder (2001). This method isolates T i and V into an ulvospinel component and is considered the most accurate calculation technique for cations in spinel-group minerals. 3.5 RESULTS Table 3.1 contains representative chromite and magnetite analyses from the various ultramafic lithologies and the complete set o f spinel analyses from this study are presented in Append ix I. B e l o w , the variations in spinel chemistry are described for spinels from each o f the major rock types o f the Turnagain intrusion. Table 3.1a: Representative spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Chromitite Dunite Dunite Dunite Wehrlite Sample: 05ES-01 -04-01 04ES-19-01-02 04ES-03-02-01 04ES-08-01-01 04ES-11-03-03 Cluster: 6 2 5 2 4 Grain Number: 1 1 1 1 2 Style: I. anh. s. anh. I. sub. s. eu. m. sub. Zone: Core Mid Rim Core Mid Rim Core Mid Rim Core Mid Rim Core Mid Rim Oxides (wt. %) S i 0 2 0.00 0.00 0.00 0.02 0.06 0.03 0.02 0.01 0.08 0.03 0.03 0.05 0.00 0.00 0.01 T i0 2 0.22 0.28 0.22 0.79 0.94 0.76 0.47 0.51 0.02 0.52 0.54 0.53 1.35 1.28 1.26 A l 2 0 3 5.94 5.81 5.07 8.98 8.99 8.73 6.72 5.72 0.02 7.35 7.28 7.47 10.23 10.26 10.47 C r 2 0 3 62.86 63.01 65.24 54.58 54.66 54.61 50.24 42.89 0.57 46.49 46.40 44.81 44.37 44.27 43.31 v 2o 3 0.05 0.01 0.02 0.10 0.14 0.18 0.07 0.08 0.02 0.07 0.09 0.06 0.32 0.30 0.30 FejOj 5.82 5.70 3.82 4.71 4.31 5.15 13.72 20.56 68.76 15.97 15.98 16.75 11.65 11.95 13.03 FeO 11.78 11.64 11.22 22.75 22.84 23.24 21.46 23.84 29.45 22.94 22.81 22.94 26.10 26.05 26.18 MnO 0.00 0.05 0.04 0.34 0.32 0.42 0.25 0.48 0.14 0.22 0.22 0.24 0.31 0.34 0.40 MgO 14.14 14.18 14.19 7.12 7.17 6.86 7.79 5.75 0.93 6.84 6.90 6.64 5.54 5.53 5.50 NiO 0.17 0.17 0.13 - - - - - - - - - - - - CaO 0.01 0.01 0.00 0.01 0.03 0.00 0.01 0.00 0.01 0.02 0.01 0.00 0.01 0.00 0.01 Total 100.99 100.85 99.96 99.42 99.46 99.99 100.74 99.84 99.99 100.46 100.26 99.48 99.87 99.97 100.45 Cations (p.f.u.) Ti 0.005 0.007 0.006 0.020 0.024 0.019 0.012 0.013 0.000 0.013 0.014 0.014 0.035 0.033 0.032 Cr 1.615 1.621 1.695 1.472 1.472 1.469 1.351 1.184 0.017 1.260 1.259 1.227 1.202 1.198 1.167 AJ 0.228 0.223 0.196 0.361 0.361 0.350 0.270 0.234 0.001 0.297 0.295 0.305 0.413 0.414 0.420 V 0.001 0.000 0.000 0.002 0.003 0.004 0.002 0.002 0.000 0.002 0.002 0.001 0.007 0.007 0.007 Fe-"* 0.142 0.140 0.094 0.121 0.110 0.132 0.351 0.550 1.977 0.412 0.413 0.436 0.300 0.308 0.334 Fe'** 0.320 0.317 0.308 0.649 0.651 0.661 0.610 0.701 0.941 0.657 0.655 0.664 0.748 0.746 0.746 Mn 0.000 0.001 0.001- 0.010 0.009 0.012 0.007 0.015 0.005 0.006 0.006 0.007 0.009 0.010 0.012 Mg 0.685 0.688 0.695 0.362 0.364 0.348 0.395 0.298 0.053 0.349 0.353 0.343 0.283 0.282 0.279 Ni 0.004 0.004 0.004 - - - - - - - - - - - - Ca 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 Total 3.001 3.001 3.001 2.998 2.995 2.997 2.998 2.999 2.995 2.998 2.998 2.997 2.997 2.997 2.997 Trivalent End Members Cr/Z3+ 0.814 0.817 0.854 0.753 0.757 0.753 0.685 0.601 0.009 0.640 0.640 0.623 0.628 0.624 0.607 AI/Z3+ 0.115 0.112 0.099 0.185 0.186 0.179 0.137 0.119 0.000 0.151 0.150 0.155 0.216 0.216 0.219 Fe/I3+ 0.072 0.070 0.048 0.062 0.057 0.068 0.178 0.280 0.991 0.209 0.210 0.222 0.157 0.160 0.174 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (sm< Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each secti o Table 3.1b: Representative spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehrlite Wehrlite Olivine Clinopyroxenite Olivine Clinopyroxenite Hornblende Clinopyroxenite Sample: 04ES-16-08-01 04ES-10-06-01 04ES-06-06-01 05ES-05-01-01 DDH04^t7-7-49 Cluster: 6 1 4.5 8 5 Grain Number: 3 2 2 1 1 Style: s. eu. m. anh. m. anh. s. eu. I. anh. Zone: Rim Mid Mid Core Mid Rim Core Mid Mid Core Mid Rim Core Mid Rim Oxides (wt. %) S i 0 2 0.01 0.03 0.04 0.00 0.03 0.03 0.02 0.00 0.01 0.03 0.00 0.03 0.03 0.03 0.03 T i0 2 1.03 1.05 1.01 0.89 0.94 0.11 1.02 0.98 0.84 2.51 2.48 2.42 3.27 3.11 0.35 A l 2 0 3 7.99 7.85 8.01 11.86 12.00 0.03 8.35 8.61 8.25 4.64 4.44 4.18 2.27 0.95 0.16 C r 2 0 3 49.53 50.34 49.73 42.92 42.33 4.83 48.48 48.60 46.95 28.34 27.45 26.90 0.13 0.14 0.13 v 2 o 3 0.08 0.08 0.08 0.16 0.20 0.00 0.22 0.24 0.25 0.11 0.08 0.07 0.46 0.45 0.73 F e ^ 11.56 11.46 11.60 13.33 13.34 64.67 10.11 9.68 11.33 30.20 31.67 32.01 59.94 61.20 67.39 FeO 20.19 19.79 19.79 24.21 24.16 28.70 26.30 26.26 25.75 25.09 25.31 25.19 34.04 33.80 31.82 MnO 0.18 0.25 0.26 0.30 0.37 0.35 0.41 0.35 0.78 4.07 3.92 3.87 0.26 0.23 0.02 MgO 8.88 9.22 9.11 6.70 6.68 1.43 4.92 4.96 4.70 3.08 2.98 2.79 0.46 0.24 0.15 NiO - - - - - - - - - - - - - - - CaO 0.00 0.01 0.00 0.01 0.00 0.00 0.01 0.01 0.03 0.17 0.26 0.34 0.03 0.02 0.01 Total 99.45 100.09 99.64 100.39 100.05 100.17 99.85 99.69 98.90 98.24 98.60 97.80 100.90 100.17 100.78 Cations (p.f.u.) Ti 0.026 0.027 0.026 0.023 0.024 0.003 0.027 0.026 0.022 0.069 0.068 0.067 0.092 0.089 0.010 Cr 1.329 1.340 1.329 1.140 1.127 0.145 1.330 1.333 1.303 0.821 0.795 0.787 0.004 0.004 0.004 Al 0.320 0.311 0.319 0.470 0.476 0.002 0.342 0.352 0.341 0.200 0.192 0.182 0.100 0.043 0.007 V 0.002 0.002 0.002 0.004 0.005 0.000 0.005 0.005 0.006 0.003 0.002 0.002 0.011 0.011 0.018 F e " * 0.295 0.290 0.295 0.337 0.338 1.846 0.264 0.253 0.299 0.833 0.873 0.891 1.687 1.751 1.929 Fe~* 0.573 0.557 0.560 0.680 0.681 0.910 0.763 0.762 0.756 0.769 0.775 0.779 1.064 1.074 1.012 Mn 0.005 0.007 0.007 0.009 0.011 0.011 0.012 0.010 0.023 0.126 0.122 0.121 0.008 0.008 0.001 Mg 0.449 0.463 0.459 0.336 0.335 0.081 0.255 0.257 0.246 0.168 0.163 0.154 0.026 0.014 0.008 Ni Ca 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.007 0.010 0.014 0.001 0.001 0.001 Total 2.999 2.998 2.997 2.998 2.997 2.998 2.997 2.998 2.997 2.997 2.999 2.998 2.993 2.994 2.990 Trivalent End Members Crffi3+ 0.684 0.690 0.684 0.586 0.581 0.073 0.687 0.688 0.670 0.443 0.428 0.423 0.002 0.002 0.002 AI/X3+ 0.164 0.160 0.164 0.241 0.245 0.001 0.176 0.182 0.176 0.108 0.103 0.098 0.056 0.024 0.004 Fe/£3+ 0.152 0.150 0.152 0.173 0.174 0.926 0.136 0.130 0.154 0.449 0.469 0.479 0.942 0.974 0.994 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (sm; Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each secti 3.5.1 Chromitite Although volumetrical ly minor in the Turnagain intrusion, chromitite is petrologically important. Chromite grains from chromitites are characterized by the most C r - and M g - r i c h compositions o f a l l lithologies ( C r 2 0 3 = 59-67 wt.%, M g O = 10-14 wt.%) wi th correspondingly low T i 0 2 (0.24-0.66 wt.%), V 2 0 3 (0.01-0.34 wt.%), A 1 2 0 3 (4.60-7.14 wt.%), and F e 2 0 3 (3.82-6.88 wt.%) contents (Figures 3.6-3.7). T w o samples (05ES-01-03-01 and 05ES-01-04-01) contain relatively N i - r i c h chromite grains ( N i O = 0.13-0.20 wt.%). A l l chromite analyses from chromitite are distinguished by F e 3 + / ( F e 3 + + C r + A l ) <0.1 (Figure 3 .7A) . There is no iron-enrichment trend present in the chromite analyses from chromitites indicating that their compositions l ike ly record primary spinel compositions and that they have not been modified by subsolidus or post-magmatic processes (see Discussion). 3.5.2 Dunite Chromite analyses from dunite span a relatively large range in composit ion ( C r 2 0 3 = 34-56 wt.%, T i 0 2 = 0.01-1.01 wt.%, F e O = 20-29 wt.%, F e 2 0 3 = 3.5-18.6 wt.%) compared to chromite from chromitites (Figure 3.6-3.7). W i t h the exception o f sample 04ES-19-01-02, spinel analyses from each dunite sample show an overall iron-enrichment trend (Figure 3 .7A) , wh ich is a common feature o f Alaskan-type intrusions (Barnes & Roeder, 2001). A l l F e 3 + - r i c h spinel compositions from dunite represent analyses o f magnetite/ferritchromit rims around chromite grains and are associated wi th serpentine-group mineral replacement o f o l iv ine . Analyses o f spinel grains from sample 04ES-19-01-02 have Fe 3 + / (Fe 3 + +Cr+Al )<0 .1 , similar to those from the chromitites described above. 3.5.3 Wehrlite Similar to the dunite samples, chromite analyses from wehrlite in the Turnagain intrusion show a wide compositional range (Figures 3.6-3.7) and are relatively enriched in A 1 2 0 3 (7.5- 15.4 wt.%), T i 0 2 (0.7-1.8 wt.%) and F e 2 0 3 (10-18 wt.%). Magnetite and ferritchromit compositions, whi le rare, are nonetheless present and indicate that similar post-secondary process occurred in both wehrlite and dunite. Chromite analyses from one wehrlite sample (04ES-15-01-05) have markedly low F e 3 + / ( F e 3 + + C r + A l ) compared to the above wehrlites (Figure 3.6). The compositions o f chromite from this sample have the lowest F e 2 0 3 (0.94-3.97 wt.%) o f a l l spinel analyses from the Turnagain intrusion, and relatively low C r / C r + A l (0.68- Figure 3.6: Chromite compositional ternary diagrams. A) Trivalent cation (Fe3+-Cr-Al) plot of all Turnagain spinel compositions. All samples are represented by sample number. Chromites plot in the lower 40% of the diagram with the exception of magnetite rim analyses, which plot at or near the Fe3 + apex, and ferritchromit analyses, which plot in the intermediate part of the diagram. B) Ternary diagram (Mg-Fe2+-Fe3+) of all Turnagain spinel compositions. 0.9 0.8 0.7 <0.6 O + A 0.5 0 ,0.4 0.3 0.2 0.1 Chromitite • 05ES-01-01-01 • 05ES-01-04-01 • 05ES-01-03-01 Dunite • 04ES-19-01-02 • 04ES-08-01-01 O04ES-10-05-01 • 04ES-03-02-01 Wehrlite • 04ES-10-06-01 • 04ES-11-03-03 • 04ES-15-01-05 • 04ES-16-05-01 Ol cpxite A04ES-06-06-01 A04ES-01-04-01 A04ES-05-01-01 Hbl cpxite DDH04-47-7-49 XDDH05-84-19-104 magnetite "ferritchromit" O o chromitites 0.2 0.4 0.6 0.8 Fe2+/(Fe2++ Mg) 0.9 h 0.8 r 0.7 0.6 < t P 0.5 0.4 0.3 0.2 0.1 0.2 0.4 0.6 0.8 Fe2+/(Fe2++ Mg) Figure 3.7: Binary plots of spinel compositions from the Turnagain intrusion represented by sample number. These plots are projections of the spinel prism (Irvine, 1965). A) Fe2+/(Fe2++Mg) (Fe#) vs. Fe3+/(Fe3++Cr+Al), or divalent vs. trivalent cation plot. A distinct Fe-enrichment trend exists for most Turnagain chromite compositions, a typical feature of Alaskan-type intrusions, with the exception of chromite grains from the chromitites and other chromite grains with Fe3+/(Fe3++Cr+Al) <0.1. B) Fe# vs. Cr/Cr+Al. Chromite grains from the chromitites have significantly lower Fe2+/(Fe2++Mg) compared to other spinel analyses. Magnetite analyses are not plotted due to their very low Cr and Mg contents. 0.73), high T i 0 2 (1.1-2.5 wt.%), and high V 2 0 3 (0.06-0.38 wt.%). In terms o f their trivalent cation abundances (Figure 3 .6A), chromite compositions from individual wehrlite samples, wi th the exception o f the above sample, are characterized by intermediate sloping trends in terms o f trivalent cations (decreasing C r , increasing F e 3 + and A l ) . Chromite compositions from sample 04ES-15-01-05 plot in the field o f the " C r - A l trend" o f Barnes and Roeder (2001) and l ike ly reflect the effect o f exchange wi th Al-bear ing clinopyroxene (see Discussion). 3.5.4 Olivine Clinopyroxenite M o s t ol ivine clinopyroxenite sampled in the Turnagain intrusion, and indeed in other Alaskan- type intrusions (Irvine, 1965), is devoid o f chromite. A few samples o f ol ivine clinopyroxenite from the Turnagain intrusion contain chromite, however the nature o f the grains (small sizes, l ow abundances) appears to have al lowed for more extensive subsolidus to post-magmatic compositional modifications compared to spinel grains from the previously described rock types. Chromite grains from ol ivine clinopyroxenite are relatively enriched in F e O (23-27 wt.%>), F e 2 0 3 (9.7-17.2 wt.%), T i 0 2 (0.9-2.1 wt.%) and V 2 0 3 (0.22-0.54 wt.%), and depleted in A 1 2 0 3 (5.68-9.40 wt.%) compared to analyses from the other rock types. One notable exception is sample 04ES-01-04-01, where the spinel grains are characterized by Fe 3 + / (Fe 3 + +Cr+Al)<0 .1 (Figure 3.7), and overlap wi th the analyses from the dunite sample 04ES-19-01-02. Spinel analyses from sample 05ES-05-01-01 are also distinct wi th high amounts o f T i 0 2 (2.5-3.2 wt.%) and Fe 3 + / (Fe 3 + +Cr+Al)>0 .4 (Figure 3 .7A, 3 .8A) , wh ich indicates that a l l analyzed grains are ferritchromit in composit ion. This sample contains small (150 um) chromite grains entirely encased wi th in cumulus diopside (Figure 3.4H), thus the ferritchromit composit ion o f the spinels in this sample is l ike ly the result o f subsolidus reequilibration wi th the hosting clinopyroxene. W i t h respect to trivalent cations, chromite grains from ol ivine clinopyroxenite do not show the strong intrasample variations as seen in the dunites and wehrlites. 3.5.5 Hornblende Clinopyroxenite In Alaskan-type intrusions, liquidus magnetite generally begins to crystallize after an extended period o f clinopyroxene saturation and after the cessation o f chromite crystallization. Chromite ceases to crystallize shortly after clinopyroxene saturation because C r is compatible in clinopyroxene (e.g. Irvine, 1965; F indlay , 1969; H i l l & Roeder, 1974; Clark , 1978). Analyses 75 4.0 3.5 3.0 2.5 e.2.0 CM o p 1.5 1.0 r 0.5 Chromitite • 05ES-01-01-01 • 05ES-01-04-01 • 05ES-01-03-01 Dunite • 04ES-19-01-02 • 04ES-08-01-01 O04ES-10-05-01 • 04ES-03-02-01 Wehrlite • 04ES-10-06-01 • 04ES-11-03-03 • 04ES-15-01-05 • 04ES-16-0&O1 Ol cpxite A04ES-06-06-01 A04ES-01-04-01 A04ES-05-01-01 Hbl cpxite DDH04-47-7-49 XDDH06-84-19-104| A X X X X 0.025 0.020 0.015 a. 6 x B X X X X X X 0.2 0.4 0.6 0.8 Fe3+/(Fe3++ Cr + Al) Ti (c.p.f.u.) Figure 3.8: Binary plots of spinel compositions from the Turnagain intrusion. A) Fe3+/(Fe3++Cr+Al) vs. Ti0 2. Spinel analyses from the Turnagain intrusion show a wide range of Ti contents. Note that both magnetite-bearing samples plot parallel to the Y-axis at almost constant Fe3+#. Coupled increases (positive trends) are indicative of re-equilibration with interstitial melt, while increasing Fe3+ without increasing Ti is indicative of serpentinization. B) Ti vs. V. Most samples are characterized by nearly vertical trends with the exception of magnetite from DDH04-47-7-49. Note the V-enrichment of magnetite from sample DDH05-84-19-104. o f spinel from two cumulus magnetite-bearing hornblende clinopyroxenites, both from drillcore, show contrasting compositions. Spinel from sample D D H 0 5 - 8 4 - 1 9 is nearly pure end-member magnetite ( F e 2 0 3 = 67.1-67.8 wt.%, C r 2 0 3 = 0.37-0.60 wt.%, A 1 2 0 3 = 0.06-0.18 wt.%), whereas magnetite from sample D D H 0 4 - 4 7 - 4 9 shows slight A l enrichment ( A 1 2 0 3 = 0.12-3.77 wt.%) and relative V enrichment ( V 2 0 3 = 0.22-0.73 wt.%), and exhibits relatively high T i 0 2 (0.15-4.0 wt.%) (Figure 3.8). 3.6 DISCUSSION 3.6.1 Primary Spinel Compositions Although spinel is an extremely sensitive petrogenetic indicator in igneous rocks, the composit ion o f primary spinel grains may be changed or reset by syn- and post-magmatic processes (e.g. Roeder & Campbel l , 1985, Power et al., 2000). In particular, reequilibration wi th interstitial melt and/or hosting silicate minerals and serpentinization can significantly change the composit ion o f spinel (e.g. Roeder & Campbel l , 1985; Sack & Ghiorso, 1991; Scowen et al., 1991; Roeder, 1994; M e l i n n i et al., 2005). A n important observation from this study is that spinel grains from chromitite schleiren, wisps, pods, and layers have the most C r - r ich , A l - and Fe 3 + -poor , and lowest Fe# compositions in the Turnagain intrusion (Figures 3.6- 3.7), suggesting that they represent primary or near primary compositions. Chromite grains in the chromitites d id not significantly interact wi th the hosting ol ivine or interstitial melt and thus preserved the highest temperature spinel compositions that crystall ized from the most primit ive (highest M g O ) magmas. Chromitite sample 05ES-01-04-01 contains chromite w i th the lowest Fe# (0.30-0.35) consistent wi th the primary nature o f these grains. In Figure 3.9, chromite analyses from most o f the dunite, wehrlite, and ol ivine clinopyroxenite samples plot along vectors that converge towards the field o f each o f the chromitite compositions, wh ich indicates that the compositions closest to the chromitite field have undergone the least amount o f re-equilibration. The proximity o f dunite, wehrlite, and ol ivine clinopyroxenite chromite compositions to those from chromitite samples, coupled wi th the region o f C r - A l - F e space where sample-specific compositional vectors intersect, is consistent wi th derivation from a primary magma composit ion similar to that wh ich precipitated the chromitites. Chromitite Dunite Wehrlite Ol cpxite ^ 0 5 E S - 0 1 - 0 1 - 0 1 • 0 4 E S - 1 9 - 0 1 - 0 2 • 04ES-10-06-01 A04ES-06-06-01 • 05ES-01-04-01 •04ES-08 -01 -01 • 04ES-11-03-03 A04ES-01-04-01 • 05ES-01 -03-01 O04ES-10-05-01 • 04ES-15-01 -05 • 04ES-03-02-01 •04ES-16 -05 -01 Figure 3.9: Trivalent cation (Fe3+-Cr-Al) plot of Turnagain spinel compositions, focusing on those compositions nearest end-member chromite (inset in upper left shows entire ternary diagram). No rim compositions are plotted. Chromite grains from chromitites plot near the Cr-apex, whereas all compositions from wehrlites plot systematically to more Al-rich compositions than spinel grains from dunite. Note the wehrlite (04ES-15-01-05) and olivine clinopyroxenite (04ES-01-04-01) samples with anomalously low Fe3+ and high Al contents. Arrows indicate trends of spinel compositions from individual samples. Note the direction of trends (some arrows trend almost directly towards the Fe3+ apex, whereas others trend towards increased Al and Fe3+), which explained by different reequilibration processes, and that all trends converge towards the area of the chromitite analyses. 3.6.2 Re-equilibration Trends A l l chromite grains, except those from the chromitites, have undergone substantial compositional modification at high temperatures during cool ing and interaction wi th evolved interstitial melt, enclosing silicates, or ox id iz ing fluids. The intersample change o f chromite Fe# from chromitite to other lithologies at near-constant F e 3 + , as exhibited by specific samples in Figures 3.6, 3.7, and 3.9, is l ike ly the result o f olivine+chromite fractionation - o l iv ine depletes the melt in M g during crystallization and chromite depletes the melt in C r such that co-precipitating chromite w i l l have progressively higher Fe# and lower C r / A l . The spinel trends wi th intermediate slopes on Figure 3.9, wh ich contains only core and intermediate posit ion analyses (no rims)mostly from wehrlite and ol ivine clinopyroxenite, converge towards the chromitite field and exhibit intrasample variations toward higher A l and F e 3 + w i th increasing Fe#. These trends can be explained by equilibration wi th evolved interstitial melt: the melt wi th wh ich these chromite grains were in contact (either directly or by diffusion through olivine) was l ike ly relatively r ich in C a , A l , T i , and Fe . A l though the compositions o f some samples in this trend may be related to their crystall ization from a fractionated l iquid , the dunite sample that parallels them d id not and thus exhibits compositions related to re- equilibration wi th trapped melt. Chromite compositions wi th Fe 3 + / (Fe 3 + +Cr+Al )>0 .1 , wh ich also exhibit an increase in Fe# (Figure 3.7), appear to have been modified by subsolidus re- equilibration wi th enclosing or enveloping ol ivine and by ox id iz ing fluids. The chromite compositions from dunites 04ES-03-02-01 and 04ES-08-0T-01 overlap in the C r - A l - F e 3 + ternary (Figure 3.9), extending parallel to the Cr -Fe j o i n but are distinct wi th respect to Fe# (Figure 3 .7A) . M o s t o f the spinel grains in these two samples occur along ol iv ine grain boundaries, not inside ol iv ine , and the increase in F e 3 + / ( C r + A l + F e 3 + ) can be attributed to oxidation by fluids that local ly precipitated magnetite (but d id not involve serpentinization). The increase o f chromite Fe# is the result o f the exchange o f F e 2 + from ol ivine to chromite during cool ing; the spinel grains from these two dunite samples do not show enrichments in A l or T i , thus the trend towards lower Fe# is best explained by exchange wi th ol ivine, in the absence o f interstitial melt. The unusual spinel compositions from wehrlite sample 04ES-15- 01-05 and ol ivine clinopyroxenite sample 04ES-01-04-01 - relatively high A l / C r and low F e 3 + - may be attributed to their silicate mineralogy. These samples contain cumulus ol ivine and chromite surrounded by 2 cm-diameter Cr - r i ch (see Chapter 4) clinopyroxene oikocrysts. The volume ratio o f clinopyroxene to chromite is approximately 50:1, such that the significant compositional changes exhibited by the chromite in these two samples is only weakly reflected in the hosting clinopyroxene. 3.6.3 Compositional Effects of Serpentinization on Spinel Chemistry Magnetite and ferritchromit rims around chromite grains in many rocks from the Turnagain intrusion were formed during serpentinization. These rims, where wide enough to analyze wi th a 10 um electron beam, exhibit compositions distinct from the primary spinel compositions in the chromitites and the high-temperature re-equilibrated compositions previously documented (Figure 3.9). The chromite analyses from dunite, wehrlite, and ol ivine clinopyroxenite samples that plot near the F e 3 + apex in Figure 3 .6A are nearly pure magnetite in composit ion and l ike ly reflect nucleation o f magnetite around pre-existing chromite during serpentinization. Ferritchromit rims are recognized by individual spot analyses that plot further towards the C r - F e 3 + j o i n than their respective intrasample chemical trends (e.g. 04ES-10-05-01; Figure 3.9). 3+ These ferritchromit rims are characterized by lower Cr , slightly lower A l , and higher Fe compared to other analyses and reflect the Fe-r ich and Cr-poor nature o f the serpentinizing fluids from wh ich these rims formed. It is unclear whether ferritchromit r ims are products o f nucleation or reaction wi th serpentinizing fluids. However , some samples exhibit both ferritchromit and magnetite rims (e.g. 04ES-03-02-01), suggesting that ferritchromit represents a reaction product between magnetite-saturated serpentinizing fluids and chromite wi th a core- to-rim order o f formation o f chromite —> ferritchromit —> magnetite. 3.6.4 Implications for the Redox State of the Turnagain Intrusion The low F e 3 + content o f chromite grains from the chromitites in the Turnagain intrusion (Clark, 1978) is consistent wi th a l ow F e 3 + / F e 2 + ratio (i.e. relatively l ow oxygen fugacity) in the parental magma (e.g. Parkinson & Arcu lus , 1999). However , most Alaskan-type intrusions appear to have formed from relatively oxidized arc magmas, wi th calculated A F M Q (log units o f oxygen relative to the fayalite-magnetite-quartz synthetic buffer) values between +1 to +3.5 (e.g. Ballhaus et al, 1991; Carmichael , 1991; Rohrbach et al, 2005). Under such oxidized conditions, sulphur w i l l be dominantly dissolved as S O 2 , SO3, or SO4 " rather than sulphide ( S 2 ) and the magmas w i l l not saturate in an immiscible sulphide l iquid unless they are reduced t o 7 O 2 values below F M Q (Jugo et al, 2004; 2005). The presence o f significant amounts o f sulphide in the Turnagain intrusion indicates that the magmas achieved sulphide saturation and therefore the oxygen fugacity was substantially lower than that typical for other Alaskan-type intrusions (e.g. Garuti et al., 2003). In Figure 3.10, an expanded v i ew o f the C r - A l - F e 3 + ternary, a l l chromite compositions from this study are plotted by li thology, wi th the data density maxima (50% and 90%) o f chromite compositions from other Alaskan-type intrusions from Barnes & Roeder (2001). The majority o f chromite compositions from the Turnagain intrusion lie to lower F e 3 + values than the established compositional fields. The compositions from chromitites contain significantly less F e 3 + than other chromite compositions and higher C r / A l , wh i ch suggests that the chromitites crystall ized from magmas wi th a lower oxygen fugacity than the parental magmas o f other Alaskan-type intrusions. The low F e 3 + f ield for other Alaskan-type intrusions on Figure 3.10 may represent compositions that result from re- equilibration wi th clinopyroxene as observed in this study. Al though not shown on Figure 3.10, chromite compositions from chromitite in the Turnagain intrusion plot w e l l wi th in the boninite field (see Barnes & Roeder, 2001), wh ich may indicate that the magmas parental to the Turnagain intrusion also originated from a mantle previously depleted by partial melt ing. Decompression melt ing at back-arc ridges segregates Pt alloys in the residue (lithospheric mantle) which , i f remelted by slab-derived fluids, w o u l d generate a Pt-r ich basaltic melt (Kepezhinskas & Defant, 2001; Batanova et al., 2005). The remelting o f a Pt-enriched, previously depleted mantle, in a subduction zone setting may explain why many Alaskan-type intrusions are relatively enriched in Pt (Green et al., 2004; Batanova et al., 2005). Inclusions o f phyll i te are observed in dril lcore from the sulphide-mineralized zones o f the Turnagain intrusion (Chapter 4) and reduction o f the Turnagain parental magmas was l ike ly achieved by the local assimilation o f this graphitic, pyri t ic phyll i te (Chapter 2 and 4). Ass imi la t ion o f the pyrite-bearing phylli te also contributed additional S to the magma, thus i n c r e a s i n g a n d a l lowing for early sulphide saturation. The relatively reducedJO2 o f the Turnagain parental magmas not only lead to early sulphide saturation, but resulted in the crystallization o f Fe -poor chromite as represented by the chromitites. Chromite compositions from chromitites, therefore, may represent a possible reconnaissance exploration tool for assessing the relative redox state o f parental magmas to ultramafic rocks where only ol iv ine is co-crystal l izing, and thus may be used as an indicator o f the potential for magmatic sulphide mineralization in Alaskan-type intrusions. Figure 3.10: Trivalent cation (Fe3+-Cr-Al) plot of Turnagain chromite compositions (inset in upper left shows entire ternary diagram). All samples are distinguished by lithology. Chromite compositions from the Turnagain intrusion are overlain by the data density maxima for other Alaskan-type intrusions from the compilation of Barnes & Roeder (2001). The 50% field is coloured dark grey (50% of all Alaskan-type spinel data plot within this field) and the 90% percent field is shaded light grey. In general the Turnagain spinel compositions have significantly lower Fe3+ and high Cr/(Cr+Al)relative to other Alaskan-type spinels, which is consistent with relatively low oxygen fugacity of the parental magmas of the Turnagain intrusion. 82 3.7 CONCLUSION The principal results o f this study on spinel compositions in ultramafic rocks from the Turnagain Alaskan-type intrusion are 1) primary spinel compositions are relatively Fe 3 + -poor and Cr - r i ch compared to published results from other Alaskan-type intrusions, especially chromite from chromitite, 2) chromites from dunite, wehrlite and ol ivine clinopyroxenite exhibit intrasample trends that can be related to a variety o f processes, including ol iv ine fractionation, re-equilibration wi th interstitial melt, re-equilibration wi th coexisting silicate phases, oxidation, and serpentinization, 3) most intrasample re-equilibration trends can be interpolated to originate from the field o f spinel compositions from chromitites, suggesting that a l l lithologies in the Turnagain intrusion crystall ized from a similar parental magma, and 4) chromite compositions from chromitite are extremely Fe 3 + -poor , indicating their crystallization from a magma characterized by a relatively l ow oxygen fugacity compared to other Alaskan-type intrusions. The reduced nature o f the parental magmas, attributed to the assimilation o f graphitic and pyrit ic country rocks, appears to have promoted local sulphide saturation. Therefore the F e 3 + content o f chromite from chromitites may be used as a reconnaissance exploration tool for assessing the relative redox state and sulphide mineralization potential o f Alaskan-type intrusions. 3.8 A C K N O W L E D G E M E N T S W e w o u l d l ike to thank M a t i Raudsepp at the Universi ty o f Br i t i sh Co lumbia for use o f the electron microprobe and support during the research phase o f this manuscript, as w e l l as Carol ine-Emmanuelle Morisset at the Pacif ic Centre for Isotopic and Geochemical Research, Univers i ty o f Br i t i sh Columbia , for her input into this manuscript. The authors are grateful to Hard Creek N i c k e l Corp . for continued field support for this project and to J i m Reed o f Pacif ic Western Helicopters for his exemplary logistical support in the field. Special thanks to Tony Hitchins , Bruce Northcote, Chris Baldys , and M a r k Jarvis (President) o f Hard Creek N i c k e l Corp . for their generous support and interactions throughout the period o f the pr incipal author's M . S c . thesis at U B C . Funding for this project was provided by a research grant from Hard Creek N i c k e l Corp . (formerly Canadian Metals Explora t ion Ltd . ) . 3.9 R E F E R E N C E S Ballhaus, C , Berry , R . F . , & Green, D . H . (1991). H i g h pressure experimental calibration o f the olivine-orthopyroxene-spinel oxygen geobarometer: implications for the oxidation state o f the upper mantle. Contributions to Mineralogy and Petrology 107 (1), 27-40 Barnes, S.J., & Roeder, P . L . (2001). The range o f spinel compositions in terrestrial mafic and ultramafic rocks. Journal of Petrology 42 (12), 2279-2302 Batanova, V . G . , Pertsev, A . N . , Kamenetsky, V . S . , A r i s k i n , A . A . , Mocha lov , A . G . , & Sobolev, A . V . (2005). Crustal evolution o f island-arc ultramafic magma: Galmoenan pyroxeni te - dunite plutonic complex, K o r y a k High land (Far East Russia). Journal of Petrology 46, 1345-1366 Carmichael , I .S .E . (1991). The redox states o f basic and si l ic ic magmas: a reflection o f their source regions? Contributions to Mineralogy and Petrology 106, 129-141 Clark , T . (1975). Geology o f an ultramafic complex on the Turnagain River , northwestern B . C . ; unpublished P h D thesis, Queen's University, 454p. Clark , T. (1978). Oxide minerals in the Turnagain ultramafic complex, northwestern Br i t i sh Columbia . Canadian Journal of Earth Sciences 15, 1893-1903 Clark , T . (1980). Petrology o f the Turnagain ultramafic complex, northwestern Br i t i sh Co lumbia . Canadian Journal of Earth Sciences 17, 744-757 D i c k , J .B . , & Bu l l en , T . (1984). Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contributions to Mineralogy and Petrology 86, 54-76 Erdmer, P. , Miha lynuk , M . G . , Gabrielse, H . , Heaman, L . M . , & Creaser, R . A . (2005). Miss iss ippian volcanic assemblage conformably over lying Cordi l leran miogeocl inal strata, Turnagain R ive r area, northern Br i t i sh Columbia , is not part o f an accreted terrane. Canadian Journal of Earth Sciences 42, 1449-1465 Findlay , D . C . (1969). Or ig in o f the Tulameen ultramafic-gabbro complex, southern Br i t i sh Columbia . Canadian Journal of Earth Sciences 6, 399-425 Foster, F . (1974). His tory and origin o f the Polaris ultramafic complex in the A i k e n Lake area o f north-central Br i t i sh Co lumbia ; unpublished B . S c . thesis, University of British Columbia, 66p. Gabrielse, H . (1998). Geology o f C r y Lake and Dease Lake map areas, north-central Br i t i sh Co lumbia ; Geological Survey of Canada, Bu l l e t in 504, 147p Garuti, G., Pushkarev, E.V., Zaccarini, F., Cabella, R., & Anikina, E. (2003). Chromite composition and platinum-group mineral assemblage in the Uktus Uralian-Alaskan-type complex (Central Urals, Russia). Mineralium Deposita 38, 312-326 Green, D.H., Schmidt, M.W., & Hibberson, W.O. (2004). Island-arc ankaramites: primitive melts from fluxed refactory lherzolitic mantle. Journal of Petrology 45, 391-403 Hill , R., & Roeder, P. (1974). The crystallization of spinel from basaltic liquid as a function of oxygen fugacity. Journal of Geology 82, 709-729 Irvine, T.N. (1965). Chromian spinel as a petrogenetic indicator. Part I. Theory. Canadian Journal of Earth Sciences 2, 648-672 Irvine, T.N. (1967). Chromian spinel as a petrogenetic indicator. Part II. Petrological applications. Canadian Journal of Earth Sciences 4, 71-103 Jugo, P.J., Luth, R.W., & Richards, J.P. (2004). Experimental data on the speciation of sulfur as a function of oxygen fugacity in basaltic melts. Geochimica et Cosmochimia Acta 69 (2), 497-503 Jugo, P.J., Luth, R.W., & Richards, J.P. (2005). An experimental study of the sulfur content in basaltic melts saturated with immiscible sulfide or sulfate liquids at 1300°C and 1.0 GPa. Journal of Petrology 46 (4), 783-798 Kamenetsky, V.S., Crawford, A.J., & Meffre, S. (2001). Factors controlling chemistry of magmatic spinel: An empirical study of associated olivine, chrome-spinel and melt inclusion from primitive rocks. Journal of Petrology 42 (4), 655-671 Kamperman, M . , Danyushevsky, L.V. , Taylor, W.R., & Jablonski, W. (1996). Direct oxygen measurements of Cr-rich spinel: Implications for spinel stoichiometry. American Mineralogist SI, 1186-1194 Kanaris-Sotiriou, R., Gibb, G.F., Carswell, D.A., & Curtis, C D . (1978). Trace-element distribution and ore formation in vein-metasomatised peridotite at Kalskaret, near Tafjord, South Norway. Contributions to Mineralogy and Petrology 67, 289-295 Kepezhinskas, P., & Defant, M.J. (2001). Nonchondritic Pt/Pd ratios in arc mantle xenoliths: Evidence for platinum enrichment in depleted island-arc mantle sources. Geology 29, 851- 854 Krause, J., Brugmann, G.E., Pushkarev, E.V. (2007). Accessory and rock forming minerals monitoring the evolution of zoned mafic-ultramafic complexes in the Central Ural Mountains. Lithos 95, 19-42 Mellini, M . , Rumori, C , & Viti, C. (2005). Hydrothermally reset magmatic spinels in retrograde serpentinites: formation of "ferritchromit" rims and chlorite aureoles. Contributions to Mineralogy and Petrology 149, 266-275 Nixon, G.T., Hammack, J.L., Ash, C.H., Cabri, L.J., Case, G., Connelly, J.N., Heaman, L . M . , Laflamme, J.H.G., Nuttall, C , Paterson, W.P.E., & Wong, R.H. (1997). Geology and platinum-group-element mineralization of Alaskan-type ultramafic-mafic complexes in British Columbia. Geological Survey of British Columbia Bulletin 93, 141p. Nixon, G.T. (1998). Ni-sulphide mineralization in the Turnagain Alaskan-type complex: A unique magmatic environment. B. C. Ministry of Energy, Mines and Petroleum Resources Paper 1998-1, 18-1 - 18-12 Parkinson, I.J., & Arculus, R.J. (1999). The redox state of subduction zones: insights from arc- peridotites. Chemical Geology 160, 409-423 Pouchou, J.L., & Pichoir, F. (1985): PAP <f>(pZ) procedure for improved quantitative microanalysis. Microbeam Analysis, 1985, 104-106. Poustovetov, A.A. , & Roeder, P.L. (2000). The distribution of chromium between basaltic melt and chromian spinel as an oxygen geobarometer. Canadian Mineralogist 39, 309-317 Power, M.R., Pirrie, D., Anderson, J.C.0., & Wheeler, P.D. (2000). Testing the validity of chrome spinel as a provenance and petrogenetic indicator. Geology 28 (11), 1027-1030 Roach, T A . , Roeder, P.L., & Hulbert, L.J. (1998). Composition of chromite in the upper chromitite, Muskox layered intrusion, North West Territories. Canadian Mineralogist 36, 117-135 Roeder, P.L., & Campbell, I.H. (1985). The effect of postcumulus reactions on composition of chrome-spinels from the Jimberlana intrusion. Journal of Petrology 26 (3), 763-786 Roeder, P.L., & Reynolds, I. (1991). Crystallization of chromite and chromium stability in basaltic melts. Journal of Petrology 32 (5), 909-934 Roeder, P.L. (1994). Chromite: from the fiery rain of chondrules to the Kilauea Iki lava lake. Canadian Mineralogist 32, 729-746 Roeder, P.L., Poustovetov, A.A. , & Oskarsson, N . (2001). Growth forms and composition of chromian spinel in MORB magma: diffusion-controlled crystallization of chromian spinel. Canadian Mineralogist 39, 397-416 Rohrbach, A . , Schuth, S., Ballhaus, C , Munker , C , Matveev, S., & Qopoto, C . (2005). Petrological constraints on the or igin o f arc picrites, N e w Georgia Group, Solomon Islands. Contributions to Mineralogy and Petrology 149, 685-698 Sack, R . O , & Ghiorso, M . S . (1991). Chromite as a petrogenetic indicator. Minera log ica l Society o f A m e r i c a - Reviews in Mineralogy 25, 323-354 Scowen, P . A . H . , Roeder, P . L . , & H e l z , R . T . (1991). Reequil ibration o f chromite wi th in Ki l auea Iki lava lake, H a w a i i . Contributions to Mineralogy and Petrology 107, 8-20 Takashi , A . , & A d a c h i , M . (1995). Ilvaite from a serpentinized peridotite in the A s a m a igneous complex, M i k a b u greenstone belt, Sambagawa metamorphic terrain, central Japan. Mineralogical Magazine 59, 489-496 Zakrzewski , M . A . (1989). Chromian spinels from Kusa , Bergslagen, Sweden. American Mineralogist 74, 448-455 88 C H A P T E R 4 PETROLOGY AND METALLOGENY OF THE TURNAGAIN ALASKAN-TYPE INTRUSION AND ASSOCIATED NI-SULPHIDE MINERALIZATION 4.1 INTRODUCTION Alaskan-type intrusions are synonymous wi th Ural ian-Alaskan-type and zoned ultramafic intrusions. The term "Ural ian-Alaskan- type" originates from the two largest concentrations o f these intrusions, in the U r a l Mountains (n>15) o f Russia (Taylor, 1967) and in southeastern A l a s k a (n=39) (Himmelberg & Loney , 1995). These intrusions are pr imari ly composed o f o l iv ine- and clinopyroxene-rich cumulate rocks and may contain appreciable hornblende- and/or feldspar-bearing lithologies. M a n y o f these intrusions are associated wi th island arcs and they are only rarely observed in other tectonic environments (e.g. Konder , Inagli, Chad, and Sibakh complexes; Johan, 2002). Alaskan-type intrusions in the U r a l Mountains (Garuti et al, 2003), in Co lumbia and Ecuador (Tist l , 1994), Br i t i sh Co lumbia (Findlay, 1969), A l a s k a (Himmelberg and Loney , 1995), and Austra l ia (Barron et al, 1991) have been associated wi th past and present placer platinum-group metal ( P G M ) min ing operations. O n l y a few Alaskan- type intrusions contain appreciable sulphide mineralization, including Salt Chuck, A l a s k a (Loney et al, 1987; Loney & Himmelberg , 1992), Duke Island, A l a s k a (Thakurta et al, 2004), and Turnagain, Br i t i sh Co lumbia (Clark, 1975; N i x o n , 1998). The Turnagain Alaskan-type intrusion is a fault-bounded ultramafic intrusion (3.5 x 8 km) composed predominantly o f dunite and wehrlite wi th minor amphibole-bearing phases, wh ich are cross-cut by intermediate to felsic intrusions and dikes. There are two distinct styles o f mineralization in the Turnagain intrusion: (1) Ni-(Cu)-sulphide mineralization that occurs in the most magnesian rock types (dunite and wehrlite) wi th minor local platinum-group element ( P G E ) enrichment, and (2) microscopic crystals o f sperrylite (PtAs2) and stibiopalladinite (PdsSb2) o f probable hydrothermal origin, wh ich was discovered in 2004 wi th in hornblende- clinopyroxene lithologies. Ni-sulphide was first discovered in 1956 along the Turnagain R ive r and the property was staked by Falconbridge (Clark, 1975). In the 1990s, the property was acquired by Bren -Mar Resources (now Hard Creek N i c k e l Corporation) and is actively being explored today. The historic N i - r i c h sulphide showing, the Horsetrail Zone, has been extensively dr i l led wi th over 100 diamond dr i l l holes. Other showings and prospects in the intrusion have been explored as we l l and the current N i resource (measured and indicated) is 428 M t grading 0.17% N i (http://www.hardcreeknickel.com), wh ich represents an increase o f 200% from the 2005 estimate. This study focuses on the petrology and geochemistry o f the Turnagain intrusion to better constrain the emplacement and crystall ization o f magmas that formed the intrusion, and to assess the origin of Ni-sulphide mineralization in this Alaskan-type intrusion. As part of recent mineral exploration by Hard Creek Nickel Corp., the entire intrusion has been systematically remapped and resampled. New field and petrographic observations, mineral and whole-rock chemistry (including platinum-group elements), and S and Pb isotopes in sulphide separates are presented in an effort to determine the processes responsible the genesis of the Turnagain intrusion and its localized Ni-sulphide mineralization. 4.2 G E O L O G Y OF T H E T U R N A G A I N INTRUSION 4.2.1 Regional Geology The 28 km2 Turnagain intrusion is located approximately 70 km east of Dease Lake, British Columbia, in the Omineca Belt (Figure 4.1). This belt is composed of accreted terranes, including Quesnellia, Cache Creek, Slide Mountain, and Yukon-Tanana. The Turnagain intrusion is situated on the eastern edge of Quesnellia and structurally overlies lithologies currently assigned to Ancestral North America, which are Cambrian to Mississippian in age and consist of steeply-dipping graphitic, variably pyritic slates and phyllites of the Road River Group (Gabrielse, 1998) that contain interbeds of marble and tuff. Phyllites flank the eastern, northern, and western edges of the Turnagain intrusion, which is entirely fault-bounded. There is no observed hornfelsing of the surrounding phyllite. The contact between ultramafic rocks and phyllite was observed in numerous drillholes (e.g. DDH03-07, DDH06-158) and, although it is intensely talc-carbonate altered, original fabrics may be locally preserved. Post-intrusive deformation, exhibited by faulting and shearing, in both the Turnagain intrusion and the surrounding phyllites, grades from minor to intense generally in a WNW direction. The steeply-dipping phyllites were likely faulted along pre-existing cleavage, although local quartz-cemented phyllite breccia has been observed at the ultramafic-country rock contact in recent drill holes. A weakly metamorphosed volcanic wacke has been observed in both outcrop and drillcore to the south of the Turnagain intrusion. This unit, considered to correlate with the hornfels unit in the northwestern part of the intrusion (Figure 4.1), has also been correlated to a similar unit to the southeast of the Turnagain intrusion (Erdmer et al., 2005). Surface exposure of the Turnagain intrusion is generally poor (~20% of the total surface area is exposed) and much of the outcrop occurs in the northern third of the intrusion above treeline in the alpine region (Figure 4.2). The Horsetrail Zone contains scattered outcrops exposing most of the major lithologies, and other rare outcrops are found along the 91 B Intrusion Centre: X 58°29'N, 128°52'W Volcanic wacke Dunite, with minor wehrlite Wehrlite, with minor dunite and olivine clinopyroxenite Olivine clinopyroxenite and clinopyroxenite, undivided Hornblende clinopyroxenite, with minor clinopyroxenite Hornblendite and clinopyroxene hornblendite, undivided Diorite, quartz diorite, and granodiorite, undivided Hornfels, sedimentary or volcanic protolith - j — Reverse fault, observed -j Normal fault, inferred _ ^ Fault (relative sense of motion indicated) "Cr S isotopic sample locality * Whole rock geochemical sample locality Geological contact, observed Geological contact, inferred — — • Fault, inferred — — Reverse fault, inferred ^—^— (Listric?) Fault, observed Figure 4.1: A) Simplified geological map of the Turnagain Alaskan-type intrusion showing major lithologies, structures, and sample locations for whole rock geochemistry and sulphide sulphur and lead isotopic compositions. Note that some lithologies are composites (e.g. olivine clinopyroxenite). Also shown are the main mineralized zones (from W to E): Northwest Zone, greater Horsetrail Zone (including Silesia to the south, and Fishing Rock to the east), Hatzl Zone, Cliff Zone, Duffy Zone, and Highland Zone. The inset in the upper right comer shows a map of British Columbia with the location of the Turnagain intrusion, and other major Alaskan- type intrusions in B.C. and Alaska. B) Interpreted cross-section (Z-Z') through the Turnagain intrusion, with all major lithologies, structures and contacts indicated. 92 Figure 4.2: Photographs of dunite exposures in the Turnagain intrusion. A ) Photograph of the resistant dunite core in the alpine region (view to the northwest). B) Photograph showing the extensive exposures of dunite in the highest elevations of the alpine region (view to the northwest). C) Photograph of a ridge of dunite, looking to the southwest from the top of the hornfels (volcanic wacke) knob in the northwest corner of the intrusion. The lack of outcrop beyond this ridge coincides with a magnetic-low anomaly. D) Photograph of the dunite core from within a long valley in the northern part of the intrusion, looking southeast. The small ridge (just visible in the lower left-hand corner) is primarily composed of wehrlite. The valley is filled with talus and runs parallel to the northern-bounding fault of the intrusion. Turnagain River . The southern and western areas o f the Turnagain intrusion are completely covered by 5-15 m o f t i l l , wheras east o f the Turnagain R ive r much o f the intrusion is covered wi th up to 50 m o f glaciofluvial gravels. Contacts between lithologies in the northern region o f the Turnagain intrusion are generally observed, whereas most contacts in and around the Horsetrail Zone are inferred from dr i l l core. Contacts in the western and southern areas are inferred from airborne and ground geophysics as w e l l as recent d r i l l core. The current geological map for the Turnagain intrusion, wh ich is continuously updated based on results from new dr i l l ing in relatively unknown areas, is largely based on the efforts o f Cla rk (1975) and N i x o n (1998). The original mapping and petrographic investigations o f Cla rk (1975; 1978; 1980) lead to a wealth o f fundamental information about the Turnagain intrusion. Subsequent investigations by N i x o n et al. (1989) and N i x o n (1998) focused on the origin o f the Turnagain intrusion wi th respect to regional geological interpretations, as w e l l as the or ig in o f associated Ni-(Cu)-sulphide and platinum-group element ( P G E ) mineralization. 4.2.2 Ultramafic Rocks 4.2.2.1 Dunite and Chromitite W i t h the exception o f hornblendite and diorite, the majority o f the rocks exposed in the Turnagain intrusion are dominated by cumulus ol iv ine and/or clinopyroxene. Dunite is volumetrical ly the most important l i thology in the Turnagain intrusion and occurs in outcrop throughout the alpine regions o f the intrusion, but is also observed in a l l major outcroppings in the Horsetrail Zone and the C l i f f Zone (northeastern corner o f the intrusion, Figure 4.1). Dunite weathers to a buff colour that is especially apparent in the alpine exposures (Figure 4 .2B, Figure 4.3.1 A ) . M o s t dunite is composed o f large amounts o f o l iv ine (>90 vo l .%) wi th small amounts o f interstitial clinopyroxene, disseminated chromite, and local ly interstitial phlogopite. Ol iv ine grain size in dunite is commonly ~1 m m (Figure 4.4.1 A ) , however ol ivine as large as 2 c m across or larger has been observed. Uncommonly large ol ivine occurs in association wi th much smaller ol ivine (<1 mm) in a porphyroclastic texture, wh ich is interpreted to represent the product o f high strain at high temperature. O l iv ine (~1 cm) wi th irregular grain boundaries, as w e l l as parting, has also been observed in samples from the alpine area or in associated dunite below treeline (Figure 4 .4 . IB) . Disseminated chromite is commonly 200-300 p m in diameter, exhibits euhedral to subhedral habits, and may have magnetite or ferritchromit overgrowths (Chapter 3). Chromite can also contain polyphase Figure 4.3.1: Photographs of outcrop-scale features in the Turnagain intrusion. A) Disrupted chromitite schleiren in alpine dunite. Hammer is 50 cm long. B) Olivine clinopyroxenite in alpine area with two cross- cutting dunite "dikes". Hammer is 30 cm long. C) Wehrlite showing atypical differential weathering of olivine (buff) and interstitial clinopyroxene (grey). Pencil is 12 cm long. D) Modal banding in wehrlite in the northwestern alpine region. Hammer is 30 cm long. 95 Figure 4.3.2: Photographs of outcrop-scale features in the Turnagain intrusion (continued). E) Modal banding in wehrlite, represented by alternating modal abundances of clinopyroxene (grey) and olivine (buff). Pencil is 12 cm long. F) Thick band (~1 m) of olivine clinopyroxenite (grey) within wehrlite (brown). Hammer is 30 cm long. G) Two olivine clinopyroxenite dikes (grey) cutting dunite (brown) parallel to the eastern dunite-olivine clinopyroxenite contact in the northwest. The photograph was taken 2 m east of the contact. H) Olivine clinopyroxenite dike swarm, cutting dunite, at the termination of exposure. This dike swarm originates from the easternmost dunite-olivine clinopyroxenite contact and is continuous for over 100 m. Hammer is 30 cm long. Figure 4.4.1: Photomicrographs (transmitted light, crossed-polarizers) of silicate mineral textures in the Turnagain intrusion. Scale bars (solid white bars) on all photos are 1 mm in length. A) Dunite (04ES-19-01-03) showing typical annealed texture (120° grain boundary intersections). Small black dots are disseminated chromian spinel. Note the large difference in size between individual olivine grains. B) Dunite (04ES-06-01-01) showing strong parting in olivine and irregular grain boundaries. C) Oikocrystic clinopyroxene in wehrlite (04ES-15-05-04). Note the well-preserved euhedral crystal faces of some olivine grains. D) Wehrlite (05ES-05-05-01) exhibiting large (1 mm) and small (<200 urn) olivine grains, as well as small to medium (300 um) cumulus clinopyroxene grains. Figure 4.4.2: Photomicrographs (transmitted light, crossed- polarizers) of silicate mineral textures in the Turnagain intrusion (continued). Scale bars (solid white bars) on all photos are 1 mm in length. E) Olivine clinopyroxenite (04ES-10-02-03) with abundant cumulus clinopyroxene and rarely-preserved olivine (mostly serpentinized). Note the core of an olivine in the upper-middle-left of the photograph with a serpentine margin. F) Fine-grained hornblendite dike (04ES-20-11-01) with randomly-oriented amphibole grains. Not visible at this scale are small crystals of titanite along amphibole grain boundaries. G) Diorite (DDH04-57-12.89.2) with large (cumulus) plagioclase grain. H) Diorite (DDH04-57-12-89.2) with large twinned, euhedral (cumulus), amphibole grain. silicate inclusions or sulphide inclusions. Chromiti te, observed in dunite from the alpine region o f the intrusion (Figure 4.3.1 A ) , is sparsely distributed and occurs as wisps, bands, rare layers, pods, and schleiren. It commonly contains coarser chromite than dunite, up to 1 m m in some cases, and is almost completely unimodal (99% chromite). The irregular distribution and habit o f chromite in the chromitites suggests that these rocks were disrupted or deformed at high temperatures fo l lowing crystallization. Dunite has been observed to cross-cut other ultramafic lithologies or the Turnagain intrusion, especially rocks that are spatially close to the alpine dunite. Dunite and ol ivine clinopyroxenite are local ly juxtaposed together in the northwestern part o f the intrusion (Figure 4.1), wi th no fault or obvious intrusive relationship, wh ich may indicate the presence o f primary igneous layering. However , in the above example, ~3 cm-wide dunite dikes were observed cutting the ol ivine clinopyroxenite (Figure 4 .3 . IB) . Continuous dikes (over 100 m) o f ol ivine clinopyroxenite (up to 10 c m wide) have also been observed cutting dunite (Figure 4 .3 .2G, H ) . Cla rk (1975) noted deformation o f igneous layering at the contact wi th dunite in the northwestern part o f the Turnagain intrusion. Serpentinized dunite is common near major faults, although dunite typical ly contains only minor amounts (~10 vo l .%) o f serpentine minerals. A l p i n e dunite commonly contains small fractures filled wi th green, slickensided serpentine, and dunite from other parts o f the intrusion is black due to an abundance o f secondary magnetite. B l a c k serpentine also contains traces o f elemental carbon, graphite, and local ly sulphide. Lizardi te (green, well-foliated) is the most common serpentine mineral. Crysoti le (fibrous and white) is only rarely found associated wi th serpentine veins/slips, and antigorite (massive meshes o f interlocking needles) is generally only found in the Horsetrail Zone. 4.2.2.2 Wehrli te M o s t exposures o f wehrlite occur in the northwestern alpine region o f the Turnagain intrusion (Figure 4.1), around/within the Horsetrail Zone, and in the C l i f f Zone. Phlogopite from a wehrlite in the Ha tz l zone (far southeastern edge o f the intrusion) was dated at 189±1.3 M a by A r - A r geochronology (see Chapter 2 for details). T w o types o f wehrlite occur in the Turnagain intrusion. The most common type is composed o f cumulus ol ivine (1-5 mm) and interstitial clinopyroxene (Figure 4 .3 . IC) . It typical ly weathers to a light brown colour and is easily distinguished from dunite in alpine exposures. L o c a l l y , clinopyroxene forms oikocrysts 99 up to 2 c m wide (Figure 4 .4 . IC) . Wehrli te also contains disseminated chromite (50-150 pm) and rare interstitial phlogopite. The other type o f wehrlite contains what is interpreted to represent cumulus clinopyroxene (Figure 4 .3 . ID , 4.3.2E) and occurs in exposures in the northwestern part o f the intrusion as w e l l as in exposures east o f the Turnagain R i v e r ( C l i f f Zone) (Figure 4.1). This cumulus clinopyroxene has an elongate, prismatic habit and is typical ly finer-grained than coexisting ol ivine, about 200 pm in diameter (Figure 4 .4 . ID) , although local ly clinopyroxene up to 3 m m in length can occur. Wehrli te dikes have been observed to cross-cut dunite. Bo th types o f wehrlite commonly contain abundant serpentine (up to 85 vo l .%) replacing ol ivine. 4.2.2.3 Ol iv ine Clinopyroxenite and Clinopyroxenite Ol iv ine clinopyroxenite and commonly pegmatitic clinopyroxenite are exposed in the northwestern part o f the Turnagain intrusion (Figure 4.1) (clinopyroxenite is rarely exposed elsewhere and is generally only observed in dril lcore). Interlayered ol ivine clinopyroxenite and wehrlite/dunite have been observed in recent dril lcore from east o f the Turnagain River , however layering is typical ly absent from outcrop exposures. Pegmatitic clinopyroxenite is observed as dikes that cross-cut dunite and wehrlite, and has also been observed in the northwest as segregations, presumably representing trapped volat i le-r ich residual melt, wi th in ol ivine clinopyroxenite. M o s t ol ivine clinopyroxenite in the Turnagain intrusion is composed o f cumulus ol ivine and clinopyroxene (both ~2 m m in diameter) wi th minor amounts o f fine- grained interstitial clinopyroxene. Ol iv ine clinopyroxenite weathers grey in colour wi th small ol ivine grains weathering to a buff colour. L o c a l l y , modal banding has been observed (Figure 4.3.2F). A few examples o f ol ivine clinopyroxenite occur without cumulus clinopyroxene (e.g. sample 05ES-02-01-01) and instead contain cumulus ol ivine wi th in oikocryt ic clinopyroxene (Figure 4 .4 . IC) . Chromite is rare in ol ivine clinopyroxenite (see Chapter 2). Where present, chromite is fine-grained (<150 pm) and is commonly encased in cumulus clinopyroxene. Chromite in ol ivine clinopyroxenite also does not exhibit significant secondary magnetite growth on the rims o f grains, as observed in dunites and wehrlites. Dikes o f o l iv ine clinopyroxenite and clinopyroxenite have been observed cross-cutting both wehrlite and dunite, and local ly biotite occurs along the contacts. These dikes are commonly pegmatitic, and one such example contains clinopyroxene crystals up to 20 cm in length. O l iv ine is 100 typical ly completely serpentinized in ol ivine clinopyroxenite (Figure 4.4.2E), although unaltered cores may be preserved. Magnetite clinopyroxenite, an intermediate rock type between ol ivine clinopyroxenite and hornblende clinopyroxenite, has only been observed in drillcore from the east-central portion o f the intrusion (Figure 1). Magnetite clinopyroxenite exhibits two types o f magnetite: (1) cumulus (primary) magnetite crystals up to 5 m m in diameter coexisting wi th coarse (1-3 c m in length) clinopyroxene, and (2) round blebs o f intergrown serpentine and secondary magnetite (up to 3 cm) in a matrix o f small diopside crystals (~1 mm). Cumulus magnetite may exhibit modal banding and is interpreted to be comagmatic wi th its hosting clinopyroxene. The magnetite-serpentine blebs from the second type o f magnetite clinopyroxenite are interpreted to represent clasts o f dunite that were brecciated during the intrusion o f their host clinopyroxenite. 4.2.2.4 Hornblende Clinopyroxenite Al though outcrops o f hornblende clinopyroxenite are scarce, it comprises a major portion ( -10% o f the surface area) o f the Turnagain intrusion. M u c h o f the hornblende clinopyroxenite in the intrusion occurs in the west-central portion o f the intrusion in an area cal led the D J - D B Zone, wh ich is a zone that is prospective for P G E mineralization (Figure 4.1). However a prominent dike-l ike body (1.2 k m long x 15 m wide), exposed at the southern margin o f the interbanded wehrlite and ol ivine clinopyroxenite in the northwest, provides the best exposure (Figure 4.1). Unweathered hornblende clinopyroxenite is generally porphyritic in texture and contains bright grey-green, equant clinopyroxene (1-4 c m long) and interstitial black amphibole (up to 2 c m long). Some samples contain abundant interstitial biotite, up to 35 v o l . % . Magnetite crystals, typical ly 7 m m up to 1 c m in diameter, occurs in about 2 0 % o f a l l hornblende clinopyroxenite. L o c a l l y , magnetite in hornblende clinopyroxenite represents 5 vol.%) o f the rock. Examples o f this rock type in the D J - D B Zone are commonly pegmatitic, consisting o f large (up to 10 cm wide) equant clinopyroxene and abundant interstitial amphibole. Al though typical ly unaltered, large amounts (up to 85 vo l .%) o f secondary brown amphibole were noted in hornblende clinopyroxenite adjacent to the large block o f hornfels in the southern D J zone (DDH05-84 ) . 4.2.2.5 Hornblendite Hornblendite in the Turnagain in trusion is poorly exposed but makes up about 20 v o l . % o f the ultramafic lithologies. Hornblendite may contain coarse, equant clinopyroxene or interstitial plagioclase, and rarely biotite. There are three types o f hornblendite present in the Turnagain intrusion. The first type is megacrystic to pegmatitic (with crystals up to 5 cm in length) and found in the D J - D B Zone in the west-central portion o f the intrusion. The other two types contain abundant (50-60 vo l .%) cumulus amphibole, up to 1 c m in width , and 10-20 v o l . % cumulus amphibole, respectively, wi th fine-grained interstitial hornblende matrices (<50 pm). Hornblendite commonly grades into hornblende clinopyroxenite or feldspathic hornblendite, wh ich contains sub-rounded plagioclase grains 3-10 m m in length, rarely wi th irregular grain boundaries, wi th in a matrix o f hornblende crystals up to 2 cm long. Examples o f hornblendite containing minor amounts o f clinopyroxene are observed to have either porphyritic clinopyroxene surrounded by coarse-grained hornblende (1-2 cm in length) or oikocrystic hornblende encasing fine (2 mm) clinopyroxene. Exposures o f hornblendite are rare, and the most accessible outcrop o f hornblendite is found as a splay o f unknown length off the above mentioned hornblende-rich ' d ike ' (Figure 4.1). This 30 cm-wide splay is characterized by fine- grained anhedral amphibole (Figure 4.4.2F) and intrudes the metasedimentary block in the northwest. Sample 04ES-00-07-04 from this dike was dated using both A r - A r (amphibole) and U - P b (titanite) methods, and the obtained ages from this sample are 189±1.4 M a and 190.3±4.6 M a , respectively (see Chapter 2). Alterat ion in amphibole-bearing lithologies is distinct from that observed in olivine-bearing rocks in the Turnagain intrusion. A l though minor, alteration minerals in hornblendite include chlorite and epidote after amphibole, chlorite after clinopyroxene and plagioclase, and sericite after plagioclase. 4.2.3 Other Rocks 4.2.3.1 Dior i te Dior i te covers 10% o f the exposed surface area in the Turnagain intrusion and occurs mainly in the central part o f the intrusion (Figure 4.1). Al though this unit is referred to as diorite, the central occurrence is actually a mixture o f diorite, quartz diorite, and minor granodiorite, and contains an outer margin (-10 m thick) wi th significant amphibole (up to 95 v o l . % ) . This margin may be easily confused for hornblendite (Clark, 1975). However , the presence o f cumulus/porphyritic plagioclase helps to distinguish diorite from feldspathic hornblendite. It is 102 common for diorite to contain brecciated clasts o f dunite, wehrlite, and ol ivine clinopyroxenite. In general, diorite contains 75 v o l . % amphibole, 20 v o l . % plagioclase, and minor amounts o f quartz, biotite, apatite, and z i rcon. A n outcrop o f diorite from the northern margin o f the central body (sample 04ES-00-07-01), near the contact wi th dunite, yielded a U - Pb (zircon) min imum age o f 189.2±0.6 M a (see Chapter 2). Dior i te also occurs as thin (5-20 c m in width) dikes that are observed to intrude the more magnesian lithologies o f the Turnagain intrusion. These dikes are typical ly felsic, wi th 5 v o l . % amphibole, and also contain abundant quartz. One very coarse-grained leucocratic diorite (sample DDH04-57-12-89 .2) , wi th large cumulus crystals o f amphibole and plagioclase (Figure 4 .4 .2G, H ) , y ie lded a U - P b (zircon) age o f 185 .2±0.35 M a (Chapter 2). 4.2.3.2 Hornfels The hornfels unit (Figure 4.1) refers specifically to a greenish-gray, banded, volcanosedimentary rock (volcanic wacke) found either as large blocks in the northwest (Figure 4 .2C) and southwest parts o f the intrusion, or as xenoliths observed in dril lcore. The hornfels unit is equigranular, wi th grain sizes typical ly between 0.5-1 m m , and is composed o f approximately 45 v o l . % epidote, 35 v o l . % plagioclase, 10 v o l . % amphibole, 5 v o l . % quartz, and 5 v o l . % biotite. The large b lock o f hornfels in the northwest part o f the intrusion contains pods and seams o f two-mica granite not observed elsewhere that are interpreted to represent partial melts o f country rock. Detrital zircons (subrounded to angular) are common in this l i thology and one sample from the northwestern portion o f the intrusion (sample 04ES-00-07- 02) yielded a m i n i m u m U - P b (zircon) depositional age o f 301 M a (latest Pennsylvanian- earliest Permian) wi th Precambrian inheritance (see Chapter 2). This unit commonly contains alternating 1-10 mm-wide bands o f quartz- and chlorite-rich horizons, wh ich may represent original bedding planes. Based on the above evidence, this unit is interpreted to be a volcanic wacke that was intruded by, and incorporated into, the Turnagain intrusion. 4.2.4 Sulphide Sulphide occurs in nearly a l l rocks in the Turnagain intrusion. However it is observed predominantly in dunite and wehrlite. "Barren" olivine-dominated cumulate rocks (dunite and wehrlite) in the Turnagain intrusion typical ly contain 0.5-1 v o l . % disseminated sulphide. Sulphide abundances in the mineralized zones (Horsetrail Zone and associated satellite zones; 103 Figure 4.1) range from 2 v o l . % up to 20 v o l . % or more. These zones contain disseminated, blebby, minor net-textured and rarely semi-massive sulphide. The Northwest, Si lesia , and Fish ing R o c k Zones (to the west, south, and east o f the Horsetrail , respectively, Figure 4.1) are relatively small compared to the Horsetrail Zone, wh ich is unconstrained at depth (T. Hi tchins , pers. comm., 2004). The mineralization to the east o f the Turnagain River , in an area called the Ha tz l Zone, is currently unconstrained wi th respect to grade, tonnage, or spatial distribution. A l l o f the zones were original ly interpreted to be separate areas o f sulphide mineralization, but new and proposed dr i l l ing results indicate that many o f them are connected at depth. The typical sulphide assemblage wi th in the mineralized zones consists o f pyrrhotite (~90 v o l . % o f total sulphide) and pentlandite wi th trace amounts o f chalcopyrite. Pentlandite is distinguished from pyrrhotite in hand sample and drillcore by its lighter colour and reflection o f light from cleavage planes. V i s u a l estimates o f the nickel grade are inaccurate because the N i content in pentlandite ranges from 10 to 45 wt .% (Hard Creek N i c k e l Corp. internal reports). Sulphide in clinopyroxene- and amphibole-rich lithologies, rocks that are not prospective for N i , typical ly consists o f varying proportions o f pyrrhotite, pyrite, and chalcopyrite. Cla rk (1975) and H . K u c h a (Hard Creek N i c k e l Corp . internal reports) studied the sulphide mineralogy in detail and also observed minor amounts o f violarite, bornite, millerite, molybdenite, vallerite, mackinawite, and oxysulphides. Disseminated sulphides are typical ly fine-grained (0.1-0.5 mm) and occur throughout most o f the ol iv ine-r ich lithologies o f the Turnagain intrusion. Disseminated ore in the Horsetrail Zone is common near the margins o f the zone, however it is l ow grade (<0.17% sulphide nickel) and represents the l imi t o f currently economic sulphide mineralization. Serpentinized dunite and wehrlite proximal to the northern bounding fault, in the High land Zone (Figure 4.1), contain ~0.5 v o l . % disseminated pentlandite, s imilar in texture to sulphide shown in Figure 4 .5C. These fine-grained pentlandite occurrences are interpreted to have formed by Ni-enrichment o f primary sulphide during serpentinization. B lebby sulphide is common in the mineralized zones (e.g. Northwest Zone) and is observed as small (2-3 mm) to large (-1.5 cm), sub-rounded (Figure 4 .5A) to elongate (Figure 4 .5D-F) , sulphide aggregations. The aggregations are typical ly surrounded by ol ivine grains and some sulphide is commonly present between ol ivine grains adjacent to the sulphide bleb. These blebs are interpreted to represent isolated droplets o f sulphide l iquid that crystall ized in situ. Note that the bleb shown in Figure 4 . 5 A is completely surrounded by magnetite, wh ich is Figure 4.5: Photomicrographs (reflected light, crossed polars) of sulphide textures in the Turnagain intrusion. Scale bars on all photos are 200 nm in length. Colours in silicate minerals represent minor surficial and internal reflections. A) Dunite (DDH03-12-4) showing a fringe of secondary magnetite surrounding a single sulphide bleb containing pyrrhotite (brown) and pentlandite (light yellow). B) Dunite (05ES-02-02-02) containing intergrown semi-massive pyrrhotite and chalcopyrite. Note the small needles of serpentine (black) around the edges of the massive sulphide, as well as the sulphide outside the main sulphide mass. C) Dunite (DDH04-36-16) with small blebs of pentlandite and two thin serpentine veins. D) Wehrlite (DDH04-36-5) showing an elongate bleb of pyrrhotite with smaller crystals of pentlandite. E) Wehrlite (DDH04-28-6) showing an elongate bleb of pyrrhotite with magnetite and pentandite crystals. Note the tweed-like texture in the bottom portion of the bleb. F) Wehrlite (DDH03-08-13) showing a pyrrhotite bleb with minor chalcopyrite and two large pentlandite grains. The grey grains are chromian spinel. a common feature o f sulphide in partially serpentinized rocks in the Turnagain intrusion. Occurrences o f angular sulphide blebs (some up to 3 cm in width) have been noted in dri l lcore from al l o f the major mineralized zones. These blebs typical ly contain the same proportion o f pyrrhotite and pentlandite as the more rounded blebs, however angular blebs are also observed in ol ivine clinopyroxenite, not just dunite and wehrlite. Ol iv ine clinopyroxenite in the Turnagain intrusion does not contain contemporaneous N i - r i c h sulphide mineralization, most l ike ly because it formed from a less magnesian, sulphur- and nickel-depleted magma compared to the magma(s) that formed dunite and wehrlite, and as such the rare angular blebs could not have precipitated in situ. The angular are interpreted to represent clasts o f sulphide, original ly in a massive horizon, that were brecciated during a magma influx or turbidity current and subsequently redistributed ( W . Peredery, pers. comm., 2006). Net-textured sulphide is not common in the Horsetrail , Northwest, Silesia, and F i sh ing R o c k Zones or the Discovery showing (Figure 4.1), but is noted in local accumulations and horizons. This sulphide texture typical ly contains ol ivine grains o f varying sizes wi th in a sulphide matrix. Due to the amount o f pentlandite present in such horizons (up to 10 vo l .