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Age and origin of the Turnagain Alaskan-type intrusion and associated Ni-sulphide mineralization, north-central.. Scheel, J. Erik 2007-03-16

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AGE AND ORIGIN OF THE TURNAGAIN ALASKAN-TYPE INTRUSION AND ASSOCIATED NI-SULPfflDE MINERALIZATION, NORTH-CENTRAL BRITISH COLUMBIA, CANADA by J. ERIK SCHEEL B.Sc.H. University of Alberta, 2004 A THESIS SUBMITTED FOR PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (GEOLOGICAL SCIENCES) THE UNIVERSITY OF BRITISH COLUMBIA May 2007 © J. Erik Scheel, 2007 ABSTRACT The Turnagain Alaskan-type intrusion in north-central British Columbia consists of ultramafic to dioritic rocks and contains significant magmatic sulphide mineralization. The age of the intrusion is constrained by U-Pb and Ar-Ar geochronology to be 190±1 Ma and the minimum depositional age of the youngest host rocks (volcanic wacke) is 301 Ma. Whole rock Nd isotopic compositions are characteristic of Paleozoic arc-derived mafic rocks in the northern Canadian Cordillera (£Nd(i90) = +4 to +6), but indicative of variable crustal contamination 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 Yukon-Tanana or Quesnellia, but not Ancestral North America. The Turnagain parent magmas were hydrous, arc-derived, in equilibrium with mantle peridotite, and ankaramitic. Cross-cutting and geochemical relationships define the crystallization and emplacement sequence of the Turnagain intrusion to be: dunite (~For,i) —> wehrlite (~Fog7) —> olivine clinopyroxenite (~Fo85, Mg#cpx = 0.92) —• hornblende clinopyroxenite (Mg#cpx = 0.81, Mg#hDi = 0.65) —> hornblendite (Mg#ht>i = 0.60) —> diorite. Mineral and whole-rock geochemistry indicate that all ultramafic lithologies are genetically related and relative depletion in the HFSE, specifically Nb and Ta, are consistent with an arc mantle source for the parent magmas. Variations in spinel chemistry in the Turnagain intrusion are mainly a function of post-crystallization re-equilibration and oxidation. Primary (unmodified) chromite compositions, observed in chromitite samples, are Cr-rich (Cr/(Cr+Al) = 0.86-0.90) and Fe3+-poor (Fe3+/(Fe3++Cr+Al)<0.1), indicating their crystallization from a magma with relatively low JO2 (AFMQ < 0), which is substantially lower than for other Alaskan-type intrusions. At these 2 2 relatively reduced conditions, S was dissolved as sulphide (S ") rather than sulphate (SO4 ")• Sulphur (834S = -9.7 to +1.4%o) and lead isotopic compositions of sulphide from the ultramafic rocks indicate that upper crustal sulphur and lead were added to the parent magmas by assimilation of graphitic, pyritic metasedimentary inclusions (834S = -17.9%o), which are found only in the sulphide-mineralized zones. Thus, addition of crustal carbon and sulphur reduced the Turnagain magmas and increased total S, which lead to early sulphide saturation. TABLE OF CONTENTS ABSTRACT ii TABLE OF CONTENTS iiLIST OF TABLES vLIST OF FIGURES viLIST 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 22.4.2 Ar-Ar phlogopite/amphibole 4 2.4.3 Neodymium isotopes 5 2.5 RESULTS 26 2.5.1 U-Pb geochronology 22.5.1.1 Mela-diorite2.5.1.2 Leuco-diorite 7 2.5.1.3 Volcanic wacke 30 2.5.1.4 Hornblendite2.5.2 Ar-Ar geochronology 2 2.5.2.1 Hornblendite2.5.2.2 Wehrlite2.5.3 Rare earth elements and Nd isotopes 36 2.6 DISCUSSION 32.6.1 Age and source of the Turnagain intrusion2.6.2 Age comparison with other Alaskan-type intrusions 43 2.6.3 Tectonic implications for northern British Columbia 7 2.7 CONCLUSION 49 2.8 ACKNOWLEDGEMENTS 50 2.9 REFERENCES 1 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 2 3.3.2 Wehrlite 5 3.3.3 Olivine clinopyroxenite 63.3.4 Hornblende clinopyroxenite and hornblendite 67 3.4 ANALYTICAL TECHNIQUES3.5 RESULTS 69 3.5.1 Chromitite 72 3.5.2 Dunite3.5.3 Wehrlite3.5.4 Olivine clinopyroxenite 75 3.4.1 Hornblende clinopyroxenite .. 73.6 DISCUSSION 77 3.6.1 Primary spinel compositions 73.6.2 Reequilibration trends 9 3.6.3 Compositional effects of serpentinization on spinel chemistry 80 3.6.4 Implications for the redox state of the Turnagain intrusion3.7 CONCLUSIONS 83 3.8 ACKNOWLEDGEMENTS 4 3.9 REFERENCES 5 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 geology4.2.2 Ultramafic rocks 4 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 rocks4.2.3.1 Diorite4.2.3.2 Hornfels 3 4.2.4 Sulphide 104.2.5 Inclusions 6 4.3 ANALYTICAL TECHNIQUES 107 4.3.1 Mineral chemistry4.3.2 Major and trace elements 110 4.3.3 Platinum group elements 8 4.3.4 Sulphur isotopes - sulphide 121 4.3.5 Lead isotopes - sulphide4.4 RESULTS 125 4.4.1 Olivine chemistry 124.4.2 Clinopyroxene chemistry 7 4.4.3 Amphibole and biotite chemistry 124.4.4 Major and trace element chemistry 9 4.4.4.1 High-Mg olivine-rich rocks4.4.4.2 Intermediate-Mg clinopyroxene-rich rocks 133 4.4.4.3 Hornblendites 134.4.4.4 Dioritic rocks 4 4.4.5 Platinum group elements4.4.6 Sulphur isotopic compositions 137 4.4.7 Lead isotopic compositions4.5 DISCUSSION 134.5.1 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 8 CHAPTER 5: SUMMARY AND CONCLUSIONS 153 5.1 SUMMARY AND CONCLUSIONS 154 5.2 REFERENCES 157 LIST OF TABLES Table 2.1: U-Pb TIMS analytical data from zircon and titanite grains separated from samples from the Turnagain intrusion 28 Table 2.2: 40Ar/39Ar 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 Ill 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 LIST OF FIGURES 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 8 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 2.8:40Ar/39Ar incremental-heating age spectra and 40Ar/39Ar 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 3 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. Ti02. 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 3 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 12Figure 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. 207Pb/204Pb) 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 LIST OF APPENDICES 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 18Appendix 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 EPMA 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 ACKNOWLEDGEMENTS There are many people who have contributed in some part to the development and completion of this thesis. I would never have written this thesis without the advice and support of my supervisors James Scoates and Graham Nixon, who have taught me so much since I first arrived at UBC. James was always willing to answer questions that I had about everything thesis-related or otherwise, regardless of his own workload. James also spent significant amounts of time editing various draft sections of this thesis, and for that I am extremely grateful. Graham introduced me to the Turnagain property and imparted his experiences of working on Alaskan-type intrusions on me with skill and precision. He must also be thanked for helping me set-up necessary field gear, maps, air photographs, and lodging when I visited him in Victoria. Rich Friedman, Janet Gabites, Bruno Kieffer, Thomas Ullrich, and Mati Raudsepp are thanked for their analytical work and advice during the research phase of this thesis. Also Rich Friedman, Dominique Weis, and Jim Mortensen of the PCIGR are thanked for consultations during data interpretation and the implications thereof. I also thank Andrew Greene, Caroline Emmanuelle-Morisset, and Robin Mackie for sharing their thoughts on ultramafic rocks with me. Hard Creek Nickel Corporation, its president Mark Jarvis, and its past and present employees Tony Hitchins, Chris Baldys, Bruce Northcote, and Leslie Young are all thanked for the ideas, support, and seasonal employment during the duration of this thesis as well as for funding the research project. Other past and present Hard Creek Nickel employees, including Jeff Kyba, Tyler Kuhn, Mark Greenhalgh, and Greg Ross, must also be thanked for making summer work a great experience. Jim and Sharon Reed at Pacific Western Helicopters must be thanked for transport during the numerous summers spent in the Turnagain camp. Thanks to John Schussler, the first driller on the Turnagain property and former owner of DJ Drilling, for lodging in Boulder City in 2004 and 2005. Finally, I like to thank my family for their help and support during the last 7 years of my academic career. I would like to thank Tom Chacko, Bob Luth, Larry Heaman, Sarah Gleeson, and Jeremy Richards at the University of Alberta for helping me find my calling in geology, and for making the undergraduate program there one of the best in the continent. Many thanks to all my friends at UBC and in Vancouver, because without them I would not have made it this far. x CHAPTER 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, which is located 70 km east of Dease Lake, British Columbia, Canada. The Turnagain intrusion is a 24 km2 pluton that is dominantly composed of ultramafic cumulate rocks and minor dioritic phases and that contains appreciable nickeliferrous sulphide mineralization (Figure 1.1). Globally, Alaskan-type intrusions are characteristically sulphide-poor and no other intrusion found to date contains significant concentrations of magmatic Ni-bearing sulphide. The main goal of this thesis is to assess the origin and petrogenesis of the Turnagain intrusion and to constrain the mechamism of sulphide mineralization by combined field mapping and drillcore logging, geochemistry (mineral chemistry, major and trace elements, Nd-S-Pb isotopes) and geochronology (U-Pb, Ar-Ar). The Turnagain intrusion is situated within greenschist facies metasedimentary rocks currently assigned to the Ancestral North American miogeocline (Gabrielse, 1998). The intrusion is entirely fault-bounded on all margins, and is situated 1.5 km northeast of the Kutcho Fault, which is a major tectonic structure separating the miogeocline to the east from felsic plutons and mafic volcanics of the Quesnel accreted terrane to the west. The term "Alaskan-type," synonymous with "Uralian-type", "Uralian-Alaskan-type", and "zoned ultramafic", was first used by Taylor & Noble (1960) and Noble & Taylor (1960) and originally referred to mafic-ultramafic intrusions found in the Alaskan Panhandle and in the Ural Mountains, Russia (e.g. Duke Island, Irvine, 1962; Nizhnii-Tagil, Krause et al, 2006). These two belts, along with other occurrences of Alaskan-type intrusions, are typically found in paleo-arc environments. The subduction zone or arc setting of these intrusions has been qualified in a large number of studies (e.g. Irvine, 1974; Tistl et al, 1994; Green et al., 2004; Batanova et al., 2005) by association with other arc rocks, mineralogy, and geochemistry. Despite the fact that many more of these bodies have been found throughout the world, the term "Alaskan-type" is still retained. "Zoned ultramafic" refers to the observation that many of 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 of Alaskan-type intrusions. It has long been known that Alaskan-type intrusions can be spatially associated with basaltic volcanic rocks (Findlay, 1969; Irvine, 1974), and a genetic link 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-derived ankaramites are composed of olivine- and clinopyroxene-porphyritic basalt containing groundmass amphibole and plagioclase. Ankaramite dikes, typically found cross-cutting certain Alaskan-type intrusions (e.g. Greenhills, 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 of common petrogenetic processes. The mineralogy and crystallization sequence of ankaramite and Alaskan-type intrusions is also nearly identical and the chemical signatures of both rock types indicates their common origin from the mantle (e.g. Green et al, 2004). The defining