%) , net-textured sulphides represent a high-grade target for exploration. However their apparent thickness is commonly only a few centimetres and rarely exceeds 20 cm. Semi-massive and massive sulphide (Figure 4 .5B) occurs in a l l economic zones wi th in the Turnagain intrusion. The difference between the two types o f sulphide lies in their gangue- mineral content: semi-massive sulphide contains abundant silicate and other minerals (e.g. graphite), whereas massive sulphide does not. Bo th o f these sulphide textural types typical ly have sharp contacts wi th surrounding rocks indicating that they may represent sulphide that was remobil ized. Such horizons o f massive and semi-massive sulphide are typical ly only 5 c m or less in width and are dominantly composed o f pyrrhotite and minor chalcopyrite wi th trace amounts o f pentlandite. Semi-massive and massive sulphides in the Turnagain intrusion therefore are rarely prospective for n ickel . 4.2.5 Inclusions Xenol i ths o f country rock wi th in the Turnagain intrusion are restricted to the mineral ized zones, and these have only been observed in dril lcore. N o inclusions have been observed in areas o f abundant outcrop (e.g. alpine dunite, Figure 4.2) or nearly continuous exposure. The inclusions wi th in the Turnagain intrusion are, without exception, hornfelsed equivalents o f 1 0 6 wallrocks. Figure 4.6 displays inclusions from six different dr i l l holes wi th in mineralized zones. The two most commonly encountered inclusions are metavolcanic wacke ( M V w k ) and metaphyllite ( M P h y ) . The third type o f inclusion, calc-silicate (CS) , occurs as isolated inclusions (Figure 4 .6E, F ) or as interbeds wi th in the other types o f inclusions (Figure 4 .6A) . The metavolcanic wacke, described as the hornfels unit above (section 4.2.3.2), also occurs as smaller blocks wi th in dril lcore (Figure 4 . 6 A - C ) . The inclusions o f metavolcanic wacke are typical ly identical in mineralogy and texture to the larger blocks o f hornfels. Rarely, the metavolcanic wacke inclusions are slightly coarser grained and contain small seams o f two- mica granite (partial melt) that may cross-cut banding. It is uncommon, but noted, to observe interbeds o f metavolcanic wacke and metaphyllite in the same inclusion (Figure 4 .6B, C ) . Metaphyll i te inclusions ( M P h y ) are texturally and mineralogically different from their " R o a d R i v e r " phyll i te predecessors. Metaphyll i te commonly contains brown-coloured areas that are mineralogically dominated by graphite and pyrrhotite wi th interlayered quartz (Figure 4 . 6 B - D ) . Graphite and pyrrhotite wisps and seams (typically semi-massive sulphide), interpreted to represent partially digested inclusions o f phyll i te , were also previously observed by Clark (1975) wi th in ultramafic lithologies. The lack o f pyrite (FeS2) and the abundance o f pyrrhotite (Fei.xS) indicate that sulphur was released into the host magma during contact metamorphism o f the phyll i te inclusions. Calc-si l icate inclusions (CS) are typical ly white in colour and relatively small (as small as 2-3 cm in width). However , as noted above, they may occur as interbeds wi th in either metavolcanic wacke or metaphyllite. Calc-si l icate inclusions are fine-grained (<1 mm) and typical ly consist o f a mixture o f carbonate (calcite, magnesite), wollastonite, diopside, quartz, and local ly grossular. Note that in Figure 4 .6E and F the calc-silicate inclusions have a slight reddish colour indicating their high garnet content. Calc-si l icate xenoliths typical ly do not display extensive digestion, incorporation into their host rocks, or redox halos. 4.3 A N A L Y T I C A L TECHNIQUES 4.3.1 Mineral Chemistry The ol ivine, clinopyroxene, amphibole, and biotite contents o f each sample, textural relationships wi th other phases, and relative degree o f alteration were carefully documented using both transmitted and reflected light microscopy prior to analysis. Samples were selected to represent the various rock types found in the Turnagain intrusion. Fo r each sample, typical ly 107  Figure 4.6: Photographs of sedimentary xenoliths in NQ size drillcore (2006) from the Turnagain intrusion. Core boxes are 1.5 m long, white lines indicate interlithological contacts, and labels indicate lithology. A) DDH06-123, 201-218 m. Inclusion of interbedded metavolcanic wacke (MVwk) and calc-silicate (CS) within altered dunite (AltDn) changing down-hole to a larger MVwk inclusion. B) DDH06-130, 202-219 m. Large inclusion of coarsely interbedded MVwk and metaphyllite (MPhy). C) DDH06-143, 71-88 m. Large inclusion of gradationally bedded MVwk and MPhy. Note the very small (5-20 cm) beds of MVwk in the transition zone between the two lithologies. D) DDH06-163, 294.5 m. Strongly hornfelsed metaphyllite. The only minerals present are quartz (white-blue) and a fine-grained mixture of graphite and pyrrhotite (brown). Scale-bar is 10 cm long. E) DDH06-152,247-263 m. Inclusion of CS within AltDn. Note the slight reddish colour associated with grossular. The grey zones within the inclusion are interpreted to be highly-altered dunite. F) DDH06-153, 174-190 m. Small inclusion of CS in AltDn. This inclusion also contains grossular, but unlike the inclusion documented above, contains no intermixed dunite. three different grains were analyzed wi th three spot analyses per grain (core, intermediate posit ion, and r im). Representative analyses for ol ivine and clinopyroxene, and complete analyses for amphibole and biotite are found in Tables 4.1 to 4.4, respectively. Complete analytical results for ol ivine and clinopyroxene are listed in Appendices II and III. Garnet analyses are listed in Append ix I V . A total o f 25 samples were selected for microprobe analysis, carbon-coated, and documented using the Phi l ips X L - 3 0 scanning electron microscope at the Univers i ty o f Br i t i sh Columbia , Vancouver , B . C . Quantitative analyses were carried out in wavelength-dispersion mode using the Cameca S X - 5 0 electron microprobe wi th a beam diameter o f 10 urn, an accelerating voltage o f 15 k e V , and a beam current o f 20 n A wi th 20 s peak count-time and 10 s background count-time. A list o f X - r a y lines and elements considered, as w e l l as their standards, can be found in Append ix V . Data reduction o f a l l analytical results was undertaken using the " P A P " <)>(pZ) procedure o f Pouchou & Picho i r (1985). A total o f 354 points were analyzed (207 ol ivine , 91 clinopyroxene, 48 amphibole, 8 biotite, 9 garnet). Ol iv ine and clinopyroxene were assumed to be stoichiometric. Ferric iron in ol ivine was assumed to be zero, and ferric iron in clinopyroxene was calculated using the stoichiometric technique o f Linds ley (1983). In amphibole, ferric iron and other cation ratios were calculated using the method o f Ho l l and & Blundy (1994) and mineral names were assigned using the nomenclature o f Leake et al. (1997). Chemica l compositions o f amphibole were calculated on the basis o f 23 oxygens (16 cations ideal, wi th vacancy in A site). Bioti te stoichiometry was calculated using standard techniques (22 oxygens, 16 cations, 2 O H ± CI ± F ideal). The term 'bioti te ' refers to the biotite solid solution containing phlogopite (Mg# = 0.85-1.00) and annite (Mg# = 0.00- 0.15) end-members. Garnet cation distributions were also calculated using standard stoichiometric techniques. 4.3.2 Major and Trace Elements For whole rock analyses, only the freshest portions o f individual samples were taken in the field and any remaining weathered surfaces were systematically removed during sample processing. A l l samples were crushed using a hydraulic piston crusher between W C plates. A 100 gram aliquot o f each crushed sample was powdered using the Fri tsch Pulverisette planetary mono- and-multi mi l l s in agate jars. n o Table 4.1a: Representative olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Chromitite Chromitite Dunite Dunite Dunite Wehrlite Sample: Cluster: 05ES-01-01-01 1 05ES-01 -04-01 2 04ES-10-05-01 1 04ES-08-01-01 2 04ES-19-01-02 2 04ES-10-06-01 5 Style: Zone: porph. porph. rim mid porph. core mgb. mgb. rim mid mgb. core cumu. cumu. rim mid cumu. cumu. cumu. core rim mid cumu. cumu. cumu. core rim mid cumu. porph. porph. core rim mid porph. core Oxides (wt. %) Si02 41.58 41.11 41.10 41.71 41.71 41.90 42.17 41.26 40.86 40.86 40.66 40.85 41.48 41.45 41.22 40.91 40.70 40.47 Cr 20 3 0.02 0.02 0.03 0.21 0.01 0.02 0.00 0.01 0.00 0.00 0.02 0.06 0.04 0.03 0.03 0.00 0.00 0.06 FeO 7.31 8.73 8.81 3.93 4.74 4.79 3.44 8.91 9.17 9.08 9.70 10.31 7.85 7.44 7.36 8.87 9.66 10.46 MnO 0.15 0.15 0.19 0.10 0.09 0.09 0.43 0.15 0.17 0.18 0.16 0.17 0.12 0.19 0.16 0.33 0.21 0.21 MgO 50.49 49.82 49.81 54.01 52.79 53.01 54.63 49.59 49.61 49.53 48.77 48.67 50.39 51.18 51.00 49.57 48.68 47.94 NiO 0.25 0.33 0.23 0.36 0.47 0.51 0.00 0.35 0.30 0.10 0.07 0.12 0.22 0.13 0.25 0.25 0.31 0.39 CaO 0.05 0.07 0.06 0.07 0.10 0.13 0.02 0.07 0.13 0.10 0.18 0.15 0.34 0.08 0.04 0.03 0.04 0.02 Total 99.85 100.23 100.23 100.39 99.92 100.45 100.69 100.33 100.24 99.85 99.57 100.35 100.43 100.48 100.06 99.95 99.61 99.56 Cations (p.f.u.) Si 1.008 1.001 1.000 0.992 1.001 1.001 0.998 1.004 0.997 1.000 1.000 1.000 1.003 1.000 0.999 1.000 1.002 1.000 Cr 0.000 0.000 0.001 0.004 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.000 0.001 0.000 0.000 0.001 Fe 0.148 0.178 0.179 0.078 0.095 0.096 0.068 0.181 0.187 0.186 0.200 0.211 0.159 0.150 0.149 0.181 0.199 0.216 Mn 0.003 0.003 0.004 0.002 0.002 0.002 0.009 0.003 0.004 0.004 0.003 0.004 0.002 0.004 0.003 0.007 0.004 0.004 Mg 1.825 1.808 1.808 1.915 1.889 1.887 1.927 1.799 1.805 1.807 1.789 1.776 1.817 1.840 1.842 1.806 1.786 1.767 Ni 0.005 0.006 0.005 0.007 0.009 0.010 0.000 0.007 0.006 0.002 0.001 0.002 0.004 0.002 0.005 0.005 0.006 0.008 Ca 0.001 0.002 0.002 0.002 0.002 0.003 0.000 0.002 0.003 0.003 0.005 0.004 0.009 0.002 0.001 0.001 0.001 0.001 Total 2.991 2.999 2.998 3.000 2.999 2.999 3.002 2.996 3.003 3.000 2.999 2.998 2.995 2.999 3.000 3.000 2.998 2.997 End Members (%) Fo 92.5 91.1 91.0 96.1 95.2 95.2 96.6 90.8 90.6 90.7 90.0 89.4 92.0 92.5 92.5 90.9 90.0 89.1 Fa 7.5 8.9 9.0 3.9 4.8 4.8 3.4 9.2 9.4 9.3 10.0 10.6 8.0 7.5 7.5 9.1 10.0 10.9 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster refers to a specific location on each section Table 4.1 b: Representative olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Wehrlite Wehrlite Wehrlite Olivine Cpxite Olivine Clinopyroxenite Olivine Clinopyroxenite Sample: 04ES-09-01-01 Cluster: 1 04ES-09-01-01 4 04ES-15-01-05 1 04ES-06-06-01 1 05ES-05-01-01 4 04ES-01-04-01 1 Style: Zone: porph. rim porph. mid porph. core porph. mid porph. mid porph. core def. rim def. mid def. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core Oxides (wt. %) Si02 40.06 39.91 40.23 39.83 39.78 39.92 40.53 40.69 40.49 39.92 40.09 40.32 39.22 39.43 39.17 40.44 40.18 40.31 Cr 20 3 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.04 0.02 0.02 0.00 0.01 0.02 0.01 0.01 0.02 FeO 12.69 13.18 12.98 12.78 12.40 13.07 10.79 11.50 11.17 12.96 12.87 13.14 '14.95 15.63 15.61 12.27 12.73 12.75 MnO 0.28 0.18 0.19 0.21 0.24 0.19 0.22 0.18 0.24 0.25 0.23 0.21 0.23 0.26 0.22 0.16 0.22 0.21 MgO 45.82 45.41 45.67 45.66 45.72 45.64 47.80 47.44 47.53 46.30 46.01 46.53 44.46 44.21 44.25 46.38 46.67 46.55 NiO 0.20 0.25 0.22 0.18 0.25 0.19 0.27 0.29 0.38 0.10 0.04 0.05 0.08 0.08 0.14 0.09 0.11 0.05 CaO 0.05 0.05 0.01 0.00 0.02 0.02 0.02 0.08 0.06 0.03 0.04 0.05 0.03 0.01 0.02 0.00 0.03 0.05 Total 99.09 98.98 99.31 98.67 98.41 99.04 99.65 100.22 99.88 99.61 99.31 100.33 98.98 99.62 99.44 99.35 99.95 99.95 Cations (p.f.u.) Si 1.005 1.004 1.007 1.004 1.004 1.003 1.002 1.003 1.001 0.997 1.003 1.000 0.996 0.997 0.993 1.008 0.999 1.001 Cr 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Fe 0.266 0.277 0.272 0.269 0.262 0.275 0.223 0.237 0.231 0.271 0.269 0.272 0.318 0.331 0.331 0.256 0.265 0.265 Mn 0.006 0.004 0.004 0.005 0.005 0.004 0.005 0.004 0.005 0.005 0.005 0.005 0.005 0.006 0.005 0.003 0.005 0.004 Mg 1.713 1.704 1.705 1.715 1.720 1.710 1.762 1.744 1.752 1.724 1.716 1.720 1.683 1.667 1.673 1.723 1.729 1.724 Ni 0.004 0.005 0.004 0.004 0.005 0.004 0.005 0.006 0.007 0.002 0.001 0.001 0.002 0.002 0.003 0.002 0.002 0.001 Ca 0.001 0.001 0.000 0.000 0.001 0.001 0.001 0.002 0.002 0.001 0.001 0.001 0.001 0.000 0.001 0.000 0.001 0.001 Total 2.995 2.996 2.993 2.996 2.996 2.997 2.997 2.996 2.999 3.001 2.996 2.999 3.004 3.003 3.006 2.992 3.001 2.998 End Members (%) Fo 86.6 86.0 86.2 86.4 86.8 86.2 88.8 88.0 88.4 86.4 86.4 86.3 84.1 83.4 83.5 87.1 86.7 86.7 Fa 13.4 14.0 13.8 13.6 13.2 13.8 11.2 12.0 11.6 13.6 13.6 13.7 15.9 16.6 16.5 12.9 13.3 13.3 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Table 4.2a: Representative clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Wehrlite Wehrlite Wehrlite Olivine Clinopyroxenite Olivine Clinopyroxenite Olivine Clinopyroxenite Sample: 04ES-10-06-01 04ES-11-03-03 04ES-09-01-01 04ES-06-06-01 05ES-05-01-01 04ES-01-04-01 Cluster: 1 6 5 5 6 2 Style: cumu. cumu. cumu. inter. inter. inter. inter. inter. inter. cumu. cumu. cumu. cumu. cumu. cumu. inter. inter. inter. Zone: rim mid core rim mid core rim mid core rim mid core rim mid core rim mid core Oxides (wt. %) Si0 2 54.02 53.50 54.01 54.20 54.41 54.03 54.78 54.27 54.42 54.19 53.96 54.14 53.91 53.61 53.29 53.84 54.76 54.56 Ti0 2 0.17 0.16 0.19 0.14 0.17 0.19 0.08 0.12 0.06 0.16 0.11 0.14 0.22 0.25 0.18 0.12 0.11 0.12 A l 2 0 3 1.17 1.11 1.10 0.78 0.95 0.93 0.25 0.36 0.41 0.74 0.88 1.08 1.12 1.20 1.23 0.81 0.80 0.71 C r 2 0 3 0.58 0.73 0.68 0.42 0.57 0.53 0.13 0.16 0.20 0.48 0.50 0.61 0.42 0.54 0.42 0.61 0.71 0.59 FeO* 3.03 2.70 2.73 3.02 3.52 3.54 2.06 2.83 3.02 2.86 3.19 3.39 3.98 4.43 4.31 3.09 3.51 3.29 MnO 0.07 0.10 0.13 0.12 0.12 0.17 0.10 0.09 0.08 0.13 0.12 0.14 0.12 0.09 0.15 0.11 0.13 0.06 MgO 17.66 17.53 17.60 17.61 17.55 17.64 17.46 17.66 17.40 17.54 17.24 17.47 17.09 17.48 17.45 17.70 17.95 18.15 CaO 23.24 23.69 23.25 23.61 22.61 22.67 25.03 24.11 24.18 23.43 23.47 22.83 23.38 22.35 22.32 22.66 22.77 22.67 Na 2 0 0.25 0.29 0.28 0.27 0.29 0.29 0.05 0.12 0.13 0.20 0.18 0.19 0.29 0.29 0.24 0.22 0.22 0.21 Total 100.20 99.81 99.98 100.17 100.19 100.00 99.94 99.71 99.89 99.74 99.66 99.99 100.52 100.24 99.59 99.15 100.95 100.37 Cations (p.f.u.) Si 1.962 1.967 1.968 1.960 1.961 1.953 1.958 1.958 1.974 1.958 1.982 1.976 1.981 1.973 1.978 1.971 1.961 1.972 Ti 0.004 0.005 0.004 0.007 0.006 0.007 0.007 0.005 0.004 0.007 0.002 0.003 0.003 0.004 0.005 0.005 0.007 0.007 A1 , 1 V' 0.038 0.033 0.032 0.040 0.039 0.047 0.042 0.042 0.026 0.042 0.018 0.024 0.019 0.027 0.022 0.029 0.039 0.028 A l ' v " 0.008 0.014 0.018 0.009 0.004 0.006 0.010 0.011 0.004 0.009 0.021 0.010 0.014 0.007 0.019 0.011 0.011 0.009 Cr 0.021 0.019 0.019 0.015 0.010 0.017 0.016 0.012 0.014 0.022 0.013 0.020 0.014 0.012 0.016 0.015 0.018 0.013 Fe 3* 0.009 0.000 0.000 0.012 0.021 0.019 0.013 0.017 0.009 0.007 0.000 0.000 0.000 0.009 0.000 0.002 0.006 0.000 Fe 2* 0.073 0.083 0.088 0.120 0.095 0.107 0.122 0.115 0.080 0.105 0.072 0.106 0.099 0.083 0.107 0.106 0.092 0.101 Mn 0.002 0.004 0.003 0.004 0.003 0.004 0.003 0.005 0.003 0.003 0.002 0.004 0.003 0.004 0.004 0.005 0.004 0.004 Mg 0.940 0.956 0.953 0.946 0.934 0.936 0.951 0.956 0.966 0.939 0.918 0.966 0.957 0.956 0.952 0.959 0.939 0.930 Ca 0.938 0.907 0.905 0.885 0.927 0.903 0.875 0.879 0.917 0.904 0.955 0.881 0.896 0.921 0.881 0.886 0.917 0.928 Na 0.009 0.010 0.009 0.009 0.009 0.010 0.010 0.008 0.008 0.009 0.013 0.008 0.010 0.009 0.010 0.010 0.009 0.008 Total 4.004 3.999 3.998 4.006 4.011 4.009 4.007 4.009 4.004 4.004 3.997 3.998 3.997 4.005 3.994 4.001 4.003 4.000 End Members (%) Wo 46.4 47.7 46.6 47.0 45.4 45.4 49.1 47.6 47.8 46.8 47.0 45.9 46.8 44.9 45.1 45.6 45.1 44.9 En 49.1 49.1 49.1 48.8 49.1 49.2 47.7 48.5 47.8 48.7 48.0 48.8 47.6 48.8 49.0 49.6 49.5 50.0 Fs 4.5 3.2 4.3 4.2 5.5 5.4 3.2 3.9 4.4 4.5 5.0 5.3 5.7 6.3 5.9 4.8 5.4 5.1 Mg# 0.920 0.898 0.919 0.903 0.888 0.910 0.886 0.893 0.922 0.899 0.929 0.900 0.918 0.899 0.900 0.969 0.913 0.907 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section Table 4.2b: Representative clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Hornblende Clinopyroxenite Hornblende Clinopyroxenite Hornblende Clinopyroxenite Sample: DDH04-47-7-49 Cluster: 5 04ES-09-02-02 3 DDH05-84-19-104 5 Style: Zone: cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core Oxides (wt. %) Si0 2 49.54 49.73 49.90 53.33 52.74 53.79 50.74 51.37 50.77 Ti0 2 0.65 0.53 0.62 0.17 0.17 0.04 0.44 0.35 0.40 A l 2 0 3 4.79 4.52 4.48 0.68 0.90 0.30 3.83 2.94 3.60 C r 2 0 3 0.00 0.01 0.03 0.04 0.07 0.02 0.03 0.01 0.00 FeO* 7.73 7.41 7.06 6.42 6.90 6.54 7.56 7.45 7.48 MnO 0.16 0.20 0.15 0.22 0.22 0.24 0.13 0.18 0.16 MgO 13.43 13.41 13.92 15.67 15.55 15.32 13.78 13.93 13.87 CaO 23.37 23.19 23.09 23.05 22.30 24.16 23.15 23.31 23.26 Na 2 0 0.24 0.28 0.28 0.13 0.13 0.06 0.26 0.19 0.27 Total 99.91 99.28 99.54 99.70 98.97 100.47 99.92 99.73 99.79 Cations (p.f.u.) Si 1.918 1.897 1.913 1.854 1.870 1.867 1.977 1.972 1.985 Ti 0.010 0.011 0.010 0.018 0.015 0.018 0.005 0.005 0.001 A r ' 0.082 0.103 0.087 0.146 0.130 0.133 0.023 0.028 0.015 At"" 0.047 0.055 0.043 0.066 0.070 0.065 0.007 0.011 0.000 Cr 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.002 0.001 Fe 3* 0.021 0.036 0.031 0.052 0.041 0.042 0.010 0.010 0.015 Fe 2* 0.211 0.198 0.175 0.190 0.192 0.179 0.189 0.206 0.187 Mn 0.006 0.005 0.004 0.005 0.006 0.005 0.007 0.007 0.008 Mg 0.775 0.772 0.813 0.750 0.752 0.776 0.866 0.867 0.843 Ca 0.932 0.931 0.933 0.937 0.934 0.926 0.916 0.893 0.955 Na 0.007 0.010 0.007 0.009 0.010 0.010 0.005 0.005 0.002 Total 4.011 4.018 4.015 4.026 4.020 4.021 4.005 4.005 4.011 End Members (%) Wo 49.9 49.7 49.2 46.5 45.4 48.1 48.8 48.6 49.0 En 39.9 40.0 41.3 43.9 44.1 42.4 40.4 40.4 40.6 Fs 10.1 10.2 9.5 9.6 10.5 9.4 10.8 11.0 10.4 Mg# 0.780 0.791 0.816 0.818 0.829 0.828 0.802 0.790 0.805 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section Table 4.3a: Amphibole compositions from ultramafic rocks of the Turnagain intrusion Rock Type: Hornblende Clinopyroxenite Hornblende Clinopyroxenite Hornblende Clinopyroxenite Sample Cluster Description Location Oxides (wt. %) Si0 2 TiCb Al203 Cr 20 3 Fe£)3* FeO* MnO MgO CaO Na^ KjO CI F HjO* Total DDH04-47-7-49 DDH05-84-19-104 04ES-O9-02-02 1 6 9 3 4 7 2 4 inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. cumu. cumu. cumu. cumu. cumu. cumu. cumu. cumu. rim mid core rim core rim mid core rim mid core Rim Mid rim mid core rim mid mid core rim mid mid core 39.25 39.39 39.17 39.35 39.38 39.82 39.47 39.59 40.14 40.23 39.88 39.85 40 08 40.81 40.31 40.66 48.15 48.71 48.75 49.25 49.09 47.23 46.00 48.10 1.65 1.54 1.53 1.62 1.56 1.49 1.56 1.55 1.36 1.40 1.48 1.31 1.42 1.17 1.41 1.36 0.81 1.26 1.23 0.89 1.22 1.46 1.87 1.25 13.92 14.07 14.04 13.71 13.99 14.20 13.89 13.98 13.39 13.34 13.25 13.05 13.28 12.77 12.80 12.71 7.49 7.78 7.36 7.18 7.21 8.27 9.71 7.59 0.00 0.06 0.00 0.02 0.07 0.00 0.00 0.00 0.03 0.03 0.04 0.03 0.00 0.05 0.05 0.00 0.23 0.17 0.13 0.15 0.22 0.21 0.15 0.16 7.28 7.32 7.68 7.05 7.80 6.93 7.08 7.16 7.00 6.54 6.95 5.78 6.26 6.74 6.05 6.61 3.98 3.82 3.64 3.70 3.61 4.25 4.17 3.59 5.70 5.54 5.19 5.78 5.48 4.73 5.80 5.60 5.50 5.76 5.55 7.37 5.94 5.62 6.46 5.39 6.11 5.41 5.58 5.75 5.16 6.60 5.33 6.69 0.14 0.17 0.13 0.15 0.12 0.10 0.13 0.12 0.09 0.15 0.12 0.09 0.12 0.13 0.09 0.12 0.16 0.17 0.15 0.13 0.15 0.15 0.12 0.14 13.10 13.14 13.19 13.05 13.18 13.79 13.06 13.21 13.68 13.62 13.58 13.03 13.55 13.85 13.56 14.07 16.18 17.10 17.08 16.56 17.21 15.53 15.96 15.86 12.23 12.24 12.18 12.32 12.31 12.35 12.15 12.18 12.13 12.15 12.20 12.15 12.14 12.22 12.16 12.15 12.32 11.72 11.65 11.84 11.95 11.40 11.55 12.09 1.65 1.64 1.58 1.67 1.72 1.66 1.67 1.68 1.61 1.58 1.51 1.84 1.54 1.69 1.75 1.72 1.16 0.84 0.75 1.19 0.86 1.17 0.98 1.07 1.61 1.60 1.62 1.39 1.50 1.50 1.50 1.50 1.81 1.87 1.90 1.93 1.96 1.56 1.78 1.63 0.54 0.68 0.59 0.48 0.56 0.73 0.91 0.55 0.08 0.05 0.08 0.07 0.06 0.06 0.07 0.07 0.05 0.03 0.04 0.14 0.08 0.16 0.06 0.06 0.09 0.06 0.10 0.07 0.09 0.18 0.18 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.10 0.16 0.09 0.10 0.09 0.07 0.16 0.17 1.95 1.96 1.95 1.95 1.97 1.97 1.95 1.96 1.97 1.98 1.96 1.93 1.95 1.94 1.96 1.97 1.99 1.99 2.01 2.01 2.02 1.97 1.93 1.95 98.57 98.73 98.34 98.13 99.14 98.62 98.35 98.59 98.76 98.70 98.46 98.50 98.32 98.71 98.46 98.44 99.31 99.86 99.11 99.32 99.43 99.23 99.01 99.31 Cations (p.f.u.) Si 5.864 5.868 5.855 5.897 5.849 5.901 5.899 5.897 5.967 5.986 5.955 5.991 5.992 Al(iv) 2.136 2.132 2.145 2.103 2.151 2.099 2.101 2.103 2.033 2.014 2.045 2.009 2.008 Al(vi) 0.315 0.339 0.329 0.318 0.297 0.381 0.347 0.351 0.313 0.326 0.287 0.303 0.332 Ti 0.185 0.172 0.172 0.183 0.174 0.166 0.175 0.173 0.152 0.157 0.166 0.148 0.160 Cr 0.000 0.007 0.000 0.002 0.009 0.000 0.000 0.000 0.003 0.004 0.004 0.003 0.000 Fe3'* 0.818 0.821 0.864 0.795 0.872 0.772 0.796 0.803 0.784 0.733 0.781 0.653 0.704 Mg 2.918 2.918 2.939 2.915 2.919 3.046 2.911 2.933 3.032 3.020 3.022 2.921 3.019 Mn 0.018 0.021 0.017 0.019 0.016 0.013 0.017 0.015 0.011 0.019 0.015 0.012 0.015 Fe2*<M, 0.713 0.691 0.649 0.725 0.680 0.587 0.725 0.698 0.684 0.717 0.693 0.927 0.743 Ca(M> 0.034 0.032 0.030 0.043 0.034 0.036 0.028 0.027 0.022 0.024 0.031 0.033 0.027 Fe 2 ^, 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Ca { B ) 1.924 1.921 1.920 1.935 1.924 1.926 1.918 1.917 1.910 1.913 1.921 1.923 1.916 Na,B) 0.076 0.079 0.080 0.065 0.076 0.074 0.082 0.083 0.090 0.087 0.079 0.077 0.084 N a m 0.402 0.395 0.378 0.421 0.418 0.404 0.403 0.401 0.375 0.370 0.357 0.460 0.362 K 0.307 0.305 0.309 0.267 0.284 0.284 0.286 0.286 0.344 0.355 0.362 0.371 0.374 Total 15.710 15.700 15.687 15.687 15.702 15.688 15.689 15.687 15.719 15.725 15.720 15.831 15.736 OH 1.980 1.987 1.980 1.983 1.984 1.985 1.983 1.983 1.988 1.992 1.989 1.963 1.978 CI 0.020 0.013 0.020 0.017 0.016 0.015 0.017 0.017 0.012 0.008 0.011 0.037 0.022 F 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Mg# 0.656 0.659 0.660 0.657 0.653 0.691 0.657 0.662 0.674 0.676 0.672 0.649 0.676 6.064 1.936 0.300 0.130 0.006 0.753 3.067 0.017 0.698 0.028 0.000 1.917 0.083 0.404 0.295 15.699 1.959 0.041 0.000 6.027 1.973 0.283 0.159 0.006 0.681 3.022 0.012 0.808 0.029 0.000 1.919 0.081 0.427 0.340 15.767 1.985 0.015 0.000 6.049 1.951 0.278 0.152 0.000 0.741 3.119 0.015 0.671 0.024 0.000 1.913 0.087 0.408 0.309 15.717 1.985 0.015 0.000 6.941 1.059 0.213 0087 0.026 0.432 3.477 0.020 0.737 0.008 0.000 1.895 0.105 0.220 0.099 15.319 1.931 0.023 0.046 6.936 1.064 0.241 0.135 0.019 0.409 3.630 0.020 0.546 0.000 0.098 1.788 0.115 0.117 0.124 15.241 1.911 0.016 0.073 6.988 1.012 0.231 0.133 0.014 0.393 3.650 0.018 0.561 0.000 0.107 1.790 0.103 0.105 0.107 15.212 1.934 0.025 0.041 7.051 0.949 0.262 0.096 0.017 0.399 3.535 0.016 0.675 0.000 0.014 1.816 0.170 0.161 0.088 15.249 1.937 0.017 0.046 7.005 0.995 0.218 0.130 0.025 0.388 3.661 0.018 0.559 0.000 0.056 1.827 0.117 0.119 0.102 15.221 1.937 0.023 0.041 0.679 0.670 0.749 0.775 0.775 0.765 0.785 6.834 6.650 6.939 1.166 1.350 1.061 0.244 0.304 0230 0.159 0.203 0.135 0.024 0.017 0.018 0.463 0.453 0.389 3.351 3.440 3.411 0.018 0.015 0.017 0.740 0.568 0.799 0.000 0.000 0.000 0.059 0.075 0.008 1.767 1.788 1.869 0.174 0.136 0123 0.154 0.139 0.175 0.135 0.167 0.100 15.289 15.306 15.276 1.924 1.883 1.895 0.045 0.045 0.028 0.031 0.072 0.077 0.726 0.758 0.740 Crystal textural style is abbreviated: cumu. (cumulus), inter, (interstitial), porph. (porphyritic) Note: Other phases (cpx, mt, phlog) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Calculated Table 4.3b: Amphibole compositions from ultramafic rocks of the Turnagain intrusion Rock Type: Hornblendite Hornblendite Sample Cluster Description Location 05ES-05-06-02 2 4 5 6 04ES-00-07-04 1 2 3 porph. mid porph. mid porph. core porph. rim porph. mid porph. mid porph. core porph. rim porph. mid porph. mid porph. core cumu. rim cumu. mid cumu. mid cumu. core porph. rim porph. mid porph. core porph. rim porph. mid porph. core porph. rim porph. mid porph. core Oxides (wt. %) Si0 2 40.82 40.98 41.28 41.44 40.71 41.01 40.78 40.90 40.69 40.70 40.73 46.98 45.39 44.75 45.00 43.13 45.79 42.72 41.28 42.00 41.64 42.41 42.16 4226 TiOj 2.03 2.11 1.97 1.98 2.12 2.07 1.97 1.99 2.13 2.08 2.03 1.58 1.93 1.77 1.39 1.56 1.34 2.23 2.39 2.24 2.26 2.09 1.96 2.10 AI2O3 12.88 12.73 12.80 12.51 12.92 13.16 13.30 12.50 13.05 13.29 12.93 9.44 11.12 11.10 10.97 11.80 10.57 11.30 12.49 11.87 12.18 11.54 11.62 11.42 Cr2Q, 0.01 002 0.00 0.02 0.04 0.03 0.02 0.00 0.01 0.00 0.05 0.17 0.11 0.07 0.05 0.06 0.01 0.06 0.04 0.09 0.11 0.01 0.02 0.03 FeA* 5.61 5.30 5.33 5.16 5.40 4.58 5.92 5.85 5.22 4.71 5.01 4.05 4.11 4.66 4.58 4.60 1.30 4.59 4.52 4.26 4.55 5.02 5.40 5.38 FeO* 8.11 8.27 8.10 8.91 8.58 8.00 6.94 8.34 8.35 8.71 8.09 4.26 4.71 4.23 4.21 9.38 12.37 9.24 11.28 11.14 10.86 9.48 9.52 9.26 MnO 0.16 0.16 0.15 0.20 0.19 0.18 0.10 0.23 0.19 0.14 0.14 0.11 0.16 0.17 0.11 0.34 0.45 0.37 0.31 0.34 0.33 0.22 0.26 0.27 MgO 12.51 12.57 12.67 12.36 12.20 12.75 13.26 12.26 12.32 12.29 12.59 16.96 16.18 16.16 16.41 12.40 10.97 12.47 10.86 10.98 11.08 12.29 12.16 12.28 CaO 11.63 11.61 11.44 11.68 11.53 11.73 10.81 11.35 11.50 11.71 11.68 11.97 11.72 11.78 11.67 11.65 10.89 11.44 11.48 11.21 11.48 11.57 11.68 11.56 NaJD 1.88 1.95 .1.87 1.86 1.90 1.85 1.80 1.82 1.87 1.93 1.88 0.95 1.11 1.08 1.16 1.78 1.01 1.73 1.73 1.61 1.69 1.71 1.75 1.72 K 20 1.07 0.98 1.07 1.07 1.02 1.12 1.76 1.04 1.07 1.11 1.10 0.83 1.00 0.94 0.85 0.75 1.25 0.72 0.97 0.82 0.81 0.86 0.90 0.81 Cl 0.14 0.11 0.07 0.09 0.14 0.06 0.10 0.11 0.12 0.08 0.08 0.08 0.13 0.15 0.09 0.17 0.32 0.21 0.11 0.10 0.14 0.11 0.21 0.15 F 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.17 0.17 0.15 0.15 0.00 0.00 0.01 0.00 0.00 0.02 0.00 0.00 0.00 HzO* 1.95 1.96 1.97 1.97 1.94 1.98 1.97 1.95 1.95 1.97 1.96 1.98 1.96 1.94 1.95 1.97 1.92 1.94 1.96 1.95 1.94 1.97 1.94 1.95 Total 98.81 98.74 98.71 99.26 98.68 98.53 98.72 98.32 98.46 98.73 98.27 99.54 99.81 98.95 98.60 99.60 98.19 99.01 99.42 98.60 99.09 99.26 99.57 99.21 Cations (p.f.u.) Si 6.082 6.105 6.137 6.154 6.082 6.104 6.057 6.128 6.082 6.071 6.092 6.711 6.501 6.466 6.511 6.358 6.827 6.338 6.171 6.300 6.226 6.291 6.256 6.278 Al(iv) 1.918 1.895 1.863 1.846 1.918 1.896 1.943 1.872 1.918 1.929 1.908 1.289 1.499 1.534 1.489 1.642 1.173 1.662 1.829 1.700 1.774 1.709 1.744 1.722 Al(vi) 0.344 0.341 0.381 0.343 0.357 0.412 0.385 0.335 0.381 0.407 0.371 0.299 0.379 0.357 0.381 0.407 0.683 0.315 0.372 0.398 0.374 0.307 0.287 0.277 Ti 0.228 0.236 0.220 0.222 0.238 0.232 0.221 0.225 0.239 0.233 0.229 0.170 0.207 0.192 0.151 0.173 0.151 0.248 0.268 0.252 0.255 0.233 0.218 0.235 Cr 0.001 0.002 O.OOO 0.003 0.004 0.003 0.003 0.000 0.001 0.000 0.005 0.019 0.012 0.008 0.006 0.007 0.001 0.007 0.005 0.011 0.013 0.001 0.002 0.004 Fe3** 0.629 0.594 0.596 0.577 0.607 0.512 0.661 0.659 0.587 0.529 0.563 0.436 0.443 0.506 0.499 0.510 0.146 0.512 0.508 0.481 0.512 0.560 0.603 0.601 Mg 2.779 2.792 2.807 2.736 2.717 2.828 2.936 2.738 2.745 2.733 2.808 3.611 3.456 3.481 3.539 2.724 2.438 2.758 2.419 2.455 2.470 2.717 2.690 2.720 Mn 0.021 0.020 0.018 0.026 0.024 0.023 0.013 0.029 0.023 0.018 0.018 0.014 0.019 0.021 0.014 0.043 0.056 0.046 0.040 0.044 0.041 0.027 0.032 0.034 Fe 2*w ) 0.997 1.015 0.978 1.094 1.053 0.989 0.782 1.015 1.023 1.080 1.006 0.451 0.483 0.434 0.410 1.135 1.525 1.115 1.388 1.359 1.336 1.154 1.167 1.130 Ca(M) 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 F e 2 * (B) 0.013 0.015 0.030 0.012 0.019 0.007 0.080 0.030 0.021 0.007 0.007 0.058 0.081 0.077 0.100 0.021 0.017 0.032 0.022 0.038 0.022 0.022 0.014 0.021 Ca ( B ) 1.857 1.853 1.822 1.859 1.845 1.871 1.720 1.822 1.841 1.872 1.871 1.832 1.799 1.825 1.810 1.841 1.740 1.818 1.839 1.802 1.839 1.839 1.857 1.840 Na(B, 0.129 0.132 0.148 0.129 0.136 0.122 0.200 0.148 0.138 0.122 0.122 0.109 0.120 0.098 0.091 0.138 0.243 0.150 0.139 0.160 0.139 0.139 0.130 0.138 Na (A) 0.413 0.431 0.391 0.406 0.415 0.413 0.319 0.379 0.404 0.437 0.423 0.154 0.187 0.203 0.235 0.369 0.048 0.346 0.362 0.308 0.351 0.352 0.373 0.356 K 0.203 0.187 0.204 0.203 0.195 0.214 0.334 0.198 0.205 0.212 0.210 0.151 0.182 0.173 0.157 0.141 0.237 0.135 0.185 0.158 0.154 0.162 0.171 0.154 Total 15.616 15.617 15.594 15.609 15.610 15.626 15.652 15.577 15.608 15.649 15.633 15.305 15.369 15.377 15.391 15.510 15.285 15.482 15.547 15.465 15.505 15.514 15.545 15.510 OH 1.964 1.971 1.983 1.977 1.964 1.986 1.976 1.973 1.970 1.979 1.981 1.900 1.888 1.894 1.907 1.956 1.919 1.942 1.973 1.975 1.955 1.971 1.944 1.962 Cl 0.036 0.029 0.017 0.023 0.036 0.014 0.024 0.027 0.030 0.021 0.019 0.020 0.033 0.037 0.023 0.044 0.081 0.054 0.027 0.025 0.036 0.028 0.055 0.038 F 0.000 0.000 0.000 0.000 O.OOO 0.000 0.000 0.000 0.000 0.000 0.000 0.079 0.079 0.069 0.071 0.000 0.000 0.005 0.000 0.000 0.009 0.001 0.002 0.000 Mg# 0.629 0.632 0.636 0.619 0.618 0.652 0.658 0.616 0.627 0.629 0.641 0.793 0.774 0.774 0.778 0.620 0.591 0.624 0.558 0.566 0.569 0.610 0.601 0.608 Crystal textural style is abbreviated: cumu. (cumulus), inter, (interstitial), porph. (porphyritic) Note: Other phases (cpx, mt, phlog) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Calculated Table 4.4: Biotite compositions from biotite-bearing ultramafic rocks of the Turnagain intrusion Rock Type: Hornblende Clinopyroxenite Wehrlite Sample: DDH05-84-19-104 05ES-03-01-01 Cluster: 6 11 2 Description: inter. inter. inter. inter. inter. inter. Location: mid core mid core rim core Oxides (wt. %) Si02 36.47 36.55 36.84 36.33 39.16 39.06 Ti0 2 1.31 1.54 1.56 1.53 1.10 1.15 Al 2 0 3 14.89 15.27 15.12 15.14 13.85 14.30 Cr 2 0 3 0.03 0.00 0.01 0.00 1.16 1.22 FeO 17.70 15.98 17.75 17.39 4.61 5.19 MnO 0.02 0.02 0.00 0.00 0.06 0.07 MgO 14.64 16.16 15.01 14.68 24.95 23.75 BaO 0.61 0.49 0.65 0.53 0.44 0.51 CaO 0.15 0.09 0.09 0.14 0.08 0.06 Na20 0.24 0.24 0.21 0.18 0.06 0.06 K 20 9.44 9.31 9.87 9.73 8.73 9.30 Cl 0.04 0.09 0.03 0.04 0.00 0.04 F 0.00 0.00 0.00 0.00 0.10 0.08 H20* 1.96 1.97 1.99 1.96 2.08 2.06 Total 97.51 97.72 99.13 97.66 96.36 96.85 Cations (p.f.u.) Si 5.550 5.494 5.520 5.516 5.639 5.630 AI(IV' 2.450 2.506 2.480 2.484 2.350 2.370 A | ( V D 0.220 0.200 0.190 0.226 0.000 0.059 Ti 0.150 0.174 0.176 0.174 0.119 0.124 Cr 0.003 0.000 0.001 0.000 0.132 0.139 Fe 2.253 2.008 2.224 2.208 0.555 0.626 Mn 0.003 0.003 0.000 0.000 0.007 0.009 Mg 3.321 3.622 3.351 3.323 5.354 5.103 Ba 0.037 0.029 0.038 0.032 0.025 0.029 Ca 0.024 0.015 0.014 0.022 0.012 0.009 Na 0.072 0.070 0.062 0.054 0.016 0.017 K 1.833 1.786 1.887 1.884 1.604 1.710 Total 15.916 15.906 15.944 15.923 15.812 15.824 Cl 0.011 0.023 0.007 0.011 0.000 0.011 F 0.000 0.000 0.000 0.000 0.006 0.004 OH 1.989 1.977 1.993 1.989 1.994 1.985 Mg# 0.60 0.64 0.60 0.60 0.91 0.89 Crystal textural style is abbreviated: inter, (interstitial) Note: Other phases (ol, cpx, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Calculated Major and trace element concentrations (Table 4.5) o f 23 whole rock powders, 3 b l ind duplicates, and one procedural duplicate (Appendix V I ) were analyzed at Ac t iva t ion Laboratories L t d . (Actlabs) in Ancaster, Ontario. For the major elements, a 0.2 g sample was fused in a graphite crucible after it was mixed wi th a combination o f l i th ium metaborate/lithium tetraborate. The mixture, once molten, was poured into 5% HNO3 and shaken for 30 minutes until dissolved. The samples then were analyzed for selected trace elements and major oxides using a simultaneous/sequential Thermo Jarrel l -Ash Env i ro II inductively coupled plasma optical emission spectrometer ( I C P - E O S ) . Addi t iona l trace elements were analyzed by both the I N A A (instrumental neutron activation analysis) and I C P - M S (inductively couple plasma mass spectrometry) methods. Internal calibration was achieved using a variety o f international reference materials and independent control samples. Fo r the I N A A analyses, 1.5-2.5 g o f sample was weighed into small polyethylene vials and irradiated wi th control international reference material C A N M E T W M S - 1 and N i C r f lux wires at a thermal neutron flux o f 7 x 1 0 1 2 ncm 'V 2 in the M c M a s t e r Nuclear Reactor. The samples were measured on an Ortec high-purity Ge detector l inked to a Canberra Series 95 multichannel fo l lowing a 7-day decay. Act iv i t ies for each element were compared to a detector calibration developed from multiple international certified reference materials and decay- and weight- corrected. For the I C P - M S analyses, 0.25 g o f sample was digested in H F , fol lowed by a mixture o f FINO3 and H C I O 4 , heated and taken to dryness. The samples were brought back into solution wi th H C I . Samples were analyzed using a Perk in E lmer Opt ima 3000 I C P . In-lab standards or certified reference materials were used for quality control. The normal iz ing values for the R E E (chondrite) and extended trace elements (primitive mantle) are from M c D o n o u g h & Sun (1995). 4.3.3 Platinum Group Elements The P G E concentrations o f 21 whole rock samples, 3 b l ind duplicates, and 1 procedural duplicate were determined by the N i S fire-assay technique at Geoscience Laboratories (Sudbury, Ontario) fo l lowing the procedures outlined in Jackson et al. (1990) and Richardson & Burnham (2003). N i c k e l , sulphur, sodium carbonate and sodium tetraborate are added to a 15 g aliquot o f sample powder. This mixture is then fused for 1.5 hrs in a fire-clay crucible at 1050°C, after wh ich the crucible is broken to recover the nickel sulphide button after cool ing . The button, in order to remove the N i S matrix, is then dissolved using hydrochloric acid in a Table 4.5a: Major (wt. % oxide)and trace element abundances (ppm) in mafic/ultramafic rocks of the Turnagain intrusion Rock Type: Dunite Dunite Dunite Dunite Dunite Dunite Wehrlite Wehrlite Wehrlite Wehrlite Wehrlite Sample Prefix: 04ES 04ES 04ES 04ES 05ES 05ES 04ES 04ES 05ES 05ES 05ES Sample #: 03-01-02 06-01-01 03-02-01 07-02-01 04-06-01 04-05-01 03-04-01 07-02-04 05-06-01 05-02-01 05-03-01 Oxides (wt. %) Si0 2 38.17 38.08 37.04 35.64 36.47 35.80 37.86 38.14 39.04 39.19 38.49 Ti0 2 0.04 0.01 0.01 0.01 0.03 0.04 0.03 0.02 0.09 0.03 0.05 A l 2 0 3 0.32 0.05 0.03 0.07 0.22 0.61 0.17 0.15 0.37 0.18 0.33 Fe 2 0 3 * 7.15 9.26 12.02 7.72 14.22 9.78 14.93 13.69 12.12 13.53 11.32 MgO 48.54 48.00 46.86 45.13 41.56 41.26 41.18 42.40 43.10 42.73 43.02 MnO 0.10 0.14 0.13 0.10 0.23 0.13 0.19 0.21 0.20 0.21 0.18 CaO 0.29 0.01 0.13 0.06 0.05 1.43 1.06 2.94 2.08 2.07 Na 20 0.02 0.03 0.01 0.04 0.04 0.02 0.03 0.05 0.03 0.06 K 2 0 0.20 0.03 0.04 0.08 0.11 0.09 0.03 0.12 0.08 0.10 P 2 O 5 LOI 5.06 3.72 3.37 11.29 7.00 11.44 4.06 3.96 0.92 1.79 4.18 Total 99.93 99.36 99.65 100.10 99.95 99.23 99.91 99.77 99.41 99.77 99.79 S 0.09 0.07 0.39 0.11 0.08 0.18 1.39 0.18 0.03 0.18 0.06 Mg #: 0.931 0.911 0.885 0.921 0.853 0.893 0.845 0.860 0.876 0.862 0.883 Trace Elements (ppm) Co 141 160 209 126 163 125 206 167 163 175 136 Cr 2580 2850 2000 3360 1600 4350 3640 2660 3740 4240 5390 Cu 9 18 492 5 34 261 126 72 471 17 Ni 3310 2185 1760 1790 1190 2360 1740 988 1080 1590 1940 Sc 3.2 3.2 3.6 2.8 5.7 3.8 10.9 8.7 15.0 9.7 11.7 V 14 114 12 31.5 7 27 Zn 42 46 34 35 55 61 102 58 56.5 62 69 Rb 2 Ba 16 2 8 Th 0.13 U 0.31 0.10 0.44 Ta Nb 0.2 0.2 La 0.41 Ce 0.6 Pb Pr 0.02 0.08 0.03 Sr 2 2 3 4 3 7 7 7 Nd 0.15 0.14 0.40 0.15 0.09 0.22 0.14 0.15 Zr 2 Hf Sm 0.07 0.02 0.01 0.05 0.12 0.07 0.04 0.10 0.07 0.07 Eu 0.021 0.013 0.039 0.016 0.022 Gd 0.08 0.02 0.13 0.07 0.06 0.13 0.07 0.09 Tb 0.01 0.02 0.01 0.02 0.01 Dy 0.07 0.03 0.16 0.08 0.04 0.16 0.06 0.09 Ho 0.01 0.04 0.02 0.03 0.01 0.02 Er 0.05 0.01 0.12 0.05 0.02 0.10 0.04 0.06 Tm 0.01 0.02 0.01 0.01 0.01 0.01 Yb 0.06 0.02 0.02 0.12 0.05 0.04 0.09 0.04 0.06 Lu 0.008 0.017 0.006 0.004 0.015 0.006 0.008 Y 4 4 2 0 1 Note: Blank entries represent values that were below detection limits. Abbreviated rock types: cpxite (clinopyroxenite), hblite (hornblendite) Abbreviated minerals: ol (olivine), hbl (hornblende) Mg# = Mg/(Mg+Fe) assuming all iron as Fe2* * Total Table 4.5b: Major (wt. % oxide)and trace element abundances (ppm) In mafic/ultramafic rocks of the Turnagain intrusion Rock Type: Wehrlite Wehrlite Wehrlite Ol Cpxite Ol Cpxite Cpxite Cpxite Hbl Cpxite Hblite Hblite Diorite Wacke Sample Prefix: 05ES 05ES 05ES 04ES 05ES 05ES 05ES 04ES 05 ES 04ES DDH04 04ES Sample #: 05-01-02 03-01-01 05-05-01 10-02-04 05-01-01 05-04-01 03-01-02 09-02-02 05-06-02 00-07-04 57-12-89.2 00-07-02 Oxides (wt. %) Si0 2 38.20 37.07 42.85 50.62 51.23 48.99 49.04 47.14 38.53 41.93 53.56 49.67 Ti0 2 0.04 0.07 0.11 0.19 0.20 0.38 0.29 0.75 2.32 2.16 0.29 0.80 A l 2 0 3 0.21 0.50 0.42 1.00 1.05 2.21 2.07 4.20 12.06 12.21 20.82 16.19 Fe 2 0 3 * 18.60 15.13 10.71 8.07 7.45 7.65 8.55 11.64 15.51 14.30 4.14 10.01 MgO 37.72 34.25 35.67 21.74 22.45 18.65 20.30 16.46 12.99 11.95 3.60 4.86 MnO 0.25 0.16 0.17 0.15 0.13 0.15 0.19 0.16 0.21 0.26 0.09 0.20 CaO 2.28 1.56 7.40 17.76 17.26 19.12 15.25 16.04 13.85 11.62 7.68 9.82 Na 20 0.06 0.02 0.03 0.17 0.17 0.20 0.17 0.63 0.67 0.78 6.02 3.57 K 2 0 0.01 0.08 0.05 0.12 0.10 0.08 0.11 0.40 0.32 0.89 1.17 1.86 P2O5 0.03 0.14 0.01 0.31 0.19 0.37 LOI 2.45 11.07 2.38 2.20 3.37 2.35 3.31 2.80 2.12 1.88 Total 99.83 99.92 99.78 99.08 99.34 99.65 99.36 99.92 99.78 99.20 99.68 99.23 s 0.66 1.65 0.23 0.78 0.42 0.04 0.33 1.08 0.14 0.35 0.10 0.31 Mg #: 0.801 0.818 0.868 0.842 0.857 0.829 0.825 0.737 0.624 0.624 0.633 0.491 Trace Elements (ppm) Co 192 181 163 110 98 59 56 151 85 66 15 30 Cr 683 1910 1380 2610 3200 1480 2690 1320 38 404 11 79 Cu 475 233 248 381 292 292 47 249 133 84 12 101 Ni 858 956 777 335 511 173 56 130 132 136 9 20 Sc 11.1 14.5 28.8 58.8 55.4 68.1 41.8 68.8 69.3 73.7 12.9 36.1 V 23 54 49 101 81 147 265 343 645 492 110 291 Zn 88 34 41 22 18 20 57 49 69 99 29 74 Rb 3 12.0 11 28 Ba 6 1 12 36 35 69 422 1980 700 Th 0.06 0.29 0.17 0.10 0.36 0.07 1.54 U 0.16 0.08 0.06 0.12 0.09 0.21 Ta 0.1 0.2 0.1 0.3 Nb 0.5 0.5 0.3 0.5 1.8 1.6 3.9 2.3 4.1 La 0.07 0.19 0.09 0.17 0.19 0.52 1.56 4.47 2.11 6.61 1.50 10.50 Ce 0.2 0.5 0.3 0.8 0.8 2.0 3.8 14.5 7.0 20.5 3.4 21.6 Pb 5 13 34 36 5 12 Pr 0.03 ,0.09 0.07 0.18 0.18 0.41 0.64 2.57 1.40 3.35 0.52 2.65 Sr 7 \ 4 14 32 35 71 60 62 336 284 2808 949 Nd 0.23 0.59 0.53 1.33 1.33 2.64 3.60 12.60 8.64 18.25 2.62 11.60 Zr 2 7 12 14 30 49 17 38 Hf 0.3 0.4 0.7 1.3 2.1 0.7 1.4 Sm 0.11 0.24 0.24 0.61 0.60 1.04 1.16 3.69 3.26 5.95 0.80 2.99 Eu 0.032 0.051 0.077 0.200 0.204 0.318 0.277 0.928 1.310 1.845 0.386 1.020 Gd 0.13 0.28 0.30 0.84 0.80 1.31 1.36 3.62 4.10 7.18 0.86 3.21 Tb 0.02 0.05 0.06 0.16 0.15 0.25 0.25 0.63 0.76 1.33 0.15 0.56 Dy 0.13 0.32 0.35 0.95 0.92 1.57 1.56 3.49 4.74 7.91 0.95 3.42 Ho 0.03 0.06 0.07 0.18 0.18 0.31 0.31 0.65 0.97 1.62 0.19 0.70 Er 0.08 0.17 0.19 0.52 0.49 0.86 0.90 1.84 2.79 4.54 0.57 2.13 Tm 0.01 0.02 0.03 0.07 0.07 0.12 0.13 0.26 0.39 0.65 0.09 0.31 Yb 0.08 0.14 0.16 0.42 0.44 0.74 0.81 1.49 2.25 3.82 0.53 1.82 Lu 0.011 0.022 0.022 0.055 0.053 0.100 0.108 0.193 0.310 0.530 0.073 0.287 Y 2 2 5 10 8 19 28 42 4 19 Note: Blank entries represent values that were below detection limits. Abbreviated rock types: cpxite (clinopyroxenite), hblite (hornblendite) Abbreviated minerals: ol (olivine), hbl (hornblende) Mg# = Mg/(Mg+Fe) assuming all iron as Fe2* * Total closed Teflon vessel. A n y A u or P G E that may have been dissolved during button dissolution are recovered by co-precipitation wi th tel lurium. This produces a concentrate that contains A u and a l l P G E . The concentrate is vacuum-filtered and re-dissolved in aqua regia prior to analysis by I C P - M S . O s m i u m is not reported because, at the aqua regia re-dissolution stage, it may be lost as a volatile oxide. P G E concentrations in the samples, detection l imits , duplicate results, and reference material values are reported in Table 4.6. The normal iz ing values for P G E (primitive mantle) are from M a i e r & Barnes (1999). 4.3.4 Sulphur Isotopes - Sulphide A total o f 27 samples from sulphide-rich lithologies including 3 b l ind duplicates, sampled from dril lcore and outcrop, were analyzed for their sulphur isotopic composit ion. Samples o f massive sulphide were sampled using a scriber wi th a tungsten-carbide tip and a l l other samples were crushed using a steel hammer and base. Sulphide was then hand-picked using a binocular microscope to assure the lack o f any attached silicate, oxide, or other phases. 5 3 4 S was determined on separates that yielded appreciable sulphide. M o s t ultramafic samples contained pyr rho t i t e±pen t land i te wi th trace amounts o f pyrite, although some also contained chalcopyrite. Hornblende-rich samples typical ly contained pyrite and/or chalcopyrite (see Table 4.7). Sulphur was extracted online wi th continuous-flow technology, using a F innigan M A T 252 isotope-ratio mass spectrometer, at the Queen's Fac i l i ty for Isotope Research, Queen's Universi ty , Kings ton , Ontario. A l l values are reported in units o f per m i l (%o) , and were corrected using the N I S T standard 8556. Sulphur is reported relative to Canon Diab lo Troil i te ( C D T ) . Ana ly t ica l precision for 8 3 4 S is 0.3 % o . 4.3.5 Lead Isotopes - Sulphide A total o f 16 sulphide samples from sulphide-rich lithologies, 2 duplicates, sampled from dril lcore and outcrop, and the standard reference material N B S - 9 8 1 were analyzed for their lead isotopic composit ion and the results are presented in Table 4.8. A l l samples were subject to the separation procedure described above for sulphur isotopes. Sulphide separates chosen for analysis were then leached in dilute hydrochloric acid to remove surface contamination before dissolution in nitric acid. Ion exchange columns were employed for the separation and purification o f Pb . The samples were converted to bromide form, and the solution was passed through ion exchange columns in hydrobromic acid, and the lead eluted in 6 N hydrochloric acid. Approximate ly 25-50 ng o f the 121 Table 4.6: PGE concentrations of representative ultramafic rocks from the Turnagain intrusion Rock Type: Sample: MgO S Ni Ir Ru Rh Pd Pt Au Cu Pd/Pt Cu/Pd prefix number (wt. %) (wt. %) (ppm) (ppb) (ppb) (PPb) (PPb) (PPb) (PPb) (ppm) dunite 04ES 03-01-02 51.2 0.09 3310 13.6 9.44 6.27 36.44 44.47 1.97 9 0.82 247 dunite 04ES 06-01-01* 50.2 0.07 2185 1.63 4.67 0.515 0.96 0.975 18 0.98 18750 dunite 04ES 03-02-01 48.7 0.39 1760 1.76 2.73 1.81 23.35 24.13 1.85 492 0.97 21071 dunite 04ES 07-02-01 50.8 0.11 1790 2.77 3.34 0.98 4.18 3.51 5 1.19 1196 dunite 05ES 04-06-01 44.7 0.08 1190 1.17 0.87 1.62 10.85 10.26 34 1.06 3134 dunite 05ES 04-05-01 47.0 0.18 2360 1.3 3.09 0.55 5.58 8.57 0.65 wehrlite 04ES 03-04-01 43.0 1.4 1740 1.46 3.04 1.41 11.54 9.53 2.37 261 1.21 22617 wehrlite 04ES 07-02-04 44.3 0.18 988 3.36 2.62 8.1 102.58 82.62 2.90 126 1.24 1228 wehrlite 05ES 05-06-01* 43.8 0.03 1080 1.2 0.24 1.88 45.08 35.33 5.89 72 1.28 1597 wehrlite 05ES 05-02-01 43.6 0.18 1590 2.94 2.25 3.29 52.61 52.33 17.65 471 1.01 8953 wehrlite 05ES 05-03-01 45.0 0.06 1940 4.21 4.25 4.68 54.6 85.42 1.72 17 0.64 311 wehrlite 05ES 05-01-02 38.7 0.66 858 1.17 2.36 0.75 7.02 6.72 475 1.04 67664 wehrlite 05ES 03-01-01 38.5 1.7 956 0.07 0.16 0.1 4.54 1.77 0.89 233 2.56 51322 wehriite 05ES 05-05-01 36.6 0.23 777 1.05 2.25 0.88 7.23 8.49 248 0.85 34302 ol cpxite 04ES 10-02-04 21.9 0.78 335 0.48 0.15 0.28 5.75 6.4 1.12 381 0.90 66261 ol cpxite 05ES 05-01-01 22.6 0.42 511 1.86 0.5 1.53 23.15 33.32 1.12 292 0.69 12613 cpxite 05ES 05-04-01 19.1 0.04 173 0.23 0.29 1.77 4 292 0.44 164972 cpxite 05ES 03-01-02 21.1 0.33 56 0.06 0.17 4.11 4.22 0.77 47 0.97 11436 hbl cpxite 04ES 09-02-02 16.9 1.1 130 2.15 0.86 8.02 249 2.50 115814 hblite 05ES 05-06-02 13.5 0.14 132 0.41 133 324390 hblite 04ES 00-07-04* 12.4 0.35 136 0.06 0 0.17 4.11 4.35 0.76 84 0.94 20463 Detection Limit: 0.04 0.13 0.08 0.11 0.14 0.71 Intl STD TDB 1-0506 0.08 0.27 0.48 4.91 22.87 6.45 Intl STD TDB 1-0507 0.07 0.26 0.46 4.70 22.71 6.05 Accepted Value: n/a n/a n/a 5.8 22.4 6.3 original 04ES 06-01-01 1.77 5.18 0.53 1.18 1.2 duplicate 05ES 05-07-01 1.49 4.16 0.5 0.74 0.75 original 05ES 05-06-01 1.2 0.22 1.67 45.29 35.08 5.24 duplicate 04ES 00-07-01 1.2 0.26 2.09 44.87 35.58 6.53 original 04ES 00-07-04 0.06 0.17 4.10 4.48 0.75 duplicate 05ES 03-02-01 0.06 0.17 4.11 4.22 0.77 Some rock types have been abbreviated: cpxite (clinopyroxenite), hblite (hornblendite) The last part of the table contains 2 internal standard analyses and 3 sample sets (sample followed by its respective blind duplicate) Samples with an asterisk represent the average between the specific analysis and its blind duplicate Blank entries represent analyses that were below detection Table 4.7: Sulphur isotopic data from the Turnagain intrusion and surrounding lithologies Sample Rock Type Depth (m) Mineralogy Texture S content (%) 6 3 4S (CDT) DDH03-12-4 dunite 31.9 po+pn diss, to crs. bleb., mt rim 37.6 -9.7 DDH04-29-9 dunite 63.8 po+pn fine bleb. 14.6 -9.0 DDH03-16-24 dunite 166 po+pn msv. remob. 42.7 -6.9 05ES-02-02-02 dunite N/A po+pn+cpy+py crs. bleb., mt rim 32.0 -6.7 05ES-02-02-02A dunite N/A po+pn net tex., mt frac. 40.2 -6.4 DDH03-18-13 dunite 84.8 po+pn diss, to crs. bleb.+ inter. 41.0 -5.4 05ES-02-04-01 dunite N/A po+pn diss, to inter. 37.7 -5.3 DDH04-37-6 dunite 39.7 po+/-pn+/-cpy fine bleb. + minor remob. 33.3 -5.1 DDH04-24-31 dunite 220.4 po+cpy+/-pn fine to med. bleb. 38.4 -4.1 DDH04-36-16 dunite 108.1 po+pn diss, to fine bleb. 29.6 -3.4 DDH04-36-5 wehrlite 39.7 po+pn diss, to med. bleb. 40.9 -8.4 DDH04-33-5 wehrlite 37.9 po+pn crs. bleb. 33.8 -8.2 DDH04-23-11 wehrlite 76.2 po+pn net tex., mt rim + frac. 36.8 -8.0 DDH03-06-25 wehrlite 181.5 po+pn msv. remob. 32.3 -5.4 05ES-03-01-01 wehrlite N/A po+pn crs. bleb. 37.4 -5.2 DDH04-28-6 wehrlite 44.8 po+pn+/-cpy fine bleb, to net tex. 37.0 -4.8 DDH03-05-45 wehrlite 325 po med. bleb, to inter. 42.9 -4.7 DDH03-07-25 wehrlite 183 po+pn+cpy fine bleb., mt rim + frac. 35.4 -3.9 DDH04-35-5 wehrlite 40.1 po+pn diss, to med. bleb. 32.2 -3.5 05ES-02-01-01 wehrlite N/A po+pn+cpy net tex., heavy alt. 30.2 -1.7 DDH03-08-13 wehrlite 100.7 po+/-pn diss, to fine bleb. 35.2 -1.1 DDH03-05-8 clinopyroxenite 89.7 po remob. 38.6 -1.3 DDH03-09-18 clinopyroxenite 134.3 po med. bleb. 41.3 -0.6 DDH04-47-17 hbl clinopyroxenite 126.5 py crs. bleb. 58.4 1.4 DDH03-03-59 hornblendite 426 py med. bleb. 43.2 -0.1 04ES-13-01-02 felsic tuff(?) N/A py porph. 45.5 -1.7 DDH03-07-54 graphitic phyllite 389 py porph. 55.8 -17.9 Textures are abbreviated as follows: med. (medium), crs. (coarse), diss, (disseminated), bleb, (blebby), msv. (massive), net tex. (net textured), porph. (porphyroblastic), remob. (remobilized), inter, (interstitial), mt rim (magnetite rim), frac. (fracture) Minerals are abbreviated as follows: po (pyrrhotite), pn (pentlandite), cpy (chalcopyrite), py (pyrite) N/A in "Depth" column indicates that the sample is from a surface exposure Table 4.8: Pb isotopic compositions of selected sulphide fractions from the Turnagain intrusion and surrounding lithologies Sample Rock Type Depth Mineral 206Pb/ 207PW 208PW 207Pb/ 208PW Number 204Pb 2a 204Pb 2a 204Pb 2a 206Pb 2a 206Pb 2a DDH03-16-24 dunite 166 po±pn 18.794 0.015 15.679 0.012 38.36 0.03 0.8343 0.0006 2.027 0.001 05ES-02-02-02 dunite N/A po+pn+cpy±py 18.845 0.027 15.644 0.025 38.62 0.07 0.8302 0.0005 2.042 0.002 05ES-02-02-02A dunite N/A po+pn 18.826 0.022 15.632 0.026 38.50 0.08 0.8303 0.0004 2.045 0.002 DDH04-37-6 dunite 39.7 po±pn±cpy 18.944 0.030 15.681 0.031 38.46 0.09 0.8278 0.0004 2.030 0.002 DDH03-06-25 wehrlite 181.5 po+pn 19.003 0.023 15.675 0.017 38.72 0.05 0.8249 0.0007 2.023 0.002 DDH04-28-6 wehrlite 44.8 po+pn±cpy 19.078 0.025 15.724 0.022 38.62 0.06' 0.8242 0.0002 2.024 0.001 DDH03-05-45 wehrlite 325 po 18.561 0.021 15.527 0.017 38.40 0.04 0.8366 0.0006 2.054 0.001 DDH03-07-25 wehrlite 183 po+pn+cpy 18.882 0.035 15.648 0.034 37.91 0.10 0.8287 0.0004 2.008 0.002 DDH03-08-13 wehrlite 100.7 po±pn 18.726 0.020 15.584 0.016 38.50 0.04 0.8322 0.0007 2.041 0.001 DDH03-05-08 clinopyroxenite 89.7 po+pn 18.106 0.015 15.636 0.012 38.12 0.03 0.8636 0.0007 2.091 0.002 DDH04-47-17 hbl clinopyroxenite 126.5 py±po 18.732 0.015 15.605 0.013 38.45 0.03 0.8331 0.0006 2.038 0.001 DDH03-03-59 hornblendite 426 po+pn 18.855 0.024 15.634 0.016 38.71 0.05 0.8292 0.0009 2.039 0.002 04ES-13-01-02 felsic tuff N/A py 19.155 0.033 15.649 0.033 38.57 0.10 0.8170 0.0004 2.013 0.002 DDH03-07-54 graphitic phyllite 389 py 18.920 0.020 15.629 0.024 38.47 0.08 0.8260 0.0004 2.033 0.002 Minerals are abbreviated as follows: po (pyrrhotite), pn (pentlandite), cpy (chalcopyrite), py (pyrite) Note: All errors are kj absolute N/A in "Depth" column indicates that the sample is from a surface exposure lead in chloride form was loaded on a rhenium filament using a phosphoric acid-s i l ica gel emitter, and isotopic compositions were determined in peak-switching mode using a modified V G 5 4 R thermal ionization mass spectrometer at the Pacif ic Centre for Isotopic and Geochemical Research, Univers i ty o f Br i t i sh Co lumbia . The measured ratios were corrected for instrumental mass fractionation o f 0.10%/amu (Faraday collector) per mass unit based on repeated measurements o f the N . B . S . S R M 981 Standard Isotopic Reference Mater ia l and the values recommended by Th i r lwa l l (2000). Errors were numerically propagated including a l l mass fractionation and analytical errors, using the technique o f Rodd ick (1987). A l l errors are quoted at the 2CT level . 4.4 RESULTS 4.4.1 Olivine Mineral Chemistry Ol iv ine core compositions from olivine-bearing ultramafic rocks o f the Turnagain intrusion become progressively less magnesian from chromitites (F091.96) through dunites (F089-92.5) and wehrlites (F085-90) to ol ivine clinopyroxenites (~Fo83-87) (Figure 4 .7A , Table 4.1). The most M g - r i c h ol ivine in dunite not associated wi th chromitite is F092.5, wh i ch is consistent wi th crystall ization from a primit ive parent magma in equi l ibr ium wi th ol iv ine in mantle peridotite, as originally proposed by N i x o n (1998). Ol iv ine grains from chromitites extend to more M g - rich compositions (up to F096), however these are l ike ly due to F e - M g exchange between ol ivine and neighbouring chromite during sub-solidus re-equilibration (Clark, 1978). The progressive decrease in the forsterite content o f ol ivine wi th decreasing ol ivine abundance in the Turnagain cumulate rocks is consistent wi th progressive decrease in the M g / F e o f the parent magma(s) due to continued ol iv ine precipitation. There is a general positive correlation between the forsterite and N i contents in ol ivine for a l l olivine-bearing lithologies in the Turnagain intrusion (Figure 4 .7B) . Three distinct groups can be identified wi th in this trend. The first group contains the majority o f the ol ivine core analyses, ranging from F091 and N i = 3150 ppm down to F083.5 and N i = 1000 ppm, and reflects progressive M g and N i depletion due to ol ivine crystallization. The second group consists o f ol ivine grains enclosed wi th in or adjacent to chromitite. These compositions extend to higher M g (F096) and N i (2750-4715 ppm) contents, and appear to reflect sub-solidus exchange between ol ivine and chromite as noted above. The third group consists o f ol ivine core compositions that are distinctly depleted in N i at a given Fo content, relative to the ol ivine 125 ol cpxitek wehrliteh dunite chromitite - r—i— i—•— i—i—i—i- • chromitite cores • chromitite rims O dunite cores • dunite rims • wehrlite cores • wehrlite rims A ol cpxite cores A ol cxpite rims 82 84 88 90 92 Fo content 94 96 98 5000 P B 4000 H - i — I — r — i — i — i — r i i i i i i r n — i — i — i — i — i — i — r 82 84 86 88 90 92 Fo content 94 96 98 Figure 4.7: Olivine chemistry from the Turnagain intrusion. A) Forsterite content vs. rock type showing the intra- and interlithological olivine compositional variation (cores and rims). Note the systematic progressive decrease in Fo content of olivine from dunite through wehrlite to olivine clinopyroxenite. Olivine in chromitite has Mg-rich olivine extending up to Fo9 6 due to subsolidus re-equilibration with chromite B) Forsterite content vs. Ni (ppm) showing three distinct populations: olivine from dunite, wehrlite, and olivine clinopyroxenite with "normal" Ni concentrations (1); olivine from chromitite (2) with high Mg/Fe and Ni; and dunite, wehrlite, and olivine clinopyroxenite showing relative Ni depletion (3) compared to the first population. compositions in the first group (Figure 4 .7B) . This N i depletion is consistent wi th the effect o f sulphide l iquid saturation and segregation in the parent magma(s) to these specific dunite, wehrlite, and ol ivine clinopyroxenite samples, wi th N i being strongly partitioned into the sulphide l iquid relative to coexisting ol ivine (e.g. sulphide/silicate l iqu id partition coefficient for N i in basaltic melts is - 8 0 0 (Peach et al, 1990)). 4.4.2 Clinopyroxene Mineral Chemistry Clinopyroxene (diopside) compositions in the Turnagain intrusion range from Mg# = 0.77 to 0.97 (Figure 4 .8A , Table 4.2), where M g # = M g / ( M g + F e 2 + ) . There are no systematic compositional differences between interstitial and cumulus clinopyroxene. There is also relatively little variation in clinopyroxene M g # in wehrlite and ol ivine clinopyroxenite, and significant variation between ol ivine clinopyroxenite and hornblende clinopyroxenite (Figure 4 .8A) . The lower Mg# (0.84) o f clinopyroxene from hornblende clinopyroxenite is consistent wi th its crystallization from more evolved magmas depleted in M g due to abundant early ol ivine (and clinopyroxene) crystallization. The A l and T i contents o f clinopyroxene are also distinctive between the different lithologies o f the Turnagain intrusion. The magnesian diopside grains in wehrlite and ol ivine clinopyroxenite are A l - p o o r (AI2O3 = 0.25-1.54 wt.%) (Figure 4 .8B) , whereas the lower Mg# o f clinopyroxene grains from hornblende clinopyroxenites extend to higher A 1 2 0 3 (0.30-5.27 wt.%) and T i 0 2 (0.04-0.72 wt.%) contents. 4.4.3 Amphibole and Biotite Chemistry Primary cumulus amphibole in the Turnagain intrusion occurs in hornblende clinopyroxenite, hornblendite, and hornblende diorite. Due to the significant size difference between cumulus amphibole (-200-1000 pm) and interstitial amphibole (<75 pm) in hornblendites (Figure 4.4.2F), only cumulus amphibole was analyzed (Table 4.3). Amphibo le is generally halogen- poor (Cl+F = 1-5% o f O H site), contains a moderate amount o f alkalis (Na+K = 0.315-0.908 c.p.f.u.), T i (0.096-0.239 c.p.f.u.), and A l (1.213-2.480 c.p.f.u.), and has a composit ional range between magnesiohastingsite and hornblende (based on the classification scheme o f Leake et al, 1997) (Table 4.3). Smal l amounts o f biotite (1-3 vo l .%) are commonly observed in dunite and wehrlite, whereas hornblende clinopyroxenite may contain 10 v o l . % biotite. Rare, but local ly significant pegmatoidal biotite clinopyroxenite, observed both at surface and in d r i l l core from the D J Zone (Figure 4.1), may contain 50-60 v o l . % biotite. The biotite occurrence in 127 ol cpxite h wehrlite k- 1 1 1 A — i — i — i — i — i — i — i — i — i — • wehrlite cores • wehrlite rims • ol cpxite cores ^ m w w * ol cpxite rims • hbl cpxite cores • hbl cpxite rims i i H i i t t MM k • A i i i 0.75 0.025 0.02 3 0.015 4-1 d • ~ 0.01 0.005 0.85 Mg# ~l—' " — i — i — I — i — i — i — i 1—r 0.95 • wehrlite cores • wehrlite rims • ol cpxite cores Aol cpxite rims • hbl cpxite cores O hbl cpxite rims B t # O, 9* j i i_ J L 0.05 0.1 0.15 0.2 0.25 Al (c.p.f.u.) Figure 4.8: Clinopyroxene chemistry from the Turnagain intrusion. A) Mg# vs. rock type. Note that clinopyoxene from olivine clinopyroxenite and wehrlite have similar Mg#. B) Al vs. Ti. Note the small range both Al and Ti in the Mg-rich lithologies, but the wide range (and linear correlation) of Al and Ti contents in hornblende clinopyroxenite. these rocks suggests that it crystall ized in place o f hornblende. Bioti te analyses in wehrlite are typical ly more magnesian (phlogopite, Mg# = 0.90) than analyses in hornblende clinopyroxenite (biotite, Mg# = 0.60) (Table 4.4). 4.4.4 Major and Trace Element Geochemistry Whole rock samples from the Turnagain intrusion display a large distribution in major element oxide contents (Figure 4.9) and trace element concentrations, wh ich are largely controlled by the abundance and type o f cumulus minerals, and the relative proportions o f cumulus to intercumulus phases. There are four main l i thological groupings: (1) h i g h - M g rocks (dunite and wehrlite), (2) intermediate-Mg rocks (olivine clinopyroxenite and hornblende clinopyroxenite), (3) hornblendites, and (4) diorit ic rocks, represented by one sample ( D D H 0 4 - 57-12-89) in this study. 4.4.4.1 Group 1: H i g h - M g Ol iv ine- r ich Rocks These rocks are dominated by cumulus ol ivine and chromite wi th interstitial, and rarely cumulus, clinopyroxene. Their whole rock M g O contents range from 35 to 51 wt .% and they have a restricted range in M g # (0.80-0.95), consistent wi th the presence o f abundant cumulus ol ivine (>Fooo) and minor amounts o f clinopyroxene. W i t h respect to elements compatible in ol ivine or chromite, the h i g h - M g rocks contain significant C r (500-5500 ppm) and N i (800- 3400 ppm) (Figure 4.10). The h i g h - M g rocks are also extremely poor in a l l elements not incorporated into ol ivine or chromite (e.g. C a , A l , T i , R E E ) to the extent that incompatible trace element abundances are generally at or below detection limits for nearly a l l o f the dunites analyzed. Wehrlites exhibit slightly concave-down chrondrite-normalized rare earth element patterns (Figure 4.11 A ) ranging from 0.3-0.8 x chondrite (La) wi th a ( L a / Y b ) c n o f 0.4-0.9. Wehrlites generally exhibit similar extended trace element patterns (Figure 4.1 I B ) . The single dunite sample (05ES-04-05-01) wi th trace element concentrations significantly above detection limits has distinctive LREE-en r i chmen t relative to a l l other ultramafic samples from the Turnagain intrusion (Figure 4.11 A ) . This sample contains abundant 1-2 m m serpentine veinlets wi th minor rutile and chlorite, thus the distinctive chemistry is l ikely due to post- crystallization modification during fluid-rock interaction and serpentinization, wh ich may have implications for minor L R E E mobi l i ty in rocks o f the Turnagain intrusion during serpentinization. 129 I 45 9 09 I Whole Rocks | ^ Dunite _ Wehrlite |A Olivine cpxite Hbl cpxite |0 Hblite U- Diorite X Wacke 10 20 30 40 50 MgO (wt. %) -I—rj—i—i—|—i—i—i i |—i—i—i—i—|—I—I—i—i—| i i 8 o ce X + 10 20 30 40 MgO (wt. %) =•* 0.75 2 i i i—I—| i i r i | i i i i | i i i—i—|— E fl f: x • * • • i i_ _l I 1 I I I I I L 20 30 40 50 MgO (wt. %) B -i—i—i—i—|—i—i—i—i—i—i—i— Minerals Olivine (dunite) • Olivine (wehrlite) A Olivine (ol cpxite)| • Cpx (wehrlite) A Cpx (ol cpxite) • Cpx (hbl cpxite) O hbl (hbl cpxite) O hbl (hblite) _ i . • i . • 10 20 30 40 MgO (wt. %) 10 20 30 MgO (wt. %) O « 10 -I—I—i—I I I i^Q—I F 4 | + - ^ Q O t ^ - 1 - 20 30 MgO (wt. %) Figure 4.9: Select major element oxides and Mg# vs. MgO for whole rock samples from the Turnagain intrusion. Individual whole rock analyses are plotted as large symbols shaded in grey, with the exception of hornblendite (open circles). Mineral analyses from specific lithologies have the same symbol as the whole rock sample, however they are smaller and variably shaded i.e. olivine from dunite is diamond-shaped, but smaller and open. Whole rock Mg# = Mg/(Mg+Fe). Note the large compositional gap between dunite/wehrlite and olivine clinopyroxenite/hornblende clinopyroxenite. All ultramafic rock types have high Mg# (-0.80) reflecting accumulation of olivine and/or clinopyroxene, whereas the hornblendites have relatively low Mg# (0.63). Abbreviations are: cpx (clinopyroxene), cpxite (clinopyroxenite), hbl (hornblende), hblite (hornblendite). 130 I I I I I I I I I I I I I I I E a a 3000 Whole Rocks ^ Dunite Wehrlite A Olivine cpxite 0 Hbl cpxite 0 Hblite - | - Diorite X Wacke • | 4L -I*- 20 30 40 MgO (wt. %) • E 2000 a a —i—i—i—|—l—i—i—r— Minerals Olivine (dunite) • Olivine (wehrlite) A Olivine (ol cpxite)| • Cpx (wehrlite) A Cpx (ol cpxite) • Cpx (hbl cpxite) O hbl (hbl cpxite) hbl (hblite) B 4*- 20 30 40 MgO (wt. %) 70 60 50 E o. 40 a u co 30 20 10 0 ;D • • A • X - • ; + B i i i i i i 20 30 40 MgO (wt. %) 20 30 MgO (wt. V4 Figure 4.10: Select trace element concentrations vs. MgO for whole rock samples from the Turnagain intrusion. The same symbol style as Figure 9 is applied here. The large compositional gap present in Figure 9, between olivine cumulate rocks and clinopyroxene4iornblende cumulate rocks, is also apparent with respect to trace elements. 100 I I I I I I I I I I I l I I I i i I I i i i r Ba Ta Nb La Ce Pr Sr Nd Zr Hf Sm Eu Gd Tb Ti Dy Ho Er Tm Yb Lu Y Figure 4.11: Chondrite-normalized rare earth element and primitive mantle-normalized trace element diagrams for whole rocks from the Turnagain intrusion (normalizing values from McDonough and Sun, 1998). A) Ultramafic rocks from the Turnagain intrusion, showing a progressive overall enrichment in REE and in LREE from wehrlite to olivine clinopyroxenite to hornblendite. Note that, with the exception of one sample, REE concentrations in the dunite samples were near or below detection limits and have not been plotted. B) Note the very low abundances of trace elements in the most magnesian rock types, consistent with their status as cumulate rocks, and the prominent negative Zr-Hf and Ta-Nb anomalies in all rock types where concentrations are above detection limits. 4.4.4.2 Group 2: Intermediate-Mg Cl inopyroxene-Rich Rocks Ol iv ine clinopyroxenite and hornblende clinopyroxenite, l ike the h i g h - M g ol iv ine-r ich rocks, exhibit major element oxide contents that correlate wi th their clinopyroxene-dominant mineralogy. They have a relatively restricted M g O range (16-22 wt.%) and M g # (0.75-0.85), both o f wh ich are lower than in the ol iv ine-r ich rocks, wh ich is consistent wi th the presence o f abundant cumulus clinopyroxene. Cl inopyroxene-r ich lithologies have relatively high whole rock A 1 2 0 3 (1-2 wt.%) and C a O (16-20 wt.%) contents (Figure 4.9) and exhibit moderate C r enrichment (1200-3200 ppm) (Figure 4 .10A) . Note that, wi th respect to major elements, the whole rock hornblende clinopyroxenite sample (05ES-05-06-02) plots between its respective amphibole and clinopyroxene mineral compositions in Figure 4.9. Chondrite-normalized R E E patterns show a concave-down shape similar to the h i g h - M g group ( ( L a / Y b ) c n = 0.3-2.0), but wi th higher R E E contents (0.8-9 x chondrite L a ) (Figure 4.11 A ) . The cl inopyroxene-rich rocks also have similar primit ive mantle-normalized trace element patterns to h i g h - M g rocks, but again wi th higher overal l abundances. Negative Ta -Nb and Z r - H f anomalies are present where the abundances o f these elements are above detection limits (Figure 4.1 I B ) . 4.4.4.3 Group 3: Hornblendites The whole rock hornblendite samples are characterized by moderate M g O contents (12-13 wt.%) wi th a relatively l ow Mg# (0.64) (Figure 4.9) and have significantly higher C a O (-13 wt.%), A I 2 O 3 (-13 wt.%), and T i 0 2 (-2.4 wt.%) contents compared wi th h i g h - M g rocks. Incompatible trace elements are also enriched in hornblendites (10-30 x chondrite L a ) (Figure 4.11 A ) compared wi th clinopyroxene-rich lithologies. The hornblendites, s imilar to the intermediate-Mg and h i g h - M g rocks, display concave-down R E E patterns wi th ( L a / Y b ) c n from 0.6-1.2. Note that the two analyzed hornblendite samples have sub-parallel R E E patterns but distinctly different concentrations. The most R E E - r i c h hornblendite (04ES-00-07-04) is an extremely fine-grained rock (grain size <1 mm) and thus has a composit ion closest to the original silicate magma (where the interstitial amphibole and other accessory phases represent the chi l led melt). The other hornblendite (05ES-05-06-02) is coarse-grained and contains substantial large cumulus amphibole crystals resulting in di lut ion to lower incompatible element concentrations. The primit ive mantle-normalized trace element patterns o f the hornblendites are sub-parallel to the cl inopyroxene-rich lithologies and ol iv ine-r ich lithologies, 133 albeit at higher concentrations (Figure 4.1 IB), and exhibit prominent negative Ta-Nb and Zr- Hf anomalies. 4.4.4.4 Group 4: Dioritic Rocks The dioritic rocks are represented by a single whole rock sample in this study (DDH04-57-12). This sample is a cumulate-textured hornblende diorite composed of coarse amphibole (15 vol.%) and plagioclase (80 vol.%) and contains moderate silica (55 wt.%) and high alumina (21 wt.%) contents and has a comparable Mg# (0.64) to the hornblendites (Figure 4.9). These characteristics are consistent with the high modal plagioclase and moderate amphibole contents of this sample. The hornblende diorite contains low abundances of all incompatible trace elements, comparable to dunite (Table 4.5), reflecting its cumulate nature. This sample displays a significant positive Eu anomaly (Eu/Eu* = 1.418) and, with respect to primitive mantle-normalized trace elements, displays high positive Sr and Ba anomalies (2800 ppm and 1980 ppm, respectively), which is consistent with the high modal abundance of cumulus plagioclase. 4.4.5 Platinum-Group Elements Concentrations of Pt and Pd in whole rock samples from the Turnagain intrusion range from <0.14-85 ppb Pt and 0.4-102 ppb Pd, respectively (Figure 4.12A, Table 4.6 ). Pt/Pd ratios vary between 0.4-2.5 with an average value of 0.9 and a median value of ~1 (Figure 4.12A). The absolute abundances of the PGE vary systematically between rock types (Figures 4.12, 4.13). Most olivine clinopyroxenite and all hornblende-bearing lithologies have low to negligible PGE contents, dunite is characterized by low to moderate PGE concentrations, and wehrlite contains the highest PGE concentrations of all ultramafic lithologies in the Turnagain intrusion. There is no correlation between whole rock PGE content and sulphur (Figure 4.12B), which suggests that the PGE reside as discrete PGM alloy phases (e.g. Pt3Fe, or isoferroplatinum) in wehrlite. Primitive mantle-normalized PGE patterns show an overall increase from Ir to Pt with a Pt/Ir ratio varying from 0.6-72 (mean value of 19.1), with some samples exhibiting a negative Ru anomaly (Figure 4.13); a common trait of PGM alloys in chromitites from other Alaskan-type intrusions (G. Nixon, pers. comm., 2007). 200 180 160 140 Q. 120 a. •a 1 0 0 a. i 80 Q- 60 40 20 0 20 i i I i i 40 o ~ . ° 60 80 100 120 Pd (ppb) i • • r B • dunite • wehrlite A olivine clinopyroxenite • hornblende clinopyroxenite| • hornblendite • A 0.2 0.4 0.6 1.2 1.4 1.6 1.8 0.8 1 S (wt. %) Figure 4.12: Platinum-group element compositional variations for whole rocks from the Turnagain intrusion. A) Pd vs. Pt. B) S vs. Pt+Pd. Note that wehrlite samples contain the highest Pt and Pd abundances. The absence of a positive correlation between sulphur and metal contents indicates that the PGE are likely contained in discrete platinum group minerals or alloys and not in sulphides. 135 Figure 4.13: Primitive-mantle normalized platinum group element diagrams for whole rocks from the Turnagain intrusion (normalizing values from Maier and Barnes (1999)). The thick black line in all graphs represents the detection limits. Wehrlites have the highest overall abundances of PGE and distinct positive slopes from Ru to Pt. 136 4.4.6 Sulphur Isotopic Compositions The range o f sulphur isotopic compositions o f sulphide separates from lithologies in the Turnagain intrusion and proximal host rocks is presented in Figure 4.14. Pyrite from the R o a d R ive r phyll i te has the most negative 8 3 4 S value at -17.8 %o (Table 4.7). Sulphides from dunite and wehrlite (mostly pyrrhotite and pentlandite) show large ranges in their sulphur isotopic compositions ( 8 3 4 S = -10 %o to -1 %o), w i th dunite sulphide shifted to more negative values ( 8 3 4 S = -9.7 %o to -3.4 %o) relative to wehrlite sulphide ( 5 3 4 S = -8.4 %o to -1.1 %o). Sulphide separates from ol ivine clinopyroxenite and hornblende-bearing lithologies in the Turnagain intrusion have sulphur isotopic compositions close to mantle values (0 ± 3 %o, Schneider, 1970; Sakai et al., 1984; R ip ley , 1999). There is no direct correlation between the presence o f alteration associated wi th sulphide in dunite and wehrlite (see Figure 4.6) and its sulphur isotopic composit ion. 4.4.7 Lead Isotopic Compositions The range o f lead isotopic compositions o f sulphide separates from various lithologies wi th in , and proximal to, the Turnagain intrusion is: 2 0 6 P b / 2 0 4 P b = 18.11-19.16 , 2 0 7 P b / 2 0 4 P b = 15.53- 15.72, 2 0 8 P b / 2 0 4 P b = 37.91-38.72 (Table 4.8). There is no apparent correlation between the lead isotopic composit ion o f a sulphide separate and its host l i thology. The sulphide analyses form a broadly linear array between the mantle Pb growth curve and the upper continental crust (Zartman & Zoe , 1981) and/or average Cordi l leran shale curve (Godwin & Sinclair , 1982), wh ich is interpreted as a m i x i n g line (Figure 4.15 A ) . The Pb isotopic composit ion o f most o f the sulphide separates is shifted towards more radiogenic values relative to mantle values, indicating a greater contribution o f Pb from crustal sources. 4.5 DISCUSSION 4.5.1 Parent Magma Characteristics The petrology and geochemistry o f rocks from the Turnagain Alaskan-type intrusion indicate that it was formed by the emplacement and crystallization o f M g - r i c h , primit ive, hydrous magmas in an arc setting. The primit ive nature o f the parent magmas is constrained by the M g - rich ol iv ine compositions (up to F092.5) in dunite that has not re-equilibrated wi th chromite. The hydrous nature o f the parent magma is supported by 1) primary interstitial phlogopite in the olivine-clinopyroxene cumulates, 2) late interstitial to cumulus hornblende in rocks from Hornblendite |- Clinopyroxene Hornblendite Olivine Clinopyroxenite Wehrlite Dunite Felsic Tuff Road River Phyllite 1 f 1 I 1 1 1 I 1 I 1 1 1 I 1 1 1 1 1 1 1 # • I m ' i • A . 