characteristic of Alaskan-type intrusions is their mineralogy. Their typical order of crystallization is olivine+chromite —> diopside —*• magnetite —> hornblende+calcic plagioclase. Chromite is an early (high temperature) crystallizing phase in Alaskan-type intrusions and typically 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 within many Alaskan-type intrusions. Orthopyroxene is typically absent, save a few isolated examples (e.g. Salt Chuck, Alaska, Loney & Himmelberg, 1992; Gabbro Akarem, Egypt, Helmy & El Mahalawi, 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 of early plagioclase crystallization is due to the relatively high water contents of the magmas as elevated water contents in silicate magmas are known to suppress the crystallization of plagioclase to low temperatures (e.g. Irvine, 1965; Gaetani et al., 1993). The presence of small amounts of primary phlogopite in the most ultramafic parts of intrusions is also a diagnostic feature, and may reflect the alkaline to subalkaline chemical characteristics of primitive Alaskan-type magmas (Findlay, 1969; Irvine, 1974; Nixon et al., 1997). Many intrusions have lode and associated placer Pt (± Pd) mineral deposits (e.g. Tulameen, B.C., Findlay, 1969; Alto Condoto, Columbia, Tistl, 1994; Nizhnii Tagil, Russia, Johan, 2002) and they are commonly explored for platinum-group metals (PGM). The majority of these PGM are found in chromitite as PtsFe (isoferroplatinum) (e.g. Nixon et al., 1990; Johan et ah, 2000), however there are also occurrences of Os-Ir alloys (e.g. Garuti et al., 2003) and possible alloys, such as Pt2CuFe (tulameenite, Nixon et al., 1990), of hydrothermal origin. Two Alaskan-type intrusions contain significant sulphide (Salt Chuck and Turnagain), each with a distinctive sulphide mineralogy and lithologic association. The Salt Chuck intrusion contains Pd-rich, bornite-bearing clinopyroxenite and gabbro (Loney & Himmelberg, 1992). In contrast, the Turnagain intrusion contains disseminated to semi-massive pyrrhotite and pentlandite with minor secondary phases, but also contains a late-stage, hydrothermal Pt-Pd zone associated with a Cu soil geochemical anomaly (Figure 1.1). Thirty-five of the 39 known Alaskan-type intrusions (e.g. Duke Island; Irvine, 1962) in southeastern Alaska occur in a 560 km long by 50 km wide belt (Taylor, 1967). The other four occurrences (e.g. Salt Chuck; Loney et ah, 1987) are to the west of this belt, are older, and have different petrological characteristics (e.g. more plagioclase, trace orthopyroxene). Similar large belts occur in the Ural Mountains (15 large bodies; Taylor, 1967; Krause, 2006), which is approximately 1000 km long and 60 km wide; the Kamchatka Peninsula, Far East Russia (Batanova et al., 2005; and references therein), which contains over 20 Alaskan-type intrusions; and British Columbia, which has 9 known occurrences (e.g. Tulameen; Findlay, 1969; Turnagain; Clark, 1980; Nixon et al., 1997). Alaskan-type intrusions in Columbia and Ecuador (Tistl, 1994; Tistl 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 of the Sea of Japan has been proposed to link Alaskan-type intrusions in Japan, northeastern China, and Far East Russia (Ishiwatari & Ichiyama, 2004). There are also a number of other Alaskan-type intrusions that occur as either single intrusions (e.g. Papua New Guinea; Johan et al, 2000; Greenhills; Mossman et al., 2000) or as small groups of intrusions (e.g. Fifield, Australia; Johan, 2002). 1.2 EXPLORATION HISTORY OF THE TURNAGAIN INTRUSION Sulphide mineralization in the Turnagain intrusion was discovered along the banks of the Turnagain River ca. 1956, and this semi-massive sulphide showing has henceforth been called the Discovery showing (Figure 1.1). Falconbridge Nickel Mines Ltd., interested in the nickel potential of the semi-massive sulphide, owned and explored the Turnagain property between 1966 and 1973 and drilled the major sulphide showings (Northwest, Horsetrail, Fishing Rock, Discovery, Hatzl; Figure 1) with small, portable "packsack" drills. Airborne magnetic surveys were also flown across the entire intrusion. A Ph.D. thesis on the geology and petrography of the intrusion was completed by Tom Clark in 1975 at Queens University (Clark, 1975), followed by several publications derived from the thesis (Clark, 1978; Clark, 1980). Interest in the platinum-group element (PGE) potential of Alaskan-type intrusions in British Columbia during the 1980s resulted in significant government survey mapping and associated geochemical studies (especially PGE) of these intrusions across the province (Nixon etal, 1989; 1990; 1997). Interest in the nickel potential of the intrusion was renewed when Bren-Mar Ltd. acquired the property in 1996 (Bren-Mar Ltd. became Canadian Metals Exploration Ltd. in 2002, and then became Hard Creek Nickel Corp. in 2004). Contour-defined and grid soil sampling was conducted over the entire intrusion to constrain existing nickel targets and to find covered targets (the intrusion is only -30% exposed). A zone of hydrothermal Pt-Pd-Cu mineralization was discovered as a result of extensive soil sampling in the summer of 2004. Sulphide mineralogical and chemical studies have been carried out by Dr. Harry Kucha at the University of Krakow, Poland (Hard Creek Nickel internal reports), and are ongoing. Recent air photographs, and airborne and ground geophysics (magnetic, electromagnetic), were acquired in late 2005. To date, Hard Creek Nickel Corp. has drilled ~50 km of BQ and NQ drillcore in -170 holes, and has outlined a Ni resource of 429 Mt (measured and indicated) containing 0.17% sulphide Ni (see http://www.hardcreeknickel.com). The author spent 8 weeks in the summer of 2004 at the Turnagain property as part of his field work, during which time detailed mapping and sampling of outcrops within and around the Turnagain intrusion were conducted. In the summer of 2005, the author conducted two weeks of drillcore sampling from the Turnagain intrusion for sulphides of various textures and tenors, and sulphide from the wallrocks where the contact had been penetrated by drilling. The author also sampled for chromitite and whole-rock geochemical samples. For the remainder of the summer, the author was involved in the summer exploration program of Hard Creek Nickel Corp., which involved logging core and in-fill mapping. The current map of the Turnagain intrusion, based on the map of Clark (1975), was created as a joint effort by the author and Bruce Northcote (formerly of Hard Creek Nickel Corp.). 1.3 OVERVIEW OF THESIS There are three complimentary studies on the Turnagain intrusion presented in this thesis. Prior 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 of this thesis were 1) to determine the age and tectonic significance of the intrusion and its host rocks, 2) to characterize the lithologies and magmatic evolution of the Turnagain intrusion using mineral and whole rock chemistry, and 3) to ultimately constrain the origin of 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 of the Turnagain intrusion. The age of the intrusion is determined by the dating of four ultramafic and mafic samples using both U-Pb and Ar-Ar geochronological techniques. A fifth sample, representing the stratigraphically-highest wallrocks to the Turnagain intrusion, was also dated using detrital zircon U-Pb geochronology. The Nd isotopic compositions of eight whole rock samples were determined to help constrain the source of the Turnagain intrusion and to ascertain the relative degree of crustal contamination. Additionally, available age data from other Alaskan-type intrusions in B.C. and southeastern Alaska were compiled in an effort to constrain the temporal evolution of their respective arc systems. The results from this study place important constraints on the source of the Turnagain intrusion, terrane assessment, and the temporal evolution of the host rocks to the intrusion. Mineral separation (zircon, titanite, phlogopite, hornblende) was performed by the author, Rich Friedman, Hai Lin, and Tom Ullrich at UBC. Gwen Williams, Bruno Keiffer, and Jane Barling were responsible for aquiring the Nd isotopic compositions (sample dissolution, column chemistry, and mass spectrometry), and U-Pb and Ar-Ar goechonologic analyses were carried out by Rich Friedman and Tom Ullrich, respectively. Chapter 3 documents the chemistry of chromite in the Turnagain intrusion with emphasis on the origin and significance of compositional variations. Spinel grains from sixteen samples were analyzed by electron microprobe (a total of 320 point analyses). From these analyses, a primary spinel composition for the Turnagain intrusion has been defined. The intrasample chemical trends present in the analyzed chromite grains are used to discriminate reequilibration with olivine, clinopyroxene, interstitial liquid, and the effects of oxidizing and serpentinizing fluids. Establishment of primary chromite compositions also provides constraints on the relative oxygen fugacity of the parental magmas, which is critical for understanding the origin of the nickeliferrous sulphide mineralization in the Turnagain intrusion. All analytical work was carried out by the author with supervision by Mati Raudsepp. Chapter 4 involves a detailed petrological study of 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 of sulphides. The forsterite contents of olivine confirm the primitive nature of the Turnagain parent magmas (up to F092.5 in olivine that has not reequilibrated with chromitite) and the Ni contents of olivine provide a clear signal of sulphide liquid saturation during formation of some of the dunites, wehrlites, and olivine clinopyroxenites. The major element geochemistry of 23 whole rock samples was used in tandem with olivine, clinopyroxene, and amphibole mineral chemistry to constrain the chemical relationships of whole rock samples relative to their mineralogy. These results have important implications for the crystallization sequence and emplacement history of the magmas that formed the Turnagain intrusion. Trace element chemistry from the whole rock suite further constrains the genetic relationship between all lithologies present in the Turnagain intrusion and allows for recognition of an arc affinity. Twenty-seven sulphur isotopic compositions and 14 lead isotopic compositions of sulphide separates from hand samples and drillcore samples are used evaluate the extent of crustal contamination involved in sulphide saturation in the Turnagain intrusion, which is important for understanding the formation of nickeliferrous magmatic sulphide deposits in Alaskan-type intrusions. All microprobe analyses were carried out by the auther under the supervision of Mati Raudsepp at UBC. The author also produced the sulphide separates for Pb and S isotopic anaysis, and Janet Gabites at UBC processed the sulphides for chemistry and perfomed the Pb-isotopic analyses. Finally, the appendices contain the full datasets for spinel, olivine, clinopyroxene, and garnet microprobe analyses, the X-ray lines and standards for all microprobe analyses, and the comparison between whole rock geochemical samples and respective blind duplicates. Additionally, the UTM coordinates for all samples relevant to this thesis are listed in the final appendix. 