1 1 1 1 1 1 1 1 1 1 1 1 1 .1 1 1 -20 -15 -10 5 M S (CDT) Figure 4.14: Sulphur isotopic composition of sulphide vs. lithology in the Turnagain intrusion. Note the wide variation in 534S in both dunite and wehrlite, extending towards the highly negative value of pyrite from the Road River phyllite (834S = -17.9 %o). The blue region represents the mantle range of 834S. 138 15.8 15.7 -Q CL •* o !B CL 15.6 15.5 15.4 - i — i — i — i — i — i — r \2o A ~ i— i — I — r 0 Ma 400 Ma 800 Ma 400 Ma 16.9 17.4 17.9 18.4 18.9 2MPb/J04Pb 39.5 39.0 •Q Q. ^ 38.5 -Q CL 00 o tM 38.0 37.5 37.0 | 2 a B 0 Ma 16.9 17.4 17.9 18.4 18.9 206Pb/204Pb 19.4 Dunite • DDH03-16-24-166 • 05ES-02-02-02 O05ES^)2-02-02A • DD0H4-37-6-39.7a Wehrlite • DDH03-06-25-181.5 • DDH04-38^6-44.8 A • DDH03-05-45-325 • DDH03-07-25-183A • DDH03-08-13-100.7 Hornblendite • DDH04-47-17-126.5 • DDH03-03-5&426 Road River X04ES-13-01^32 DDH03-07-34-38.9 19.4 Figure 4.15: Lead isotopic compositions (A: 206Pb/204Pb vs. 207Pb/204Pb, B: 206Pb/204Pb vs. 208Pb/204Pb) of sulphide from the Turnagain intrusion with upper continental crust and mantle growth curves from Zartman & Doe (1981) and the shale curve from Godwin and Sinclair (1982). 139 the central part o f the intrusion, 3) the late appearance o f plagioclase as a cumulus phase relative to clinopyroxene and hornblende (e.g. Gaetani et al, 1993), and 4) the presence o f a fine- grained hornblendite dike (sample 04ES-00-07-04) that intruded wallrocks o f the Turnagain intrusion. Sub-parallel trace element patterns, especially the rare earth elements ( R E E ) , indicate a genetic association between the different ultramafic rock types o f the Turnagain intrusion. The range in concentrations reflects the relative abundances o f cumulus ol ivine (and spinel), which both contain extremely low abundances o f incompatible trace elements, cumulus and interstitial clinopyroxene, hornblende, and accessory minerals that crystall ized from an evolved interstitial melt. The arc geochemical signature for the Turnagain parent magmas is based on combined trace element and N d isotopic (see Chapter 2) characteristics o f the analyzed samples. The prominent negative high field strength element ( H F S E ) anomalies (Figure 4.1 I B ) , specifically N b and Ta, is typical o f arc-derived magmas, reflecting (for example) the retention o f the H F S E in refactory minerals such as rutile during subduction and magma genesis (e.g. Ryerson & Watson, 1987). Addi t iona l ly , the most radiogenic N d compositions o f samples from the Turnagain intrusion (Chapter 2) fall wi thin the general range o f Paleozoic arc-derived mafic volcanic rocks from the northern Canadian Cordi l le ra ( e N d = +4 to +7; Piercey et al, 2006). 4.5.2 Sequence of Crystallization The relative order o f crystallization and emplacement in the Turnagain intrusion is dunite —> wehrlite —* ol ivine clinopyroxenite —> hornblende clinopyroxenite —* hornblendite —• diorite. The entire sequence o f rocks crystall ized and cooled down to ~ 3 5 0 ° C at 190±1 M a , based on the combined results from U - P b and A r - A r geochronometry (Chapter 2). Cross-cutting relations and ferromagnesian silicate M g / ( M g + F e 2 + ) (e.g. Fo 0 n V ine, M g # c p x , M g # h b i ) are consistent wi th the sequential crystallization and emplacement o f ultramafic and mafic lithologies in the Turnagain intrusion. Dunite (~Foai) cumulates are cross-cut by wehrlite dikes, wehrlite (-Fogy) is cross-cut by ol ivine clinopyroxenite dikes, ol ivine clinopyroxenite (-Fogs, M g # c p x = 0.92) is cross-cut by hornblende clinopyroxenite dikes, hornblende clinopyroxenite ( M g # c p x = 0.81, M g # n b i = 0.65) is cross-cut by hornblendite dikes, and hornblendite (Mg# h b i = 0.60) is cross-cut by diorite. Later lithologies typical ly cross-cut al l earlier lithologies (e.g. diorite dikes are observed to intrude dunite at the southeastern contact between these two lithologies (Figure 4.1)), however some contacts between lithologies (e.g. dunite-wehrlite) may be gradational. There are local examples o f dunite dikes cutting ol ivine clinopyroxenite (Figure 4 .3 . IB) , near the contact between these two lithologies in the northwestern part o f the intrusion (Figure 4.1). These "dikes" are interpreted to represent fractures wi th in the ol ivine clinopyroxenite through which primitive melts were injected. The primit ive melts dissolved clinopyroxene and precipitated ol ivine, similar to dunite dikes observed in ophiolites (Kelemen & D i c k , 1995; Braun & Kelemen, 2002). Alternatively, the dikes could represent injected dunite cumulates. The dunite dikes in the Turnagain intrusion do not appear to present replacive dunites as observed in other Alaskan-type intrusions (e.g. Duke Island, A laska ; Irvine, 1974). Combined with trace-element and P G E results, the chemical and l i thological constraints on the evolution o f the Turnagain intrusion imply that a l l lithologies are genetically related and that they crystallized from an evolving magma in an open system. 4.5.3 Implications for associated volcanic rocks Based on petrologic and geochemical relations, the Turnagain intrusion can be interpreted as part o f a magmatic feeder system to an arc volcano. The relationship between Alaskan-type intrusions and basaltic volcanic rocks has been discussed since some o f the earliest studies o f these intrusions (e.g. Findlay, 1969; Irvine, 1974; Clark, 1975). This association has typical ly been spatial, as belts o f basaltic volcanic rocks have been observed to be broadly sub-parallel to belts o f Alaskan-type intrusions. A temporal association between volcanic rocks and Alaskan-type intrusions has been established in B . C . (Late Triassic Takla/Nicola/Stuhini Groups; N i x o n et al, 1997), Co lumbia (Tist l et al, 1994), and Kamchatka (Batanova et al, 2005), and a genetic relationship between ankaramitic dikes and Alaskan-type intrusions was proposed by Mossman et al (2000). A r c ankaramite and picri t ic ankaramite have been observed as volcanic rocks near, or intruded by, Alaskan-type intrusions in southern Ala ska (Irvine, 1974) and the Kamchatka Peninsula, Russia (Batanova et al, 2005), and as dikes cross-cutting Alaskan-type intrusions in N e w Zealand (Mossman et al, 2000; Spandler et al, 2003) and central M e x i c o (Hernandez, 2000). A r c ankaramite dikes, wi th a whole rock C a O / A i 2 0 3 > l , share three key characteristics wi th Alaskan-type intrusions: mineralogy, crystallization sequence, and zonation. Ankaramite dikes are typical ly composed o f ol ivine and clinopyroxene phenocrysts set in a groundmass containing hornblende and minor plagioclase. The crystallization sequence in the ankaramite dikes is ol ivine —> clinopyroxene —> hornblende —• plagioclase, similar to that i n many Alaskan-type intrusions. F ina l ly , the 141 zonation in these dikes is delimited by olivine and clinopyroxene phenocrysts at the centre, which reduce in size outwards and grade into fine-grained hornblende that may contain interstitial plagioclase adjacent to the margin. Extrusive equivalents o f the Turnagain and other Alaskan-type intrusions should occur as olivine+clinopyroxene-phyric basalts in the field, characterized by primit ive mineral compositions, and as such may potentially be found in any arc mafic volcanic formations o f Ear ly Jurassic age in B . C . (e.g. Rossland Group, southern B . C . ) . 4.5.4 Origin of sulphide mineralization in the Turnagain intrusion The presence o f abundant sulphide, predominantly pyrrhotite and pentlandite, in the Turnagain intrusion is unusual for Alaskan-type intrusions. Basalts generated in subduction zone settings (arc basalts) typical ly contain 900-2500 ppm sulphur, higher than mid-ocean ridge basalts at comparable F e O (Wallace, 2005). The speciation o f dissolved S in arc magmas is important in the genesis o f magmatic sulphide in the Turnagain intrusion. Sulphur may exist in multiple valence states (S 2", S°, S 4 + , S 6 + ) depending on the relative oxygen fugacity (/O2) o f its hosting magma. The relative oxygen fugacity and sulphur content o f basaltic melts, illustrated in Figure 4.16, are cri t ical factors in assessing the development o f sulphide saturation (e.g. Jugo et al., 2004; 2005). At7D2 values at or below the reference oxygen buffer fayalite + O2 <->• magnetite + quartz ( F M Q ) , the dominant sulphur species in basaltic l iquids is sulphide (S2") (Figure 4 .16A) , where A F M Q is the J02 relative to F M Q . Magmas with a relatively high fd2 (greater than A F M Q = 0 to +1) w i l l have S dominantly speciated as sulphate (S0 4 2 ~), and as such need significantly more S (approximately an order o f magnitude more) to become sulphate-saturated (Figure 4.16B). This is consistent wi th the observations that most arc magmas are relatively oxidized (e.g. Ballhaus et al., 1991; Carmichael , 1991; Parkinson & Arcu lus , 1999; Rohrbach et al, 2005), and the general absence o f magmatic sulphide deposits associated with most arc plutonic and volcanic rocks. A s documented in this study, the Turnagain intrusion contains abundant localized sulphide mineralization (pyrrhotite+pentlandite), thus requiring that the7D2 o f the parent magmas was relatively low, especially compared with other typical arc magmas (Figure 4.16). This reduced nature o f the parent magmas is consistent wi th the extremely low ferric iron content and F e 3 + / S F e (e.g. Parkinson & Arcu lus , 1999) o f chromite from chromitite in the intrusion (Figure 3.10; Chapter 3). In addition, relatively early sulphide saturation in the crystallization sequence o f the 142 1.0 0.9 X o O 0.6 re o 0.5 o E 0.4 5 0.3 3 0.2 (A 0.1 0.0 10.00 c - »2- T 1 1 r Typical Arc Volcanics ceo SO. 2 ' - 3 - 2 - 1 0 1 2 3 4 oxidation state (AFMQ) B ? 1.00 c a> c o u 3 0.10 Q. 3 (0 0.01 basalt trachyandesite CCO (hydrous)' I J Typical Arc Vocanics Arc Peridotites I 1 - 4 - 3 - 2 - 1 0 1 2 3 4 oxidation state (AFMQ) Figure 4.16: Diagrams showing the effects of oxygen fugacity on sulphur speciation and saturation in silicate magmas. The ranges in/0 2 for arc magmas (Carmichael, 1991; Rohrbach et al., 2005) and arc peridotites (Parkinson & Arculus, 1999) are plotted as closed lines. A) Oxidation state (log AFMQ) vs. sulphate mole fraction, modified from Jugo et al'. (2004). Note the transition between sulphide (S2) and sulphate (S042') between AFMQ = 0 to +2.5. B) Oxidation state (log AFMQ) vs. sulphur content required to induce saturation, modified from Jugo et al. (2005). An order of magnitude more sulphur is needed to saturate a silicate magma in sulphate than sulphide. Turnagain intrusion is demonstrated by the. local presence o f crystall ized mss inclusions in chromite grains (Figure 3.3D, Chapter 3) and Ni-deplet ion o f ol ivine in some dunite and wehrlite samples (Figure 4 .7B) . Sulphide separates from the Turnagain intrusion display S 3 4 S values from +1 %o (mantle-like; e.g. R ip ley , 1999) down to -9.7 %o (Figure 4.14), shifted in the direction o f pyrite from the enclosing graphitic phyllite (-17.9 %o) . M a n y o f the analyzed sulphide separates exhibit highly radiogenic Pb isotopic compositions (Figure 4.15), consistent wi th the incorporation o f crustal Pb, and some whole rock ultramafic samples exhibit low 8 N q values (Figure 2 .10B; Chapter 2) outside the range for typical mafic volcanics. Combined, these results indicate that crustal material was added to the Turnagain parent magmas, especially S, wh ich may have aided in achieving sulphide saturation. Inclusions o f graphitic, pyrit ic phylli te are observed in drillcore from areas proximal to or wi th in the sulphide-mineralized zones o f the Turnagain intrusion (Figure 4.6). The pyrite in these inclusions has been completely converted to pyrrhotite, wh ich is indicative o f the prograde reaction 2 FeS2 <-> 2 FeS + S 2 . The phylli te inclusions released sulphur and carbon into the surrounding mafic l iqu id during heating and partial assimilation, wi th the graphite acting as a reducing agent, possibly fo l lowing reactions such as C0 3 2 "( m e i t ) *-> C02( g) + 0 2~(m ei t) (N ixon , 1998) or C(S) +0(m eit) CO( g ) . The fact that partially digested phylli te wi th remnant graphite is sti l l present in many ultramafic rocks from the mineralized zones indicates that the magmas proximal to these inclusions may have had a jOi near the C C O buffer (carbon-carbon monoxide) ( A F M Q = -1 at upper crustal pressures and hydrous conditions; Parkinson & Arcu lus , 1999). Therefore the phyll i te inclusions acted as both a sulphur source and a reducing agent, thus a l lowing the Turnagain intrusion to achieve early sulphide saturation. 4.5.5. Petrogenesis of the Turnagain intrusion and associated Ni-sulphide mineralization The Turnagain Alaskan-type intrusion was formed in a subduction zone and the parent magma were l ike ly generated from the fluid-fluxed partial melting o f a peridotitic mantle wedge (e.g. Spandler et al., 2003; Green et ah, 2004; Batanova et al, 2005). The parental magma generated i n this setting was hydrous, l ike ly volati le-rich (S, C l ) , and primitive, as defined by the high forsterite content o f ol ivine (F092.5). This magma ascended through the mantle lithosphere and overlying crust wi th relatively minor interaction, based on the highly magnesian ol ivine compositions, the mineral assemblage o f the hornfelsed volcanic wacke 144 (epidote + plagioclase ± amphibole ± biotite), and the whole rock N d isotopic compositions o f the various lithologies (Chapter 2), until it reached the upper crust. The intrusion was emplaced and crystallized wi th in a tectonically active environment, perhaps explaining the presence o f erratic chromitite schieren in dunite and rare modal layering in other lithologies (interpreted to have formed by magmatic turbidity currents), as evidenced by the presence o f Alaskan-type intrusions along major structures (Nixon et al, 1997; Krause et al., 2006). The magmas differentiated and cooled in a relatively short interval o f time at 190 M a , producing the entire range o f lithologies present in the Turnagain intrusion, wi th periodic injections o f primit ive melt, as evidenced from the near-constant Pt /Pd ratio and possibly the dunite dikes. Stoping o f roof- and wall-rocks, as observed by hornfelsed inclusions o f phylli te and volcanic wacke, introduced significant amounts o f local crustal material that were partially incorporated into the magma. Metasedimentary inclusions are only observed wi th in or near areas containing abundant sulphide. The pyrite-rich graphitic phylli te, the dominant host rock enclosing the intrusion, released S and C into the surrounding magma during heating. M a n y Alaskan-type intrusions are typical ly hosted in intrusive rocks, volcanic sequences, and juvenile clastic sedimentary rocks, and as such do not appear to be prospective for magmatic sulphide mineralization. The composit ion o f the host rocks o f the Turnagain intrusion is distinct from those that host other Alaskan-type intrusions, and thus the key factor that promoted local ly abundant sulphide mineralization in Turnagain intrusion was this distinctive package o f pyritic and graphitic phyllites. 4.6 C O N C L U S I O N The origin, emplacement, and crystallization o f the Turnagain Alaskan-fype intrusion in north- central Br i t i sh Co lumbia are constrained by 1) the high fersterite content (F092.5) o f ol ivine from the central dunite, 2) the progressively decreasing Fo content o f ol ivine, Mg# o f clinopyroxene and hornblende, and decreasing whole rock Mg# from ultramafic lithologies in the intrusion, 3) cross-cutting relationships between lithologies, 4) sub-parallel rare earth element ( R E E ) patterns between ultramafic lithologies, 5) the presence o f phlogopite in early ol ivine cumulates (dunite, wehrlite), the presence o f late, primary hornblende in clinopyroxene-hornblende cumulates, and the absence o f early plagioclase, and 6) high field strength element ( H F S E ) depletions, especially T a and N d , in a l l ultramafic rocks. These results indicate that the Turnagain parent magmas were primitive melts generated in the mantle, wi th in a subduction zone setting, and that each lithology 145 in the crystallization sequence formed from progressively fractionated magmas. Disseminated to semi-massive Ni-sulphide mineralization, which occurs in a number o f zones wi th in the Turnagain intrusion, is variable in tenor and texture. A number o f features constrain the origin o f the sulphide-rich zones: 1) ol ivine from select dunite and wehrlite samples exhibits Ni-deplet ion, 2) the 8 3 4 S values o f sulphide separates span a wide range, from mantle-like values (0±1.1 %o) down to light values (-9.7 %o), wi th the most magnesian rocks (dunites) systematically shifted to lighter 8 3 4 S values, 3) the Pb isotopic compositions o f the sulphide separates indicate the presence o f a significant component o f radiogenic Pb derived from upper crustal rocks, and 4) partially digested inclusions o f graphitic phylli te found in the mineralized zones contain pyrrhotite instead o f pyrite. These results indicate that the sulphide mineralization in the Turnagain intrusion occurred as a result o f assimilation o f local upper crustal material, specifically the hosting Road River phyllite, which contains significant graphite and pyrite (8 3 4 S = -17.9%o). The graphite acted as a reducing agent such that sulphur in the parent magmas was dominantly speciated as sulphide (S2~) rather than sulphate (SO4 2"), wh ich is typical o f most arc-derived magmas. The reduced nature and the addition o f crustal sulphur al lowed for sulphide saturation to occur in the regions o f the Turnagain intrusion where the majority o f graphitic phyllite inclusions occur, and where the addition o f crustal S was needed to saturate in earlier lithologies. The composit ion o f the country rocks was crit ical in a l lowing the Turnagain Alaskan-type intrusion to host magmatic Ni-sulphide mineralization. 146 4.7 A C K N O W L E D G E M E N T S I am grateful to Hard Creek N i c k e l Corp. for continued field support for this project and to J im Reed o f Pacific Western Helicopters for his exemplary logistical support in the field. Special thanks to Tony Hitchins, Bruce Northcote, Chris Baldys , and M a r k Jarvis (President) o f Hard Creek N i c k e l Coro . for their generous support and interactions throughout the period o f my M . S c . thesis at U B C . Thanks to M a t i Raudsepp at the Univers i ty o f Br i t i sh Columbia for guidance in the use o f the electron microprobe and support during the research phase o f this manuscript, Janet Gabites at the Pacific Centre for Isotopic and Geochemical Research ( U B C ) for processing the sulphide Pb isotopic analyses, and Andrew Greene for input into this manuscript. Thanks also to Reza Tafti o f the M i n e r a l Deposits Research Uni t ( U B C ) for support during the research phase o f this manuscript as we l l as Dr . A k i r a Isiwatari for mai l ing his published works on the Alaskan-type intrusions in Kamchatka, China , and Japan. Funding for this project was provided by a research grant from Hard Creek N i c k e l Corp. 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Geological Survey Professional Paper P 1275, 169-170 CHAPTER 5 SUMMARY AND CONCLUSIONS 5.1 S U M M A R Y A N D C O N C L U S I O N S This comprehensive study o f the Turnagain Alaskan-type intrusion in north-central Bri t ish Columbia , Canada, is based on the combined results o f field relations, petrography, mineral (spinel, ol ivine, clinopyroxene, and amphibole) chemistry, whole rock major and trace element geochemistry, neodymium isotopic geochemistry, sulphide sulphur and lead isotopic geochemistry, and A r - A r and U - P b geochronology. The major goals o f this study included 1) constraining the age and source o f the parent magmas to the Turnagain intrusion, 2) evaluating the or ig in and petrogenesis o f the intrusion, and 3) identifying the mechanism(s) responsible for the genesis o f anomalous nickeliferrous sulphide mineralization in an Alaskan-type intrusion. The magmas parental to the Turnagain intrusion were hydrous and primitive, and were derived in a subduction zone. The intrusion consists o f cumulate dunite (~Fo 0iiVine = 91), wehrlite (~Fo 0iiVine = 87), ol ivine clinopyroxenite (~Fo 0iiVine = 85, M g # c p x = 0.92), hornblende clinopyroxenite ( M g # c p x = 0.81, Mg# h bi = 0.65), hornblendite (Mg# n bi = 0.60), and diorite. This intrusive sequence and their relative order o f emplacement is constrained by cross-cutting relationships. Ol iv ine , clinopyroxene, and amphibole chemistry suggest that a l l lithologies crystall ized from a progressively fractionating parent magma. Trace element geochemistry, especially the rare earth elements, o f whole rock ultramafic samples indicates a genetic relationship between al l lithologies, and corroborates their relationship by crystallization from a progressively evolving l iquid . A l l lithologies in the Turnagain intrusion, based on the similari ty o f A r - A r (phlogopite, hornblende) and U - P b (zircon, titanite) geochronological results, were emplaced and crystallized in a short time interval at 190±1 M a . The presence o f irregularly distributed chromitite schleiren in the central dunite, wh ich may have formed by gravity flows in a upper crustal magma chamber, is consistent wi th the emplacement o f the Turnagain intrusion in an active tectonic setting. The hydrous nature o f the Turnagain intrusion, based on the presence o f early interstitial and late cumulus hydrous phases and late plagioclase, indicate that the parent magmas were generated i n a subduction zone setting and the high forsterite content o f ol ivine in dunite (maximum o f F092.5 in ol ivine that did not re- equilibrate with chromite) requires that the parent magmas were in equil ibrium with the peridotitic mantle from which they were generated. Chromite in the Turnagain intrusion exhibits chemical trends that can be related to specific magmatic and post-magmatic processes. A l l disseminated chromite, due to its 154 relatively small volume proportion in dunite, wehrlite, and ol ivine clinopyroxenite has been composit ionally modified by ol ivine and clinopyroxene fractionation, oxidation, re- equilibration wi th silicate phases, and equilibration with interstitial l iquid . Each o f these processes is clearly delineated on chromite compositional plots that establish post- crystallization processes based on inter- and intra-sample trends. Pr imit ive chromite compositions (Cr / (Fe 3 + +Cr+Al ) = 0.90, F e 2 + / ( F e 2 + + M g ) = 0.3, F e 3 + / ( F e 3 + + C r + A l ) = 0.75) in the Turnagain intrusion occur in chromitite and are the most primit ive spinel compositions observed in Alaskan-type intrusions to date. The ferric iron content o f chromite from chromitite, and the F e 3 + / S F e , in the Turnagain intrusion is extremely low and reflects the relatively low oxygen fugacity (/02) o f the parent magmas. The relatively reduced nature o f the Turnagain intrusion may have been an intrinsic property o f its parent magmas, however the majority o f arc-derived plutonic rocks are relatively oxidized ( A F M Q = +1 to +3.5, e.g. Carmichael , 1991). Therefore^ reducing agent added to the magmas was required to lower the /O2 enough to a l low the parent magmas to saturate in sulphide (e.g. Jugo et al., 2004; 2005). Thus the ferric iron content and F e 3 + / S F e o f chromite from chromitite in Alaskan-type intrusions could be considered as a possible exploration tool for evaluating the sulphide mineralization potential o f Alaskan-type intrusions. Sulphide in the Turnagain intrusion occurs in local ized areas o f dunite and wehrlite as disseminated to semi-massive pyrrhotite and pentlandite wi th other minor phases (e.g. violarite, molybdenite). Hornfelsed inclusions o f wallrocks have been intersected in drillcore wi th in the sulphide-mineralized zones. The inclusions are dominantly volcanic wacke, graphitic phylli te, and lesser quartzite and marble. The inclusions o f graphitic phylli te are the most important in the context o f sulphide mineralization in the Turnagain intrusion because they contain sulphide and graphite. The graphitic phylli te proximal to the Turnagain intrusion is pyrite-rich (FeS2), whereas the inclusions contain pyrrhotite (FeuxS). The prograde reaction between these two minerals released sulphur into the Turnagain magmas, and the graphite in the inclusions acted as a reducing agent. The local ized Ni-sulphide mineralization in the Turnagain intrusion is therefore the result o f the interaction between sulphur- and graphite-rich fluids released from the graphitic phyll i te inclusions and the primit ive, hydrous parent magmas. Ass imi la t ion o f crustal material is also demonstrated by systematic variations in sulphide sulphur and lead, and whole-rock neodymium isotopic compositions. Sulphur isotopic analyses o f sulphide separates (5 3 4 S = +1.2 to -9.7 %o) indicate that crustal sulphur 155 was added to the Turnagain intrusion, especially the more magnesian lithologies. The lead isotopic results ( 2 0 6 P b / 2 0 4 P b = 18.11-19.15 , 2 0 7 P b / 2 0 4 P b = 15.53-15.72 , 2 0 8 P b / 2 0 4 P b = 37.91- 38.72) indicate that much o f the lead in sulphide originated from an upper crustal source. F ina l ly , the neodymium isotopic results from ultramafic rocks in the Turnagain intrusion indicate that the mantle-derived parent magmas (eNd = +5 to +6) were heterogeneously contaminated by crustal material such that some results are shifted towards more crustal values (£Nd ( i90) = +2 to -3). Fina l ly , the Turnagain intrusion, which ascended through and stalled in graphitic phylli te and volcanic wacke, was dated by A r - A r and U - P b geochronology at 1 9 0 ± l M a , which has implications for the tectonic history o f this part o f northern Bri t ish Columbia . The wallrocks were previously assigned to the paleo-passive margin o f Ancestral North Amer i ca by Gabrielse (1998) as the undifferentiated Road River and Earn Groups, wi th an overlying volcanic/sedimentary package o f "unknown affinity". The graphitic phyllites are, however, conformably overlain by a volcanic wacke, as observed in outcrop by Erdmer et al. (2005) and in drillcore (this study). A min imum depositional age o f 301 M a for the volcanic wacke was determined by U - P b dating o f detrital zircon. The volcanic wacke also contains z i rcon grains with numerous Precambrian inherited cores. The l i thological characteristics, age, and R E E chemistry o f the volcanic wacke are similar to the L a y Range Assemblage/Harper Ranch Subterrane o f Quesnell ia and the K l i n k i t Group o f Yukon-Tanana. Inclusions o f "Road R i v e r " phylli te and volcanic wacke in two Ear ly Jurassic arc-derived intrusions (the Turnagain intrusion and R i n g Complex to the southeast) requires that the wallrocks were situated in crust above a subduction zone, and the only known subduction zones o f Ear ly Jurassic age were located beneath the Stikine, Quesnel, and Yukon-Tanana terranes. Therefore the volcanic wacke and graphitic phyllites, along with the Turnagain Alaskan-type intrusion, belong to either the Quesnel terrane or the Yukon-Tanana terrane. However , these two terranes (along wi th the Stikine terrane) may have been part o f a super-terrane after - 3 6 0 M a (e.g. Simard et al., 2003; Ne l son & Friedman, 2004; Ne l son et al., 2006). Alaskan-type intrusions are we l l - documented in Quesnell ia (e.g. N i x o n et al., 1997), but none have been described to date in Yukon-Tanana. I f Alaskan-type intrusions were to be found hosted in the K l i n k i t Group, the proposed genetic association between Quesnell ia and Yukon-Tanana wou ld be further supported. 5.2 REFERENCES Carmichael , I .S .E. (1991). The redox states o f basic and s i l ic ic magmas: a reflection o f their source regions? Contributions to Mineralogy and Petrology 106, 129-141 Erdmer, P. , Miha lynuk , M . G . , Gabrielse, H . , Heaman, L . M . , & Creaser, R . A . (2005). Miss iss ippian volcanic assemblage conformably overlying Cordil leran miogeoclinal strata, Turnagain R ive r area, northern Bri t ish Columbia , is not part o f an accreted terrane. Canadian Journal of Earth Sciences 42, 1449-1465 Gabrielse, H . (1998). Geology o f C r y Lake and Dease Lake map areas, north-central Br i t i sh Columbia ; Geological Survey of Canada, Bul le t in 504, 147p Jugo, P.J . , Luth , R . W . , & Richards, J.P. (2004). Experimental data on the speciation o f sulfur as a function o f oxygen fugacity in basaltic melts. Geochimica et Cosmochimia Acta 69 (2), 497-503 Jugo, P.J . , Luth , R . W . , & Richards, J.P. (2005). A n experimental study o f the sulfur content in basaltic melts saturated with immiscible sulfide or sulfate liquids at 1300°C and 1.0 G P a . Journal of Petrology 46 (4), 783-798 Nelson , J . L . , & Friedman, R. (2004). Superimposed Quesnel (late Paleozoic-Jurassic) and Yukon-Tanana (Devonian -Miss i ss ipp ian) arc assemblages, Cassiar Mountains, northern Br i t i sh Co lumbia : field, U - P b , and igneous petrochemical evidence. Canadian Journal of Earth Sciences 41, 1201-1235 Nelson , J .L . , Colpron, M . , Piercey, S.J., Dusel -Bacon, C , Murphy , D . C , & Roots, C F . (2006). Paleozoic tectonic and metallogenetic evolution o f pericratonic terranes in Y u k o n , northern Br i t i sh Columbia and eastern Alaska . In: Colpron, M . , and Nelson , J . L . (ed.) Paleozoic Evolu t ion and Metal logeny o f Pericratonic Terranes at the Ancient Pacific M a r g i n o f Nor th Amer ica . Geological Association of Canada, Special Paper 45, 323-260 N i x o n , G .T . , Hammack, J .L . , A s h , C . H . , Cabr i , L . J . , Case, G . , Connel ly , J . N . , Heaman, L . M . , Laf lamme, J . H . G . , Nuttal l , C , Paterson, W . P . E . , & W o n g , R . H . (1997). Geology and platinum-group-element mineralization o f Alaskan-type ultramafic-mafic complexes in Br i t i sh Columbia . Geological Survey of British Columbia Bul le t in 93, 141p 157 Piercey, S.J., Nelson , J . - A . L . , Dusel -Bacon, C , Simard, R . - L . , Roots, C F , (2006). Paleozoic magmatism and crustal recycl ing along the Ancient Pacific M a r g i n o f North Amer ica , Northern Cordi l lera . In: Colpron, M . , and Nelson, J .L . (ed.) Paleozoic Evolu t ion and Metal logeny o f Pericratonic Terranes at the Ancient Pacific M a r g i n o f Nor th Amer ica . Geological Association of Canada, Special Paper 45, 281-322 Simard, R - L . , Dostal , J . , & Roots, C F . (2003). Development o f late Paleozoic volcanic arcs in the Canadian Cordi l lera: an example from the K l i n k i t Group, northern Br i t i sh Columbia and southern Y u k o n . Canadian Journal of Earth Sciences 40, 907-924 APPENDICES 159 Appendix I: Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Chromitite Chromitite Sample: Cluster: Grain Number: 05ES-01-01-01 7 1 6 1 5 1 4 1 3 1 05ES-01-04-01 7 1 Style: Zone: m. anh. Rim Mid m. sub. Core Rim Mid m. sub. Core Rim Mid m. eu. Core Rim Mid m. anh. Core Rim Mid I. anh. Core Rim Mid Mid Oxides (wt. %) S i 0 2 0 02 0 02 0.03 0 01 0 02 0 02 0.00 0 00 0 16 0.01 0 02 0 00 0 00 0 00 0 03 0.00 0.00 0.08 T i0 2 0 63 0 61 0.66 0 55 0 60 0 61 0.59 0 51 0 54 0.61 0 59 0 56 0 65 0 55 0 54 0.22 0.21 0.24 A l 2 0 3 7 02 6 82 6.70 6 53 6 61 6 63 6.77 6 25 6 16 6.77 6 64 6 46 7 14 6 61 6 53 4.60 5.84 5.83 C r 2 0 3 58 93 59 39 59.52 60 32 59 60 59 77 59.17 59 90 60 97 59.12 59 05 59 34 59 03 59 86 60 40 66.65 63.40 62.91 V 2 0 3 0 34 0 30 0.32 0 28 0 34 0 26 0.33 0 27 0 23 0.33 0 31 0 29 0 31 0 31 0 34 0.00 0.03 0.01 F e 2 0 3 5 01 4 47 4.57 4 35 4 78 4 57 5.06 4 59 4 24 5.09 5 12 5 01 4 76 4 85 4 83 3.98 5.62 6.05 FeO 19 21 18 64 18.70 18 17 18 23 18 14 18.41 18 08 18 37 18.08 17 86 17 89 18 19 18 01 17 99 11.55 11.32 11.14 MnO 0 10 0 15 0.19 0 10 0 13 0 16 0.14 0 14 0 16 0.19 0 14 0 14 0 14 0 17 0 09 0.00 0.00 0.00 MgO 9 74 9 88 9.89 10 19 10 19 10 18 10.09 10 02 10 00 10.24 10 30 10 22 10 29 10 30 10 48 14.23 14.42 14.51 NiO 0 10 0 06 0.08 0 05 0 06 0 07 0.05 0 06 0 05 0.06 0 06 0 06 0 09 0 08 0 07 0.16 0.20 0.20 CaO 0 00 0 00 0.00 0 00 0 00 0 00 0.00 0 00 0 01 0.02 0 01 0 01 0 00 0 00 0 00 0.01 0.00 0.02 Total 101 11 100 34 100.64 100 56 100 57 100 40 100.61 99 82 100 89 100.51 100 08 99 97 100 58 100 74 101 30 101.40 101.05 100.99 Cations (p.f.u.) Ti 0.016 0.015 0.016 0.014 0.015 0.015 0.015 0.013 0.014 0.015 0.015 0.014 0.016 0.014 0.014 0.005 0.005 0.006 Cr 1.550 1.572 1.572 1.592 1.572 1.580 1.561 1.596 1.608 1.559 1.564 1.575 1.553 1.576 1.580 1.714 1.625 1.612 Al 0.275 0.269 0.264 0.257 0.260 0.261 0.266 0.248 0.242 0.266 0.262 0.256 0.280 0.259 0.255 0.176 0.223 0.223 V 0.008 0.007 0.007 0.006 0.008 0.006 0.007 0.006 0.005 0.007 0.007 0.006 0.007 0.007 0.007 0.000 0.001 0.000 Fe J** 0.125 0.112 0.115 0.109 0.120 0.115 0.127 0.116 0.106 0.128 0.129 0.127 0.119 0.121 0.120 0.097 0.137 0.148 F e / T * 0.534 0.522 0.522 0.507 0.509 0.507 0.514 0.510 0.512 0.504 0.500 0.502 0.506 0.501 0.498 0.314 0.307 0.302 Mn 0.003 0.004 0.005 0.003 0.004 0.004 0.004 0.004 0.005 0.005 0.004 0.004 0.004 0.005 0.002 0.000 0.000 0.000 Mg 0.483 0.493 0.493 0.507 0.507 0.507 0.502 0.503 0.497 0.509 0.514 0.512 0.510 0.512 0.517 0.690 0.697 0.701 Ni 0.003 0.002 0.002 0.001 0.002 0.002 0.001 0.002 0.001 0.002 0.002 0.002 0.002 0.002 0.002 0.004 0.005 0.005 Ca 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 Total 2.997 2.996 2.996 2.997 2.996 2.997 2.997 2.998 2.990 2.997 2.996 2.998 2.998 2.998 2.996 3.001 3.001 2.997 Trivalent End Members Cr/I3+ 0.795 0.805 0.806 0.813 0.805 0.808 0.799 0.814 0.822 0.798 0.800 0.805 0.796 0.805 0.808 0.862 0.819 0.813 AI/I3+ 0.141 0.138 0.135 0.131 0.133 0.133 0.136 0.127 0.124 0.136 0.134 0.131 0.143 0.133 0.130 0.089 0.112 0.112 Fe/I3+ 0.064 0.058 0.059 0.056 0.061 0.059 0.065 0.059 0.054 0.065 0.066 0.065 0.061 0.062 0.062 0.049 0.069 0.074 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Chromitite Chromitite Sample: 05ES-01-04-01 05ES-01-03-01 Cluster: 7 6 5 4 1 2 Grain Number: 1 1 1 1 ] 1 Style: I. anh. I. anh. I. anh. I. eu. I. eu. Zone: Core Rim Mid Mid Core Rim Mid Mid Core Rim Mid Mid Core Rim Mid Mid Core Rim Oxides (wt. %) S i 0 2 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.03 0.10 0.00 0.00 0.00 0.04 0.00 0.00 TiOj 0.24 0.22 0.27 0.30 0.22 0.30 0.27 0.29 0.28 0.23 0.25 0.23 0.27 0.21 0.22 0.22 0.23 0.23 A l 2 0 3 5.80 5.07 5.80 5.82 5.94 5.26 5.88 5.92 5.99 4.77 5.77 5.82 5.96 4.88 5.18 5.46 5.54 5.48 C r 2 0 3 63.75 65.24 62.85 63.17 62.86 64.23 62.47 62.92 63.28 64.51 62.62 62.89 63.00 62.90 61.92 61.88 61.03 62.10 V 2 0 3 0.03 0.02 0.02 0.00 0.05 0.04 0.01 0.02 0.00 0.00 0.03 0.05 0.07 0.01 0.00 0.03 0.00 0.02 F e 2 0 3 5.44 3.82 5.43 5.97 5.82 4.35 5.52 5.36 5.20 4.30 5.37 5.51 5.54 6.45 6.51 6.63 6.85 6.12 FeO 11.68 11.22 11.59 11.68 11.78 12.69 12.03 12.15 12.28 12.48 11.62 11.86 12.04 14.58 14.26 13.93 13.67 13.39 MnO 0.00 0.04 0.02 0.07 0.00 0.03 0.00 0.00 0.00 0.04 0.05 0.03 0.01 0.05 0.08 0.09 0.07 0.09 MgO 14.26 14.19 14.09 14.26 14.14 13.40 13.80 13.86 13.85 13.29 13.96 13.92 14.01 12.23 12.29 12.63 12.62 12.87 NiO 0.18 0.13 0.16 0.18 0.17 0.12 0.14 0.17 0.15 0.13 0.15 0.16 0.15 0.10 0.09 0.12 0.12 0.14 CaO 0.05 0.00 0.01 0.00 0.01 0.00 0.01 0.02 0.01 0.00 0.01 0.06 0.02 0.03 0.00 0.00 0.01 0.00 Total 101.53 99.96 100.26 101.44 100.99 100.43 100.14 100.70 101.09 99.75 99.87 100.61 101.07 101.42 100.56 101.02 100.13 100.44 Cations (p.f.u.) Ti 0.006 0.006 0.007 0.007 0.005 0.007 0.007 0.007 0.007 0.006 0.006 0.006 0.007 . 0.005 0.006 0.005 0.006 0.006 Cr 1.628 1.695 1.626 1.616 1.615 1.670 1.621 1.623 1.626 1.693 1.627 1.622 1.618 1.639 1.623 1.609 1.600 1.621 Al 0.221 0.196 0.224 0.222 0.228 0.204 0.227 0.228 0.229 0.187 0.223 0.224 0.228 0.189 0.202 0.212 0.217 0.213 V 0.001 0.000 0.001 0.000 0.001 0.001 0.000 0.000 0.000 0.000 0.001 0.001 0.001 0.000 0.000 0.001 0.000 0.000 F e " * 0.132 0.094 0.134 0.145 0.142 0.108 0.136 0.132 0.127 0.107 0.133 0.135 0.136 0.160 0.162 0.164 0.171 0.152 F e " * 0.315 0.308 0.317 0.316 0.320 0.349 0.330 0.331 0.334 0.346 0.319 0.324 0.327 0.402 0.395 0.383 0.379 0.370 Mn 0.000 0.001 0.001 0.002 0.000 0.001 0.000 0.000 0.000 0.001 0.001 0.001 0.000 0.001 0.002 0.002 0.002 0.002 Mg 0.687 0.695 0.688 0.688 0.685 0.657 0.675 0.674 0.671 0.657 0.684 0.677 0.679 0.601 0.607 0.619 0.624 0.633 Ni 0.005 0.004 0.004 0.005 0.004 0.003 0.004 0.004 0.004 0.004 0.004 0.004 0.004 - - - - - Ca 0.002 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.002 0.001 0.001 0.000 0.000 0.000 0.000 Total 2.997 3.001 3.001 3.001 3.001 3.000 3.001 3.001 2.998 3.001 2.999 2.996 3.000 2.998 2.998 2.996 2.998 2.997 Trivalent End Members Cr/I3+ 0.822 0.854 0.820 0.815 0.814 0.843 0.817 0.819 0.820 0.852 0.820 0.819 0.817 0.824 0.817 0.811 0.805 0.816 AI/S3+ 0.111 0.099 0.113 0.112 0.115 0.103 0.115 0.115 0.116 0.094 0.113 0.113 0.115 0.095 0.102 0.107 0.109 0.107 Fe/£3+ 0.067 0.048 0.067 0.073 0.072 0.054 0.069 0.066 0.064 0.054 0.067 0.068 0.068 0.080 0.082 0.083 0.086 0.077 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Chromitite Dunite Sample: 05ES-01-03-01 04ES-19-01-02 Cluster: 2 3 4 1 Grain Number: 1 1 1 Style: m. anh. m. eu. I. sub. Zone: Mid Mid Core Rim Mid Mid Core Rim Mid Mid Core Mid Mid Mid Mid Mid Mid Core Oxides (wt. %) S i 0 2 0.02 0.01 0.02 0.01 0.02 0.02 0.02 0.00 0.00 0.02 0.00 0.04 0.02 0.03 0.08 0.06 0.00 0.01 T i0 2 0.25 0.22 0.24 0.24 0.23 0.24 0.28 0.21 0.21 0.25 0.22 0.77 0.81 0.82 0.73 0.80 0.89 0.71 A l 2 0 3 5.45 5.56 5.53 5.26 5.55 5.52 5.66 4.93 5.47 5.59 5.47 8.74 8.87 8.86 8.81 8.81 8.75 8.37 C r 2 0 3 61.93 61.29 61.44 62.68 62.32 61.23 61.91 62.33 61.24 62.19 62.63 53.75 55.41 55.43 55.51 55.75 54.45 54.04 v 2 o 3 0.02 0.03 0.03 0.02 0.01 0.02 0.03 0.00 0.04 0.02 0.00 0.18 0.15 0.15 0.15 0.15 0.15 0.12 F e 2 0 3 6.37 6.72 6.73 6.61 6.53 6.88 6.28 6.50 6.56 6.33 6.54 6.37 4.31 4.34 4.32 4.66 4.65 5.70 FeO 13.57 13.41 13.50 14.52 14.24 13.79 14.01 13.75 13.61 13.86 13.71 23.15 22.63 22.21 21.78 22.23 22.26 23.16 MnO 0.02 0.02 0.06 0.07 0.16 0.09 0.00 0.01 0.06 0.05 0.08 0.34 0.30 0.24 0.35 0.29 0.31 0.39 MgO 12.82 12.85 12.83 12.42 12.52 12.61 12.68 12.59 12.61 12.76 12.91 7.05 7.35 7.64 7.72 7.73 7.41 6.68 NiO 0.13 0.14 0.12 0.13 0.12 0.13 0.13 0.11 0.13 0.13 0.14 - - - - - - - CaO 0.00 0.01 0.00 0.02 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.00 0.00 0.00 0.01 0.00 0.01 0.00 Total 100.57 100.25 100.50 101.98 101.70 100.53 100.99 100.45 99.94 101.22 101.70 100.40 99.83 99.73 99.47 100.48 98.88 99.18 Cations (p.f.u.) Ti 0.006 0.006 0.006 0.006 0.006 0.006 0.007 0.005 0.005 0.006 0.005 0.020 0.021 0.021 0.019 0.020 0.023 0.018 Cr 1.615 1.602 1.603 1.620 1.612 1.599 1.608 1.633 1.608 1.612 1.616 1.439 1.487 1.485 1.490 1.483 1.474 1.470 Al 0.212 0.216 0.215 0.203 0.214 0.215 0.219 0.193 0.214 0.216 0.210 0.349 0.355 0.354 0.352 0.349 0.353 0.339 V 0.000 0.001 0.001 0.001 0.000 0.000 0.001 0.000 0.001 0.000 0.000 0.004 0.003 0.003 0.003 0.003 0.003 0.003 F e " * 0.158 0.167 0.167 0.163 0.161 0.171 0.155 0.162 0.164 0.156 0.161 0.162 0.110 0.111 0.110 0.118 0.120 0.147 Fe ' T * 0.374 0.371 0.373 0.397 0.390 0.381 0.385 0.381 0.378 0.380 0.374 0.656 0.642 0.630 0.618 0.626 0.637 0.667 Mn 0.001 0.001 0.002 0.002 0.004 0.002 0.000 0.000 0.002 0.001 0.002 0.010 0.009 0.007 0.010 0.008 0.009 0.011 Mg 0.630 0.633 0.631 0.605 0.610 0.621 0.621 0.622 0.624 0.624 0.628 0.356 0.372 0.386 0.391 0.388 0.378 0.342 Ni Ca 0.000 0.001 0.000 0.001 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 Total 2.996 2.997 2.996 2.997 2.997 2.997 2.997 2.998 2.997 2.996 2.997 2.996 2.998 2.997 2.995 2.995 2.999 2.998 Trivalent End Members Cr/I3+ 0.814 0.807 0.808 0.816 0.811 0.806 0.811 0.822 0.810 0.812 0.813 0.738 0.762 0.762 0.763 0.760 0.757 0.751 AI/I3+ 0.107 0.109 0.108 0.102 0.108 0.108 0.111 0.097 0.108 0.109 0.106 0.179 0.182 0.182 0.180 0.179 0.181 0.173 Fe/X3+ 0.080 0.084 0.084 0.082 0.081 0.086 0.078 0.081 0.083 0.079 0.081 0.083 0.056 0.057 0.057 0.061 0.062 0.075 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Dunite Sample: Cluster: Grain Number: 04ES-19-01-02 2 1 2 3 1 2 Style: Zone: s. anh. Rim Mid Core I. anh. Rim Mid Mid Mid Mid Mid Mid Mid Mid Mid s. sub. Core Rim Mid m. sub. Core Rim Oxides (wt. %) S i 0 2 0.03 0.06 0.02 T i0 2 0.76 0.94 0.79 A l 2 0 3 8.73 8.99 8.98 C r 2 0 3 54.61 54.66 54.58 v 2 o 3 0.18 0.14 0.10 F e 2 0 3 5.15 4.31 4.71 FeO 23.24 22.84 22.75 MnO 0.42 0.32 0.34 MgO 6.86 7.17 7.12 NiO - - - CaO 0.00 0.03 0.01 Total 99.99 99.46 99.42 Cations (p.f.u.) Ti 0.019 0.024 0.020 Cr 1.469 1.472 1.472 Al 0.350 0.361 0.361 V 0.004 0.003 0.002 Fe-"* 0.132 0.110 0.121 Fe'** 0.661 0.651 0.649 Mn 0.012 0.009 0.010 Mg 0.348 0.364 0.362 Ni - - - Ca 0.000 0.001 0.000 Total 2.997 2.995 2.998 Trivalent End Members Cr/Z3+ 0.753 0.757 0.753 AI/I3+ - 0.179 0.186 0.185 Fe/I3+ 0.068 0.057 0.062 0.25 0.01 0.00 0.07 0.17 0.05 0.55 0.72 0.73 0.74 0.04 2.71 8.87 8.95 8.85 3.34 48.55 54.85 54.41 55.04 0.03 0.19 0.13 0.14 0.15 67.65 18.21 4.84 4.61 4.84 28.29 22.00 22.73 22.38 22.29 0.09 1.07 0.33 0.37 0.35 2.12 6.29 7.16 7.20 7.47 0.01 0.01 0.01 0.02 0.01 01.86 99.58 99.63 98.88 99.91 0.001 0.015 0.018 0.019 0.019 0.098 1.362 1.477- 1.473 1.473 0.002 0.113 0.356 0.361 0.353 0.001 0.004 0.003 0.003 0.003 1.887 0.486 0.124 0.119 0.123 0.877 0.652 0.647 0.641 0.631 0.003 0.032 0.009 0.011 0.010 0.117 0.333 0.364 0.368 0.377 0.000 0.000 0.000 0.001 0.000 2.986 2.998 2.999 2.995 2.990 0.049 0.694 0.755 0.754 0.756 0.001 0.058 0.182 0.185 0.181 0.950 0.248 0.063 0.061 0.063 0.02 0.00 0.01 0.05 0.05 0.88 0.77 0.89 0.81 0.76 8.92 8.88 9.04 9.05 8.94 54.73 55.44 55.68 54.92 54.68 0.15 0.11 0.14 0.15 0.18 4.76 4.58 4.05 4.79 4.79 21.67 21.76 21.90 21.75 22.76 0.35 0.31 0.33 0.27 0.32 7.86 7.84 7.89 7.91 7.20 0.04 0.02 0.00 0.03 0.00 99.39 99.72 99.92 99.73 99.68 0.023 0.020 0.022 0.021 0.019 1.469 1.484 1.486 1.468 1.470 0.357 0.354 0.360 0.360 0.358 0.003 0.002 0.003 0.003 0.004 0.121 0.117 0.103 0.122 0.123 0.615 0.616 0.618 0.615 0.647 0.010 0.009 0.010 0.008 0.009 0.398 0.396 0.397 0.399 0.365 0.002 0.001 0.000 0.001 0.000 2.997 2.999 2.998 2.996 2.996 0.754 0.759 0.763 0.753 0.754 0.183 0.181 0.185 0.185 0.184 0.062 0.060 0.053 0.063 0.063 0.06 0.05 0.01 0.03 0.03 0.39 0.78 0.81 0.83 0.42 2.15 8.78 9.01 9.00 7.37 32.04 55.15 54.72 55.01 52.94 0.12 0.16 0.16 0.13 0.20 35.06 4.49 4.09 4.16 8.83 22.88 23.26 22.83 22.92 21.74 0.73 0.31 0.40 0.28 0.69 5.43 6.91 7.01 7.11 7.17 0.00 0.02 0.00 0.00 0.00 98.86 99.90 99.03 99.46 99.39 0.011 0.020 0.021 0.021 0.011 0.920 1.483 1.482 1.483 1.440 0.092 0.352 0.364 0.361 0.299 0.003 0.004 0.004 0.003 0.004 0.958 0.115 0.105 0.107 0.229 0.695 0.662 0.654 0.653 0.625 0.022 0.009 0.012 0.008 0.020 0.294 0.351 0.358 0.361 0.368 0.000 0.001 0.000 0.000 0.000 2.995 2.996 2.998 2.997 2.997 0.467 0.761 0.760 0.760 0.732 0.047 0.180 0.186 0.185 0.152 0.486 0.059 0.054 0.055 0.116 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Dunite Dunite Sample: 04ES-19-01-02 04ES-03-02-01 Cluster: 3 2 4 Grain Number: 2 1 2 1 Style: m. sub. I. sub. m. sub. Zone: Mid Mid Mid Core Rim Mid Mid Mid Mid Core Mid Mid Mid Mid Mid Core Mid Mid Oxides (wt. %) S i 0 2 0.02 0.02 0.01 0.05 0.07 0.04 0.05 0.00 0.01 0.03 0.03 0.01 0.01 0.03 0.02 0.00 0.07 0.00 T i0 2 0.80 0.81 0.83 0.79 0.02 0.50 0.48 0.43 0.47 0.43 0.44 0.44 0.41 0.48 0.41 0.45 0.41 0.43 A l 2 0 3 9.21 9.04 9.01 9.12 0.03 0.54 7.16 7.11 6.97 7.08 7.02 6.85 6.81 6.76 6.81 6.66 1.18 7.04 C r 2 0 3 54.64 55.28 55.27 55.68 5.58 34.24 45.71 47.15 47.76 48.05 44.92 46.79 46.99 47.96 48.41 47.32 29.87 45.24 v 2 o 3 0.22 0.14 0.14 0.17 0.04 0.08 0.08 0.07 0.04 0.06 0.10 0.08 0.08 0.09 0.11 0.09 0.06 0.08 F e 2 0 3 4.32 4.25 3.85 3.57 65.02 33.26 15.95 15.11 14.53 14.21 16.12 15.74 15.19 14.78 14.62 15.06 36.60 16.39 FeO 22.95 22.73 22.66 22.80 29.52 25.69 25.01 23.93 23.54 23.16 24.75 24.34 23.70 23.37 23.11 22.71 25.32 24.53 MnO 0.47 0.40 0.27 0.29 0.08 1.17 0.24 0.30 0.29 0.25 0.32 0.35 0.25 0.29 0.27 0.23 1.13 0.31 MgO NiO CaO 7.05 7.24 7.27 7.24 1.34 3.16 5.37 6.02 6.23 6.47 5.22 5.74 6.01 6.39 6.58 6.61 3.24 5.48 0.01 0.02 0.00 0.00 0.02 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.02 0.02 0.01 0.00 Total 99.68 99.94 99.31 99.72 101.71 98.72 100.05 100.13 99.84 99.74 98.93 100.34 99.45 100.16 100.36 99.15 97.89 99.51 Cations (p.f.u.) Ti 0.020 0.021 0.021 0.020 0.001 0.014 0.013 0.011 0.012 0.011 0.012 0.011 0.011 0.012 0.011 0.012 0.012 0.011 Cr 1.469 1.482 1.490 1.494 0.165 1.009 1.258 1.290 1.309 1.315 1.251 1.282 1.296 1.310 1.318 1.304 0.886 1.251 Al 0.369 0.361 0.362 0.365 0.001 0.024 0.294 0.290 0.285 0.289 0.292 0.280 0.280 0.275 0.276 0.273 0.052 0.290 V 0.005 0.003 0.003 0.004 0.001 0.002 0.002 0.002 0.001 0.001 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 F e " * 0.111 0.108 0.099 0.091 1.828 0.933 0.418 0.393 0.379 0.370 0.427 0.411 0.399 0.384 0.379 0.395 1.033 0.431 Fe ' T * 0.652 0.644 0.646 0.647 0.922 0.801 0.728 0.693 0.683 0.670 0.729 0.706 0.691 0.675 0.665 0.662 0.794 0.718 Mn 0.013 0.011 0.008 0.008 0.002 0.037 0.007 0.009 0.008 0.007 0.010 0.010 0.007 0.009 0.008 0.007 0.036 0.009 Mg Ni Ca 0.357 0.366 0.370 0.366 0.075 0.175 0.278 0.311 0.322 0.334 0.274 0.296 0.313 0.329 0.338 0.343 0.181 0.286 0.000 0.001 0.000 0.000 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.000 0.000 Total 2.997 2.998 2.998 2.996 2.995 2.997 2.997 2.999 2.999 2.998 2.997 2.999 2.999 2.998 2.998 2.999 2.996 2.999 Trivalent End Members Cr/I3+ 0.754 0.759 0.764 0.766 0.083 0.513 0.639 0.654 0.664 0.666 0.635 0.650 0.656 0.665 0.668 0.661 0.449 0.634 AI/I3+ 0.189 0.185 0.186 0.187 0.001 0.012 0.149 0.147 0.144 0.146 0.148 0.142 0.142 0.140 0.140 0.139 0.026 0.147 Fe/I3+ 0.057 0.055 0.051 0.047 0.917 0.475 0.212 0.199 0.192 0.188 0.217 0.208 0.202 0.195 0.192 0.200 0.524 0.219 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Dunite Sample: 04ES-03-02-01 Cluster: 4 5 Grain Number: 1 2 1 Style: I. sub. I. sub. Zone: Mid Mid Core Mid Mid Mid Mid Mid Mid Mid Core Rim Mid Mid Mid Mid Mid Mid Oxides (wt. %) S i 0 2 0.03 0.02 0.01 0.02 0.05 0.00 0.03 0.00 0.00 0.03 0.03 0.08 0.03 0.00 0.03 0.00 0.00 0.00 T i0 2 0.43 0.43 0.42 0.46 0.47 0.46 0.47 0.41 0.45 0.42 0.39 0.02 0.74 0.58 0.45 0.44 0.42 0.41 A l 2 0 3 6.95 6.98 6.88 6.06 6.81 6.98 7.06 6.88 6.94 6.92 6.71 0.02 0.60 6.36 6.85 6.81 6.80 6.88 C r 2 0 3 47.56 47.49 48.44 42.83 43.67 44.09 44.96 45.19 46.01 46.56 46.01 0.57 27.18 38.63 44.90 47.74 49.07 49.83 v 2 o 3 0.09 0.06 0.08 0.06 0.09 0.13 0.08 0.11 0.10 0.07 0.09 0.02 0.01 0.07 0.10 0.12 0.10 0.11 F e 2 0 3 15.27 14.69 14.44 19.59 17.60 17.30 16.78 16.37 16.32 15.30 15.80 68.76 40.45 23.24 17.07 14.79 14.31 13.51 FeO 23.93 23.01 22.81 25.90 25.67 25.52 25.01 24.44 24.59 24.24 23.65 29.45 26.57 26.02 24.94 23.00 21.18 21.31 MnO 0.27 0.27 0.22 0.39 0.37 0.27 0.35 0.31 0.30 0.20 0.36 0.14 1.09 0.62 0.38 0.29 0.25 0.28 MgO 6.11 6.47 6.78 4.45 4.64 4.91 5.25 5.45 5.63 5.71 5.83 0.93 2.88 4.31 5.23 6.55 7.78 7.73 NiO CaO 0.02 0.01 0.00 0.01 0.01 0.00 0.00 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.02 0.00 0.01 0.00 Total 100.67 99.42 100.07 99.77 99.39 99.68 99.97 99.18 100.35 99.46 98.86 99.99 99.54 99.84 99.95 99.75 99.92 100.06 Cations (p.f.u.j Ti 0.011 0.011 0.011 0.012 0.013 0.012 0.012 0.011 0.012 0.011 0.010 0.000 0.021 0.015 0.012 0.011 0.011 0.011 Cr 1.295 1.304 1.320 1.198 1.218 1.223 1.240 1.255 1.262 1.286 1.278 0.017 0.799 1.081 1.240 1.308 1.330 1.348 Al 0.282 0.286 0.280 0.253 0.283 0.289 0.290 0.285 0.284 0.285 0.278 0.001 0.026 0.265 0.282 0.278 0.275 0.278 V 0.002 0.001 0.002 0.001 0.002 0.003 0.002 0.003 0.002 0.002 0.002 0.000 0.000 0.002 0.002 0.003 0.002 0.002 Fe J** 0.396 0.384 0.375 0.521 0.467 0.457 0.441 0.433 0.426 0.402 0.418 1.977 1.132 0.619 0.449 0.386 0.369 0.348 F e ^ * 0.689 0.669 0.657 0.766 0.758 0.749 0.730 0.718 0.713 0.708 0.695 0.941 0.826 0.770 0.729 0.666 0.607 0.610 Mn 0.008 0.008 0.006 ' 0.012 0.011 0.008 0.010 0.009 0.009 0.006 0.011 0.005 0.034 0.019 0.011 0.008 0.007 0.008 Mg 0.314 0.335 0.348 0.235 0.244 0.257 0.273 0.285 0.291 0.298 0.306 0.053 0.160 0.228 0.272 0.338 0.398 0.394 Ni Ca 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 Total 2.997 2.999 2.999 2.998 2.996 2.999 2.998 2.999 2.999 2.998 2.998 2.995 2.998 2.999 2.997 2.999 2.999 2.999 Trivalent End Members Cr/X3+ 0.656 0.661 0.669 0.607 0.619 0.621 0.629 0.636 0.640 0.652 0.648 0.009 0.408 0.550 0.629 0.663 0.674 0.683 AI/Z3+ 0.143 0.145 0.142 0.128 0.144 0.147 0.147 0.144 0.144 0.144 0.141 0.000 0.013 0.135 0.143 0.141 0.139 0.141 Fe/Z3+ 0.201 0.194 0.190 0.264 0.237 0.232 0.224 0.219 0.216 0.204 0.212 0.991 0.578 0.315 0.228 0.196 0.187 0.176 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Dunite Dunite Sample: 04ES-03-02-01 04ES-08-01-01 Cluster: 5 1 2 Grain Number: 1 2 1 2 1 2 Style: s. eu. s. eu. m. sub. s. eu. I. sub. Zone: Core Rim Mid Core Rim Mid Core Mid Mid Mid Mid Mid Core Rim Mid Core Rim Mid Oxides (wt. %) S i 0 2 0.02 0.01 0.02 0.00 0.12 0.05 0.01 0.01 0.00 0.00 0.05 0.02 0.02 0.05 0.03 0.03 0.05 0.00 T i0 2 0.47 0.48 0.46 0.48 0.39 0.49 0.48 0.70 0.55 0.49 0.48 0.49 0.48 0.53 0.54 0.52 0.02 1.01 A l 2 0 3 6.72 7.70 6.96 7.04 5.94 6.87 6.94 4.78 7.07 7.08 6.99 6.99 6.96 7.47 7.28 7.35 0.00 2.91 C r 2 0 3 50.24 44.00 47.32 47.22 38.98 44.74 45.08 34.02 39.23 41.17 42.61 43.95 43.80 44.81 46.40 46.49 2.06 30.59 V 2 0 3 0.07 0.06 0.08 0.11 0.06 0.05 0.08 0.07 0.08 0.07 0.07 0.06 0.09 0.06 0.09 0.07 0.01 0.04 F e 2 0 3 13.72 17.56 15.39 15.57 22.67 16.87 16.76 27.82 22.78 20.39 19.73 18.83 18.57 16.75 15.98 15.97 67.87 33.99 FeO 21.46 22.87 22.41 22.57 24.38 24.82 25.03 24.47 24.32 23.33 23.39 22.99 22.82 22.94 22.81 22.94 29.51 26.50 MnO 0.25 0.29 0.17 0.26 0.52 0.21 0.25 1.32 0.49 0.23 0.14 0.24 0.17 0.24 0.22 0.22 0.08 1.27 MgO 7.79 6.68 7.05 7.00 4.87 5.33 5.28 4.22 5.63 6.20 6.37 6.67 6.71 6.64 6.90 6.84 1.09 3.30 NiO CaO 0.01 0.00 0.00 0.00 0.01 0.00 0.02 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.01 0.02 0.00 0.00 Total 100.74 99.64 99.87 100.25 97.94 99.43 99.90 97.42 100.15 98.96 99.83 100.25 99.63 99.48 100.26 100.46 100.69 99.62 Cations (p.f.u.) Ti 0.012 0.012 0.012 0.012 0.011 0.013 0.013 . 0.019 0.014 0.013 0.012 0.013 0.013 0.014 0.014 0.013 0.000 0.028 Cr 1.351 1.202 1.289 1.282 1.107 1.241 1.245 0.985 1.080 1.140 1.169 1.198 1.201 1.227 1.259 1.260 0.062 0.883 Al 0.270 0.314 0.283 0.285 0.252 0.284 0.286 0.206 0.290 0.292 0.286 0.284 0.285 0.305 0.295 0.297 0.000 0.125 V 0.002 0.001 0.002 0.003 0.001 0.001 0.002 0.002 0.002 0.002 0.002 0.001 0.002 0.001 0.002 0.002 0.000 0.001 F e J r * 0.351 0.456 0.399 0.402 0.613 0.445 0.440 0.766 0.597 0.538 0.515 0.489 0.485 0.436 0.413 0.412 1.935 0.934 0.610 0.661 0.646 0.648 0.732 0.728 0.731 0.749 0.708 0.683 0.679 0.663 0.662 0.664 0.655 0.657 0.935 0.809 Mn 0.007 0.009 0.005 0.008 0.016 0.006 0.007 0.041 0.015 0.007 0.004 0.007 0.005 0.007 0.006 0.006 0.003 0.039 Mg 0.395 0.344 0.362 0.358 0.261 0.278 0.275 0.231 0.292 0.324 0.330 0.343 0.347 0.343 0.353 0.349 0.062 0.180 Ni Ca 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 Total 2.998 2.999 2.998 2.999 2.993 2.997 2.999 2.999 2.999 2.999 2.997 2.998 2.998 2.997 2.998 2.998 2.997 2.999 Trivalent End Members Cr/I3+ 0.685 0.610 0.654 0.651 0.562 0.630 0.632 0.503 0.549 0.579 0.593 0.608 0.610 0.623 0.640 0.640 0.031 0.455 AI/I3+ 0.137 0.159 0.143 0.145 0.128 0.144 0.145 0.105 0.147 0.148 0.145 0.144 0.144 0.155 0.150 0.151 0.000 0.064 Fe/X3+ 0.178 0.231 0.202 0.204 0.311 0.226 0.223 0.392 0.304 0.273 0.262 0.248 0.246 0.222 0.210 0.209 0.969 0.481 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Dunite Sample: 04ES-08-01-01 Cluster: 2 3 Grain Number: 2 1 2 Style: s. sub. I. sub. Zone: Mid Mid Mid Mid Mid Mid Mid Core Rim Mid Core Rim Mid Mid Mid Mid Mid Mid Oxides (wt. %) S i 0 2 0.00 0.01 0.00 0.03 0.01 0.00 0.03 0.01 0.03 0.01 0.01 0.13 0.02 0.03 0.01 0.00 0.01 0.02 T i 0 2 0.45 0.46 0.50 0.43 0.47 0.47 0.47 0.47 0.54 0.54 0.58 0.01 0.55 0.53 0.52 0.49 0.48 0.47 A l 2 0 3 5.89 6.98 7.10 7.24 7.10 7.17 7.22 7.10 7.32 7.32 7.27 0.01 7.49 7.40 7.28 7.25 7.26 7.06 C r 2 0 3 44.28 45.96 46.79 47.40 47.52 47.83 47.95 47.69 45.01 45.87 45.92 1.07 44.08 44.28 44.61 45.44 46.12 45.96 v 2 o 3 0.08 0.09 0.05 0.05 0.06 0.06 0.10 0.05 0.06 0.07 0.04 0.02 0.08 0.09 0.06 0.10 0.11 0.05 F e 2 0 3 18.94 16.84 15.79 15.14 15.28 15.04 14.76 15.44 16.15 15.47 15.48 68.97 18.05 17.02 17.77 16.94 16.57 16.19 FeO 24.13 22.95 21.96 21.97 21.73 22.05 22.24 22.00 23.86 24.10 23.98 28.99 23.45 22.97 23.05 22.84 22.81 22.49 MnO 0.24 0.17 0.19 0.19 0.22 0.20 0.15 0.22 0.28 0.25 0.26 0.10 0.19 0.23 0.26 0.19 0.28 0.23 MgO NiO CaO 5.69 6.77 7.31 7.29 7.47 7.33 7.28 7.39 5.95 5.90 5.95 1.38 6.55 6.55 6.68 6.84 6.90 6.83 0.00 0.00 0.02 0.00 0.00 0.01 0.01 0.00 0.00 0.02 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 Total 99.70 100.23 99.71 99.73 99.86 100.15 100.20 100.37 99.19 99.54 99.53 100.69 100.46 99.11 100.25 100.09 100.53 99.31 Cations (p.f.u.) Ti 0.012 0.012 0.013 0.011 0.012 0.012 0.012 0.012 0.014 0.014 0.015 0.000 0.014 0.014 0.013 0.013 0.012 0.012 Cr 1.229 1.251 1.274 1.289 1.290 1.296 1.298 1.290 1.243 1.262 1.264 0.032 1.197 1.218 1.214 1.237 1.250 1.261 Al 0.243 0.283 0.288 0.293 0.288 0.289 0.291 0.286 0.301 0.300 0.298 0.000 0.303 0.304 0.295 0.294 0.293 0.289 V 0.002 0.002 0.001 0.001 0.001 0.001 0.002 0.001 0.001 0.002 0.001 0.000 0.002 0.002 0.001 0.002 0.002 0.001 Fe J ' * 0.500 0.437 0.409 0.392 0.395 0.388 0.380 0.397 0.424 0.405 0.406 1.962 0.467 0.445 0.460 0.439 0.427 0.423 Fe'** 0.708 0.661 0.633 0.632 0.624 0.632 0.637 0.629 0.697 0.701 0.698 0.916 0.674 0.668 0.664 0.658 0.653 0.653 Mn 0.007 0.005 0.005 0.006 0.006 0.006 0.004 0.006 0.008 0.007 0.008 0.003 0.006 0.007 0.008 0.006 0.008 0.007 Mg Ni Ca 0.298 0.348 0.375 0.374 0.382 0.374 0.371 0.377 0.310 0.306 0.309 0.078 0.336 0.340 0.343 0.351 0.352 0.353 0.000 0.000 0.001 0.000 0.000 0.001 0.000 0.000 0.000 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.000 Total 2.999 2.999 3.000 2.998 2.999 2.999 2.998 2.999 2.998 2.999 2.999 2.992 2.998 2.997 2.999 2.999 2.999 2.998 Trivalent End Members Cr/I3+ 0.623 0.635 0.646 0.653 0.654 0.657 0.659 0.654 0.631 0.642 0.642 0.016 0.609 0.619 0.616 0.628 0.634 0.639 AI/I3+ 0.123 0.144 0.146 0.149 0.146 0.147 0.148 0.145 0.153 0.153 0.152 0.000 0.154 0.154 0.150 0.149 0.149 0.146 Fe/I3+ 0.254 0.221 0.208 0.198 0.200 0.197 0.193 0.201 0.216 0.206 0.206 0.984 0.237 0.226 0.234 0.223 0.217 0.214 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Dunite Wehrlite Sample: Cluster: Grain Number: 3 2 04ES-10-05-01 6 1 2 5 1 2 4 1 2 04ES-11-03-03 4 1 Style: Zone: Core m. eu. Rim Mid Core s. eu. Mid Core s. eu. Rim Mid m. eu. Core Rim Mid Core s. eu. Mid Core s. eu. Rim m. sub. Mid Rim Mid Oxides (wt. %) S i 0 2 0 00 0 00 0 05 0 10 0.05 0 00 0 04 0 03 0 00 0 02 0.00 0.02 0 00 0 02 0 01 0.01 0 06 0.03 T i 0 2 0 54 0 58 0 79 0 70 0.80 0 78 0 52 0 75 0 73 0 70 0.75 0.76 0 64 0 64 0 61 0.66 0 67 1.51 A l 2 0 3 7 08 4 89 7 54 7 48 7.64 7 59 0 65 7 57 7 66 7 68 7.78 7.75 6 90 6 87 5 86 7.00 2 73 9.00 C r 2 0 3 46 35 46 77 50 65 51 00 49.33 50 39 33 65 51 05 50 85 48 88 51.15 50.78 53 29 53 68 49 81 52.52 15 26 41.57 V 2 0 3 0 04 0 19 0 26 0 22 0.26 0 26 0 09 0 21 0 24 0 25 0.24 0.24 0 21 0 24 0 27 0.23 0 10 0.32 F e 2 0 3 16 45 17 12 9 43 9 50 10.62 9 73 34 34 9 37 9 47 10 56 9.15 9.56 8 66 8 52 12 95 8.45 49 60 14.16 FeO 22 73 20 27 25 39 24 33 25.08 25 15 20 38 25 36 25 10 24 83 25.16 24.90 23 09 23 05 20 56 23.46 27 85 26.50 MnO 0 23 2 90 0 34 0 39 0.54 0 38 3 07 0 38 0 38 0 96 0.29 0.40 0 30 0 33 2 39 0.31 1 03 0.38 MgO NiO CaO 6 93 6 36 5 35 5 88 5.42 5 47 5 26 5 37 5 53 5 07 5.61 5.70 6 72 6 81 6 72 6.34 2 18 4.83 0 01 0 02 0 00 0 01 0.00 0 02 0 01 0 00 0 00 0 02 0.00 0.00 0 02 0 00 0 00 0.00 0 01 0.01 Total 100 36 99 11 99 82 99 59 99.73 99 76 98 01 100 09 99 96 98 97 100.14 100.11 99 83 100 16 99 19 98.98 99 50 98.31 Cations (p.f.u.) Ti 0.014 0.015 0.021 0.018 0.021 0.020 0.014 0.020 0.019 0.018 0.019 0.020 0.017 0.016 0.016 0.017 0.019 0.040 Cr 1.259 1.303 1.390 1.397 1.354 1.382 0.982 1.397 1.391 1.354 1.395 1.385 1.452 1.457 1.374 1.445 0.448 1.156 Al 0.287 0.203 0.308 0.305 0.312 0.310 0.028 0.309 0.312 0.317 0.316 0.315 0.280 0.278 0.241 0.287 0.120 0.373 V 0.001 0.004 0.006 0.005 0.006 0.006 0.002 0.005 0.005 0.006 0.006 0.006 0.005 0.005 0.006 0.005 0.002 0.007 F e " * 0.425 0.454 0.246 0.248 0.277 0.254 0.954 0.244 0.247 0.278 0.238 0.248 0.225 0.220 0.340 0.221 1.387 0.375 F e " * 0.653 0.597 0.737 0.705 0.728 0.730 0.630 0.734 0.726 0.728 0.726 0.718 0.665 0.662 0.600 0.683 0.866 0.779 Mn 0.007 0.086 0.010 0.011 0.016 0.011 0.096 0.011 0.011 0.029 0.008 0.012 0.009 0.010 0.071 0.009 0.032 0.011 Mg M i 0.355 0.334 0.277 0.303 0.280 0.283 0.289 0.277 0.285 0.265 0.289 0.293 0.345 0.348 0.350 0.329 0.121 0.253 Nl Ca 0.000 0.001 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.001 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 Total 3.000 2.998 2.995 2.993 2.995 2.997 2.997 2.997 2.998 2.997 2.998 2.997 2.998 2.996 2.997 2.997 2.996 2.995 Trivalent End Members Cr/23+ 0.639 0.665 0.715 0.716 0.697 0.710 0.500 0.716 0.713 0.694 0.716 0.711 0.742 0.745 0.703 0.740 0.229 0.607 AI/I3+ 0.146 0.104 0.159 0.157 0.161 0.159 0.014 0.158 0.160 0.163 0.162 0.162 0.143 0.142 0.123 0.147 0.061 0.196 Fe/X3+ 0.216 0.232 0.127 0.127 0.143 0.130 0.486 0.125 0.126 0.143 0.122 0.127 0.115 0.113 0.174 0.113 0.709 0.197 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehrlite Sample: Cluster: Grain Number: 04ES-11-03-03 4 1 2 2 1 2 Style: Zone: Mid Mid m. sub. Core Rim Mid Mid I. irreg. Core Rim Mid Mid Mid Mid Mid Mid m. anh. Core Mid Core Oxides (wt. %) S i 0 2 0 01 0.00 0 00 0.01 0 00 0 00 0 00 0.02 0.01 0 03 0 06 0 01 0 05 0 03 0.03 0.04 0.04 T i 0 2 1 45 1.44 1 48 1.26 1 28 1 29 1 35 1.36 1.66 1 55 1 49 1 37 1 26 1 19 1.19 1.59 1.56 A l 2 0 3 9 54 9.62 9 61 10.47 10 27 10 24 10 23 9.23 9.25 8 82 8 69 8 37 8 03 7 80 7.57 9.36 9.48 C r 2 0 3 42 62 42.70 42 64 43.31 43 96 44 58 44 37 45.81 45.10 46 26 46 57 47 81 48 57 49 40 49.08 44.73 44.05 v 2 o 3 0 28 0.27 0 35 0.30 0 29 0 30 0 32 0.26 0.21 0 20 0 20 0 18 0 21 0 19 0.21 0.29 0.28 F e 2 0 3 13 46 13.67 13 71 13.03 12 24 11 66 11 65 11.17 11.77 11 24 11 28 10 32 10 72 10 09 10.01 11.36 12.09 FeO 26 44 26.53 26 57 26.18 26 04 26 05 26 10 24.88 25.27 25 14 25 05 24 78 24 92 24 75 24.43 26.32 26.27 MnO 0 39 0.38 0 36 0.40 0 34 0 34 0 31 0.40 0.27 0 27 0 31 0 26 0 31 0 38 0.37 0.35 0.81 MgO NiO CaO 5 08 5.14 5 21 5.50 5 52 5 54 5 54 5.96 6.08 6 04 6 05 6 04 6 03 5 97 5.97 5.27 5.07 0 01 0.01 0 00 0.01 0 00 0 00 0 01 0.07 0.02 0 02 0 02 0 02 0 02 0 01 0.01 0.02 0.00 Total 99 28 99.76 99 92 100.45 99 95 100 00 99 87 99.17 99.65 99 57 99 70 99 16 100 12 99 81 98.88 99.33 99.65 Cations (p.f.u.) Ti 0.038 0.037 0.038 0.032 0.033 0.033 0.035 0.035 0.043 0.040 0.039 0.036 0.033 0.031 0.031 0.041 0.040 Cr 1.169 1.166 1.161 1.167 1.190 1.206 1.202 1.250 1.225 1.260 • 1.267 1.309 1.320 1.348 1.353 1.224 1.204 Al 0.390 0.391 0.390 0.420 0.414 0.413 0.413 0.376 0.375 0.358 0.352 0.342 0.325 0.318 0.311 0.382 0.386 V 0.006 0.006 0.008 0.007 0.007 0.007 0.007 0.006 0.005 0.004 0.005 0.004 0.005 0.004 0.005 0.007 0.006 Fe-"* 0.351 0.355 0.355 0.334 0.315 0.300 0.300 0.290 0.304 0.291 0.292 0.269 0.277 0.262 0.263 0.296 0.315 Fe'** 0.767 0.766 0.765 0.746 0.746 0.745 0.748 0.718 0.726 0.724 0.721 0.718 0.717 0.715 0.712 0.762 0.759 Mn 0.012 0.011 0.011 0.012 0.010 0.010 0.009 0.012 0.008 0.008 0.009 0.008 0.009 0.011 0.011 0.010 0.024 Mg 0.263 0.264 0.268 0.279 0.282 0.282 0.283 0.307 0.311 0.310 0.310 0.312 0.309 0.307 0.310 0.272 0.261 Ni Ca 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.003 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.001 0.000 Total 2.997 2.997 2.997 2.997 2.997 2.997 2.997 2.996 2.997 2.997 2.995 2.998 2.996 2.997 2.996 2.995 2.995 Trivalent End Members Cr/I3+ 0.612 0.610 0.609 0.607 0.620 0.628 0.628 0.653 0.643 0.660 0.663 0.682 0.687 0.699 0.702 0.644 0.632 AI/I3+ 0.204 0.205 0.205 0.219 0.216 0.215 0.216 0.196 0.197 0.188 0.184 0.178 0.169 0.165 0.161 0.201 0.203 Fe/£3+ 0.184 0.186 0.186 0.174 0.164 0.156 0.157 0.151 0.160 0.153 0.153 0.140 0.144 0.136 0.136 0.156 0.165 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehrlite ; Wehrlite Sample: 04ES-11-03-03 04ES-15-01-05 Cluster: 1 7 6 Grain Number: 1 2 1 2 1 Style: s. eu. m. sub. s. eu. m. sub. m. sub. Zone: Rim Mid Core Rim Mid Mid Mid Mid Core Mid Core Mid Mid Mid Core Mid Mid Core Oxides (wt. %) S i 0 2 0.02 0.00 0.06 0.03 0.03 0.02 0.02 0.00 0.01 0.03 0.04 0.03 0.02 0.03 0.03 0.04 0.05 0.00 T i 0 2 1.75 1.72 1.69 1.81 1.58 1.52 1.59 1.56 1.64 1.17 1.48 1.41 1.67 1.37 1.46 1.38 1.51 1.34 A l 2 0 3 10.07 9.82 9.87 10.18 9.69 9.87 9.98 9.83 10.07 14.94 15.41 14.31 14.38 14.27 14.27 14.45 14.52 14.10 C r 2 0 3 41.38 42.63 42.79 39.97 43.41 44.05 43.83 44.25 43.39 48.11 48.54 50.35 51.19 50.31 50.07 49.22 49.73 50.37 v 2 o 3 0.28 0.27 0.28 0.25 0.29 0.32 0.29 0.33 0.28 0.35 0.31 0.20 0.17 0.22 0.23 0.18 0.14 0.21 F e 2 0 3 13.34 12.79 12.67 14.07 12.19 12.13 12.26 12.25 12.43 3.71 2.21 2.35 1.51 2.47 2.40 2.68 2.35 2.40 FeO 27.12 27.14 27.31 26.22 26.33 26.35 26.64 26.52 26.34 23.66 23.62 22.71 23.39 22.94 22.70 23.49 23.44 23.13 MnO 0.55 0.36 0.37 1.00 0.38 0.37 0.33 0.34 0.31 0.34 0.20 0.48 0.28 0.27 0.30 0.27 0.30 0.18 MgO NiO CaO 4.75 4.92 4.84 4.91 5.25 5.42 5.37 5.46 5.53 7.57 7.89 8.14 8.16 8.12 8.25 7.64 7.83 7.96 0.02 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.02 0.02 0.00 0.04 0.02 0.02 0.02 0.00 0.00 0.02 Total 99.27 99.64 99.89 98.44 99.16 100.05 100.30 100.55 100.02 99.90 99.69 100.03 100.79 100.03 99.74 99.36 99.87 99.70 Cations (p.f.u.) Ti 0.046 0.045 0.044 0.047 0.041 0.039 0.041 0.040 0.042 0.029 0.037 0.035 0.041 0.034 0.036 0.034 0.037 0.033 Cr 1.135 1.165 1.167 1.103 1.189 1.194 1.186 1.194 1.175 1.253 1.260 1.308 1.320 1.307 1.303 1.290 1.295 1.315 Al 0.412 0.400 0.401 0.419 0.396 0.399 0.403 0.395 0.407 0.580 0.597 0.554 0.553 0.553 0.554 0.565 0.564 0.549 V 0.006 0.006 0.006 0.006 0.007 0.007 0.006 0.007 0.006 0.008 0.007 0.004 0.004 0.005 0.005 0.004 0.003 0.005 F e " * 0.348 0.333 0.329 0.370 0.318 0.313 0.316 0.315 0.320 0.092 0.055 0.058 0.037 0.061 0.059 0.067 0.058 0.060 F e " * 0.787 0.785 0.788 0.766 0.763 0.756 0.762 0.757 0.754 0.652 0.649 0.624 0.638 0.630 0.625 0.651 0.646 0.639 Mn 0.016 0.011 0.011 0.029 0.011 0.011 0.009 0.010 0.009 0.010 0.005 0.013 0.008 0.008 0.008 0.008 0.008 0.005 Mg Ni Ca 0.246 0.254 0.249 0.256 0.271 0.277 0.274 0.278 0.282 0.372 0.386 0.399 0.397 0.398 0.405 0.378 0.385 0.392 0.001 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.001 0.001 0.000 0.001 0.001 0.001 0.001 0.000 0.000 0.001 Total 2.996 2.997 2.994 2.996 2.995 2.996 2.996 2.997 2.997 2.995 2.995 2.996 2.998 2.996 2.996 2.996 2.996 2.998 Trivalent End Members Cr/23+ 0.599 0.614 0.615 0.583 0.625 0.627 0.623 0.627 0.618 0.651 0.659 0.681 0.691 0.680 0.680 0.671 0.676 0.684 AI/I3+ 0.217 0.211 0.212 0.221 0.208 0.209 0.211 0.208 0.214 0.301 0.312 0.289 0.289 0.288 0.289 0.294 0.294 0.285 Fe/S3+ 0.184 0.175 0.173 0.195 0.167 0.164 0.166 0.165 0.168 0.048 0.029 0.030 0.019 0.032 0.031 0.035 0.030 0.031 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehrlite Wehrlite Sample: 04ES-15-01-05 04ES-16-08-01 Cluster: 6 5 6 Grain Number: 2 1 2 1 Style: s. sub. m. eu. m. sub. s. eu. Zone: Rim Mid Core Mid Mid Mid Mid Mid Core Mid Mid Mid Mid Mid Core Rim Mid Core Oxides (wt. %) S i 0 2 0.07 0.03 0.03 0.06 0.04 0.03 0.02 0.01 0.02 0.07 0.04 0.03 0.02 0.07 0.02 0.04 0.02 0.03 T i0 2 1.09 1.21 1.23" 1.30 1.58 1.22 1.26 1.14 1.83 1.23 1.96 1.35 1.20 2.54 1.86 1.24 0.99 0.90 A l 2 0 3 12.65 12.69 12.46 14.98 14.72 14.67 14.53 14.57 14.50 15.92 15.54 15.49 15.44 14.86 15.01 8.00 8.92 8.90 C r 2 0 3 50.37 51.63 52.16 49.44 49.38 50.01 50.30 50.56 50.62 47.60 48.93 49.09 48.44 48.75 49.11 37.46 43.84 43.86 v 2 o 3 0.20 0.14 0.17 0.24 0.21 0.24 0.22 0.24\. 0.16 0.41 0.32 0.29 0.38 0.20 0.30 0.09 0.09 0.12 F e 2 0 3 3.64 2.67 2.85 2.80 2.27 2.57 2.38 2.39 0.94 3.27 1.40 2.80 2.87 0.99 1.70 18.91 14.09 14.28 FeO 23.72 23.65 23.75 23.18 23.26 22.97 23.03 23.03 23.50 23.37 23.79 22.90 22.64 23.84 23.50 25.66 25.82 25.40 MnO 0.34 0.28 0.28 0.29 0.21 0.25 0.23 0.23 0.22 0.32 0.29 0.30 0.26 0.26 0.26 1.55 0.33 0.35 MgO NiO CaO 6.97 7.26 7.35 8.01 8.03 8.08 8.05 8.06 8.04 8.00 8.18 8.42 8.33 8.24 8.15 3.89 5.09 5.28 0.08 0.03 0.02 0.07 0.06 0.03 0.02 0.00 0.01 0.00 0.00 0.00 0.00 0.01 0.02 0.03 0.02 0.03 Total 99.15 99.59 100.30 100.38 99.77 100.08 100.03 100.24 99.85 100.20 100.43 100.66 99.58 99.75 99.91 96.85 99.21 99.15 Cations (p.f.u.) Ti 0.028 0.030 0.031 0.032 0.039 0.030 0.031 0.028 0.045 0.030 0.048 0.033 0.030 0.063 0.046 0.034 0.026 0.024 Cr 1.339 1.365 1.371 1.278 1.284 1.297 1.306 1.310 1.316 1.227 1.259 1.259 1.255 1.265 1.273 1.071 1.207 1.207 Al 0.501 0.500 0.488 0.577 0.571 0.567 0.562 0.563 0.562 0.612 0.596 0.592 0.596 0.575 0.580 0.341 0.366 0.365 V 0.005 0.003 0.004 0.005 0.004 0.005 0.005 0.005 0.004 0.009 0.007 0.006 0.008 0.004 0.006 0.002 0.002 0.003 F e " * 0.092 0.067 0.071 0.069 0.056 0.063 0.059 0.059 0.023 0.080 0.034 0.068 0.071 0.024 0.042 0.515 0.369 0.374 Fe'"* 0.667 0.661 0.660 0.634 0.640 0.630 0.632 0.631 0.646 0.637 0.647 0.621 0.621 0.654 0.644 0.776 0.752 0.739 Mn 0.010 0.008 0.008 0.008 0.006 0.007 0.006 0.006 0.006 0.009 0.008 0.008 0.007 0.007 0.007 0.047 0.010 0.010 Mg Ni Ca 0.350 0.362 0.364 0.390 0.394 0.395 0.394 0.394 0.394 0.389 0.397 0.407 0.407 0.403 0.398 0.210 0.264 0.274 0.003 0.001 0.001 0.003 0.002 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.001 0.001 Total 2.994 2.997 2.997 2.995 2.996 2.996 2.997 2.997 2.998 2.993 2.995 2.996 2.995 2.995 2.996 2.997 2.998 2.997 Trivalent End Members Cr/I3+ 0.693 0.706 0.710 0.664 0.672 0.673 0.678 0.678 0.692 0.639 0.666 0.656 0.653 0.679 0.672 0.556 0.621 0.620 AI/I3+ 0.259 0.259 0.253 0.300 0.299 0.294 0.292 0.291 0.296 0.319 0.315 0.309 0.310 0.308 0.306 0.177 0.188 0.188 Fe/Z3+ 0.048 0.035 0.037 0.036 0.029 0.033 0.031 0.031 0.012 0.042 0.018 0.036 0.037 0.013 0.022 0.267 0.190 0.192 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehrlite Sample: 04ES-16-08-01 Cluster: 6 4 Grain Number: 2 3 1 2 Style: s. eu. s. eu. s. sub. m. sub. Zone: Rim Mid Core Rim Mid Mid Core Rim Mud Mid Core Rim Mid Mid Mid Mid Mid Mid Oxides (wt. %) S i 0 2 0 11 0 00 0 06 0.01 0 04 0.03 0.03 0 06 0.03 0.01 0 02 0 05 0 04 0.04 0.03 0.05 0.01 0.04 T i0 2 0 79 1 06 1 01 1.03 1 01 1.05 1.03 1 69 0.92 0.74 0 71 0 87 1 25 1.15 0.96 0.97 1.00 1.10 A I 2 O 3 6 60 8 08 7 92 7.99 8 01 7.85 7.99 9 82 10.40 9.40 9 18 4 87 9 15 8.87 8.35 8.28 8.38 8.28 C r 2 0 3 46 05 47 84 48 90 49.53 49 73 50.34 50.02 38 04 42.19 46.21 48 86 38 97 44 45 45.29 47.93 48.31 48.39 48.70 v 2 o 3 0 09 0 04 0 06 0.08 0 08 0.08 0.09 0 11 0.06 0.06 0 10 0 10 0 11 0.09 0.09 0.08 0.07 0.09 F e 2 0 3 13 28 11 86 11 94 11.56 11 60 11.46 10.92 16 52 14.19 11.45 10 38 22 43 13 40 13.21 11.69 11.69 11.41 11.38 FeO 24 05 24 86 21 20 20.19 19 79 19.79 20.46 25 57 25.68 24.50 24 52 24 77 26 01 25.11 24.14 23.69 23.76 23.88 MnO 2 19 0 23 0 27 0.18 0 26 0.25 0.20 1 61 0.45 0.33 0 34 2 04 0 36 0.28 0.33 0.30 0.34 0.37 MgO NiO CaO 4 31 5 89 8 12 8.88 9 11 9.22 8.70 4 64 5.18 5.72 6 05 3 75 5 29 5.81 6.27 6.62 6.56 6.63 0 00 0 02 0 02 0.00 0 00 0.01 0.00 0 04 0.00 0.00 0 00 0 09 0 05 0.03 0.00 0.01 0.02 0.01 Total 97 46 99 87 99 51 99.45 99 64 100.09 99.43 98 09 99.10 98.42 100 17 97 94 100 11 99.89 99.80 100.00 99.94 100.47 Cations (p.f.u.) Ti 0.021 0.027 0.026 0.026 0.026 0.027 0.026 0.045 0.024 0.019 0.018 0.024 0.032 0.030 0.025 0.025 0.026 0.028 Cr 1.310 1.306 1.318 1.329 1.329 1.340 1.343 1.058 1.155 1.272 1.321 1.122 1.210 1.233 1.304 1.309 1.312 1.313 Al 0.280 0.329 0.318 0.320 0.319 0.311 0.320 0.407 0.424 0.386 0.370 0.209 0.371 0.360 0.339 0.334 0.339 0.333 V 0.002 0.001 0.001 0.002 0.002 0.002 0.002 0.003 0.001 0.001 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 F e " * 0.359 0.308 0.306 0.295 0.295 0.290 0.279 0.438 0.370 0.300 0.267 0.615 0.347 0.342 0.303 0.301 0.294 0.292 Fe'** 0.723 0.718 0.604 0.573 0.560 0.557 0.581 0.753 0.743 0.713 0.701 0.754 0.749 0.723 0.695 0.679 0.681 0.681 Mn 0.067 0.007 0.008 0.005 0.007 0.007 0.006 0.048 0.013 0.010 0.010 0.063 0.011 0.008 0.009 0.009 0.010 0.011 Mg KM 0.231 0.303 0.413 0.449 0.459 0.463 0.440 0.244 0.267 0.297 0.308 0.204 0.272 0.298 0.322 0.338 0.335 0.337 N I Ca 0.000 0.001 0.001 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.004 0.002 0.001 0.000 0.000 0.001 0.000 Total 2.993 3.000 2.996 2.999 2.997 2.998 2.998 2.996 2.998 2.999 2.998 2.996 2.997 2.997 2.997 2.997 2.999 2.997 Trivalent End Members Cr/I3+ 0.672 0.672 0.678 0.684 0.684 0.690 0.692 0.556 0.593 0.650 0.675 0.577 0.627 0.637 0.670 0.673 0.675 0.678 AI/I3+ 0.144 0.169 0.164 0.164 0.164 0.160 0.165 0.214 0.218 0.197 0.189 0.107 0.193 0.186 0.174 0.172 0.174 0.172 Fe/I3+ 0.184 0.159 0.158 0.152 0.152 0.150 0.144 0.230 0.190 0.153 0.136 0.316 0.180 0.177 0.156 0.155 0.151 0.151 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehriite Wehrlite Sample: 04ES-16-08-01 04ES-10-06-01 Cluster: 4 5 6 Grain Number: 2 1 2 1 2 Style: m. sub. s. eu. m. sub. m. sub. Zone: Mid Core Mid Mid Mid