1.4 REFERENCES Batanova, V.G., Pertsev, A.N., Kamenetsky, V.S., Ariskin, A.A., Mochalov, A.G., & Sobolev, A.V. (2005). Crustal evolution of island-arc ultramafic magma: Galmoenan pyroxenite-dunite plutonic complex, Koryak Highland (Far East Russia). Journal of Petrology 46, 1345-1366 Clark, T. (1975). Geology of an ultramafic complex on the Turnagain River, northwestern British Columbia. Unpublished Ph.D. dissertation, Queens University, 453p Clark, T. (1978). Oxide minerals in the Turnagain ultramafic complex, northwestern British Columbia. Canadian Journal of Earth Sciences 15 (12), 1893-1903 Clark, T. (1980). Petrology of the Turnagain ultramafic complex, northwestern British Columbia. Canadian Journal of Earth Sciences 17, 744-757 Findlay, D.C. (1969). Origin of the Tulameen ultramafic-gabbro complex, southern British Columbia. Canadian Journal of Earth Sciences 6, 399-425 Gabrielse, H. (1998). Geology of Cry Lake and Dease Lake map areas, north-central British Columbia; Geological Survey of Canada, Bulletin 504, 147p Gaetani, G.A., Grove, T.L., Bryan, W.B. (1993). The influence of water on the petrogenesis of subduction-related igneous rocks. Nature 365, 332-334 Garuti, G., Pushkarew, E.V., Zaccarini, F., Cabella, R., and 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 refractory lherzolitic mantle. Journal of Petrology 45, 391-403 Helmy, H.M., El Mahallawi, M.M. (2003). Gabbro Akarem mafic-ultramafic complex, Eastern Desert, Egypt: A late Precambrian analogue of Alaskan-type complexes. Mineralogy and Petrology 11, 85-108 Irvine, T.N. (1962). Mineralogy and petrology of the ultramafic complex at Duke Island, S.E. Alaska. 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 of the Duke Island ultramafic complex, southeastern Alaska. 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., & Kelly, D.A. (2000). Platinum nuggets from the Kompiam area, Enga Province, Papua New 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: Cabri, L.J. (ed.) The Geology, Geochemistry, Mineralogy and Mineral Benefwiation of Platinum-Group Elements. Canadian Institute of Mining, Metallurgy and Petroleum, Special Volume 54, 669-719 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 Loney, R.A., Himmelberg, G.R., Shaw, N.B. (1987). Salt Chuck palladium-bearing ultramafic body, Prince of Wales Island. U.S. Geological Survey Circular Report C 0998, 126-127 Loney, R.A., Himmelberg, G.R. (1992). Petrogenesis of the Pd-rich intrusion at Salt Chuck, Prince of Wales Island: An Early Paleozoic Alaskan-type ultramafic body. Canadian Mineralogist 30, 1005-1022 Mossman, D.J., Coombs, D.S., Kawachi, Y., & Reay, A. (2000). High-Mg arc ankaramitic dikes, Greenhills Complex, Southland, New Zealand. Canadian Mineralogist 38, 191-216 Nixon, G.T., Ash, C.H., Connelly, J.N., Case, G. (1989). Geology and noble metal geochemistry of the Turnagain ultramafic complex, northern British Columbia. B.C. Ministry of Energy, Mines, and Petroleum Resources, Open File 1989-18 Nixon, G.T., Cabri, L.J., & Laflamme, J.H.G. (1990). Platinum-group-element mineralization in lode and placer deposits associated with the Tulameen Alaskan-type complex, British Columbia. Canadian Mineralogist 28, 503-535 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. B.C. Ministry of Employment and Investment, Bulletin 93, 141p Noble, J.A., & Taylor, H.P., Jr. (1960). Correlation of the ultramafic complexes of southeastern Alaska with those of other parts of North America and the World. 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 with Uralian-type and zoned ultramafic intrusions (e.g. Taylor & Noble, 1960), are predominantly composed of ultramafic cumulate rocks (e.g. dunite, wehrlite, hornblendite) with minor dioritic phases. The majority of Alaskan-type intrusions occur within paleo-arcs (e.g. Quesnel terrane, B.C., Nixon et al, 1997; Alexander terrane, Alaska, Himmelberg & Loney, 1995) that are island or continental in nature, and a few occur in cratonic environments (e.g. Kondyor Complex, Russia, Johan, 2002). A number of Alaskan-type intrusions have been studied with respect to their platinum-group-element potential in lode and associated placer deposits (e.g. Ural Mountains, Russia, Garuti et al, 2003). In general, few precise ages of crystallization are available for Alaskan-type intrusions, which is critical for understanding their tectonic setting and proposed relationships to contemporaneous intrusive rocks or volcanic sequences. The Turnagain intrusion, situated in north-central British Columbia, is distinct from other Alaskan-type intrusions in that it contains unusually high, and perhaps economic, concentrations of Ni-sulphide mineralization. The current resource estimate (measured and indicated) is 428 Mt grading 0.17% Ni (http://www.hardcreeknickel.com). The age and tectonic history of the Turnagain intrusion, as well as the origin of the magmas, are important for understanding the evolution of the northern Canadian Cordillera. Nixon (1998) proposed two contrasting interpretations for the tectonic setting of the Turnagain intrusion. The first interpretation is that the Turnagain intrusion was emplaced into miogeoclinal metasedimentary rocks of Ancestral North America in a subduction zone environment. The second interpretation is that the Turnagain intrusion lies within a series of northeast-verging imbricated thrusts. This study presents new U-Pb and Ar-Ar geochronologic data, coupled with whole-rock Nd isotopic compositions, to constrain the age and origin of the Turnagain intrusion and its host rocks. Determining the precise age of crystallization of ultramafic rocks in Alaskan-type intrusions is typically difficult as abundances of U-bearing (e.g. zircon, baddeleyite) accessory minerals are relatively low to absent, and primary K-bearing (e.g. biotite, feldspar) phases tend to be altered. The results from this study have implications for the significance of Alaskan-type intrusions and tectonic evolution of a portion of the northern Canadian Cordillera. 2.2 GEOLOGICAL SETTING OF THE TURNAGAIN INTRUSION The Turnagain Alaskan-type intrusion is located approximately 70 km east of the town of Dease Lake, in north-central British Columbia (Figure 2.1). The intrusion is fault-bounded and proximal to the Kutcho Fault, which is a major tectonic structure that is interpreted to separate intrusive and volcanic sequences of the accreted Quesnel terrane from passive margin sedimentary rocks and post-accretionary Cretaceous granitoids of Ancestral North America (Gabrielse, 1998). The Quesnel terrane is part of the Intermontane Belt, a composite of terraries that extend south into Washington State and north into Yukon Territory (Figure 2.1). Seven Alaskan-type intrusions have been identified in the Quesnel terrane, including the Polaris intrusion and the Tulameen intrusion, which is the largest Alaskan-type intrusion in the world and is associated with concentrations of placer platinum-group metals in both lode and placer occurrences (Findlay, 1963; Nixon et al., 1990) (Figure 2.1). The Tulameen is one of the three precisely dated (U-Pb zircon) Alaskan-type intrusions in B.C. (Rublee, 1994; Nixon et al., 1997). The Alaskan-type intrusions of Quesnellia are typically associated with dioritic plutons of Triassic-Jurassic age and mafic volcanics, specifically the Late Triassic Takla, Nicola, and Stuhini groups. These mafic volcanics have been considered to be genetically associated with Alaskan-type intrusions (e.g. Findlay, 1969; Irvine, 1974; Nixon et al., 1997), and the Turnagain intrusion is 20 km northwest of an exposure of Takla volcanics (Figure 2.2), although their genetic association with the intrusion remains to be evaluated. Numerous Alaskan-type intrusions of Cretaceous age occur within 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 of the Cretaceous intrusions are Paleozoic in age and include the Salt Chuck intrusion, which exhibits extensive Pd-enriched Cu-sulphide mineralization at a major lithological boundary (Loney et al., 1987; Loney & Himmelberg, 1992; Watkinson & Melling, 1992). Pelagic sedimentary rocks of the Road River and Earn Groups (-Ordivician-Mississippian) were mapped by Gabrielse (1998) to occur along the northern and eastern edges of the Turnagain intrusion (Figure 2.2). The Road River and Earn Groups have been interpreted to represent ocean basin sediments deposited on the margin of Ancestral North America (Gabrielse, 1998; Erdmer et al., 2005). The lithologically diverse Road River Formation in the McDame locality has a type thickness of 95 m (Gabrielse, 1998) and varies from a lower member of black, graptolitic, locally calcareous shale, a middle member of 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 Quesnellia 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 of calcareous siltstone and shale. The entire package ranges in biostratigraphic age from Early Ordivician to Middle Silurian (Gabrielse, 1998). The Earn Group also exhibits extreme lithological diversity depending on where it is observed. In general, the Earn Group is a darkly coloured slate to siltstone that is locally pyritic 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 Mississippian in age. However, the age of the phyllite to the north and east of the Turnagain intrusion has not been determined and is currently assigned to the undivided Road River and Earn Groups based on lithological similarities with these two sedimentary packages (Gabrielse, 1998). Constrastingly, the Sandpile, Ramhorn, and McDame formations, which are observed between the Road River Formation and the Earn Group elsewhere in B.C., are not observed in the vicinity of the Turnagain intrusion. Due to these discrepancies, the greenschist-facies pelagic sediments proximal to the Turnagain intrusion are referred to as "graphitic phyllite" in this manuscript. Graphitic pre-Devonian sediments are also associated with the Yukon-Tanana terrane (Mortensen, 1992; Simard et al., 2003; Nelson & Friedman, 2004) and have been observed stratigraphically below the Lay Range Assemblage (Ferri & Melville, 1990), which is a volcano-sedimentary, arc-derived, package of rocks observed in Quesnellia. The graphitic phyllite to the north and east of the Turnagain intrusion, possibly part of the Road River Formation and Earn Groups, is composed of unfossiliferous, graphitic, and pyritic slates and phyllites containing interbeds of tuff, calcareous phyllite, and rare quartzite (Gabrielse, 1998; Erdmer et al., 2005; Scheel et ah, 2005). The graphitic phyllite is typically recessive-weathering and crops out along the Turnagain River to the north and southeast of the intrusion, as well as in alpine areas to the east of the Turnagain River (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 of 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 of the metasedimentary unit to the south of the Turnagain intrusion have been interpreted by Massey et al. (2005) as the Nizi 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 of 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 km 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 phyllite with minor wacke" and is observed to conformably overlie "Road River" strata. However, Gabrielse (1998) proposed that this metasedimentary unit was separated from "Road River" strata by a fault. A westward extension of this fault was postulated to merge into the north-bounding and east-bounding faults bounding the Turnagain intrusion, creating a small nappe. Because of the inferred ages of the volcanic wacke and the Turnagain intrusion (both considered to be Late Triassic), Gabrielse (1998) associated this apparently "fault-bounded" package of rocks with the Quesnel terrane. However, recent geochronological studies of Erdmer et al. (2005) indicate that the metasedimentary package, coupled with its conformable nature to the underlying graphitic phyllites, is Mississippian in age. The graphitic phyllite is also observed to be intruded by an Early Jurassic "granodiorite" pluton (Erdmer et al., 2005), a relationship that is not observed in "bona fide" Ancestral North American lithologies (J.K. Mortensen, pers. comm., 2006). Additionally, relatively small (0.5-20 m) inclusions of metamorphosed graphitic phyllite (containing graphite, quartz, and pyrrhotite bands) and volcanic wacke are observed in drillcore from the sulphide-mineralized zones within the Turnagain intrusion. 2.3 GEOLOGY OF THE TURNAGAIN INTRUSION The 3.5 km x 8 km Turnagain Alaskan-type intrusion was the subject of a Ph.D. dissertation by Tom 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 of the intrusion, whereas the hornblende-rich central portion of the intrusion is considered to represent part of the roof zone. Dunite in the Turnagain intrusion contains Mg-rich cumulus olivine (F089-F093) (Chapter 4), disseminated cumulus chromite, minor intercumulus clinopyroxene and rare interstitial phlogopite. Local accumulations of 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. Wehrlite in the Turnagain intrusion occurs as either olivine cumulates or olivine-clinopyroxene cumulates (olivine: Fogs to F090). Disseminated sulphide reaches ~0.5 vol.% in most lithologies of the Turnagain intrusion. In the sulphide-mineralized Horsetrail Zone (Figure 2.3), both dunite and wehrlite can contain significant abundances of sulphide (typically 5 vol.%, but up to 50 vol.% locally). Olivine clinopyroxenite is a relatively uncommon lithology and is typically an olivine-clinopyroxene cumulate with olivine compositions ranging from F083 to F089. Hornblende clinopyroxenite with local cumulus magnetite is rarely exposed and is typically observed in drillcore from the east-central part of the intrusion. Hornblende clinopyroxenite is typically composed of cumulus clinopyroxene and intercumulus amphibole; as such it commonly grades into clinopyroxene hornblendite and vice versa. Hornblendite is a recessive lithology and is also rarely exposed. A fine-grained (<1 mm) hornblendite dike, 30 to 50 cm in width, in the northwestern part of the intrusion (Figure 2.3) contains abundant igneous amphibole (magnesiohastingsite) and accessory titanite. The crystallization sequence of the Turnagain intrusion, from dunite —» wehrlite —• olivine clinopyroxenite —* hornblende clinopyroxenite —* hornblendite —• diorite, is constrained by cross-cutting and gradational contact relationships, as well 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 drillcore, and inferred from aeromagnetic data) against graphitic phyllite and on its western and southern margins by volcanic wacke. The entire intrusion is interpreted to represent a small klippe, however based on the results of this study and others (Chapters 3 and 4), this klippe 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 of the Turnagain intrusion (<1 mm). The metasedimentary inclusion in the northwest is composed of hornfelsed volcanic wacke that contains abundant detrital zircon. The volcanic wacke appears to represent an inclusion of wallrock within the Turnagain intrusion in contrast to the lower-grade, finer-grained, metasediments observed to the south of the intrusion. This inclusion does not appear to be fault-bounded, but is in igneous contact with the ultramafic lithologies. Small pods (1-5 cm wide) of 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. Melanocratic to leucocratic dioritic rocks in the Turnagain intrusion have gradational contacts with, or cross-cut, ultramafic rocks and represent the youngest intrusive phases. Dioritic rocks are the only zircon-bearing lithology present in the Turnagain intrusion. The largest diorite occurrence is located in the central part of the intrusion (Figure 2.3). The margins of this pluton are melanocratic (85 vol.% amphibole, 14 vol.% plagioclase) and fine-to medium-grained (1-5 mm grain sizes), whereas the central part of 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 SAMPLE DESCRIPTIONS AND ANALYTICAL TECHNIQUES 2.4.1 U-Pb Zircon/Titanite Four samples were selected for U-Pb geochronology (see sample locations on Figure 2.3). Zircon (ZrSi04) was separated from three samples (04ES-00-07-01, DDH04-57-12, 04ES-00-07-02) and titanite (CaTiSi05) 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. All 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, University of British Columbia. Zircon and titanite were separated from the rocks using conventional crushing, grinding, and Wilfley table techniques. Final concentration incorporated the use of heavy liquids and a magnetic separator. Zircon and titanite fractions were selected for analysis based on magnetic susceptibility, grain quality, size, and morphology. Using the technique of Krogh (1982), all zircon fractions were air-abraded prior to dissolution to minimize the effects of post-crystallization Pb-loss. Titanite grains were dissolved on a hotplate in 7 mL screwtop PFA beakers for at least 48 hours at ~130°C. Zircon grains were dissolved in sub-boiled 48% HF and 14 M HNO3 (ratio of-10:1, respectively) in the presence of a mixed 233-235tj-205Pb tracer for 40 hours at 240°C in 300 uL PTFE or PFA microcapsules contained in high-pressure vessels (Parr™ acid digestion vessels with 125 mL PTFE liners). Sample solutions were then dried to salts at ~130°C. Zircon residues were redissolved in -100 uL of sub-boiled 3.1 M HCI for 12 hours at 210°C in high-pressure vessels and titanite residues were redissolved on a hotplate in -1 mL of sub-boiled 6.2 M HCI in the same 7 mL screwtop PFA beakers for at least 24 hours at ~130°C. Titanite solutions were again dried to salts and were again redissolved on a hotplate, in the same beakers, in 1 mL of sub-boiled 3.1 M HCI at ~130°C for at least 24 hours. For zircon fractions of about 10 ug or less, 3.1 M HCI was transferred to 7 mL PFA beakers, dried to a small droplet after addition of 2 uL of 1 M phosphoric acid (H3PO4), and loaded directly onto Re filaments for analysis, as described below (referred to as the "no chemistry" method). For larger fractions of both minerals, separation and purification of 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 mL screwtop PFA beakers on a hotplate at ~120°C in the presence of 2 uL of ultrapure 1 M H3PO4. Samples were then loaded on single, degassed zone-refined Re filaments in 5 uL of a silica gel (SiCl4) phosphoric acid emitter. Isotopic ratios were measured using a modified single collector VG-54R thermal ionization mass spectrometer equipped with an analogue Daly photomultiplier. Measurements were done in peak-switching mode on the Daly detector. Analytical blanks were <1 pg for U and for 1-3 pg Pb for the "no chemistry" fractions. For dissolved zircon and titanite that passed through ion exchange columns, a blank of 2-10 pg Pb was used. Pb isotopic ratios were corrected for fractionation of 0.32-0.37 %/amu, based on replicate analyses of the NBS-982 Pb standard reference material and the values recommended by Thirlwall (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 3xl016 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. All 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: (40Ar/39Ar)K=0.0005±0.00006, (37Ar/39Ar)Ca=l048±0.9, (36Ar/39Ar)Ca=0.3542±0.0008, Ca/K= 1.83±0.01 (37ArCa/39ArK). The plateau and correlation ages were calculated using Isoplot 3.09 (Ludwig, 2003). Errors are quoted at the 2a (95% confidence) level and are propagated from all sources except mass spectrometer sensitivity and age of the flux monitor. The best statistically-justified plateau and plateau ages for both samples were picked based on the following criteria: (1) three or more contiguous steps comprising more than 50% of the 39Ar; (2) a probability of fit of the weighted mean age greater than 5%; (3) a slope of the error-weighted line through the plateau ages equals zero at 5% confidence; (4) the ages of 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 of a plateau must not have non-zero slopes with the same sign (at 1.8a nine or more steps only). 2.4.3 Neodymium Isotopes A total of eight samples were selected for neodymium isotopic composition measurements and were chosen to reflect the lithological range of the Turnagain intrusion. Dunites were excluded from analysis due to their extremely low Nd concentrations (<0.1-0.4 ppm). Samarium and neodymium concentrations, as well as major elements and other incompatible trace elements, were determined by ICP-MS at Activation Laboratories Ltd. (Actlabs) in Ancaster, Ontario (see complete analytical techniques description in Chapter 4). The accuracy of the suite of elements analyzed was determined by the use of USGS reference materials ranging in composition from basalt to granite and by various in-house standard materials. Relative standard deviations from three duplicated analyses are typically less than 5% for most elements. Low concentrations of Sm and Nd in one duplicate (sample 05ES-05-06-01, a hornblende clinopyroxenite) resulted in higher standard deviations; however when concentrations of Sm and Nd are an order of magnitude higher than their respective detection limits (04ES-00-07-04) the standard deviation drops to below 5% relative. The Nd isotopic compositions of samples from the Turnagain intrusion were measured at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. The volcanic wacke and leuco-diorite samples (04ES-00-07-02 and DDH04-57-12, respectively) were digested in Teflon bombs enclosed in metallic bombs (modified Krogh design) and placed for 120 hrs in HF-HNO3-HCIO4 (7:1:1) and 24 hrs in HCI in an oven at 190°C. All other samples were dissolved in Savillex™ and subject to the above digestion procedure. The Nd isotopic ratios were measured using a Thermo Finnigan Triton-TI thermal ionization mass spectrometer (TIMS) in static mode with relay matrix rotation. The measured composition of each sample is the average of 125-130 separate analyses. The La Jolla Nd standard was measured once giving a value of 143Nd/144Nd = 0.511858 ± 0.000008 (2a) and the Rennes Nd standard was measured 48 times within one week giving a mean value of 143Nd/144Nd = 0.511960 ± 0.000008 (2a). The Nd isotopic compositions of procedural duplicates of three samples (04ES-09-02-02, 05ES-05-06-02, 04ES-00-07-02) are within the 2a error (less than 0.001% relative). All measurements were corrected using 146Nd/144Nd = 0.7219 for internal mass fractionation. The USGS GSP-2 reference material was also analyzed for its Nd isotopic composition, and the results are within the 2a analytical error of 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 Ar-Ar and U-Pb geochronological techniques. The two Ar-Ar samples are from opposite corners of the intrusion (~8 km apart) (Figure 2.3). Additional U-Pb (zircon) dates were determined from a mela-diorite, a leuco-diorite, and the hosted volcanic wacke inclusion. Neodymium 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-diorite The mela-diorite was sampled from the north-central margin of the large dioritic body that intruded, and/or is gradational with, the central part of the Turnagain intrusion (Figure 2.3). The margin of the diorite is hornblende-rich, locally resembling hornblendite elsewhere in the Turnagain intrusion. However, this hornblende-rich outer phase grades inwardly to a more felsic diorite over a distance of -100 m on surface. The presence of euhedral (cumulus) plagioclase (~1 cm in diameter) helps discriminate this lithology from feldspathic hornblendite elsewhere in the Turnagain intrusion. The least magnetic fraction of sample 04ES-00-07-01 yielded abundant (>500) zircon grains typically 150-250 um in length. The zircon 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 yellow. A distinct population of grains exhibit inherited cores (not analyzed), some of which are metamict. Each analyzed fraction contained 2-18 grains with the exception of Fraction F (Figure 2.4A), which is represented by a single grain of zircon. Uranium concentrations range from 123-283 ppm and Th/U ratios from 0.32 to 0.79 (Table 2.1). The U-Pb data from the analyzed fractions yield similar 206pb/238TJ ages> ranging from 186.3±0.4 Ma to 189.2±0.6 Ma, the latter of which (Fraction B, seven 75-100 pm equant grains) has the highest 206Pb/238U and 207Pb/235U and is interpreted to be the minimum age of crystallization of the mela-diorite. Each of the error ellipses (2a) for each of the five fractions overlap concordia (Figure 2.5 A), however their distribution suggests that zircon from all fractions may have undergone Pb-loss. A free-fit discordia line through all fractions (MSWD =0.17) yields an upper intercept with concordia of 190.5±6.6 Ma (and a poorly constrained lower intercept of 705±2500 Ma) (Figure 2.5A). Alternatively, a fixed regression (lower intercept at 0 Ma) yields an older upper intercept of 199.2±6.6 Ma. Neither the upper intercept age of 190.5 +6.6/-1.9 Ma from the free-fit regression (lower error combined with the error of the oldest fraction), nor the fixed regression age of 199.2±6.6 Ma are considered to represent the true crystallization age of the mela-diorite, because the calculated upper intercept ages have relatively large 2a errors due to the relatively small dispersion of points along the fitted discordia lines. The better constrained minimum age of 189.2±0.6 Ma of fraction B is interpreted to be the minimum age of the Turnagain intrusion. These results are consistent with the Ar-Ar geochronological results (see below). 