Mid Mid Core Rim Mid Core Rim Mid Core Rim Mid Core Oxides (wt. %) S i 0 2 0.01 0.02 0.04 0.03 0.05 0.08 0.04 0.01 0.04 0.05 0.02 0.04 0.01 0.03 0.69 0.04 0.04 T i0 2 1.01 1.09 0.99 0.90 0.80 0.81 0.79 0.80 1.04 0.92 0.88 1.24 1.00 1.11 0.28 1.07 1.07 A l 2 0 3 8.39 8.31 11.74 10.90 10.46 9.94 10.15 10.24 8.06 7.69 7.48 10.25 10.62 10.37 1.29 10.31 10.50 C r 2 0 3 47.81 47.74 42.95 45.30 46.69 46.20 47.18 46.85 45.50 48.74 49.40 34.72 40.68 40.35 10.29 40.46 41.22 v 2 o 3 0.07 0.08 0.09 0.11 0.08 0.07 0.12 0.07 0.10 0.03 0.13 0.19 0.23 0.19 0.02 0.16 0.19 F e 2 0 3 12.07 11.54 12.65 11.62 11.14 11.15 10.97 10.84 13.27 11.87 11.68 20.34 15.91 16.44 58.44 16.56 15.88 FeO 23.59 23.55 24.23 24.18 24.23 23.12 24.50 24.29 25.62 24.97 25.01 24.12 25.51 25.77 26.10 25.66 25.90 MnO 0.30 0.31 0.32 0.31 0.39 0.35 0.33 0.32 0.51 0.28 0.31 2.71 0.35 0.39 0.90 0.45 0.31 MgO NiO CaO 6.72 6.61 6.51 6.50 6.38 6.71 6.25 6.27 4.93 5.68 5.75 4.72 5.66 5.54 3.06 5.52 5.59 0.00 0.02 0.00 0.01 0.01 0.00 0.00 0.00 0.19 0.10 0.05 0.00 0.02 0.00 0.10 0.02 0.03 Total 99.97 99.28 99.53 99.86 100.23 98.44 100.35 99.70 99.25 100.32 100.71 98.34 99.99 100.16 101.16 100.27 100.73 Cations (p.f.u.) Ti 0.026 0.028 0.025 0.023 0.020 0.021 0.020 0.021 0.027 0.024 0.023 0.033 0.026 0.028 0.008 0.028 0.027 Cr 1.294 1.302 1.152 1.215 1.252 1.259 1.266 1.264 1.258 1.329 1.343 0.963 1.100 1.092 0.297 1.094 1.108 Al 0.339 0.338 0.469 0.436 0.418 0.404 0.406 0.412 0.332 0.312 0.303 0.424 0.428 0.418 0.056 0.416 0.421 V 0.002 0.002 0.002 0.002 0.002 0.002 0.003 0.002 0.002 0.001 0.003 0.004 0.005 0.004 0.000 0.004 0.004 Fe J T * 0.311 0.299 0.323 0.297 0.284 0.289 0.280 0.279 0.349 0.308 0.302 0.537 0.409 0.423 1.606 0.426 0.406 Fe'** 0.675 0.679 0.687 0.686 0.687 0.666 0.695 0.693 0.749 0.720 0.719 0.708 0.730 0.737 0.797 0.734 0.736 Mn 0.009 0.009 0.009 0.009 0.011 0.010 0.009 0.009 0.015 0.008 0.009 0.081 0.010 0.011 0.028 0.013 0.009 Mg Ni Ca 0.343 0.340 0.329 0.329 0.323 0.344 0.316 0.319 0.257 0.292 0.294 0.247 0.289 0.282 0.167 0.282 0.283 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.007 0.004 0.002 0.000 0.001 0.000 0.004 0.001 0.001 Total 2.999 2.998 2.997 2.997 2.997 2.995 2.997 2.999 2.997 2.997 2.998 2.996 2.997 2.997 2.962 2.996 2.996 Trivalent End Members Cr/Z3+ 0.666 0.671 0.593 0.624 0.641 0.645 0.649 0.647 0.649 0.682 0.689 0.501 0.568 0.565 0.152 0.565 0.573 AI/I3+ 0.174 0.174 0.241 0.224 0.214 0.207 0.208 0.211 0.171 0.160 0.156 0.220 0.221 0.216 0.028 0.215 0.217 Fe/Z3+ 0.160 0.154 0.166 0.152 0.145 0.148 0.144 0.142 0.180 0.158 0.155 0.279 0.211 0.219 0.820 0.220 0.210 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Wehrlite Olivine Clinopyroxenite Sample: Cluster: Grain Number: 04ES-10-06-01 2 1 1 1 2 04ES-06-06-01 8 1 2 7 1 Style: Zone: m. sub. Rim Mid m. anh. Core Rim Mid m. anh. Core Rim Mid m. sub. Core Mid Mid Mid s. anh. Core Mid m. anh. Core Rim Mid Mid Oxides (wt. %) S i 0 2 0.00 0.02 T i0 2 0.91 0.96 A l 2 0 3 12.76 11.86 C r 2 0 3 40.57 43.47 v 2 o 3 0.20 0.14 F e 2 0 3 13.53 12.68 FeO 22.71 24.23 MnO 2.03 0.60 MgO 6.39 6.56 NiO - - CaO 0.01 0.00 Total 99.12 100.51 Cations (p.f.u.) Ti 0.023 0.024 Cr 1.088 1.154 Al 0.510 0.469 V 0.005 0.003 F e " * 0.345 0.321 F e " * 0.644 0.680 Mn 0.058 0.017 Mg 0.323 0.329 Ni - - Ca 0.000 0.000 Total 2.998 2.998 Trivalent End Members Cr/I3+ 0.560 0.594 AI/I3+ 0.263 0.241 Fe/X3+ 0.178 0.165 0.05 0.01 0.00 0.03 0.89 0.79 0.94 0.94 11.74 12.14 11.14 11.50 43.64 43.35 43.98 43.81 0.16 0.13 0.16 0.16 12.20 12.38 12.95 12.66 23.94 23.02 23.86 23.74 0.27 0.31 0.30 0.28 6.72 7.17 6.84 6.96 0.01 0.09 0.01 0.00 99.62 99.38 100.17 100.08 0.023 0.020 0.024 0.024 1.167 1.156 1.173 1.167 0.468 0.483 0.443 0.456 0.004 0.003 0.003 0.003 0.311 0.314 0.329 0.321 0.677 0.650 0.673 0.669 0.008 0.009 0.009 0.008 0.339 0.361 0.344' 0.349 0.000 0.003 0.000 0.000 2.996 2.998 2.998 2.997 0.600 0.592 0.603 0.600 0.241 0.247 0.228 0.235 0.160 0.161 0.169 0.165 0.03 0.03 0.00 0.00 0.11 0.94 0.89 1.13 0.03 12.00 11.86 9.09 4.83 42.33 42.92 46.48 0.00 0.20 0.16 0.32 64.67 13.34 13.33 10.52 28.70 24.16 24.21 25.65 0.35 0.37 0.30 0.48 1.43 6.68 6.70 5.30 0.00 0.00 0.01 0.00 00.17 100.05 100.39 98.97 0.003 0.024 0.023 0.030 0.145 1.127 1.140 1.278 0.002 0.476 0.470 0.372 0.000 0.005 0.004 0.007 1.846 0.338 0.337 0.275 0.910 0.681 0.680 0.746 0.011 0.011 0.009 0.014 0.081 0.335 0.336 0.275 0.000 0.000 0.000 0.000 2.998 2.997 2.998 2.997 0.073 0.581 0.586 0.664 0.001 0.245 0.241 0.193 0.926 0.174 0.173 0.143 0.02 0.02 0.00 0.00 1.09 1.06 1.08 0.90 9.18 9.16 9.10 8.81 47.13 47.69 48.02 44.03 0.36 0.28 0.34 0.34 10.00 9.96 9.68 13.94 25.37 25.83 25.76 26.25 0.73 0.39 0.41 0.93 5.38 5.34 5.43 4.59 0.00 0.02 0.03 0.00 99.26 99.76 99.84 99.80 0.028 0.027 0.028 0.024 1.290 1.300 1.307 1.210 0.375 0.372 0.369 0.361 0.008 0.006 0.008 0.008 0.260 0.258 0.251 0.365 0.735 0.745 0.742 0.763 0.022 0.012 0.012 0.027 0.277 0.274 0.279 0.238 0.000 0.001 0.001 0.000 2.995 2.996 2.997 2.996 0.670 0.673 0.678 0.625 0.195 0.193 0.192 0.186 0.135 0.134 0.130 0.188 0.06 0.02 0.03 0.06 1.03 1.11 1.28 1.10 9.40 7.13 7.68 7.49 44.41 42.33 45.25 45.57 0.39 0.43 0.36 0.33 12.61 16.23 12.52 13.12 26.54 25.42 26.42 25.72 0.31 1.56 0.65 1.09 4.94 4.42 4.56 4.66 0.03 0.03 0.03 0.01 99.72 98.69 98.77 99.16 0.027 0.030 0.034 0.029 1.214 1.187 1.262 1.266 0.383 0.298 0.319 0.310 0.009 0.010 0.008 0.008 0.328 0.433 0.332 0.347 0.767 0.754 0.779 0.756 0.009 0.047 0.019 0.032 0.255 0.234 0.240 0.244 0.001 0.001 0.001 0.001 2.993 2.994 2.995 2.994 0.631 0.619 0.659 0.658 0.199 0.155 0.167 0.161 0.170 0.226 0.174 0.180 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix i(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Olivine Clinopyroxenite Olivine Clinopyroxenite Sample: Cluster: Grain Number: 04ES-06-06-01 7 1 2 4.5 1 2 04ES-01-04-01 5 1 2 Style: Zone: m. anh. Core Rim Mid I. anh. Core Mid Mid Mid m. anh. Core Mid Mid m. irreg. Core Rim Mid Mid Core s. eu. Mid Core Oxides (wt. %) S i 0 2 0.02 0.03 0.03 0.05 0.04 0.05 0.05 0.02 0.01 0.00 0.02 0.05 0.02 0.05 0.01 0.04 0.03 T i0 2 1.11 1.22 1.44 2.11 1.05 1.05 1.04 1.07 0.84 0.98 1.02 0.85 0.86 0.87 0.79 0.90 0.86 A l 2 0 3 7.67 5.68 6.23 0.34 8.74 8.60 8.49 8.53 8.25 8.61 8.35 8.52 8.29 8.17 8.10 8.99 8.86 C r 2 0 3 45.38 42.41 42.90 21.09 46.87 47.79 48.06 48.20 46.95 48.60 48.48 53.59 55.09 55.38 55.37 53.34 52.62 v 2 o 3 0.37 0.39 0.54 0.24 0.27 0.24 0.25 0.22 0.25 0.24 0.22 0.30 0.25 0.23 0.26 0.26 0.27 F e 2 0 3 13.08 17.21 15.80 42.67 10.27 10.02 9.72 9.56 11.33 9.68 10.11 5.58 4.93 4.71 4.83 4.88 5.27 FeO 26.25 25.92 26.93 27.42 26.42 26.05 25.90 26.19 25.75 26.26 26.30 24.73 24.78 24.67 24.30 23.73 23.35 MnO 0.76 1.50 0.93 2.22 0.35 0.47 0.49 0.42 0.78 0.35 0.41 0.29 0.29 0.24 0.32 0.37 0.26 MgO 4.61 3.91 4.02 2.15 4.73 4.96 4.99 4.88 4.70 4.96 4.92 5.87 6.09 6.17 6.29 6.46 6.57 NiO CaO 0.00 0.09 0.06 0.02 0.00 0.02 0.00 0.00 0.03 0.01 0.01 0.25 0.05 0.02 0.00 0.08 0.07 Total 99.25 98.36 98.88 98.31 98.74 99.24 99.00 99.10 98.90 99.69 99.85 100.03 100.67 100.50 100.27 99.05 98.17 Cations (p.f.u.) Ti 0.029 0.033 0.038 0.060 0.028 0.028 0.027 0.028 0.022 0.026 0.027 0.022 0.022 0.022 0.020 0.023 0.023 Cr 1.260 1.206 1.209 0.632 1.298 1.316 1.326 1.330 1.303 1.333 1.330 1.452 1.484 1.494 1.496 1.449 1.442 Al 0.317 0.241 0.262 0.015 0.361 0.353 0.349 0.351 0.341 0.352 0.342 0.344 0.333 0.328 0.326 0.364 0.362 V 0.009 0.009 0.013 0.006 0.006 0.006 0.006 0.005 0.006 0.005 0.005 0.007 0.006 0.005 0.006 0.006 0.006 F e " * 0.346 0.466 0.424 1.218 0.271 0.262 0.255 0.251 0.299 0.253 0.264 0.144 0.126 0.121 0.124 0.126 0.137 Fe'** 0.771 0.780 0.803 0.870 0.774 0.759 0.756 0.765 0.756 0.762 0.763 0.709 0.706 0.704 0.694 0.682 0.677 Mn 0.023 0.046 0.028 0.071 0.010 0.014 0.014 0.012 0.023 0.010 0.012 0.008 0.008 0.007 0.009 0.011 0.008 Mg 0.241 0.210 0.213 0.121 0.247 0.258 0.260 0.254 0.246 0.257 0.255 0.300 0.309 0.314 0.320 0.331 0.339 Ni Ca 0.000 0.004 0.002 0.001 0.000 0.001 0.000 0.000 0.001 0.000 0.000 0.009 0.002 0.001 0.000 0.003 0.003 Total 2.995 2.994 2.993 2.995 2.995 2.995 2.995 2.997 2.997 2.998 2.997 2.994 2.996 2.995 2.997 2.996 2.996 Trivalent End Members Cr/23+ 0.655 0.630 0.638 0.339 0.673 0.681 0.687 0.688 0.670 0.688 0.687 0.748 0.764 0.769 0.769 0.747 0.743 AI/I3+ 0.165 0.126 0.138 0.008 0.187 0.183 0.181 0.182 0.176 0.182 0.176 0.177 0.171 0.169 0.168 0.188 0.186 Fe/I3+ 0.180 0.244 0.224 0.653 0.140 0.136 0.132 0.130 0.154 0.130 0.136 0.074 0.065 0.062 0.064 0.065 0.071 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Olivine Clinopyroxenite Olivine Clinopyroxenite Hornblende Clinopyroxenite Sample: Cluster: Grain Number: 04ES-01-04-01 6 1 2 05ES-05-01-01 8 1 9 1 DDH04-47-7-49 3 1 Style: Zone: m. sub. Rim Mid Mid m. anh. Core Rim Mid Mid s. eu. Core Rim Mid Core Rim Mid I. anh. Core Mid Mid Mid Mid Oxides (wt. %) S i 0 2 0.02 0.03 0.33 0.32 0.24 0.03 0.04 0.01 0.03 0.00 0.03 0.01 0.02 0.02 0.03 0.02 0.05 0.05 T i0 2 0.84 0.81 0.76 0.72 0.84 0.83 0.85 0.86 2.42 2.48 2.51 3.08 3.13 3.13 0.15 2.83 3.62 3.73 A l 2 0 3 8.77 7.99 7.80 7.70 7.00 8.95 8.83 8.73 4.18 4.44 4.64 6.63 6.48 6.50 0.12 0.69 2.71 1.22 C r 2 0 3 54.05 55.06 55.11 55.11 39.85 52.54 53.14 53.67 26.90 27.45 28.34 29.49 30.10 30.21 0.12 0.15 0.18 0.18 v 2 o 3 0.23 0.19 0.19 0.22 0.24 0.32 0.28 0.27 0.07 0.08 0.11 0.19 0.15 0.20 0.69 0.48 0.43 0.38 F e 2 0 3 4.91 4.96 5.48 5.59 19.25 5.46 5.54 4.95 32.01 31.67 30.20 26.23 26.42 26.69 67.96 61.90 58.63 60.00 FeO 23.53 23.61 23.28 23.11 25.89 25.73 25.95 25.62 25.19 25.31 25.09 26.10 27.29 27.49 31.70 33.48 34.32 34.40 MnO 0.23 0.28 0.34 0.27 1.13 0.36 0.30 0.35 3.87 3.92 4.07 3.54 2.02 1.96 0.08 0.20 0.26 0.21 MgO 6.62 6.55 6.72 6.79 3.95 5.25 5.32 5.43 2.79 2.98 3.08 3.59 4.01 4.07 0.09 0.23 0.51 0.31 NiO CaO 0.16 0.02 0.04 0.08 0.15 0.06 0.02 0.02 0.34 0.26 0.17 0.10 0.03 0.04 0.00 0.04 0.00 0.00 Total 99.35 99.51 100.04 99.90 98.51 99.52 100.27 99.90 97.80 98.60 98.24 98.96 99.67 100.31 100.95 100.01 100.71 100.48 Cations (p.f.u.) Ti 0.022 0.021 0.020 0.018 0.022 0.021 0.022 0.022 0.067 0.068 0.069 0.083 0.084 0.083 0.004 0.081 0.102 0.106 Cr 1.464 1.496 1.487 1.488 1.124 1.434 1.441 1.460 0.787 0.795 0.821 0.836 0.846 0.843 0.004 0.005 0.005 0.005 Al 0.354 0.324 0.314 0.310 0.294 0.364 0.357 0.354 0.182 0.192 0.200 0.280 0.272 0.271 0.005 0.031 0.119 0.054 V 0.005 0.004 0.004 0.005 0.006 0.007 0.006 0.006 0.002 0.002 0.003 0.004 0.004 0.005 0.017 0.012 0.011 ' 0.009 F e " * 0.127 0.128 0.141 0.144 0.517 0.142 0.143 0.128 0.891 0.873 0.833 0.708 0.707 0.709 1.944 1.776 1.648 1.706 F e " * 0.674 0.679 0.664 0.660 0.772 0.743 0.744 0.737 0.779 0.775 0.769 0.783 0.811 0.812 1.008 1.068 1.072 1.087 Mn 0.007 0.008 0.010 0.008 0.034 0.010 0.009 0.010 0.121 0.122 0.126 0.108 0.061 0.059 0.003 0.006 0.008 0.007 Mg 0.338 0.336 0.342 0.346 0.210 0.270 0.272 0.278 0.154 0.163 0.168 0.192 0.212 0.214 0.005 0.013 0.028 0.017 Ni Ca 0.006 .0.001 0.001 0.003 0.006 0.002 0.001 0.001 0.014 0.010 0.007 0.004 0.001 0.002 0.000 0.002 0.000 0.000 Total 2.997 2.997 2.981 2.981 2.985 2.995 2.995 2.997 2.998 2.999 2.997 2.998 2.997 2.997 2.991 2.994 2.993 2.993 Trivalent End Members Cr/23+ 0.753 0.768 0.766 0.766 0.581 0.739 0.742 0.752 0.423 0.428 0.443 0.458 0.464 0.463 0.002 0.002 0.003 0.003 AI/I3+ 0.182 0.166 0.162 0.160 0.152 0.188 0.184 0.182 0.098 0.103 0.108 0.154 0.149 0.148 0.003 0.017 0.067 0.031 Fe/I3+ 0.065 0.066 0.072 0.074 0.267 0.073 0.074 0.066 0.479 0.469 0.449 0.388 0.387 0.389 0.995 0.980 0.930 0.966 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Hornblende Clinopyroxenite Hornblende Clinopyroxenite Sample: DDH04-47-7-49 DDH05-84-19-104 Cluster: 3 4 5 9 8 Grain Number: 1 1 1 1 1 Style: I. anh. I. anh. I. interg. I. anh. Zone: Core Rim Mid Mid Core Rim Mid Mid Core Rim Mid Mid Core Rim Mid Mid Core Oxides (wt. %) S i 0 2 0.01 0.03 0.05 0.02 0.04 0.03 0.03 0.03 0.03 0.02 0.00 0.04 0.03 0.01 0.04 0.03 0.03 T i0 2 3.55 4.00 2.33 2.03 2.56 0.35 3.04 3.19 3.27 0.15 0.09 0.08 0.01 0.21 0.07 0.08 0.08 A l 2 0 3 3.45 0.16 3.77 1.30 1.43 0.16 0.78 1.12 2.27 0.03 0.06 0.07 0.04 0.04 0.13 0.18 0.18 C r 2 0 3 0.15 0.09 0.17 0.13 0.11 0.13 0.12 0.15 0.13 0.49 0.45 0.47 0.46 0.60 0.48 0.37 0.38 V 2 0 3 0.42 0.22 0.52 0.59 0.49 0.73 0.45 0.45 0.46 0.94 0.94 0.87 0.92 0.85 0.97 0.95 0.95 F e 2 0 3 57.77 61.29 60.21 63.38 62.12 67.39 61.56 60.85 59.94 67.70 67.60 68.25 67.51 67.23 67.13 67.77 67.50 FeO 34.13 34.56 33.29 33.29 33.50 31.82 33.76 33.83 34.04 32.00 31.87 32.00 31.60 31.70 31.62 32.03 31.76 MnO 0.30 0.26 0.23 0.17 0.17 0.02 0.25 0.22 0.26 0.02 0.06 0.08 0.06 0.08 0.06 0.06 0.08 MgO 0.58 0.22 0.67 0.27 0.33 0.15 0:19 0.29 0.46 0.12 0.10 0.11 0.14 0.12 0.16 0.09 0.14 NiO CaO 0.00 0.00 0.00 0.01 0.02 0.01 0.04 0.00 0.03 0.04 0.03 0.04 0.00 0.09 0.01 0.00 0.03 Total 100.37 100.83 101.25 101.19 100.76 100.78 100.21 100.12 100.90 101.50 101.19 102.02 100.77 100.93 100.67 101.56 101.13 Cations (p.f.u.) Ti 0.100 ' 0.114 0.065 0.057 0.072 0.010 0.087 0.091 0.092 0.004 0.003 0.002 0.000 0.006 0.002 0.002 0.002 Cr 0.004 0.003 0.005 0.004 0.003 0.004 0.004 0.004 0.004 0.015 0.013 0.014 0.014 0.018 0.014 0.011 0.011 Al 0.152 0.007 0.164 0.058 0.063 0.007 0.035 0.050 0.100 0.002 0.003 0.003 0.002 0.002 0.006 0.008 0.008 V 0.010 0.006 0.013 0.015 0.012 0.018 0.011 0.011 0.011 0.023 0.024 0.022 0.023 0.021 0.024 0.024 0.024 F e " * 1.622 1.749 1.673 1.792 1.761 1.929 1.762 1.739 1.687 1.925 1.929 1.931 1.934 1.922 1.923 1.925 1.925 Fe'** 1.065 1.096 1.028 1.046 1.056 1.012 1.074 1.074 1.064 1.011 1.010 1.006 1.006 1.007 1.006 1.011 1.006 Mn 0.010 0.008 0.007 0.005 0.005 0.001 0.008 0.007 0.008 0.001 0.002 0.003 0.002 0.002 0.002 0.002 0.002 Mg 0.032 0.013 0.037 0.015 0.018 0.008 0.011 0.017 0.026 0.007 0.005 0.006 0.008 0.007 0.009 0.005 0.008 Ni Ca 0.000 0.000 0.000 0.000 0.001 0.001 0.001 0.000 0.001 .0.001 0.001 0.001 0.000 0.004 0.001 0.000 0.001 Total 2.995 2.996 2.991 2.993 2.993 2.990 2.994 2.994 2.993 2.989 2.990 2.988 2.988 2.990 2.987 2.988 2.988 Trivalent End Members Cr/23+ 0.002 0.002 0.003 0.002 0.002 0.002 0.002 0.002 0.002 0.008 0.007 0.007 0.007 0.009 0.007 0.006 0.006 AI/I3+ 0.085 0.004 0.089 0.031 0.035 0.004 0.019 0.028 0.056 0.001 0.001 0.002 0.001 0.001 0.003 0.004 0.004 Fe/I3+ 0.912 0.994 0.908 0.967 0.964 0.994 0.978 0.970 0.942 0.992 0.992 0.991 0.992 0.990 0.990 0.990 0.990 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix l(continued): Spinel compositions from spinel-bearing ultramafic rocks of the Turnagain intrusion Rock: Hornblende Clinopyroxenite Sample: DDH05-84-19-104 Cluster: 1 Grain Number: 1 Style: I. anh. Zone: Rim Mid Mid Core Oxides (wt. %) S i 0 2 0.01 0.02 0.05 0.01 TiOj 0.04 0.05 0.08 0.14 A l 2 0 3 0.04 0.06 0.18 0.15 C r 2 0 3 0.37 0.42 0.37 0.38 V 2 0 3 0.89 0.86 0.91 0.93 F e 2 0 3 67.86 68.12 67.80 67.77 FeO 31.85 31.98 31.85 32.10 MnO 0.00 0.01 0.02 0.00 MgO 0.11 0.09 0.17 0.11 NiO - - - - CaO 0.00 0.01 0.02 0.00 Total 101.16 101.61 101.46 101.59 Cations (p.f.u.) Ti 0.001 0.001 0.002 0.004 Cr 0.011 0.012 0.011 0.011 Al 0.002 0.003 0.008 0.006 V 0.022 0.022 0.023 0.023 F e " * 1.937 1.936 1.926 1.925 Fe'"* 1.010 1.010 1.006 1.013 Mn 0.000 0.000 0.001 0.000 Mg 0.006 0.005 0.010 0.006 Ni - - - - Ca 0.000 0.000 0.001 0.000 Total 2.990 2.990 2.987 2.989 Trivalent End Members Cr/£3+ 0.006 0.006 0.006 0.006 AI/I3+ 0.001 0.001 0.004 0.003 Fe/I3+ 0.993 0.992 0.990 0.991 Crystal textural style is abbreviated: euh. (euhedral), sub. (subhedral), anh. (anhedral), interg. (intergrown), irreg. (irregular); I. (large), m. (medium), s. (small) Grain number refers to a particular grain within a cluster: most clusters have multiple grain Note: Other phases (ol, cpx, hbl) were also analyzed on certain sections, such that Cluster refers to a specific location on each section Appendix II: Olivine compositions from olivitie-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Chromitite Chromitite Sample: 05ES-01-01-01 05ES-01-04-01 Cluster: 1 3 8 1 2 Style: Zone: porph. rim porph. mid porph. mid porph. mid porph. core cumu. rim cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. core mgb. rim Oxides (wt. %) S i 0 2 41.58 41.11 40.91 40.81 41.10 40.76 40.93 40.86 41.02 40.99 40.91 40.95 41.12 41.11 41.87 41.51 41.82 41.71 C r 2 0 3 0.02 0.02 0.00 0.00 0.03 0.00 0.00 0.01 0.00 0.01 0.00 0.01 0.01 0.01 0.00 0.03 0.02 0.21 FeO 7.31 8.73 8.81 8.57 8.81 8.72 8.43 8.81 8.33 8.64 8.57 8.68 8.16 8.65 5.04 5.27 5.26 3.93 MnO 0.15 0.15 0.17 0.14 0.19 0.15 0.17 0.17 0.19 0.17 0.11 0.12 0.19 0.15 0.07 0.09 0.06 0.10 MgO 50.49 49.82 49.71 49.93 49.81 49.61 49.86 49.79 49.95 49.85 49.95 49.77 49.95 49.79 52.73 52.69 52.61 54.01 NiO 0.25 0.33 0.28 0.32 0.23 0.32 0.33 0.35 0.35 0.27 0.36 0.40 0.31 0.40 0.42 0.52 0.45 0.36 CaO 0.05 0.07 0.09 0.05 0.06 0.04 0.09 0.06 0.08 0.03 0.06 0.07 0.07 0.07 0.11 0.12 0.13 0.07 Total 99.85 100.23 99.96 99.81 100.23 99.58 99.80 100.05 99.92 99.96 99.97 99.99 99.82 100.18 100.24 100.23 100.35 100.39 Cations (p.f.u.) Si 1.008 1.001 0.999 0.998 1.000 0.999 1.000 0.998 1.000 1.000 0.998 1.000 1.003 1.001 1.002 0.996 1.001 0.992 Cr 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.004 Fe 0.148 0.178 0.180 0.175 0.179 0.179 0.172 0.180 0.170 0.176 0.175 0.177 0.166 0.176 0.101 0.106 0.105 0.078 Mn 0.003 0.003 0.004 0.003 0.004 0.003 0.003 0.004 0.004 0.003 0.002 0.002 0.004 0.003 0.001 0.002 0.001 0.002 Mg 1.825 1.808 1.810 1.820 1.808 1.813 1.816 1.812 1.816 1.813 1.817 1.811 1.816 1.808 1.882 1.885 1.878 1.915 Ni 0.005 0.006 0.005 0.006 0.005 0.006 0.006 0.007 0.007 0.005 0.007 0.008 0.006 0.008 0.008 0.010 0.009 0.007 C a 0.001 0.002 0.002 0.001 0.002 0.001 0.002 0.002 0.002 0.001 0.002 0.002 0.002 0.002 0.003 0.003 0.003 0.002 Total 2.991 2.999 3.001 3.002 2.998 3.001 3.000 3.002 3.000 2.999 3.002 3.000 2.997 2.998 2.998 3.002 2.998 3.000 End Members (%) Fo 92.5 91.1 91.0 91.2 91.0 91.0 91.3 91.0 91.4 91.1 91.2 91.1 91.6 91.1 94.9 94.7 94.7 96.1 Fa 7.5 8.9 9.0 8.8 9.0 9.0 8.7 9.0 8.6 8.9 8.8 8.9 8.4 8.9 5.1 5.3 5.3 3.9 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Chromitite Chromitite Sample: 05ES-01-04-01 05ES-01-03-01 Cluster: 2 3 7 6 5 Style: Zone: mgb. mid mgb. mid mgb. core cumu. rim cumu. mid cumu. core porph. rim porph. mid porph. mid porph. core mgb. rim mgb. mid mgb. core mgb. rim mgb. mid mgb. mid mgb. core Oxides (wt. %) S i 0 2 41.71 41.59 41.90 41.14 41.50 41.56 41.78 41.57 41.43 41.41 41.58 41.38 41.32 41.58 41.52 41.50 41.25 C r 2 0 3 0.01 0.01 0.02 0.09 0.00 0.03 0.02 0.00 0.00 0.03 0.00 0.01 0.00 0.03 0.00 0.00 0.04 FeO 4.74 4.82 4.79 3.81 4.33 4.70 6.44 6.52 6.64 6.47 6.24 6.44 6.44 5.83 6.39 6.40 6.20 MnO 0.09 0.07 0.09 0.05 0.08 0.10 0.08 0.13 0.11 0.12 0.10 0.14 0.12 0.14 0.08 0.13 0.09 MgO 52.79 52.88 53.01 53.62 53.35 53.35 51.37 51.70 51.60 51.43 51.76 51.73 51.56 52.04 51.49 51.64 51.96 NiO 0.47 0.47 0.51 0.63 0.59 0.61 0.41 0.41 0.40 0.43 0.42 0.43 0.44 0.40 0.46 0.41 0.43 CaO 0.10 0.10 0.13 0.11 0.08 0.12 0.09 0.12 0.13 0.14 0.13 0.13 0.14 0.08 0.13 0.14 0.12 Total 99.92 99.93 100.45 99.45 99.92 100.47 100.18 100.46 100.31 100.02 100.23 100.25 100.02 100.10 100.08 100.22 100.09 Cations (p.f.u.) Si 1.001 0.999 1.001 0.990 0.995 0.993 1.006 1.000 0.999 1.000 1.001 0.998 0.999 1.001 1.002 1.000 0.995 Cr 0.000 0.000 0.000 0.002 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.001 0.000 0.000 0.001 Fe 0.095 0.097 0.096 0.077 0.087 0.094 0.130 0.131 0.134 0.131 0.126 0.130 0.130 0.117 0.129 0.129 0.125 Mn 0.002 0.001 0.002 0.001 0.002 0.002 0.002 0.003 0.002 0.002 0.002 0.003 0.002 0.003 0.002 0.003 0.002 Mg 1.889 1.892 1.887 1.923 1.908 1.901 1.845 1.854 1.855 1.852 1.858 1.859 1.858 1.867 1.853 1.856 1.869 Ni 0.009 0.009 0.010 0.012 0.011 0.012 0.008 0.008 0.008 0.008 0.008 0.008 0.009 0.008 0.009 0.008 0.008 C a 0.002 0.003 0.003 0.003 0.002 0.003 0.002 0.003 0.003 0.004 0.003 0.003 0.004 0.002 0.003 0.004 0.003 Total 2.999 3.001 2.999 3.007 3.005 3.006 2.993 3.000 3.001 2.998 2.999 3.002 3.001 2.998 2.998 3.000 3.003 End Members (%) Fo 95.2 95.1 95.2 96.2 95.6 95.3 93.4 93.4 93.3 93.4 93.7 93.5 93.4 94.1 93.5 93.5 93.7 Fa 4.8 4.9 4.8 3.8 4.4 4.7 6.6 6.6 6.7 6.6 6.3 6.5 6.6 5.9 6.5 6.5 6.3 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix Ii (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Dunite Dunite Dunite Sample: 04ES-10-05-01 Cluster: 3 2 04ES-10-05-01 1 04ES-06-01-01 1 2 Style: Zone: mgb. rim mgb. mid mgb. mid mgb. core cumu. rim cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. core porph. rim porph. mid porph. core porph. rim porph. mid porph. mid porph. core Oxides (wt. %) S i 0 2 41.05 40.72 40.76 41.22 40.43 40.85 41.04 40.90 42.17 41.26 40.86 41.02 41.14 41.06 40.97 40.65 41.29 40.92 C r 2 0 3 0.00 0.00 0.00 0.00 0.01 0.00 0.07 0.00 0.00 0.01 0.00 0.01 0.04 0.12 0.09 0.05 0.00 0.01 FeO 8.91 9.47 9.09 8.66 8.85 8.52 8.77 8.42 3.44 8.91 9.17 8.91 9.33 8.88 9.54 8.92 9.26 9.50 MnO 0.16 0.18 0.18 0.16 0.16 0.16 0.12 0.12 0.43 0.15 0.17 0.18 0.21 0.15 0.17 0.21 0.14 0.14 MgO 49.74 48.52 49.19 49.55 49.78 49.58 49.77 49.59 54.63 49.59 49.61 49.29 48.81 49.83 49.00 49.52 47.90 49.15 NiO 0.29 0.35 0.30 0.31 0.27 0.30 0.30 0.41 0.00 0.35 0.30 0.31 0.34 0.29 0.35 0.29 0.29 0.31 CaO 0.17 0.25 0.06 0.02 0.05 0.05 0.05 0.05 0.02 0.07 0.13 0.06 0.25 0.04 0.30 0.02 0.66 0.05 Total 100.33 99.49 99.59 99.92 99.55 99.45 100.13 99.48 100.69 100.33 100.24 99.79 100.12 100.37 100.41 99.67 99.55 100.08 Cations (p.f.u.) Si 1.000 1.003 1.001 1.006 0.993 1.001 1.000 1.002 0.998 1.004 0.997 1.004 1.005 0.998 1.000 0.997 1.014 1.001 Cr 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.001 0.002 0.002 0.001 0.000 0.000 Fe 0.181 0.195 0.187 0.177 0.182 0.175 0.179 0.172 0.068 0.181 0.187 0.182 0.191 0.181 0.195 0.183 0.190 0.194 Mn 0.003 0.004 0.004 0.003 0.003 0.003 0.002 0.002 0.009 0.003 0.004 0.004 0.004 0.003 0.003 0.004 0.003 0.003 Mg 1.806 1.782 1.800 1.802 1.822 1.812 1.808 1.811 1.927 1.799 1.805 1.798 1.778 1.806 1.783 1.810 1.755 1.792 Ni 0.006 0.007 0.006 0.006 0.005 0.006 0.006 0.008 0.000 0.007 0.006 0.006 0.007 0.006 0.007 0.006 0.006 0.006 C a 0.004 0.007 0.002 0.000 0.001 0.001 0.001 0.001 0.000 0.002 0.003 0.002 0.007 0.001 0.008 0.001 0.017 0.001 Total 3.000 2.997 2.999 2.994 3.007 2.999 2.997 2.998 3.002 2.996 3.003 2.996 2.993 2.997 2.997 3.001 2.985 2.998 End Members (%) Fo 90.9 90.1 90.6 91.1 90.9 91.2 91.0 91.3 96.6 90.8 90.6 90.8 90.3 90.9 90.2 90.8 90.2 90.2 Fa 9.1 9.9 9.4 8.9 9.1 8.8 9.0 8.7 3.4 9.2 9.4 9.2 9.7 9.1 9.8 9.2 9.8 9.8 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Dunite Dunite Dunite Sample: 04ES-06-01-01 Cluster: 3 04ES-08-01-01 1 2 3 04ES-03-02-01 1 2 Style: Zone: mgb. rim mgb. mid mgb. mid mgb. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu.. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid Oxides (wt. %) S i 0 2 40.99 41.04 41.02 41.44 40.78 40.87 40.78 40.86 40.66 40.85 40.78 41.02 40.79 41.25 40.85 40.91 40.72 40.84 C r 2 0 3 0.00 0.00 0.00 0.02 0.03 0.03 0.08 0.00 0.02 0.06 0.01 0.00 0.02 0.00 0.02 0.01 0.00 0.00 FeO 8.98 9.10 9.29 7.67 10.23 10.09 10.12 9.08 9.70 10.31 9.46 9.99 9.88 8.20 9.14 9.35 9.28 9.08 MnO 0.20 0.20 0.19 0.17 0.16 0.15 0.17 0.18 0.16 0.17 0.14 0.20 0.12 0.16 0.16 0.14 0.14 0.14 MgO 49.31 49.53 49.16 50.77 48.56 48.45 48.53 49.53 48.77 48.67 49.32 48.88 48.97 50.10 49.39 49.37 49.58 49.40 NiO 0.27 0.27 0.32 0.13 0.14 0.13 0.05 0.10 0.07 0.12 0.03 0.14 0.11 0.06 0.16 0.12 0.16 0.10 CaO 0.15 0.00 0.02 0.00 0.17 0.16 0.15 0.10 0.18 0.15 0.11 0.17 0.18 0.07 0.17 0.16 0.15 0.14 Total 99.91 100.14 100.00 100.20 100.07 99.88 99.89 99.85 99.57 100.35 99.85 100.41 100.06 99.83 99.89 100.06 100.03 99.70 Cations (p.f.u.) Si 1.002 1.002 1.003 1.003 1.001 1.004 1.001 1.000 1.000 1.000 0.999 1.002 0.999 1.004 1.000 1.000 0.996 1.001 Cr 0.000 0.000 0.000 0.000 0.000 0.001 0.002 0.000 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Fe 0.184 0.186 0.190 0.155 0.210 0.207 0.208 0.186 0.200 0.211 0.194 0.204 0.202 0.167 0.187 0.191 0.190 0.186 Mn 0.004 0.004 0.004 0.003 0.003 0.003 0.004 0.004 0.003 0.004 0.003 0.004 0.002 0.003 0.003 0.003 0.003 0.003 Mg 1.798 1.802 1.793 1.832 1.777 1.774 1.776 1.807 1.789 1.776 1.801 1.780 1.789 1.818 1.802 1.799 1.808 1.804 Ni 0.005 0.005 0.006 0.002 0.003 0.003 0.001 0.002 0.001 0.002 0.001 0.003 0.002 0.001 0.003 0.002 0.003 0.002 C a 0.004 0.000 0.001 0.000 0.004 0.004 0.004 0.003 0.005 0.004 0.003 0.004 0.005 0.002 0.005 0.004 0.004 0.004 Total 2.997 2.998 2.997 2.996 2.998 2.995 2.995 3.000 2.999 2.998 3.001 2.998 3.000 2.996 3.000 3.000 3.004 2.999 End Members (%) Fo 90.7 90.7 90.4 92.2 89.4 89.5 89.5 90.7 90.0 89.4 90.3 89.7 89.8 91.6 90.6 90.4 90.5 90.7 Fa 9.3 9.3 9.6 7.8 10.6 10.5 10.5 9.3 10.0 10.6 9.7 10.3 10.2 8.4 9.4 9.6 9.5 9.3 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Dunite Dunite Wehrlite Sample: 04ES-03-02-01 Cluster: 2 3 04ES-19-01-02 1 2 3 04ES-10-06-01 5 4 Style: Zone: cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. core porph. rim porph. mid porph. mid porph. mid porph. core porph. mid porph. mid Oxides (wt. %) S i 0 2 40.85 40.74 40.49 41.00 41.67 41.56 41.48 41.45 41.22 41.45 41.31 40.91 40.27 40.70 40.16 40.47 40.16 40.38 C r 2 0 3 0.05 0.01 0.04 0.02 0.00 0.03 0.04 0.03 0.03 0.00 0.01 0.00 0.01 0.00 0.02 0.06 0.00 0.00 FeO 9.35 7.34 9.00 8.57 7.66 7.51 7.85 7.44 7.36 7.56 7.02 8.87 10.58 9.66 10.87 10.46 10.88 9.84 MnO 0.20 0.23 0.15 0.16 0.16 0.21 0.12 0.19 0.16 0.21 0.12 0.33 0.19 0.21 0.22 0.21 0.21 0.32 MgO 49.63 49.99 49.13 49.97 50.88 51.00 50.39 51.18 51.00 50.85 51.08 49.57 48.03 48.68 47.85 47.94 47.60 48.79 NiO 0.12 0.12 0.10 0.09 0.17 0.25 0.22 0.13 0.25 0.27 0.21 0.25 0.27 0.31 0.36 0.39 0.27 0.31 CaO 0.10 0.11 0.18 0.15 0.02 0.03 0.34 0.08 0.04 0.06 0.00 0.03 0.05 0.04 0.04 0.02 0.03 0.03 Total 100.31 98.54 99.09 99.96 100.55 100.58 100.43 100.48 100.06 100.41 99.75 99.95 99.39 99.61 99.52 99.56 99.15 99.67 Cations (p.f.u.) Si 0.996 1.002 0.998 1.000 1.005 1.002 1.003 1.000 0.999 1.002 1.002 1.000 0.998 1.002 0.996 1.000 0.999 0.995 Cr 0.001 0.000 0.001 0.000 0.000 0.001 0.001 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 Fe 0.191 0.151 0.186 0.175 0.155 0.151 0.159 0.150 0.149 0.153 0.142 0.181 0.219 0.199 0.226 0.216 0.226 0.203 Mn 0.004 0.005 0.003 0.003 0.003 0.004 0.002 0.004 0.003 0.004 0.002 0.007 0.004 0.004 0.005 0.004 0.004 0.007 Mg 1.804 1.833 1.806 1.816 1.829 1.833 1.817 1.840 1.842 1.832 1.847 1.806 1.774 1.786 1.769 1.767 1.765 1.793 Ni 0.002 0.002 0.002 0.002 0.003 0.005 0.004 0.002 0.005 0.005 0.004 0.005 0.005 0.006 0.007 0.008 0.005 0.006 C a 0.003 0.003 0.005 0.004 0.000 0.001 0.009 0.002 0.001 0.002 0.000 0.001 0.001 0.001 0.001 0.001 0.001 0.001 Total 3.002 2.997 3.000 3.000 2.995 2.997 2.995 2.999 3.000 2.998 2.998 3.000 3.002 2.998 3.003 2.997 3.001 3.005 End Members (%) Fo 90.4 92.4 90.7 91.2 92.2 92.4 92.0 92.5 92.5 92.3 92.8 90.9 89.0 90.0 88.7 89.1 88.6 89.8 Fa 9.6 7.6 9.3 8.8 7.8 7.6 8.0 7.5 7.5 7.7 7.2 9.1 11.0 10.0 11.3 10.9 11.4 10.2 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Sample: Cluster: Style: Zone: Wehrlite Wehrlite Wehrlite 04ES-10-06-01 4 3 04ES-16-08-01 2 4 5 04ES-11-03-03 2 porph. porph. core rim porph. mid cumu. cumu. rim mid cumu. mid cumu. cumu. core rim cumu. mid cumu. cumu. core rim cumu. mid cumu. mid cumu. porph. porph. core rim mid porph. mid porph. mid Oxides (wt. %) S i 0 2 40.43 40.42 40.55 40.61 40.47 40.38 40.23 40.07 40.51 40.68 40.71 41.00 40.39 40.45 40.37 40.07 40.23 40.38 C r 2 0 3 0.02 0.00 0.00 0.04 0.07 0.02 0.00 0.03 0.01 0.02 0.03 0.01 0.04 0.00 0.02 0.04 0.00 0.02 FeO 11.16 11.13 11.04 11.67 11.52 11.66 11.67 11.11 11.69 11.14 10.95 10.13 11.28 10.65 12.93 13.15 13.51 13.08 MnO 0.21 0.18 0.20 0.21 0.18 0.18 0.22 0.21 0.21 0.21 0.26 0.25 0.25 0.23 0.24 0.27 0.21 0.32 MgO 47.50 47.54 47.79 47.23 47.36 47.06 47.32 46.86 47.62 47.74 47.91 48.98 47.68 48.12 46.06 46.31 45.86 46.15 NiO 0.26 0.35 0.35 0.16 0.13 0.23 0.18 0.16 0.22 0.22 0.09 0.31 0.23 0.17 0.19 0.10 0.16 0.15 CaO 0.02 0.02 0.04 0.05 0.14 0.05 0.08 0.05 0.09 0.06 0.03 0.03 0.06 0.08 0.01 0.01 0.03 0.03 Total 99.60 99.63 99.98 99.96 99.88 99.59 99.69 98.49 100.34 100.07 99.99 100.72 99.91 99.69 99.82 99.96 99.99 100.13 Cations (p.f.u.) Si 1.002 1.001 1.001 1.004 1.001 1.003 0.998 1.004 0.999 1.002 1.003 1.000 0.998 0.999 1.005 0.998 1.003 1.003 Cr 0.000 0.000 0.000 0.001 0.001 0.000 0.000 0.001 0.000 0.000 0.001 0.000 0.001 0.000 0.000 0.001 0.000 0.000 Fe 0.231 0.231 0.228 0.241 0.238 0.242 0.242 0.233 0.241 0.230 0.226 0.207 0.233 0.220 0.269 0.274 0.282 0.272 Mn 0.004 0.004 0.004 0.004 0.004 0.004 0.005 0.004 0.004 0.004 0.006 0.005 0.005 0.005 0.005 0.006 0.004 0.007 Mg 1.754 1.756 1.758 1.740 1.746 1.742 1.751 1.749 1.750 1.754 1.759 1.781 1.757 1.772 1.710 1.720 1.704 1.710 Ni 0.005 0.007 0.007 0.003 0.003 0.005 0.004 0.003 0.004 0.004 0.002 0.006 0.004 0.003 0.004 0.002 0.003 0.003 C a 0.001 0.001 0.001 0.001 0.004 0.001 0.002 0.001 0.002 0.002 0.001 0.001 0.002 0.002 0.000 0.000 0.001 0.001 Total 2.998 2.999 2.999 2.995 2.996 2.997 3.002 2.995 3.001 2.997 2.996 3.000 3.000 3.001 2.994 3.000 2.997 2.996 End Members (%) Fo 88.4 88.4 88.5 87.8 88.0 87.8 87.8 88.3 87.9 88.4 88.6 89.6 88.3 89.0 86.4 86.3 85.8 86.3 Fa 11.6 11.6 11.5 12.2 12.0 12.2 12.2 11.7 12.1 11.6 11.4 10.4 11.7 11.0 13.6 13.7 14.2 13.7 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Wehrlite Wehriite Sample: 04ES-11-03-03 04ES-09-01-01 Cluster: 2 4 5 1 3 4 Style: Zone: porph. core porph. rim porph. mid porph. mid porph. core porph. rim porph. mid porph. mid porph. core porph. rim porph. mid porph. mid porph. core cumu. rim cumu. mid cumu. mid cumu. core porph. rim Oxides (wt. %) S i 0 2 39.82 40.18 40.68 40.93 40.58 40.17 40.03 40.10 40.17 40.06 39.91 40.02 40.23 40.29 39.86 39.81 39.88 39.98 C r 2 0 3 0.01 0.04 0.00 0.02 0.02 0.00 0.00 0.01 0.00 0.00 0.00 0.02 0.00 0.00 0.06 0.03 0.00 0.00 FeO 12.93 12.45 11.91 10.13 12.28 13.54 13.48 13.55 13.90 12.69 13.18 12.98 12.98 9.51 12.40 12.77 12.97 13.12 MnO 0.55 0.32 0.36 0.34 0.29 0.29 0.26 0.28 0.26 0.28 0.18 0.24 0.19 0.22 0.27 0.24 0.30 0.32 MgO 45.48 46.48 46.95 47.90 46.62 45.53 45.58 45.24 45.47 45.82 45.41 45.79 45.67 44.44 45.76 46.11 45.71 45.50 NiO 0.32 0.15 0.10 0.16 0.18 0.12 0.16 0.21 0.16 0.20 0.25 0.20 0.22 0.19 0.20 0.22 0.26 0.20 CaO 0.04 0.01 0.02 0.04 0.02 0.04 0.04 0.01 0.03 0.05 0.05 0.03 0.01 0.01 0.04 0.01 0.02 0.11 Total 99.14 99.64 100.01 99.51 99.99 99.69 99.54 99.41 100.00 99.09 98.98 99.28 99.31 94.67 98.59 99.18 99.15 99.23 Cations (p.f.u.) Si 1.002 1.001 1.006 1.009 1.006 1.005 1.003 1.006 1.003 1.005 1.004 1.003 1.007 1.039 1.004 0.999 1.002 1.004 Cr 0.000 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.000 0.000 Fe 0.272 0.259 0.246 0.209 0.254 0.283 0.282 0.284 0.290 0.266 0.277 0.272 0.272 0.205 0.261 0.268 0.273 0.275 Mn 0.012 0.007 0.007 0.007 0.006 0.006 0.005 0.006 0.006 0.006 0.004 0.005 0.004 0.005 0.006 0.005 0.006 0.007 Mg 1.705 1.726 1.731 1.760 1.723 1.698 1.702 1.692 1.693 1.713 1.704 1.711 1.705 1.708 1.717 1.724 1.712 1.703 Ni 0.006 0.003 0.002 0.003 0.004 0.003 0.003 0.004 0.003 0.004 0.005 0.004 0.004 0.004 0.004 0.004 0.005 0.004 C a 0.001 0.000 0.000 0.001 0.000 0.001 0.001 0.000 0.001 0.001 0.001 0.001 0.000 0.000 0.001 0.000 0.001 0.003 Total 2.998 2.997 2.994 2.990 2.993 2.995 2.997 2.994 2.997 2.995 2.996 2.996 2.993 2.961 2.994 3.000 2.998 2:996 End Members (%) Fo 86.2 86.9 87.5 89.4 87.1 85.7 85.8 85.6 85.4 86.6 86.0 86.3 86.2 89.3 86.8 86.6 86.3 86.1 Fa 13.8 13.1 12.5 10.6 12.9 14.3 14.2 14.4 14.6 13.4 14.0 13.7 13.8 10.7 13.2 13.4 13.7 13.9 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Wehrlite Wehrlite Olivine Cpxite Sample: 04ES-09-01-01 04ES-15-01-05 04ES-06-06-01 Cluster: 4 1 4 5 1 Style: porph. porph. porph. def. def. def. def. cumu. cumu. cumu. cumu. cumu. mgb. mgb. mgb. mgb. cumu. cumu. Zone: mid mid core rim mid mid core rim mid mid mid core rim mid mid core rim mid Oxides (wt. %) S i 0 2 39.83 39.78 39.92 40.53 40.69 40.72 40.49 40.77 40.45 40.33 40.67 40.76 40.97 40.51 40.50 40.79 39.92 40.09 C r 2 0 3 0.00 0.00 0.00 0.02 0.02 0.01 0.00 0.00 0.04 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.04 0.02 FeO 12.78 12.40 13.07 10.79 11.50 10.48 11.17 11.21 10.92 11.67 11.37 11.50 8.10 10.95 10.68 10.28 12.96 12.87 MnO 0.21 0.24 0.19 0.22 0.18 0.15 0.24 0.22 0.23 0.21 0.22 0.21 0.28 0.24 0.19 0.24 0.25 0.23 MgO 45.66 45.72 45.64 47.80 47.44 48.30 47.53 48.32 48.08 47.69 47.73 47.79 49.85 47.90 47.97 48.27 46.30 46.01 NiO 0.18 0.25 0.19 0.27 0.29 0.29 0.38 0.23 0.28 0.27 0.32 0.32 0.18 0.25 0.27 0.29 0.10 0.04 CaO 0.00 0.02 0.02 0.02 0.08 0.05 0.06 0.04 0.04 0.07 0.07 0.07 0.04 0.04 0.08 0.05 0.03 0.04 Total 98.67 98.41 99.04 99.65 100.22 100.00 99.88 100.79 100.04 100.24 100.39 100.65 99.46 99.89 99.69 99.92 99.61 99.31 Cations (p.f.u.) Si 1.004 1.004 1.003 1.002 1.003 1.001 1.001 0.998 0.997 0.996 1.001 1.001 1.002 1.000 1.001 1.003 0.997 1.003 Cr 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.001 0.000 0.000 0.000 0.001 0.000 Fe 0.269 0.262 0.275 0.223 0.237 0.216 0.231 0.229 0.225 0.241 0.234 0.236 0.166 0.226 0.221 0.211 0.271 0.269 Mn 0.005 0.005 0.004 0.005 0.004 0.003 0.005 0.005 0.005 0.004 0.005 0.004 0.006 0.005 0.004 0.005 0.005 0.005 Mg 1.715 1.720 1.710 1.762 1.744 1.771 1.752 1.764 1.767 1.756 1.751 1.749 1.818 1.763 1.767 1.770 1.724 1.716 Ni 0.004 0.005 0.004 0.005 0.006 0.006 0.007 0.005 0.006 0.005 0.006 0.006 0.004 0.005 0.005 0.006 0.002 0.001 C a 0.000 0.001 0.001 0.001 0.002 0.001 0.002 0.001 0.001 0.002 0.002 0.002 0.001 0.001 0.002 0.001 0.001 0.001 Total 2.996 2.996 2.997 2.997 2.996 2.998 2.999 3.002 3.001 3.004 2.999 2.999 2.997 3.000 2.999 2.997 3.001 2.996 End Members (%) Fo 86.4 86.8 86.2 88.8 88.0 89.1 88.4 88.5 88.7 87.9 88.2 88.1 91.6 88.6 88.9 89.3 86.4 86.4 Fa 13.6 13.2 13.8 11.2 12.0 10.9 11.6 11.5 11.3 12.1 11.8 11.9 8.4 11.4 11.1 10.7 13.6 13.6 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Olivine Clinopyroxenite Olivine Clinopyroxenite Sample: 04ES-06-06-01 Cluster: 1 3 4 05ES-05-01-01 3 4 Style: Zone: cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core Oxides (wt. %) S i 0 2 40.38 40.13 40.32 40.36 40.44 40.13 40.28 40.35 40.35 40.24 40.44 40.23 39.14 39.25 39.23 39.22 39.43 39.17 C r 2 0 3 0.02 0.00 0.02 0.02 0.05 0.00 0.02 0.05 0.04 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.02 FeO 12.65 12.36 13.14 12.80 12.15 12.72 12.98 12.66 12.60 12.76 12.68 12.89 15.51 15.55 15.59 14.95 15.63 15.61 MnO 0.24 0.22 0.21 0.26 0.33 0.22 0.23 0.21 0.25 0.21 0.22 0.26 0.30 0.26 0.24 0.23 0.26 0.22 MgO 46.43 46.41 46.53 46.25 46.78 46.66 46.34 46.13 46.58 45.79 45.66 46.39 44.13 44.10 44.02 44.46 44.21 44.25 NiO 0.07 0.10 0.05 0.08 0.09 0.06 0.06 0.03 0.03 0.09 0.10 0.10 0.13 0.12 0.11 0.08 0.08 0.14 CaO 0.03 0.03 0.05 0.03 0.02 0.01 0.01 0.03 0.03 0.02 0.35 0.04 0.06 0.02 0.00 0.03 0.01 0.02 Total 99.83 99.24 100.33 99.79 99.86 99.81 99.92 99.46 99.87 99.11 99.44 99.90 99.27 99.29 99.19 98.98 99.62 99.44 Cations (p.f.u.) Si 1.004 1.003 1.000 1.005 1.003 0.999 1.002 1.006 1.002 1.008 1.010 1.001 0.994 0.996 0.997 0.996 0.997 0.993 Cr 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Fe 0.263 0.258 0.272 0.266 0.252 0.265 0.270 0.264 0.262 0.267 0.265 0.268 0.329 0.330 0.331 0.318 0.331 0.331 Mn 0.005 0.005 0.005 0.005 0.007 0.005 0.005 0.004 0.005 0.004 0.005 0.005 0.006 0.005 0.005 0.005 0.006 0.005 Mg 1.721 1.729 1.720 1.716 1.730 1.731 1.718 1.715 1.725 1.710 1.700 1.721 1.671 1.669 1.667 1.683 1.667 1.673 Ni 0.001 0.002 0.001 0.002 0.002 0.001 0.001 0.001 0.001 0.002 0.002 0.002 0.003 0.002 0.002 0.002 0.002 0.003 Ca 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.001 0.001 0.000 0.009 0.001 0.002 0.001 0.000 0.001 0.000 0.001 Total 2.995 2.997 2.999 2.995 2.995 3.001 2.997 2.992 2.996 2.992 2.990 2.999 3.006 3.004 3.003 3.004 3.003 3.006 End Members (%) Fo 86.7 87.0 86.3 86.6 87.3 86.7 86.4 86.7 86.8 86.5 86.5 86.5 83.5 83.5 83.4 84.1 83.4 83.5 Fa 13.3 13.0 13.7 13.4 12.7 13.3 13.6 13.3 13.2 13.5 13.5 13.5 16.5 16.5 16.6 15.9 16.6 16.5 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section Appendix II (continued): Olivine compositions from olivine-bearing ultramafic lithologies of the Turnagain intrusion Rock type: Olivine Clinopyroxenite Olivine Clinopyroxenite Sample: 04ES-01-04-01 04ES-01-04-01 Cluster: 5 1 3 4 Style: Zone: cumu. mid cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. core Oxides (wt. %) S i 0 2 39.23 40.44 40.18 40.31 40.52 40.36 40.10 40.19 39.94 40.43 C r 2 0 3 0.02 0.01 0.01 0.02 0.00 0.00 0.05 0.00 0.00 0.02 FeO 15.67 12.27 12.73 12.75 11.37 12.47 12.41 12.94 12.76 12.88 MnO 0.24 0.16 0.22 0.21 0.22 0.21 0.19 0.18 0.21 0.21 MgO 43.96 46.38 46.67 46.55 47.29 46.59 46.97 46.30 46.59 46.61 NiO 0.12 0.09 0.11 0.05 0.07 0.02 0.06 0.16 0.07 0.12 CaO 0.03 0.00 0.03 0.05 0.02 0.02 0.05 0.01 0.04 0.03 Total 99.27 99.35 99.95 99.95 99.50 99.68 99.82 99.78 99.61 100.30 Cations (p.f.u.) Si 0.996 1.008 0.999 1.001 1.005 1.004 0.996 1.001 0.997 1.001 Cr 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 Fe 0.333 0.256 0.265 0.265 0.236 0.259 0.258 0.270 0.266 0.267 Mn 0.005 0.003 0.005 0.004 0.005 0.004 0.004 0.004 0.004 0.004 Mg 1.665 1.723 1.729 1.724 1.748 1.728 1.740 1.720 1.733 1.721 Ni 0.002 0.002 0.002 0.001 0.001 0.000 0.001 0.003 0.001 0.002 C a 0.001 0.000 0.001 0.001 0.000 0.001 0.001 0.000 0.001 0.001 Total 3.003 2.992 3.001 2.998 2.995 2.996 3.002 2.998 3.003 2.998 End Members (%) Fo 83.3 87.1 86.7 86.7 88.1 86.9 87.1 86.4 86.7 86.6 Fa 16.7 12.9 13.3 13.3 11.9 13.1 12.9 13.6 13.3 13.4 Crystal textural style is abbreviated: porph. (porphyroclast), cumu. (cumulus), def. (deformed), mgb. (modified grain boundaries) Note: Other phases (cpx, chr) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each section o c Appendix III: Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Dunite Wehrlite Wehrlite Sample: Cluster: 04ES-08-01-01 n/a 04ES-10-06-01 1 . 