2.5.1.2 DDH04-57-12 - Leuco-diorite This sample, taken from a drillhole in the south-central portion of the intrusion (Figure 2.3), is a coarse-grained leucocratic hornblende diorite composed of euhedral, cumulus plagioclase and amphibole. Multiple 10-50 cm-wide lithological variations were observed in drillcore along the 9 m-thick interval (e.g. amphibole-rich phases, quartz-rich phases). Fewer than 200 zircon 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 zircon grains, and all grains are generally colourless (Figure 2.4). Of 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. Uranium concentrations range from 183-582 ppm and Th/U ratios range from 0.17 to 0.39 (Table 2.1). The U-Pb data from the four analyzed fractions are concordant and yield 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 U2 Pb*3 206Pb4 Pb5 Th/U6 Isotopic ratios (1CT,%) 7 Apparent ages (2o,Ma)7 discordance (mg) (ppm) (ppm) 204Pb (pg) 206Pb/238U 207Pb/235U 207Pb/206Pb 2«Pb/238U 207Pb/235U 207Pb/206Pb 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 233u-235U 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 208Pb and the 207Pb/206Pb 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 207pb/235u 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 Ma. The age of the oldest fraction (fraction H, 185.6±1.2 Ma), is interpreted as the minimum age of crystallization of the leuco-diorite (Figure 2.5B). 2.5.1.3 04ES-00-07-02 - Volcanic Wacke To constrain the age of the host rocks, the volcanic wacke was sampled from the hornfelsed sedimentary unit in the northwestern portion of the intrusion (Figure 2.3), within 50 m of the hornblendite dike (04ES-00-07-04). Zircon in the least magnetic fraction is relatively abundant (>300 grains) and ranges in colour from colourless to pale yellow to dark red-brown. Three distinct zircon 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 of 4:1) (Figure 2.4E) commonly containing fluid inclusions and inherited cores, and (3) sub-equant grains (aspect ratio 2:1) ranging from <50 um to -200 um in diameter, the largest of which are commonly dark in colour. A total of eight fractions were analyzed comprising 2-12 zircon grains per fraction. Uranium concentrations range from 97-260 ppm, with a range of Th/U ratios between 0.31 and 0.51 (Table 2.1). The U-Pb data from these analyzed fractions yield an extremely large range of Pb/ U dates (244 Ma to 1652 Ma, Figure 2.6A). The results from two fractions (F and G) plot on or near concordia at -300 Ma. Fraction F is concordant with a 206pb/238u age of 3oi.4±i.2 Ma (Figure 2.6B), which is interpreted to be the maximum depositional age of the volcanic wacke. Fraction D has a significantly younger Pb/ U age (244 Ma) and is discordant, which is attributed to Pb-loss from -300 Ma. Fraction A (not shown on Figure 2.6) is highly discordant with a 206Pb/238U age of 1652 Ma and a 207Pb/206Pb age of-2090 Ma. The old 207Pb/206Pb ages of fractions A, B, C, and E indicate the presence of Early Proterozoic zircon grains in the source of the volcanic wacke. A regression line through the discordant and concordant grains (not including fraction D) has an upper intercept with concordia of -2100 Ma, which is considered to be the average age of 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 of the Turnagain intrusion discussed above (Figure 2.3). The heavy mineral separate yielded abundant (>100 grains) colourless to pale yellow to pale brown titanite grains (Figure 2.4F). Most grains are anhedral and equant, with an aspect ratio of-1:1. 00 CO CM 0.085 r 0.075 0.065 £ 0.055 to CM 0.045 0.035 0.025 i 11• T Tr 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 207PB/235U 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 of the analyzed fractions contained 20 titanite grains each. U contents range from 7 to 9.4 ppm, with Th/U ratios of ~3.9 (Table 2.1). The U-Pb data of the two titanite fractions are concordant and the zuoPb/"°U ages are 189.5 Ma and 191.1 Ma, respectively. The weighted mean of these two concordant and statistically identical results is 190.3 ± 4.6 Ma (Figure 2.7), which is interpreted to represent the minimum crystallization age of 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-Pb (titanite) method as documented above, yielded abundant, dark brown to black, low-K (Ca/K =10-32), amphibole crystals. The amount of40Ar is extremely high in the grain edge (up to 94%), however the range in 40Ar in the core of the grain is small (1.6-4.2%) (Table 2.2). The first eight heating steps (155 Ma to 1279 Ma, 6% of total Ar released) yield a distorted initial age spectrum, however a well-defined plateau (189.3±1.4 Ma) is observed for the remainder of the heating steps (94% of all Ar released) (Figure 2.8A). A similar total gas age of 190.1±1.4 Ma was also obtained. The inverse isochron age is 190.7±2.3 Ma (MSWD =0.14) (Figure 2.8B). The Ar-Ar results for this amphibole separate are consistent with the U-Pb (titanite) age of 190.3±4.6 Ma. The plateau age obtained above is considered to represent the minimum age of the hornblendite dike when the rock cooled through the closure temperature to Ar diffusion in hornblende (see Discussion). 2.5.2.2 04ES-00-07-03 - Wehrlite This sample comes from an outcrop in the far southeastern part of the Turnagain intrusion, in the southern portion of the Hatzl Zone (Figure 2.3). Although phlogopite is not abundant in this sample (<2 vol.%), there were sufficient grains for Ar-Ar analysis. Phlogopite from this sample, which has high-K interiors (Ca/K between 0.2-2), displays a large range in 40Ar (3.4-94.9%) relative to 04ES-00-07-04 (Table 2.2), but the flat plateau step analyses have a smaller range in 40Ar (3.7-48.9%). The age range in this sample is somewhat smaller than the previous sample (36-220 Ma), with a younger total gas age of 181±1 Ma. The plateau age of 189.9±1.3 Ma (Figure 2.8C), which represents 56% of all argon released during step heating analysis, is in agreement with the inverse isochron age of 190.2±1.8 Ma (MSWD =1.17, Figure 2.8D). 0.16 0.18 0.20 0.22 0.24 0.26 207Pb/235U 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 206Pb/238U 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 (%) <uAr/"Ar 2<T "Ar/^Ar 2a "Ar/"Ar 2o "ArfAr 2o ""ArV'Ar 2o- '/cTAr* Age (Ma) 2o Ca/K Cl/K fa3Ar 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 JaArK = 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 ,uAr/"Ar, J°Ar/33Ar, "Arl"Ar, and ™ArV°Ar are shown for each increment of step-heating. All errors are absolute 'Indicates atmospheric argon Volumes are 1E-13 cmJ 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 39Ar 20 40 60 80 39 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 WAr 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 39Ar 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 WAT Figure 2.8:40Ar/39Ar incremental-heating age spectra and 40Ar/39Ar 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 minimum crystallization age of the wehrlite when the rock cooled through the closure temperature to Ar diffusion in phlogopite (see Discussion). 2.5.3 Rare Earth Elements and Nd Isotopes The Sm-Nd isotopic compositions of eight whole rock samples from the Turnagain intrusion were determined in this study. With respect to rare earth element (REE) concentrations (Table 2.3), the samples have broadly subparallel chondrite-normalized patterns with prominent LREE-depletion for the ultramafic rocks (Figure 2.9A). The leuco-diorite and the volcanic wacke exhibit distinctive LREE-enriched chondrite-normalized patterns (Figure 2.9B). The volcanic wacke, as well as the samples of Erdmer et al. (2005), fall within or bracket the REE range established for the Lay Range Assemblage (Ferri, 1997) and Klinkit Group (Simard et al., 2003) (Figure 2.9B). (La/Yb)cn values in ultramafic rocks range from 0.27-2.0, with the volcanic wacke and hornblende diorite samples exhibiting (La/Yb)cn values of 3.9 and 1.9, respectively. The samples analyzed for Nd isotopes (Table 2.4) show a wide range of concentrations (Sm = 0.6-6 ppm, Nd = 1.3-18.5 ppm), variable Sm/Nd values (0.33-0.45), a wide range in 143Nd/144Nd (measured) from 0.512440 to 0.512997, and do not exhibit an isochron relationship (Figure 2.1 OA). The majority of 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 of lithologies from dunite to diorite (plagioclase + amphibole). Field relationships, and mineral and whole rock geochemistry (see Chapter 4) indicate the following general crystallization sequence: dunite —> wehrlite —> olivine clinopyroxenite —* hornblende clinopyroxenite —* hornblendite —• diorite. The Ar-Ar phlogopite date from the wehrlite (189.9+1.3 Ma) from the mineralized Hatzl Zone and the Ar-Ar hornblende date from the hornblendite (189.9+1.4 Ma) from the northwestern part of the Turnagain intrusion are identical within error and represent the ages of closure to Ar diffusion (i.e. cooling ages) at ~450°C (phlogopite) and ~575°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. %) Si02 51.23 48.99 49.04 47.14 38.53 41.93 49.67 53.56 Ti02 0.20 0.38 0.29 0.75 2.32 2.16 0.80 0.29 Al203 1.05 2.21 2.07 4.20 12.06 12.21 16.19 20.82 Fe203* 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 Na20 0.17 0.20 0.17 0.63 0.67 0.78 3.57 6.02 K20 0.10 0.08 0.11 0.40 0.32 0.89 1.86 1.17 P205 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 Fe2+ 100 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm YD 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 143 Nd 20 147 Sm 143 Nd £Nd (0) ^Nd TcHUR TDM (ppm) (ppm) 144 Nd 144 Nd 144 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 TCHuR and TDM 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 147Sm/144Nd 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) 143Nd/144Nd vs. 147Sm/144Nd 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 eNd 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 of 190.3±4.6 Ma (Figure 2.7), which represents the time of closure to Pb diffusion in titanite (~650°C) (Cherniak, 1993; Frost et al, 2000). All three dates from the ultramafic rocks of the Turnagain intrusion are identical within error and correspond to a range of closure temperatures for the respective minerals and isotopic systems from 650°C down to 450°C, which is consistent with relatively rapid cooling of the Turnagain intrusion following emplacement and crystallization. Based on these three dates, the age of crystallization and cooling of ultramafic rocks from the Turnagain intrusion is 189.9±0.9 Ma (n=3, weighted mean age, 2a). The mela-diorite sample (04ES-00-07-01) exhibits gradational contacts with hornblendite, but intrudes dunite (Figure 2.3). The closure temperature for Pb diffusion in zircon is >900°C (Cherniak & Watson, 2000), which is likely to be higher than the temperature of the fractionated hydrous melt from which the zircon in this sample precipitated; thus the U-Pb zircon date for this sample can be interpreted as a crystallization age. As noted previously, all analyzed zircon in this sample appears to have lost Pb since the time of crystallization. Based on the oldest least discordant fraction (Fraction B), the mela-diorite has a minimum crystallization age of 189.2±0.6 Ma (Figure 2.5A), which is identical within error to the weighted mean Ar-Ar (phlogopite, hornblende) and U-Pb (titanite) age noted above. The absolute crystallization age of the Turnagain intrusion is inferred to be 189.4±0.5 Ma based on a weighted mean of Fraction B from the mela-diorite and the Ar-Ar and U-Pb titanite ages referred to above. The 185.2±0.3 Ma U-Pb zircon age of the leuco-diorite (DDH-04-57-12-89) is approximately 4.5 million years younger than the crystallization age of the Turnagain intrusion established above. This younger age can be interpreted as (1) the true crystallization age of the leuco-diorite, thus implying an extended period of magmatism in the formation of the Turnagain intrusion; or (2) a function of Pb loss from zircon in this sample. Field and petrographic relations suggest that the leuco-diorite is an integral part of the 190 Ma ultramafic and mafic rocks of the Turnagain intrusion. The first interpretation is consistent with the observation that late dioritic dikes are a common feature of many Alaskan-type intrusions (e.g. Lunar Creek; Nixon et al., 1997). In addition, a diorite to granodiorite composite pluton ~5 km to the east-southeast of the Turnagain intrusion (Figure 2.2), a body considered to be a small ultramafic 'Ring Complex' genetically related to the Turnagain intrusion (Clark, 1975), was recently dated by Erdmer et al. (2005) at 187.5±2.9 Ma (U-Pb zircon). This age overlaps both 41 the ages of the leuco-diorite and the ultramafic rocks of the Turnagain intrusion. The composite Ring Complex is described by Erdmer et al. (2005) as a "medium-grained hornblende granodiorite to tonalite-diorite," which suggests that it may be a similar lithology to the mela-diorite of the Turnagain intrusion. The date of the granodiorite is a lower intercept age with concordia based on three of the five analyzed fractions (see Fig. 5 of Erdmer et al., 2005). However, the oldest analyzed fraction (not used in the above regression) is concordant and yields a 206Pb/238U age of 192.4±0.8 Ma, thus it is possible that this hornblende granodiorite may be several million years older that its proposed crystallization age of 187.5±2.9 Ma. The second interpretation of the age of the leuco-diorite from the Turnagain intrusion - Pb-loss from zircon after crystallization at ca. 190 Ma - is based on the observation of Pb-loss in all zircon fractions from the mela-diorite (sample 04ES-00-07-01) and the field and petrographic characteristics of the leuco-diorite sample. The hornblende diorite contains coarse (up to 1 cm in width) euhedral crystals of plagioclase and amphibole, interpreted to be cumulus phases that crystallized from an evolved plagioclase-amphibole-saturated magma late in the crystallization history of the Turnagain intrusion. The drillcore from which the sample was collected contains 9 metres of alternating plagioclase-rich and amphibole-rich bands, perhaps representing a layered sequence of cumulate rocks. These observations require the leuco-diorite to have crystallized at the same time as the other dated samples, thus the obtained age of 185.2±0.3 Ma is most likely a function of Pb-loss from zircon following crysallization. The Mg-rich olivine (F092.5) of some Turnagain dunites indicate that the Turnagain magmas equilibrated with peridotitic mantle (with respect to major elements). However, the Nd isotopic composition of all lithologies in the Turnagain intrusion (sNd(i90)= +5.9 to -3.3) indicates that the intrusion was variably contaminated with continental crust (depleted mantle SNd(i90Ma) = +9 to +10; DePaolo & Wasserburg, 1976). The most positive £Nd(i90) results are consistent with the range observed in Paleozoic mafic volcanic rocks in Yukon-Tanana (Piercey et al., 2006). The Nd isotopic compositions of the graphitic phyllite (Erdmer et al., 2005) and the volcanic wacke (this study) both indicate (respectively) their origin from, and contamination with, continental crust (Figure 2.10). The variable 8Nd(i90) of the analyzed ultramafic samples may reflect heterogeneous assimilation of the volcanic wacke and the graphitic phyllite, both of which 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 of Alaskan-type intrusions suggest that they form from relatively hydrous, alkalic to subalkalic, primitive 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 of Alaskan-type intrusions, therefore, are important for understanding the temporal evolution of arc systems. This is particularly relevant to the Cordilleran orogeny of B.C., Yukon, and southeastern Alaska, which consists of numerous accreted allochthonous and parautochthonous terranes (e.g. Monger et al, 1982; Schermer et al, 1984; Gabrielse & Yorath, 1991; Colpron et al, 2006) (Figure 2.1). The published and reported ages of Alaskan-type intrusions in B.C. and southeastern Alaska are compiled in Table 2.5 and shown with respect to terranes in Figure 2.11. Of the 9 known Alaskan-type intrusions in B.C. and 39 in southeastern Alaska, only 12 have been dated; mostly by the K-Ar method during the 1960s. Prior to this study, the only precise U-Pb zircon ages of Alaskan-type intrusions in B.C. and Alaska were reported by Saleeby (1992), Rubin & Saleeby (1992), Rublee (1994), and Nixon et al. (1997) (Duke Island, Union Bay, Tulameen, and Lunar Creek+Polaris, respectively). There are two important observations that can be made regarding the age distribution of Alaskan-type intrusions (see Figure 2.1 for terrane locations). Firstly, there are four age groups: -435-400 Ma, -240-205 Ma, -195-185 Ma, and -125-100 Ma. 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 Stikinia and Quesnellia (Figure 2.1). Secondly, the -240-205 Ma intrusions are observed in both Stikinia and Quesnellia, whereas the -195-185 Ma intrusions are found only in Quesnellia. Alaskan-type intrusions in B.C. and southeastern Alaska also exhibit an age distribution relative to their host rocks. The oldest group of intrusions (Salt Chuck, Dall Island, and Sukkwan Island) intrude older gabbroic plutons as well as the Descon Formation (lower Paleozoic metavolcanic and metasedimentary rocks; e.g. Rubin & Saleeby, 1992), which is unconformably overlain by the Gravina (Upper Jurassic-Lower Cretaceous metavolcanic and metasedimentary rocks) and Alva (upper Paleozoic-lower Mesozoic metabasalt, marble, and argillite) sequences. The youngest age group is also dominantly hosted by the Descon Formation, however the Union Bay intrusion is hosted by the overlying Gravina sequence (Rubin & Saleeby, 1992). This implies that the youngest age group of 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 on206 Pb/238 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 Ma) are typically hosted in the Takla (Monger, 1977) and Nicola (e.g. Shau, 1970) Groups, which are Triassic packages of volcanic rocks that occur in Quesnellia and Stikinia (Dostal et al., 1999). The Gnat Lakes Alaskan-type intrusion, however, is hosted in the Stuhini Group in Stikina, and Stuhini Group, Takla Group, and Nicola Group are considered to be coeval (Dostal et al., 1999). The Jurassic (-195-185 Ma) group of intrusions is represented by the Polaris and Turnagain intrusions, which have similar crystallization ages (186±2 Ma, 190±1 Ma, respectively) and host rocks. The Polaris intrusion is hosted in the Lay Range Assemblage, which has been correlated with the Harper Ranch Subterrane and the Klinkit Group (e.g. Ferri, 1997) and is proximal to the Upper Proterozoic Ingenika Group, whereas the Turnagain is hosted by graphitic phyllites (possibly the Road River Formation and Earn Group) and volcanic wacke that possibly correlates to the Lay Range Assemblage (see next section). The apparent 10 million year gap, based on the few reliable U-Pb dates, between the Late to Middle Triassic and Early Jurassic intrusions may be related to (1) a period of quiescence in arc magmatism, or (2) an artifact of the lack of geochronological data. Monger & Church (1977) constrain the biostratigraphic age of the Takla Group from late Carnian to early Norian (-220 to 230 Ma using the time scale of Okulitch, 1999). In addition, a Late Triassic angular unconformity with the overlying Early Jurassic Rossland Group, a package of volcanic rocks (with lateral facies changes gradational with limestone and epiclastic rocks) that are texturally and mineralogically similar to the Nicola Group, is observed in southern Quesnellia (Beatty et al., 2006). This succession is inferred to represent the uplift and erosion of the Nicola Group followed by eastward-shifted renewed arc magmatism (overlying Rossland Group) at -195 Ma (Parrish and Monger, 1992). The older biostratigraphic age of the Takla 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 of Quesnellia (Figure 2.1), may corroborate the eastward shift of arc magmatism in Quesnellia during the Early Jurassic. However, the number of precisely-dated Alaskan-type intrusions in B.C. is small (n=4). The apparent time gap may therefore simply be related to the lack of dated Alaskan-type intrusions in B.C. A 185-212 Ma plutonic suite does occur in the Yukon-Tanana terrane (Mortensen, 1992), with whole-rock compositions similar to the Takla Group (Nelson et al., 2006). Some plutons contain ultramafic rocks with 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 of preserved Late Triassic or Early Jurassic volcanic rocks, but there is no apparent age' gap of early Mesozoic plutonic rocks in Yukon-Tanana - presumably the basement to Quesnellia (Nelson et al., 2006). 