2 3 04ES-15-01-05 2 3 5 Style: Zone: inter, mid inter, core cumu. cumu. rim mid cumu. core cumu. rim cumu. mid cumu. core cumu. rim cumu. mid cumu. inter. inter, core rim mid inter, core inter, rim inter, mid inter, core inter, rim Oxides (wt. %) Si0 2 54.46 52.28 T i0 2 0.07 0.09 A l 2 0 3 0.92 0.90 C r 2 0 3 0.47 0.61 FeO* 2.38 2.79 MnO 0.06 0.03 MgO 16.92 16.59 CaO 24.49 25.03 Na 2 0 0.37 0.41 Total 100.15 98.73 Cations (p.f.u.) Si 1.964 1.956 Ti 0.005 0.004 A l " v ) 0.036 0.044 A l | v " 0.014 0.004 Cr 0.017 0.021 F e " 0.004 0.019 F e " 0.088 0.063 Mn 0.002 0.003 Mg 0.958 0.956 Ca 0.905 0.928 Na 0.009 0.010 Total 4.002 4.010 End Members (%) Wo 49.1 50.9 En 47.2 47.0 Fs 3.7 2.2 Mg# 0.936 0.927 54.02 53.50 54.01 52.14 0.17 0.16 0.19 0.14 1.17 1.11 1.10 1.06 0.58 0.73 0.68 0.65 3.03 2.70 2.73 4.93 0.07 0.10 0.13 0.09 17.66 17.53 17.60 17.39 23.24 23.69 23.25 22.49 0.25 0.29 0.28 0.26 100.20 99.81 99.98 99.14 1.962 1.967 1.968 1.959 0.004 0.005 0.004 0.004 0.038 0.033 0.032 0.041 0.008 0.014 0.018 0.016 0.021 0.019 0.019 0.024 0.009 0.000 0.000 0.004 0.073 0.083 0.088 0.084 0.002 0.004 0.003 0.003 0.940 0.956 0.953 0.951 0.938 0.907 0.905 0.905 0.009 0.010 0.009 0.011 4.004 3.999 3.998 4.002 46.4 47.7 46.6 45.5 49.1 49.1 49.1 49.0 4.5 3.2 4.3 5.5 0.920 0.898 0.919 0.901 53.96 53.60 53.69 53.09 0.15 0.15 0.15 0.16 1.17 1.32 1.10 1.03 0.65 0.82 0.51 0.43 2.88 2.89 3.61 4.60 0.11 0.09 0.14 0.10 17.52 17.46 17.42 16.78 23.16 23.12 22.80 22.16 0.26 0.31 0.23 0.24 99.87 99.75 99.66 98.60 1.966 1.972 1.968 1.963 0.004 0.004 0.004 0.005 0.034 0.028 0.032 0.037 0.014 0.017 0.015 0.006 0.015 0.013 0.016 0.016 0.005 0.000 0.001 0.012 0.106 0.143 0.097 0.111 0.004 0.003 0.003 0.004 0.951 0.929 0.953 0.969 0.895 0.882 0.901 0.874 0.008 0.009 0.009 0.008 4.002 3.999 4.000 4.006 46.5 46.7 45.8 45.1 49.0 49.0 48.7 47.5 4.5 4.3 5.4 7.3 0.870 0.907 0.896 0.910 53.69 52.48 53.64 53.61 0.16 0.27 0.30 0.34 1.10 1.54 1.33 1.45 0.57 0.85 0.88 0.85 3.19 2.28 2.48 2.43 0.10 0.07 0.11 0.04 17.44 17.90 17.22 17.06 22.94 23.11 23.72 23.80 0.26 0.23 0.26 0.28 99.46 98.73 99.94 99.87 1.978 1.963 1.978 1.974 0.003 0.003 0.004 0.004 0.022 0.037 0.022 0.026 0.011 0.000 0.010 0.010 0.019 0.017 0.014 0.011 0.000 0.021 0.000 0.004 0.099 0.088 0.087 0.087 0.004 0.004 0.004 0.004 0.954 1.002 0.955 0.940 0.899 0.869 0.916 0.935 0.007 0.007 0.007 0.007 3.996 4.011 3.998 4.002 46.2 47.1 47.8 48.2 48.8 50.8 48.3 48.0 5.0 2.1 3.9 3.8 0.906 0.918 0.915 0.914 53.16 54.32 53.53 52.76 0.39 0.25 0.30 0.26 1.45 1.05 1.35 1.22 0.87 0.70 0.94 0.76 2.41 2.67 2.85 2.59 0.08 0.09 0.05 0.04 17.00 17.63 17.33 17.45 24.04 23.46 23.40 23.59 0.28 0.25 0.29 0.26 99.68 100.42 100.05 98.92 1.975 1.972 1.984 1.972 0.003 0.003 0.002 0.004 0.025 0.028 0.016 0.028 0.013 0.013 0.005 0.019 0.014 0.017 0.008 0.018 0.000 0.000 0.003 0.000 0.098 0.098 0.094 0.103 0.004 0.002 0.003 0.004 0.940 0.947 0.947 0.949 0.920 0.912 0.935 0.891 0.006 0.008 0.004 0.007 3.999 4.000 4.002 3.995 48.7 46.9 47.1 47.9 47.9 49.0 48.6 49.3 3.5 4.2 4.3 2.8 0.905 0.907 0.909 0.903 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Total Fe Appendix 111 (continued): Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Wehrlite Wehrlite Wehrlite 04ES-15-01-05 04ES-16-08-01 04ES-11-03-03 Cluster: 5 1 3 5 1 3 6 Style: inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. inter. Zone: mid core rim mid core rim mid core rim mid core rim mid core mid . core rim mid core Oxides (wt. %) S i 0 2 53.60 53.39 54.36 54.21 53.91 52.85 53.94 53.35 53.43 53.17 53.72 54.14 54.61 54.35 54.16 54.60 54.20 54.41 54.03 T i0 2 0.33 0.31 0.13 0.10 0.19 0.16 0.19 0.18 0.16 0.24 0.27 0.14 0.16 0.13 0.14 0.12 0.14 0.17 0.19 A l 2 0 3 1.40 1.38 0.68 0.51 1.07 1.31 0.95 1.01 1.05 1.17 1.20 0.68 0.78 0.71 0.88 0.77 0.78 0.95 0.93 C r 2 0 3 1.10 0.88 0.50 0.54 0.71 0.75 0.79 0.73 0.64 0.75 0.68 0.46 0.42 0.37 0.60 0.50 0.42 0.57 0.53 FeO* 2.54 2.43 2.93 3.22 3.70 2.99 3.12 3.23 2.93 3.63 3.53 3.18 2.86 2.70 3.30 3.28 3.02 3.52 3.54 MnO 0.07 0.05 0.08 0.05 0.10 0.09 0.12 0.11 0.09 0.10 0.13 0.13 0.09 0.15 0.12 0.08 0.12 0.12 0.17 MgO 17.32 17.31 17.84 18.16 17.37 18.33 17.63 17.37 17.95 17.10 17.14 17.35 17.48 17.68 17.60 17.70 17.61 17.55 17.64 CaO 23.68 23.58 23.56 23.17 23.31 22.33 23.64 23.02 22.98 22.90 23.15 24.07 24.04 24.18 23.08 23.05 23.61 22.61 22.67 Na 2 0 0.30 0.33 0.24 0.22 0.22 0.24 0.26 0.25 0.23 0.25 0.23 0.20 0.20 0.20 0.30 0.29 0.27 0.29 0.29 Total 100.35 99.66 100.33 100.19 100.57 99.06 100.63 99.26 99.48 99.32 100.05 100.36 100.64 100.47 100.18 100.38 100.17 100.19 100.00 Cations (p.f.u.) Si 1.969 1.967 1.964 1.974 1.936 1.956 1.956 1.947 1.969 1.952 1.947 . 1.949 1.953 1.961 1.961 1.965 1.960 1.961 1.953 Ti 0.005 0.004 0.005 0.003 0.007 0.008 0.009 0.011 0.007 0.008 0.007 0.009 0.009 0.006 0.006 0.005 0.007 0.006 0.007 A l " v ' 0.031 0.033 0.036 0.026 0.064 0.044 0.044 0.053 0.031 0.048 0.053 0.051 0.047 0.039 0.039 0.035 0.040 0.039 0.047 A l , v " 0.011 0.024 0.011 0.012 0.004 0.013 0.018 0.010 0.014 0.010 0.000 0.009 0.013 0.010 0.010 0.005 0.009 0.004 0.006 Cr 0.019 0.020 0.020 0.018 0.025 0.025 0.025 0.025 0.020 0.027 0.022 0.032 0.025 0.015 0.014 0.012 0.015 0.010 0.017 F e " 0.000 0.000 0.002 0.000 0.029 0.000 0.000 0.007 0.000 0.004 0.025 0.003 0.003 0.010 0.015 0.016 0.012 0.021 0.019 Fe'* 0.107 0.103 0.106 0.102 0.042 0.076 0.074 0.067 0.081 0.083 0.055 0.074 0.071 0.113 0.108 0.102 0.120 0.095 0.107 Mn 0.004 0.003 0.002 0.003 0.002 0.003 0.001 0.002 0.003 0.002 0.001 0.002 0.002 0.005 0.004 0.005 0.004 0.003 0.004 Mg 0.955 0.956 0.953 0.951 0.984 0.937 0.928 0.928 0.952 0.943 0.960 0.939 0.944 0.928 0.939 0.937 0.946 0.934 0.936 Ca 0.891 0.874 0.895 0.903 0.914 0.927 0.930 0.944 0.911 0.914 0.933 0.923 0.924 0.909 0.901 0.917 0.885 0.927 0.903 Na 0.008 0.009 0.007 0.008 0.008 0.009 0.010 0.010 0.009 0.010 0.009 0.011 0.012 0.009 0.011 0.008 0.009 0.009 0.010 Total 4.000 3.995 4.001 3.999 4.014 3.999 3.996 4.003 3.996 4.002 4.013 4.001 4.002 4.005 4.007 4.008 4.006 4.011 4.009 End Members (%) Wo 47.7 47.7 46.7 45.8 46.5 45.3 47.1 46.5 46.2 46.4 46.5 47.8 47.5 47.9 46.1 45.9 47.0 45.4 45.4 En 48.5 48.7 49.2 49.9 48.2 51.7 48.9 48.8 50.2 48.2 47.9 48.0 48.1 48.7 48.9 49.0 48.8 49.1 49.2 Fs 3.8 3.6 4.1 4.3 5.3 3.0 4.0 4.6 3.6 5.4 5.5 4.2 4.4 3.4 5.0 5.1 4.2 5.5 5.4 Mg# 0.898 0.930 0.903 0.903 0.902 0.960 0.927 0.928 0.936 0.921 0.918 0.945 0.927 0.931 0.894 0.899 0.903 0.888 0.910 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Total Fe Appendix III (continued): Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Wehrlite ; Olivine Clinopyroxenite Sample: Cluster: 04ES-09-01-01 2 5 6 04ES-06-06-01 2 5 6 Style: Zone: inter, mid inter, core inter, rim inter, mid inter, core inter, rim inter, mid inter, core numu. cumu. cumu. rim mid core cumu. rim cumu. mid cumu. mid cumu. mid cumu. core cumu. rim cumu. mid cumu. mid Oxides (wt. %) Si0 2 53.50 53.99 54.78 54.27 54.42 T i0 2 0.24 0.24 0.08 0.12 0.06 A l 2 0 3 1.16 0.86 0.25 0.36 0.41 C r 2 0 3 0.62 0.46 0.13 0.16 0.20 FeO* 3.17 3.29 2.06 2.83 3.02 MnO 0.14 0.12 0.10 0.09 0.08 MgO 17.19 17.08 17.46 17.66 17.40 CaO 23.35 23.71 25.03 24.11 24.18 Na 2 0 0.26 0.22 0.05 0.12 0.13 Total 99.61 99.96 99.94 99.71 99.89 Cations (p.f.u.) Si 1.957 1.964 1.958 1.958 1.974 Ti 0.006 0.006 0.007 0.005 0.004 A l " V | 0.043 0.036 0.042 0.042 0.026 A r " 0.006 0.012 0.010 0.011 0.004 Cr 0.016 0.012 0.016 0.012 0.014 F e " 0.019 0.011 0.013 0.017 0.009 F e " 0.111 0.111 0.122 0.115 0.080 Mn 0.005 0.004 0.003 0.005 0.003 Mg 0.950 0.928 0.951 0.956 0.966 Ca 0.886 0.912 0.875 0.879 0.917 Na 0.011 0.010 0.010 0.008 0.008 Total 4.010 4.005 4.007 4.009 4.004 End Members (%) Wo 47.1 47.4 49.1 47.6 47.8 En 48.2 47.5 47.7 48.5 47.8 Fs 4.7 5.1 3.2 3.9 4.4 Mg# 0.895 0.894 0.886 0.893 0.922 54.33 54.31 54.37 53.76 54.38 53.83 54.19 0.10 0.17 0.12 0.19 0.11 0.12 0.16 0.32 0.49 0.34 1.00 0.78 0.85 0.74 0.16 0.26 0.15 0.56 0.66 0.60 0.48 2.22 2.57 2.33 4.03 3.27 3.56 2.86 0.08 0.12 0.11 0.14 0.12 0.12 0.13 17.59 17.64 17.49 17.80 17.59 18.43 17.54 24.67 24.30 24.69 22.34 23.06 22.25 23.43 0.11 0.14 0.12 0.23 0.20 0.21 0.20 99.58 100.00 99.72 100.05 100.16 99.97 99.74 1.973 1.961 1.944 1.959 1.962 1.958 1.958 0.003 0.005 0.004 0.005 0.005 0.005 0.007 0.027 0.039 0.056 0.041 0.038 0.042 0.042 0.000 0.006 0.001 0.000 0.006 0.003 0.009 0.015 0.020 0.022 0.023 0.021 0.019 0.022 0.014 0.010 0.033 0.017 0.009 0.020 0.007 0.084 0.103 0.059 0.077 0.090 0.070 0.105 0.001 0.003 0.003 0.004 0.004 0.003 0.003 0.985 0.942 1.005 0.954 0.953 0.980 0.939 0.904 0.908 0.880 0.920 0.907 0.902 0.904 0.008 0.008 0.009 0.009 0.009 0.008 0.009 4.015 4.005 4.016 4.009 4.004 4.010 4.004 48.7 48.0 48.8 44.7 46.0 44.4 46.8 48.3 48.5 48.1 49.6 48.9 51.1 48.7 3.0 3.5 3.2 5.7 5.1 4.5 4.5 0.919 0.903 0.942 0.926 0.931 0.905 0.899 54.21 53.96 54.64 54.14 54.16 53.96 54.04 0.14 0.11 0.08 0.14 0.20 0.15 0.18 0.84 0.88 0.50 1.08 0.98 1.33 1.09 0.40 0.50 0.28 0.61 0.65 0.70 0.70 3.02 3.19 3.21 3.39 3.51 3.39 3.56 0.12 0.12 0.11 0.14 0.15 0.10 0.07 17.32 17.24 17.49 17.47 17.62 17.60 17.59 23.97 23.47 24.03 22.83 22.87 22.38 22.98 0.19 0.18 0.12 0.19 0.23 0.26 0.20 100.21 99.66 100.47 99.99 100.34 99.87 100.41 1.962 1.982 1.976 1.976 1.978 1.966 1.970 0.007 0.002 0.003 0.003 0.003 0.003 0.002 0.038 0.018 0.024 0.024 0.022 0.034 0.030 0.013 0.021 0.011 0.010 0.008 0.002 0.002 0.020 0.013 0.018 0.020 0.017 0.026 0.028 0.000 0.000 0.000 0.000 0.000 0.010 0.006 0.108 0.072 0.095 0.106 0.100 0.091 0.091 0.004 0.002 0.003 0.004 0.002 0.005 0.004 0.933 0.918 0.968 0.966 0.981 0.971 0.974 0.906 0.955 0.891 0.881 0.880 0.888 0.887 0.008 0.013 0.008 0.008 0.007 0.009 0.009 3.999 3.997 3.998 3.998 3.999 4.005 4.003 47.6 47.0 47.3 45.9 45.6 45.2 45.8 47.9 48.0 47.9 48.8 48.9 49.5 48.8 4.5 5.0 4.8 5.3 5.5 5.4 5.4 0.956 0.929 0.909 0.900 0.905 0.913 0.910 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Total Fe Appendix III (continued): Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Sample: Olivine Clinopyroxenite Olivine Clinopyroxenite 05ES-05-01-01 04ES-01-04-01 Cluster: 6 1 2 6 2 5 6 Style: cumu. cumu. cumu. cumu. curm:. cumu. cumu. cumu. cumu. cumu. cumu. inter. inter. inter. inter. inter. inter. inter. inter. Zone: core rim mid mid core rim mid core rim mid core rim mid core rim mid core rim mid Oxides (wt. %) Si0 2 53.92 53.83 53.96 53.52 53.33 53.57 53.33 53.52 53.91 53.61 53.29 53.84 54.76 54.56 54.27 54.26 54.16 54.39 54.23 T i0 2 0.12 0.22 0.22 0.19 0.24 0.22 0.26 0.22 0.22 0.25 0.18 0.12 0.11 0.12 0.10 0.07 0.12 0.13 0.12 A l 2 0 3 0.87 1.13 1.15 0.91 1.13 1.01 1.22 1.14 1.12 1.20 1.23 0.81 0.80 0.71 0.85 0.75 0.78 0.74 0.83 C r 2 0 3 0.61 0.52 0.47 0.40 0.51 0.36 0.60 0.57 0.42 0.54 0.42 0.61 0.71 0.59 0.90 0.98 0.92 0.65 0.78 FeO* 3.32 4.06 4.04 3.85 4.28 3.78 4.11 4.25 3.98 4.43 4.31 3.09 3.51 3.29 3.33 3.19 3.17 3.16 3.26 MnO 0.10 0.16 0.15 0.17 0.12 0.11 0.13 0.15 0.12 0.09 0.15 0.11 0.13 0.06 0.18 0.13 0.09 0.12 0.13 MgO 17.42 17.08 17.33 17.12 17.27 17.13 17.14 17.42 17.09 17.48 17.45 17.70 17.95 18.15 17.98 18.00 18.13 17.95 17.92 CaO 23.01 23.29 23.15 23.31 22.47 23.65 23.00 22.61 23.38 22.35 22.32 22.66 22.77 22.67 22.88 22.80 22.42 23.09 22.60 Na 20 0.21 0.25 0.31 0.23 0.25 0.25 0.29 0.31 0.29 0.29 0.24 0.22 0.22 0.21 0.25 0.27 0.29 0.24 0.24 Total 99.59 100.53 100.79 99.70 99.61 100.08 100.07 100.20 100.52 100.24 99.59 99.15 100.95 100.37 100.73 100.44 100.08 100.46 100.09 Cations (p.f.u.) Si 1.971 1.973 1.973 1.967 1.971 1.977 1.972 1.972 1.981 1.973 1.978 1.971 1.961 1.972 1.993 1.983 1.986 1.985 1.979 Ti 0.003 0.004 0.003 0.005 0.004 0.004 0.004 0.004 0.003 0.004 0.005 0.005 0.007 0.007 0.002 0.003 0.002 0.003 0.005 Al" v ' 0.029 0.027 0.027 0.033 0.029 0.023 0.028 0.028 0.019 0.027 0.022 0.029 0.039 0.028 0.007 0.017 0.014 0.015 0.021 A r " 0.004 0.005 0.009 0.009 0.001 0.011 0.003 0.010 0.014 0.007 0.019 0.011 0.011 0.009 0.003 0.000 0.004 0.000 0.000 Cr 0.027 0.019 0.022 0.019 0.013 0.012 0.010 0.017 0.014 0.012 0.016 0.015 0.018 0.013 0.004 0.005 0.006 0.005 0.007 F e " 0.002 0.005 0.000 0.003 0.014 0.000 0.014 0.003 0.000 0.009 0.000 0.002 0.006 0.000 0.000 0.010 0.006 0.008 0.009 F e " 0.094 0.091 0.099 0.093 0.083 0.087 0.068 0.097 0.099 0.083 0:107 0.106 0.092 0.101 0.063 0.076 0.086 0.059 0.069 Mn 0.003 0.004 0.004 0.004 0.004 0.003 0.005 0.004 0.003 0.004 0.004 0.005 0.004 0.004 0.003 0.003 0.003 0.002 0.004 Mg 0.984 0.971 0.972 0.960 0.942 0.944 0.957 0.955 0.957 0.956 0.952 0.959 0.939 0.930 0.947 0.962 0.947 0.958 0.958 Ca 0.874 0.897 0.881 0.899 0.939 0.932 0.940 0.901 0.896 0.921 0.881 0.886 0.917 0.928 0.975 0.944 0.946 0.966 0.948 Na 0.010 0.008 0.008 0.008 0.007 0.007 0.007 0.011 0.010 0.009 0.010 0.010 0.009 0.008 0.002 0.004 0.005 0.004 0.005 Total 4.001 4.003 3.999 4.002 4.007 3.999 4.007 4.002 3.997 4.005 3.994 4.001 4.003 4.000 3.999 4.007 4.003 4.006 4.005 End Members (%) Wo 46.2 46.6 46.3 46.9 45.4 47.4 46.4 45.5 46.8 44.9 45.1 45.6 45.1 44.9 45.5 45.4 44.8 45:8 45.1 En 48.6 47.6 48.2 47.9 48.5 47.8 48.1 48.8 47.6 48.8 49.0 49.6 49.5 50.0 49.8 49.9 50.4 49.6 49.8 Fs 5.2 5.8 5.5 5.2 6.1 4.8 5.5 5.7 5.7 6.3 5.9 4.8 5.4 5.1 4.7 4.7 4.8 4.6 5.1 Mg# 0.913 0.903 0.910 0.919 0.916 0.933 0.906 0.905 0.918 0.899 0.900 0.969 0.913 0.907 0.939 0.927 0.919 0.942 0.934 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Total Fe Appendix III (continued): Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Hornblende Clinopyroxenite Hornblende Clinopyroxenite DDH04-47-7-49 04ES-09-02-02 Cluster: 6 2 5 8 1 3 5 Style: inter. cumu. cumu. cumu. cumu. cumu. cumu. cumu. cumu. currvj. cumu. cumu. cumu. cumu. cumu. cumu. cumu. cumu. Zone: core rim mid core rim mid core rim mid core rim core rim mid core rim mid core Oxides (wt. %) Si0 2 54.36 49.13 49.95 50.21 49.54 49.73 49.90 49.43 50.05 52.28 53.20 52.98 53.33 52.74 53.79 53.20 53.14 53.88 T i0 2 0.19 0.72 0.62 0.62 0.65 0.53 0.62 0.63 0.59 0.22 0.14 0.22 0.17 0.17 0.04 0.28 0.23 0.12 A l 2 0 3 0.98 5.27 4.18 4.19 4.79 4.52 4.48 4.92 4.12 2.12 0.59 1.10 0.68 0.90 0.30 1.22 1.09 0.36 C r 2 0 3 0.67 0.04 0.00 0.00 0.00 0.01 0.03 0.00 0.03 0.00 0.07 0.08 0.04 0.07 0.02 0.13 0.07 0.03 FeO* 3.18 7.85 6.77 6.88 7.73 7.41 7.06 7.26 6.94 6.01 . 6.30 ' 6.50 6.42 6.90 6.54 6.01 6.16 4.95 MnO 0.13 0.13 0.13 0.22 0.16 0.20 0.15 0.15 0.12 0.15 0.22 0.24 0.22 0.22 0.24 0.21 0.21 0.15 MgO 17.80 13.16 14.17 14.27 13.43 13.41 13.92 13.60 14.09 14.51 15.68 15.56 15.67 15.55 15.32 16.07 16.12 16.03 CaO 23.19 23.55 23.31 23.46 23.37 23.19 23.09 23.34 23.00 25.25 23.26 22.60 23.05 22.30 24.16 22.64 22.36 24.22 Na 2 0 0.24 0.26 0.25 0.25 0.24 0.28 0.28 0.27 0.25 0.06 0.10 0.13 0.13 0.13 0.06 0.18 0.12 0.05 Total 100.75 100.12 99.38 100.09 99.91 99.28 99.54 99.58 99.19 100.59 99.55 99.41 99.70 98.97 100.47 99.94 99.51 99.78 Cations (p.f.u.) Si 1.985 1.909 1.921 1.892 1.918 1.897 1.913 1.898 1.904 1.838 1.871 1.869 1.854 1.870 1.867 1.853 1.877 1.930 Ti 0.003 0.012 0.010 0.012 0.010 0.011 0.010 0.012 0.012 0.020 0.017 0.017 0.018 0.015 0.018 0.018 0.017 0.006 A1"VI 0.015 0.091 0.079 0.108 0.082 0.103 0.087 0.102 0.096 0.162 0.129 0.131 0.146 0.130 0.133 0.147 0.123 0.070 A l , v " 0.000 0.043 0.043 0.061 0.047 0.055 0.043 0.037 0.046 0.071 0.055 0.052 0.066 0.070 0.065 0.070 0.059 0.023 Cr 0.004 0.000 0.000 0.001 0.000 0.000 0.000 0.001 0.000 0.001 0.000 0.000 0.000 0.000 0.001 0.000 0.001 0.000 F e " 0.008 0.031 0.024 0.030 0.021 0.036 0.031 0.049 0.033 0.059 0.049 0.054 0.052 0.041 0.042 0.052 0.039 0.037 Fe'* 0.063 0.168 0.192 0.206 0.211 0.198 0.175 0.162 0.171 0.187 0.164 0.161 0.190 0.192 0.179 0.175 0.179 0.149 Mn 0.003 0.002 0.006 0.004 0.006 0.005 0.004 0.005 0.005 0.004 0.004 0.007 0.005 0.006 0.005 0.005 0.004 0.005 Mg 0.952 0.826 0.807 0.766 0.775 0.772 0.813 0.825 0.814 0.734 0.791 0.792 0.750 0.752 0.776 0.760 0.788 0.798 Ca 0.966 0.927 0.921 0.925 0.932 0.931 0.933 0.926 0.929 0.944 0.935 0.935 0.937 0.934 0.926 0.937 0.924 0.999 Na 0.004 0.007 0.009 0.009 0.007 0.010 0.007 0.008 0.007 0.009 0.009 0.009 0.009 0.010 ' 0.010 0.010 0.009 0.002 Total 4.004 4.015 4.012 4.015 4.011 4.018 4.015 4.025 4.017 4.030 4.024 4.027 4.026 4.020 4.021 4.026 4.019 4.018 End Members (%) Wo 46.0 50.6 49.5 49.6 49.9 49.7 49.2 50.1 48.9 51.3 46.9 45.9 46.5 45.4 48.1 45.8 45.2 48.2 En 49.2 39.4 41.9 41.9 39.9 40.0 41.3 40.6 41.7 41.0 44.0 44.0 43.9 44.1 42.4 45.2 45.3 44.4 Fs 4.8 10.0 8.7 8.5 10.1 10.2 9.5 9.4 9.5 7.6 9.1 10.1 9.6 10.5 9.4 9.0 9.4 7.4 Mg# 0.939 0.814 0.805 0.794 0.780 0.791 0.816 0.824 0.821 0.810 0.842 0.820 0.818 0.829 0.828 0.832 0.857 0.830 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Total Fe Appendix III (continued): Clinopyroxene compositions from clinopyroxene-bearing ultramafic lithologies of the Turnagain intrusion Rock Type: Hornblende Clinopyroxenite Sample: DDH05-84-19-104 Cluster: 2 5 10 Style: cumu. cumu. cumu. cumu. cumu. cumu. cumu. cumu. Zone: mid core rim mid core rim mid core Oxides (wt. %) Si0 2 51.23 51.40 50.74 51.37 50.77 51.77 51.26 51.25 T i0 2 0.43 0.35 0.44 0.35 0.40 0.36 0.42 0.42 A l 2 0 3 3.07 2.77 3.83 2.94 3.60 2.98 3.17 3.24 Cr 2 0 3 0.00 0.00 0.03 0.01 0.00 0.00 0.03 0.00 FeO* 6.38 6.92 7.56 7.45 7.48 6.64 6.84 6.59 MnO 0.06 0.20 0.13 0.18 0.16 0.14 0.15 0.14 MgO 14.87 14.47 13.78 13.93 13.87 14.76 14.94 14.70 CaO 23.22 22.99 23.15 23.31 23.26 23.55 23.35 23.34 Na 20 0.19 0.24 0.26 0.19 0.27 0.20 0.23 0.19 Total 99.45 99.34 99.92 99.73 99.79 100.39 100.39 99.86 Cations (p.f.u.) Si 1.976 1.969 1.977 1.972 1.985 1.962 1.968 1.986 Ti 0.004 0.006 0.005 0.005 0.001 0.008 0.007 0.003 AI" V | 0.024 0.031 0.023 0.028 0.015 0.038 0.032 0.014 A l , v " 0.002 0.017 0.007 0.011 0.000 0.016 0.016 0.002 Cr 0.002 0.002 0.001 0.002 0.001 0.004 0.002 0.001 F e " 0.016 0.004 0.010 0.010 0.015 0.009 0.005 0.006 F e " 0.180 0.198 0.189 0.206 0.187 0.176 0.185 0.147 Mn 0.007 0.008 0.007 0.007 0.008 0.007 0.007 0.005 Mg 0.868 0.862 0.866 0.867 0.843 0.884 0.890 0.881 Ca 0.926 0.900 0.916 0.893 0.955 0.895 0.887 0.957 Na 0.004 0.005 0.005 0.005 0.002 0.007 0.004 0.002 Total 4.008 4.002 4.005 4.005 4.011 4.005 4.003 4.003 End Members (%) Wo 48.3 48.0 48.8 48.6 49.0 48.6 48.4 48.5 En 43.0 42.0 40.4 40.4 40.6 42.3 43.1 42.5 Fs 8.7 10.0 10.8 11.0 10.4 9.1 8.5 9.0 Mg# 0.824 0.803 0.802 0.790 0.805 0.822 0.817 0.847 Crystal textural style is abbreviated: cumu. (cumulus), inter, (intercumulus) Note: Other phases (ol, chr, mt) were also analyzed on certain sections, such that "Cluster" refers to a specific location on each thin section * Total Fe Appendix IV: Garnet compositions from a serpentinite vein in dunite from the Turnagain intrusion Rock Type: Serpentinite Sample: 04ES-02-01-01 Cluster: 3 2 1 Description: porph. porph. porph. porph. porph. porph. porph. porph. Location rim mid core rim core rim mid core Oxides (wt. %) Si0 2 35.15 35.07 35.09 35.07 34.98 35.11 35.18 34.86 Ti0 2 0.05 0.23 0.44 0.07 0.44 0.03 0.32 0.58 A l 2 0 3 0.00 0.03 0.03 0.01 0.01 0.03 0.01 0.03 C r 2 0 3 4.43 7.66 8.31 3.50 8.21 0.92 8.02 9.17 Fe 2 0 3 26.32 22.37 21.52 26.34 21.84 29.35 22.04 20.72 MgO 0.16 0.20 0.24 0.12 0.27 0.08 0.17 0.24 MnO 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 CaO 33.33 33.49 33.51 33.75 33.48 33.53 33.68 33.61 Na 20 0.02 0.01 0.01 0.15 0.05 0.02 0.03 0.02 Total 99.47 99.06 99.15 99.03 99.29 99.09 99.46 99.22 Cations (p.f.u.) Si 2.985 2.984 2.980 2.992 2.970 2.996 2.981 2.961 Ti 0.003 0.015 0.028 0.004 0.028 0.002 0.020 0.037 Al 0.000 0.003 0.003 0.001 0.001 0.003 0.001 0.003 Cr 0.298 0.515 0.558 0.236 0.551 0.062 0.538 0.616 Fe 3 + 1.682 1.432 1.375 1.691 1.395 1.885 1.405 1.324 Mg 0.021 0.025 0.030 0.016 0.034 0.010 0.022 0.030 Mn 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 Ca 3.032 3.052 3.049 3.085 3.045 3.066 3.057 3.058 Na 0.003 0.002 0.002 0.025 0.008 0.004 0.005 0.003 Sum 8.024 8.028 8.025 8.052 8.032 8.029 8.029 8.032 End Members Andradite 0.850 0.735 0.711 0.877 0.717 0.968 0.723 0.683 Uvarovite 0.150 0.265 0.289 0.123 0.283 0.032 0.277 0.317 Crystal textural style is abbreviated: porph. (porphyroblastic) "Cluster" refers to a specific location on thin section Andradite: C a 3 F e 3 + 2 S i 3 0 1 2 Uvarovite: Ca 3 Cr 2 Si 3 0 1 2 APPENDIX V : List of X-ray lines and mineral standards for E P M A Electron-probe micro-analyses o f garnet were done on a fully automated C A M E C A S X - 5 0 instrument, operating in the wavelength-dispersion mode with the fo l lowing operating conditions: excitation voltage, 15 k V ; beam current, 20 n A ; peak count time, 20 s; background count-time, 10 s; spot diameter, 10 pm. Data reduction was done using the ' P A P ' (|>(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the fo l lowing standards, X- r ay lines and crystals were used: albite, NaKa, T A P ; almandine, MgKa, T A P ; almandine, AlKa, T A P ; diopside, SiKa, T A P ; ruble, TiKa, P E T ; grossular, CaKa, P E T ; magnesiochromite, CxKa, L I F ; synthetic rhodonite, MnKa, L I F ; almandine, FeKa, L I F . Bioti te: excitation voltage, 15 k V ; beam current, 10 n A ; peak count time, 20 s (40 s for F , CI); background count-time, 10 s (20 s for F , CI); spot diameter, 10 pm. Data reduction was done using the ' P A P ' <j)(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the fo l lowing standards, X - r a y lines and crystals were used: synthetic phlogopite, FKa, T A P ; albite, NaKa, T A P ; anorthite, A l A ^ a , T A P ; synthetic phlogopite, MgXa, T A P ; synthetic phlogopite, SiKa, T A P ; scapolite, C\Ka, P E T ; synthetic phlogopite, YLKa, P E T ; diopside, CaKa, P E T ; rutile, TiKa, P E T ; synthetic magnesiochromite, CxKa, L I F ; synthetic rhodonite, MnKa, L I F ; synthetic fayalite, FeKa, L I F ; barite, BaLa, P E T . Ol iv ine : excitation voltage, 15 k V ; beam current, 20 n A ; peak count time, 20 s; background count-time, 10 s; spot diameter, 5 pm. Data reduction was done using the ' P A P ' (|)(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the fo l lowing standards, X - r a y lines and crystals were used: albite, NaKa, T A P ; kaersutite, AlKa, T A P ; ol ivine, MgKa, T A P ; ol ivine, SiKa, T A P ; orthoclase, YJCa, P E T ; diopside, CaKa, P E T ; rutile, TiKa, P E T ; synthetic magnesiochromite, CxKa, L I F ; synthetic rhodonite, MnKa, L I F ; synthetic fayalite, FeKa, L I F ; synthetic N i 2 S i 0 4 , NiKa, L I F . APPENDIX V (continued): List of X-ray lines and mineral standards for EPMA Clinopyroxene: excitation voltage, 15 k V ; beam current, 20 n A ; peak count time, 20 s; background count-time, 10 s; spot diameter, 5 (am. Data reduction was done using the ' P A P ' (|)(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the fol lowing standards, X - r a y lines and crystals were used: albite, NaKa, T A P ; kaersutite, AlKa, T A P ; diopside, MgKa, T A P ; diopside, SiKa, T A P ; diopside, C&Ka, P E T ; ruble, T\Ka, P E T ; synthetic magnesiochromite, CxKa, L I F ; synthetic rhodonite, MnKa, L I F ; synthetic fayalite, FeKa, L I F ; synthetic N i 2 S i 0 4 , NiKa, L I F . Amphibo le : excitation voltage, 15 k V ; beam current, 20 n A ; peak count time, 20 s (40 s for F , C l ) ; background count-time, 10 s (20 s for F , C l ) ; spot diameter, 5 um. Data reduction was done using the ' P A P ' <))(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the fo l lowing standards, X - r a y lines and crystals were used: synthetic phlogopite, ¥Ka, T A P ; albite, NaKa, T A P ; kyanite, A l A ^ a , T A P ; diopside, MgKa, T A P ; diopside, SiKa, T A P ; scapolite, ClKa, P E T ; orthoclase, KJCa, P E T ; diopside, CaKa, P E T ; rutile, TiKa, P E T ; synthetic magnesiochromite, CrKa, L I F ; synthetic rhodonite, MnKa, L I F ; synthetic fayalite, FeKa, L I F ; synthetic N i 2 S i 0 4 , Nlrv«, L I F . Appendix VI: Original and duplicate whole-rock analyses Prefix 04ES 05ES 05ES 04ES Sample 06-01-01 Dunite 05-07-01 Dunite Ave 2o %RSD 05-06-01 Wehrlite 00-07-01 Wehrlite Ave 2a %RSD Oxide (wt. %) Si02 38.21 37.95 38.08 0.37 0.5 38.95 39.12 39.04 0.24 0.3 Ti02 0.005 0.005 0.01 0.00 0.0 0.086 0.09 0.09 0.01 3.2 AI203 0.04 0.05 0.05 0.01 15.7 0.37 0.37 0.37 0.00 0.0 Fe203(T) 8.04 10.47 9.26 3.44 18.6 11.43 12.8 12.12 1.94 8.0 MgO 48.74 47.25 48.00 2.11 2.2 43.02 43.17 43.10 0.21 0.2 MnO 0.142 0.145 0.14 0.00 1.5 0.196 0.199 0.20 0.00 1.1 CaO 0.09 0.1 0.10 0.01 7.4 2.91 2.97 2.94 0.08 1.4 Na20 <0.01 0.02 0.04 0.05 0.05 0.01 15.7 K20 <0.01 0.06 0.11 0.05 0.08 0.08 53.0 P205 <0.01 < 0.01 <0.01 < 0.01 LOI 3.55 3.89 3.72 0.48 6.5 1.84 < 0.0100 Total 98.78 99.94 99.36 1.64 0.8 98.96 99.85 99.41 1.26 0.6 Element (ppm) Au < 1 < 1 6 11 8.5 7.1 41.6 Ag <0.5 <0.5 <0.5 < 0.5 As < 1 < 1 < 1 < 1 Ba < 1 < 1 < 1 < 1 Be < 1 < 1 < 1 < 1 Bi <0.1 < 0.1 < 0.1 < 0.1 Br <0.5 < 0.5 < 0.5 < 0.5 Cd 2.6 2.4 2.5 0.3 5.7 2.4 2.4 2.4 0 0 Co 160 160 160 0 0 166 159 163 10 3.0 Cr 2790 2910 2850 170 3.0 3860 3620 3740 339 4.5 Cs <0.1 <0.1 <0.1 <0.1 Cu 17 19 18 2.8 7.9 71 73 72 2.8 2.0 Ga < 1 < 1 2 1 2 1.4 47.1 Ge 2.5 2 2.3 0.7 15.7 1 1.7 1.4 1.0 36.7 Hf <0.1 < 0.1 <0.1 < 0.1 Hg < 1 < 1 < 1 < 1 In <0.1 < 0.1 < 0.1 < 0.1 Ir < 1 < 1 < 1 < 1 Mo < 2 <2 < 2 <2 Nb < 0.2 <0.2 0.2 <0.2 Ni 2180 2190 2185 14 0.3 1060 1100 1080 57 2.6 Pb <5 < 5 < 5 < 5 Rb <2 < 2 <2 < 2 S (wt. %) 0.068 0.066 0 0.003 2.1 0.024 0.026 0.025 0.003 5.7 Sb <0.1 <0.1 0.2 0.2 0.2 0 0 Sc 3.22 3.25 3.24 0.04 0.7 15.2 14.7 15.0 0.7 2.4 Se <0.5 <0.5 <0.5 < 0.5 Sn < 1 1 < 1 2 Sr < 2 < 2 7 6 7 1 10.9 Ta <0.1 <0.1 <0.1 <0.1 Th <0.05 <0.05 < 0.05 <0.05 U <0.05 0.08 < 0.05 < 0.05 V < 5 <5 28 35 32 10 15.7 W 2 2 2 0 0 2 < 1 Y < 1 1 1 < 1 Zn 46 46 46 0 0 56 57 57 1.4 1.3 Zr < 1 1 < 1 < 1 La ,< 0.05 <0.05 <0.05 <0.05 Ce <0.1 <0.1 0.1 <0.1 Pr <0.02 <0.02 0.02 0.03 0.03 0.01 28.3 Nd <0.05 <0.05 0.2 0.23 0.22 0.04 9.9 Sm <0.01 <0.01 0.09 0.11 0.10 0.03 14.1 Eu < 0.005 < 0.005 0.038 0.039 0.039 0.001 1.8 Gd <0.02 < 0.02 0.13 0.13 0.13 0 0 Tb <0.01 <0.01 0.02 0.02 0.02 0 0 Dy <0.02 <0.02 0.16 0.16 0.16 0 0 Ho <0.01 <0.01 0.03 0.03 0.03 0 0 Er <0.01 <0.01 0.09 0.1 0.10 0.01 7.4 TI < 0.05 <0.05 < 0.05 < 0.05 Tm < 0.005 < 0.005 0.013 0.014 0.01 0.001 5.2 Yb <0.01 <0.01 0.08 0.09 0.09 0.01 8.3 Lu < 0.002 < 0.002 0.015 0.014 0.015 0.001 4.9 Appendix VI (continuted): Original and duplicate whole-rock analyses Prefix 04ES OSES Sample 00-07-04 Hblite 03-02-01 Hblite Ave 2a %RSD Oxide (wt. %) Si02 41.95 41.9 41.93 0.07 0.1 Ti02 2.154 2.171 2.16 0.02 0.6 AI203 12.24 12.17 12.21 0.10 0.4 Fe203(T) 14.23 14.37 14.30 0.20 0.7 MgO 11.93 11.97 11.95 0.06 0.2 MnO 0.263 0.265 0.264 0.003 0.5 CaO 11.52 11.71 11.62 0.27 1.2 Na20 0.77 0.79 0.78 0.03 1.8 K20 0.92 0.86 0.89 0.08 4.8 P205 0.31 0.3 0.31 0.01 2.3 LOI 2.83 2.77 2.80 0.08 1.5 Total 99.12 99.28 99.20 0.23 0.1 Element (ppm) Au < 1 4 Ag <0.5 < 0.5 As < 1 < 1 Ba 421 423 422 2.8 0.3 Be 1 2 1.5 1.4 47.1 Bi <0.1 < 0.1 Br <0.5 <0.5 Cd 1.5 1.5 1.5 0 0 Co 65.7 66.8 66.3 1.6 1.2 Cr 398 409 404 16 1.9 Cs 0.6 0.5 0.6 0.1 12.9 Cu 84 84 84 0 0 Ga 20 19 20 1.4 3.6 Ge < 0.5 <0.5 Hf 2.1 2.1 2.1 0 0 Hg < 1 < 1 In <0.1 <0.1 Ir < 1 11 Mo <2 <2 Nb 3.6 4.1 3.9 0.7 9.2 Ni 135 136 136 1 0.5 Pb 35 36 36 1.4 2.0 Rb 12 12 12 0 0 S (wt. %) 0.354 0.344 0.349 0.014 2.0 Sb 0.6 0.6 0.6 0 0 Sc 72.7 74.6 73.7 2.7 1.8 Se < 0.5 <0.5 Sn 6 3 5 4.2 47.1 Sr 283 284 284 1 0.2 Ta 0.2 0.2 0.2 0 0 Th 0.36 0.36 0.36 0 0 U 0.12 0.11 0.12 0.01 6.1 V 489 495 492 8 0.9 W < 1 <1 Y 39 44 41.5 7.1 8.5 Zn 99 99 99 0 0 Zr 49 49 49 0 0 La 6.61 6.6 6.61 0.01 0.1 Ce 20.3 20.7 20.5 0.6 1.4 Pr 3.34 3.36 3.35 0.03 0.4 Nd 18.1 18.4 18.3 0.4 1.2 Sm 5.97 5.93 5.95 0.06 0.5 Eu 1.83 1.86 1.85 0.04 1.1 Gd 7.11 7.25 7.18 0.20 1.4 Tb 1.31 1.35 1.33 0.06 2.1 Dy 7.9 7.91 7.91 0.01 0.1 Ho 1.61 1.63 1.62 0.03 0.9 Er 4.52 4.55 4.54 0.04 0.5 TI 0.1 0.12 0.11 0.03 12.9 Tm 0.646 0.651 0.649 0.007 0.5 Yb 3.84 3.79 3.82 0.07 0.9 Lu 0.521 0.539 0.530 0.025 2.4 04ES 04ES 00-07-01 00-07-01 lite Dunite Ave 2a %RSD 39.06 39.18 39.12 0.17 0.2 0.09 0.09 0.09 0.00 0.0 0.36 0.37 0.37 0.01 1.9 11.79 13.8 12.80 2.84 11.1 43.27 43.06 43.17 0.30 0.3 0.199 0.198 0.20 0.00 0.4 2.98 2.96 2.97 0.03 0.5 0.05 0.05 0.05 0.00 0.0 0.05 0.04 0.05 0.01 15.7 <0.01 0.02 2.09 <0.01 99.94 99.76 99.85 0.25 0.1 < 1 < 1 < 1 < 1 < 0.1 <0.1 <0.1 < 0.1 1 2 1.5 1.4 47.1 1.4 1.9 1.7 0.7 21.4 <0.1 <0.1 < 0.1 <0.1 <0.2 <0.2 < 2 < 2 1 3 2 3 70.7 6 6 6 0 0 <0.1 < 0.1 <0.05 <0.05 <0.05 <0.05 37 33 35 6 8.1 < 1 2 < 1 < 1 <0.05 <0.05 < 0.1 0.1 0.03 0.03 0.03 0 0 0.23 0.23 0.23 0 0 0.1 0.11 0.11 0.01 6.7 0.041 0.037 0.039 0.006 7.3 0.13 0.13 0.13 0 0 0.02 0.02 0.02 0 0 0.16 0.16 0.16 0 0 0.03 0.03 0.03 0 0 0.1 0.1 0.1 0 0 <0.05 <0.05 0.014 0.014 0.01 0 0 0.09 0.09 0.09 0 0 0.013 0.014 0.014 0.001 5.2 Appendix VII: Sample Locations Sample # Rock Type *Easting *Northing Applicable Table(s) 04ES-00-07-01 Meladiorite 506580 6483611 2.1 04ES-00-07-02 Vole. Wacke 505775 6484455 2.1, 2.4, 4.5 04ES-00-07-03 Wehrlite 509551 6480391 2.2 04ES-00-07-04 Hornblendite 505750 6484462 2.1, 2.2, 2.4, 4.3, 4.5, 4.6 04ES-01 -04-01 Ol Cpxite 509390 6481403 3.1, 4.1, 4.2 04ES-02-01-01 Serpentinite 507824 6483614 ' Appendix IV 04ES-03-01-02 Dunite 508158 6481584 4.5, 4.6 04ES-03-02-01 Dunite 508380 6481497 3.1, 4.1, 4.5, 4.6 04ES-03-04-01 Wehrlite 509052 6481073 4.5, 4.6 04ES-06-01-01 Dunite 507915 6481777 4.1, 4.5 04ES-06-06-01 Ol Cpxite 507735 6481705 3.1, 4.1, 4.2 04ES-07-02-01 Dunite 508610 6481485 4.5,4.6 04ES-07-02-04 Wehrlite 508559 6481379 4.5, 4.6 04ES-08-01-01 Dunite 508347 6481480 3.1, 4.1, 4.2 04ES-09-01-01 Wehrlite 506444 6484127 4.1, 4.2 04ES-09-02-02 Hbl cpxite 506176 6484247 2.4, 4.2, 4.3, 4.5, 4.6 04ES-10-02-04 Ol Cpxite 506968 6483944 4.5,4.6 04ES-10-05-01 Dunite 507506 6484333 3.1, 4.1 04ES-10-06-01 Wehrlite 507216 6484294 3.1, 4.1, 4.2 04ES-11-03-03 Wehrlite 506702 6484508 3.1, 4.1, 4.2 04ES-13-01-02 Felsic tuff 513123 6479467 4.7, 4.8 04ES-15-01-05 Wehrlite 511172 6481538 3.1, 4.1, 4.2 04ES-16-08-01 Wehrlite 511636 6481374 3.1, 4.1, 4.2 04ES-19-01-02 Dunite 507690 6481699 3.1, 4.1 05ES-01-01-01 Chromitite 506969 6483816 3.1, 4.1 05ES-01-03-01 Chromitite 507319 6484023 3.1, 4.1 05ES-01-04-01 Chromitite 507440 6484076 3.1, 4.1 05ES-02-01-01 Wehrlite 509393 6481401 4.7 05ES-02-02-02 Dunite 510055 6481749 4.7, 4.8 05ES-02-02-02A Dunite 510055 6481749 4.7, 4.8 05ES-02-04-01 Dunite 507674 6481706 4.7 05ES-03-01-01 Wehrlite 509551 6480391 4.4, 4.5, 4.6, 4.7 05ES-03-01-02 Ol Cpxite 509542 6480403 2.4, 4.5, 4.6 05ES-04-05-01 Dunite 508875 6480479 4.5, 4.6 05ES-04-06-01 Dunite 510359 6471772 4.5,4.6 05ES-05-01-01 Ol Cpxite 506839 6483982 2.4,3.1,4.1,4.2,4.5,4.6 05ES-05-01-02 Wehrlite 506866 6484017 4.5, 4.6 05ES-05-02-01 Wehrlite 506872 6484246 4.5, 4.6 05ES-05-03-01 Wehrlite 506777 6484487 4.5, 4.6 05ES-05-04-01 Ol Cpxite 506983 6484615 2.4, 4.5, 4.6 05ES-05-05-01 Wehrlite 506153 6484577 4.5, 4.6 05ES-05-06-01 Wehrlite 505878 6484575 4.5, 4.6 05ES-05-06-02 Hornblendite 505917 6484437 2.4,4.3,4.5,4.6 * All UTM coordinates are projected in NAD83, Zone 9 200 Appendix VII (continued): Sample Locations Sample # Rock Type *Easting *Northing Applicable Table(s) DDH03-03-59-426 Hornblendite 507602 6481902 4.7, 4.8 DDH03-05-8-89 Ol Cpxite 508655 6481467 4.7, 4.8 DDH03-05-45-325 Wehrlite 508655 6481467 4.7, 4.8 DDH03-06-25-181 Wehrlite 508564 6481207 4.7, 4.8 DDH03-07-25-183 Wehrlite 508583 6480856 4.7, 4.8 DDH03-07-54-389 Phyllite 508583 6480856 4.7,4.8 DDH03-08-13-100 Wehrlite 509447 6481504 4.7,4.8 DDH03-09-18-134 Ol Cpxite 509447 6481505 4.7 DDH03-12-4-32 Dunite 508730 6481199 4.7 DDH03-16-24-166 Dunite 508691 6481141 4.7, 4.8 DDH03-18-13-85 Dunite 508891 6481302 4.7 DDH04-23-11-76 Wehrlite 508745 6481184 4.7 DDH04-24-31-220 Dunite 508789 6481216 4.7 DDH04-28-6-45 Wehrlite 508729 6481198 4.7, 4.8 DDH04-29-9-64 Dunite 508826 6481132 4.7 DDH04-33-5-38 Wehrlite 508949 6481141 4.7 DDH04-35-5-40 Wehrlite 508790 6481281 4.7 DDH04-36-5-40 Wehrlite 508723 6481260 4.7 DDH04-36-16-108 Dunite 508723 6481260 4.7 DDH04-37-6-40 Dunite 508723 6481260 4.7, 4.8 DDH04-47-7-49 Hbl cpxite 506268 6482843 3.1, 4.2, 4.3 DDH04-47-17-126 Hbl cpxite 506268 6482843 4.7, 4.8 DDH04-57-12-89 Leucodiorite 506263 6482933 2.1, 2.4, 4.5 DDH05-84-19-104 Hbl cpxite 505996 6482358 3.1, 4.2, 4.3, 4.4 * All UTM coordinates are projected in NAD83, Zone 9

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