2.6.3 Tectonic Implications for Northern British Columbia The combined ages, host lithologies, and Nd isotopic compositions of the Turnagain intrusion have implications for its tectonic setting and relation to the accreted terranes of the Canadian Cordillera. The two major host lithologies, graphitic phyllite 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 limited fossil biochronology, the age of the Road River Formation sensu stricto is Early Ordivician to Middle Silurian elsewhere in B.C., and the overlying the Earn Group is Upper Devonian to Mississippian (Gabrielse, 1998). The undivided Road River 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 zircon (Figure 2.6A) and are intruded at their base by a 337 Ma porphyritic dike (Erdmer et al., 2005). A gradational contact (interbedded over 5-10 m) between the graphitic phyllite and the volcanic wacke was observed in drillcore in late 2006. The age of the phyllite 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 within the Canadian Cordillera, specifically the Quesnel, Stikine, and Yukon-Tanana terranes, have recently been argued to be genetically related (Nelson et al., 2006), partially based on lithological similarities. For example, Alaskan-type intrusions are known in Stikinia and Quesnellia, and recent unpublished findings indicate their probable presence in Yukon-Tanana (J. Nelson, pers. comm., 2007). The association between carbonaceous phyllite and overlying volcanic/volcano-sedimentary rocks has been documented in both Quesnellia and Yukon-Tanana (Ferri & Melville, 1990; Mortensen, 1992; Ferri, 1997; Simard et al., 2003; Nelson & Friedman, 2004). In Quesnellia, such volcanic-volcaniclastic rocks have been included either in the Mississippian-Permian Lay Range Assemblage or the Devonian-Middle Permian Harper Ranch Subterrane (Ferri & Melville, 1990; Ferri, 1997; Dostal etal., 1999). The Lay Range Assemblage (Ferri, 1997) contains (1) a Middle Mississippian-late Middle Pennsylvanian Lower Sedimentary division, consisting 47 predominantly of argillite and siltstone with lesser limestone, tuff, and volcanic sandstones; and (2) an Early Permian Upper Mafic Tuff division, consisting of a variety of tuffs, agglomerates, and lavas flows. The Lay Range Assemblage is considered correlative with the Middle Mississippian-Early Permian Klinkit Group in Yukon-Tanana (Simard et al., 2003; Nelson & Friedman, 2004). The Klinkit Group has been observed to tectonically overlie a succession of phyllites, grits, and tuffs of the Devonian-Middle Permian Swift River succession (Simard et al., 2003; Nelson & Friedman, 2004), while the base of the Lay Range Assemblage has been observed in central B.C. by Ferri & Melville (1990) to conformably overlie carbonaceous phyllite. The base of the Harper Ranch Subterrane has not been observed (Dostal et al., 1999). Other similarities between Yukon-Tanana and Quesnellia possibly include a shared Ancestral North America basement source. Erdmer et al. (2002) documented 313-1058 Ma detrital zircon in sedimentary rocks of the Quesnellian Nicola Horst in south-central B.C. and Untershutz et al. (2002) documented a mixture of primitive and evolved Nd isotopic compositions in Triassic sandstones overlying the Lay Range Assemblage. Ferri (1997) documented inherited Proterozoic zircon in Permian tuffs and lavas from the Upper Mafic Tuff division of the Lay Range Assemblage. In summary, the "Earn Group'VSnowcap Assemblage is overlain by the Klinkit Group/Lay Range Assemblage/Harper Ranch Subterrane, all of which contain detrital zircon of Proterozoic age. The Turnagain intrusion is the first documented Alaskan-type intrusion to be hosted in both Lay Range-equivalent rocks and older graphitic phyllite. The -300 Ma volcanic wacke, with inherited Proterozoic zircons and trace element characteristics (REE) similar to samples of the Lay Range Assemblage and the Klinkit Group (Ferri, 1997; Simard et al., 2003 - Figure 9A) (Figure 2.9B), is likely a northern equivalent of the Lay Range Assemblage. The "Road River" phyllite, as assigned by Gabrielse (1998), is conformably overlain by the Lay Range Assemblage and therefore constitutes part of the same crustal block. The conformable nature of these two rock packages is broadly consistent with the first interpreted tectonic setting of the Turnagain intrusion of Nixon (1998) as outlined in the introduction, however this lithological succession cannot be part of Ancestral North America. These lithologies are intruded by the Turnagain Alaskan-type intrusion, a composite mafic-ultramafic pluton of arc affinity (see Chapter 4). No conclusive terrane assignment can be made based on the presence of Lay Range Assemblage-equivalent rocks, on the presence of an Early Jurassic arc-derived intrusion, or on the presence of 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 CONCLUSION 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 £Nd(i90)= +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 ACKNOWLEDGEMENTS We would like to thank a number of individuals at the Pacific Centre for Isotopic and Geochemical Research, University of British-Columbia, Vancouver: Rich Friedman for U-Pb TIMS chemistry and analyses, and his continuous input into data interpretation for this manuscript; Tom Ullrich for Ar-Ar analyses; Gwen Williams and Bruno Keiffer for sample preparation, digestion, and Nd isotopic analyses; and Dominique Weis for assistance in the interpretation of the Nd isotopic results. Jim Mortensen, Luke Baranek, and Reza Tafti are thanked for sharing their opinions and ideas concerning northern B.C. tectonics, and Katrin Breitsprecher for her helpful comments on this manuscript. The authors are grateful to Hard Creek Nickel Corp. for continued field support for this project and to Jim Reed of Pacific Western Helicopters for his exemplary logistical support in the field. Special thanks to Tony Hitchins, Bruce Northcote, Chris Baldys, and Mark Jarvis (President) of Hard Creek Nickel Corp. for their generous support and interactions throughout the period of the principal author's M.Sc. thesis at UBC. Funding for this project was provided by a research grant from Hard Creek Nickel Corp. (formerly Canadian Metals Exploration Ltd.). 2.9 REFERENCES Batanova, V.G., Pertsev, A.N., Kamenetsky, V.S., Ariskin, A.A., Mochalov, A.G., & Sobolev, A. V. (2005). 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(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 Stacey, J.S., & Kramers, J.D. (1975). Approximation of terrestrial lead isotope evolution by a two-stage model. Earth and Planetary Science Letters 26, 207-221 Stevens, R.D., Delabia, R.N., & Lachance, G.R. (1982). Age determinations and geological studies; K-Ar isotopic ages, Report 16. Geological Survey of Canada, Paper 82-2, 56p Taylor, H.P., Jr., & Noble, J.A. (1960). Origin of the ultramafic complexes in southeastern Alaska. 21st International Geological Progress Report Part 13, 175-187 Thirlwall, M.F. (2000). Inter-laboratory and other errors in Pb isotope analyses investigated using a 207Pb-204Pb double spike. Chemical Geology 163, 299-322. Unterschutz, J.L.E., Creaser, R.A., Erdmer, P., Thompson, R.I., & Daughtry, K.L. (2002). North American margin origin of Quesnel terrane strata in the southern Canadian cordillera: inferences from geochemical and Nd isotopic characteristics of Triassic metasedimentary rocks. Geological Society of America Bulletin 114, 462-475 Wanless, R.K., Stevens, R.D., Lachance, G.R., & Edmonds, CM. (1968). Age determinations and geologic studies, K-Ar isotopic ages, Report 8. Geological Survey of Canada, Paper 67-2A, 141p Watkinson, D.H., & Melling, D.R. (1992). Hydrothermal origin of platinum-group mineralization in low-temperature copper sulphide-rich assemblages, Salt Chuck intrusion, Alaska. Economic Geology 87, 175-184 Weis, D., Kieffer, B., Maerschalk, C, Barling, J. de Jong, J., Williams, G.A., Hanano, D., Pretorious, W., Mattielli, N., Scoates, J.S., Goolaerts, A., Friedman, R.M., & Mahoney, J.B. (2006). High-precision isotopic characterization of USGS reference materials by TIMS and MC-ICP-MS. Geochemistry Geophysics Geosystems 7 (8), Q08006, doi: 10.1029/2006GC001283 Wong, R.H., Godwin, C.I., & McTaggart, K.C. (1985). 1977-Geology, K/Ar dates, and associated sulphide mineralization of Wrede Creek zoned ultramafic complex (94D/9E). Geology in British Columbia, 1977-1981, 148-155 CHAPTER 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 (FeC^CU with minor amounts of Mg, Al, and Fe3+ substitution), is found as an accessory mineral in a wide variety of mafic and ultramafic rocks (e.g. Barnes & Roeder, 2001). It crystallizes from magmas that are broadly basaltic in composition and is typically one of the earliest phases to saturate in a mafic melt (e.g. Roeder, 1994). The abundance of chromite in many ultramafic and mafic rocks is generally low (1 vol.%), although large accumulations called chromitite do occur in a number of 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) worldwide. The composition of chromite is extremely sensitive to its environment of formation as well as post-magmatic processes and thus can be a powerful petrogenetic indicator in petrologic studies (e.g. Irvine, 1965; Irvine, 1967; Dick & Bullen, 1984; Roeder & Campbell, 1985; Sack & Ghiorso, 1991; Scowen etal, 1991; Poustovetov & Roeder, 2000; Power et al, 2000). Variations in chromite compositions may record changes in magma compositions and types of co-precipitating phases (Roeder, 1994), oxygen fugacity (e.g. Poustovetov & Roeder, 2000), pressure (e.g. Roeder & Reynolds, 1991), and may also record the effects of sub-solidus re-equilibration and serpentinization (e.g. Roeder & Campbell, 1985). A recent compilation of chromite compositions from mafic-ultramafic rocks worldwide (Barnes & Roeder, 2001) includes only seven referenced sources of data for Alaskan-type intrusions. These intrusions are typically composed of ultramafic cumulate rocks, consisting of Mg-rich olivine, 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 typically disseminated in the most magnesian lithologies (dunite and wehrlite). The earlier chromite compositional study of Clark (1978) provided a good basis for this study, which provides an •i overview of spinel compositions from the Turnagain Alaskan-type intrusion in northwestern British Columbia (Canada) with the aims of 1) significantly increasing the spinel compositional database for Alaskan-fype intrusions, 2) assessing the crystallization sequence and subsequent chemical modifications during cooling and serpentinization using chromite compositional variability and, importantly, 3) constraining the relative oxygen fugacity of the parental magmas for the Turnagain intrusion. The Turnagain Alaskan-type intrusion is unusual in that it contains zones with significant Ni-sulphide mineralization (428 Mt - measured and indicated - @ 0.17% sulphide Ni; http://www.hardcreeknickel.com). Given the proposed arc setting for Alaskan-type intrusions, they are considered to form from relatively oxidized parental magmas (AFMQ = +1 to +3.5, e.g. Carmichael, 1991; Parkinson & Arculus, 1999) with 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 British Columbia occur within the Mesozoic Quesnel accreted arc terrane, including the Tulameen (Findlay, 1969), Polaris (Foster, 1974), Lunar Creek, Wrede Creek, Johansson Lake (Nixon et al, 1997), and Turnagain (Clark, 1975; 1978; 1980; Nixon, 1998) intrusions. The Turnagain intrusion is located in northwestern B.C., approximately 70 km east of Dease Lake, to the east of the Kutcho Fault, which is a regional strike-slip fault that represents the terrane boundary between Ancestral North America to the north and Quesnellia to the south (Gabrielse, 1998). The 24 km2 Turnagain intrusion is completely fault-bounded, and during the Early Jurassic was thrust onto graphitic and pyritic phyllites currently assigned to the undivided Ordivician-Devonian Road River Formation/Earn Group, a deep marine facies of paleo-passive margin sedimentary units of Ancestral North America (Gabrielse, 1998). Conformably overlying the phyllite is a Devonian-Mississippian volcanic to sedimentary unit (Erdmer et al, 2005) that may be correlative to the Lay Range Assemblage (see Chapter 2). The crystallization age of the Turnagain intrusion is constrained to be 190 Ma using U-Pb and Ar-Ar geochronological techniques (see Chapter 2). I 3.3 GEOLOGY AND SPINEL CONTENT OF THE TURNAGAIN INTRUSION Rocks of the Turnagain intrusion are predominantly ultramafic cumulate rocks with associated late dioritic phases and intrusions (Figure 3.1). The 3.5 km x 8.5 km Turnagain intrusion is elongate in a NW-SE direction and the apparent thickness of the intrusion is estimated at approximately 450 m based on inverse modeling of gravity data (C. Baldys, pers. comm., 2005). Exposures of the intrusion are limited to the northern and northeastern areas, which are above treeline, and near the Ni-mineralized 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 Ni-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 of the intrusion, both northwest and southeast of the Turnagain River (Figure 3.1). Chromite is common in the more magnesian olivine-rich cumulates and magnetite is typical of the more evolved, clinopyroxene/hornblende-bearing lithologies that comprise the west-central portion of the intrusion. This part is considered to represent the roof of the intrusion and contains porphyritic, megacrystic, and pegmatoidal textured rocks and appears to intrude the underlying olivine cumulate rocks based on an interpretation of aeromagnetic data and diamond drill hole results (courtesy of Hard Creek Nickel Corp.). In the section below, the typical abundances and textures of spinel in rocks of the Turnagain intrusion are described. 3.3.1 Dunite Dunite, the most abundant rock type in the Turnagain intrusion, is primarily composed of cumulus olivine and chromite with minor interstitial clinopyroxene (<10 vol.%) and rare phlogopite (0-1 vol.%). Equigranular olivine is typical of most dunite; however, local post-crystallization deformation has produced dunite with porphyroclastic textures. Olivine grain-size ranges from 2 mm in fine-grained equigranular dunite to 10 mm in porphyroclastic dunite. Kink bands, observed as discrete undulatory extinction bands in individual olivine grains, and irregular grain boundaries are also observed. Serpentinization of olivine in dunite is common, ranging from none to nearly complete, although the average amount of serpentinization is -10%. Secondary magnetite is common between olivine grains. Chromite in dunite can be found as chromitite schleiren, pods, lamellae, and rarely as layers (max. 5 cm thick) (Figure 3.2). Chromite grain sizes are typically 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). Olivine may be encased within chromitite, but more commonly olivine grains are only partially surrounded by chromite and are present near the edge of the chromitite. Dunite typically contains up to 4 vol.% disseminated euhedral to subhedral chromite (Figure 3.3 C) both included within olivine and along grain boundaries between olivine crystals, although 2 vol.% is the typical abundance. Secondary alteration has resulted in the formation of magnetite rims (~30 um thick) as overgrowths on chromite, and in some cases a 'ferritchromit' rim (Cr-rich magnetite) has been produced (Figure 3.3D). Ferritchromit, with no directly defined composition (e.g. Kanaris-Sotiriou et al., 1978; Zakrzewski, 1989; Takashi & Adachi, 1995), is a term broadly used for Cr- and Al-rich 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 „ 01 # , 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 -rich chromite, rims observed on cumulus chromite (and rarely as entire grains) in serpentinized ultramafic rocks, which appear to be overgrowths rather than alteration products (Roeder et al., 2001). The thickness of these rims appears to depend on factors such as position with respect to olivine, clinopyroxene, and degree of serpentinization. Since clinopyroxene is only rarely affected by serpentinization, chromite grains within or partially encased by clinopyroxene typically do not show secondary overgrowths/rims. 3.3.2 Wehrlite Cumulus olivine and interstitial clinopyroxene are the dominant phases in wehrlite from the Turnagain intrusion; however, rare cumulus diopsidic clinopyroxene may occur. Olivine grain size is comparable to that in dunite (2 mm), although equigranular textures are less common and only occur in clinopyroxene-poor rocks. Olivine contained, either partially or entirely, within large clinopyroxene oikocrysts is typically rounded. Porphyroclastic textures are rarely observed in wehrlite, and clinopyroxene is typically interstitial to olivine porphyroclasts and neoblasts. Cumulus clinopyroxene is commonly finer grained than neighbouring olivine, with grain sizes ranging from 75 um in diameter up to 2 mm in some samples. Serpentine minerals replace only olivine in wehrlites, and secondary magnetite is common along silicate grain boundaries. Chromite, typically -150 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 typically concentrated in specific areas, or clusters, and chromite grains in wehrlite tend to exhibit subhedral and anhedral habits. The majority of chromite grains are included in olivine or along olivine-olivine or olivine-clinpyroxene grain boundaries, with 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 lithology is typically composed of variable amounts of cumulus olivine and clinopyroxene, although a few samples contain significant oikocrystic clinopyroxene (Figure 3.4C). This latter type of olivine clinopyroxenite commonly contains more chromite than olivine clinopyroxenite where both the silicate minerals are cumulus (see Discussion). Olivine grain size (-1 mm) is significantly smaller compared to olivine 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 mm across. The size of the two cumulus silicate phases in olivine clinopyroxenite appears to be directly proportional to their modal abundance (i.e. an olivine clinopyroxenite with 60 vol.% clinopyroxene will generally have an equigranular texture, whereas an olivine clinopyroxenite with 90 vol.% clinopyroxene will have significantly larger clinopyroxene and very small olivine). Olivine in olivine-poor clinopyroxenite is typically strongly serpentinized. Chromite in olivine clinopyroxenite is typically found as inclusions within cumulus clinopyroxene or olivine, is never interstitial to the silicate minerals, and rarely contains secondary magnetite rims (Figure 3.4; C, D). Grain sizes are typically small, around 150 um, and chromite is commonly euhedral (Figure 3.4D). Chromite abundance is significantly reduced (<0.5 vol.%) compared to wehrlite. Chromite in olivine clinopyroxenite with 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 within the Turnagain intrusion. The first setting is as fine-grained dikes that are interpreted to represent evolved magma compositions. Some of these hornblendite dikes intrude a pendant of wallrock in the northwestern part of the intrusion (Figure 3.1). Hornblende-bearing rocks, some of which are cumulate, also occur in the west-central portion of the intrusion. Hornblendite dikes commonly contain subhedral ilmenite, whereas hornblende-rich lithologies of the western portion of the Turnagain intrusion typically contain primary magnetite (Figure 3.5). Although its occurrence is limited, magnetite may be found as local accumulations in hornblende-clinopyroxene-rich lithologies with grains reaching up to 1 cm across. Magnetite is typically 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 of each sample, textural relationships to other phases, and relative degree of 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 of 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 of larger spinel grains were referred to as "clusters". Chromite grains from three different clusters were analyzed in each thin section. A total of 16 samples were selected for microprobe analysis, carbon-coated, and documented using a Philips XL-30 scanning electron microscope at the University of British Columbia, Vancouver, BC. Quantitative analyses were carried out in wavelength-dispersion mode using a Cameca SX-50 electron microprobe with a beam diameter of 10 um, an accelerating voltage of 15 keV, and a beam current of 20 nA with 20 s peak count-time and 10 s background count-time. The Ni contents of chromite grains from chromitite samples were analyzed using a fixed matrix, a beam diameter of 10 pm, an accelerating voltage of 15 keV, and a beam current of 200 nA with peak count-time extended to 100 s and a background time to 50 s. For the elements considered, the following standards, X-ray lines and crystals were used: synthetic rhodonite, MnKa, LIF; diopside, CaKa, PET, and SiKa, TAP; synthetic spinel, AlKa, TAP; synthetic fayalite, VeKa, LIF; synthetic magnesiochromite, MgATa, TAP, and CrKa, LIF; rutile, TiKa, PET; V metal, VKa, PET; synthetic Ni2Si04, ~NiKa, LIF. Data reduction of all analytical results was undertaken using the "PAP" <(>(pZ) procedure of Pouchou & Pichoir (1985). Using the higher beam current and counting times for Ni as described above results in an analytical precision of <5% relative. A total of 360 points were analyzed in this study, 25 of which were magnetite analyses. Individual grains, prior to analysis, had their selected point locations ordered from rim to core. In the case of grains on the edge of chromitite schlieren, the part of the grain closest to a neighbouring silicate was analyzed first, as opposed to the grain boundary in contact with other chromite. All spinels were assumed to be stoichiometric (Kamperman et al., 1996) and cation abundances and ferrous/ferric iron were calculated using the method of Barnes and Roeder (2001). This method isolates Ti 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 of spinel analyses from this study are presented in Appendix I. Below, the variations in spinel chemistry are described for spinels from each of the major rock types of 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe^ 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 Fe"* 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 volumetrically minor in the Turnagain intrusion, chromitite is petrologically important. Chromite grains from chromitites are characterized by the most Cr- and Mg-rich compositions of all lithologies (Cr203 = 59-67 wt.%, MgO = 10-14 wt.%) with correspondingly low Ti02 (0.24-0.66 wt.%), V203 (0.01-0.34 wt.%), A1203 (4.60-7.14 wt.%), and Fe203 (3.82-6.88 wt.%) contents (Figures 3.6-3.7). Two samples (05ES-01-03-01 and 05ES-01-04-01) contain relatively Ni-rich chromite grains (NiO = 0.13-0.20 wt.%). All chromite analyses from chromitite are distinguished by Fe3+/(Fe3++Cr+Al) <0.1 (Figure 3.7A). There is no iron-enrichment trend present in the chromite analyses from chromitites indicating that their compositions likely 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 composition (Cr203= 34-56 wt.%, Ti02= 0.01-1.01 wt.%, FeO = 20-29 wt.%, Fe203 = 3.5-18.6 wt.%) compared to chromite from chromitites (Figure 3.6-3.7). With the exception of sample 04ES-19-01-02, spinel analyses from each dunite sample show an overall iron-enrichment trend (Figure 3.7A), which is a common feature of Alaskan-type intrusions (Barnes & Roeder, 2001). All Fe3+-rich spinel compositions from dunite represent analyses of magnetite/ferritchromit rims around chromite grains and are associated with serpentine-group mineral replacement of olivine. Analyses of spinel grains from sample 04ES-19-01-02 have Fe3+/(Fe3++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 A1203 (7.5-15.4 wt.%), Ti02 (0.7-1.8 wt.%) and Fe203 (10-18 wt.%). Magnetite and ferritchromit compositions, while 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 Fe3+/(Fe3++Cr+Al) compared to the above wehrlites (Figure 3.6). The compositions of chromite from this sample have the lowest Fe203 (0.94-3.97 wt.%) of all spinel analyses from the Turnagain intrusion, and relatively low Cr/Cr+Al (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 Ti02 (1.1-2.5 wt.%), and high V203 (0.06-0.38 wt.%). In terms of their trivalent cation abundances (Figure 3.6A), chromite compositions from individual wehrlite samples, with the exception of the above sample, are characterized by intermediate sloping trends in terms of trivalent cations (decreasing Cr, increasing Fe3+ and Al). Chromite compositions from sample 04ES-15-01-05 plot in the field of the "Cr-Al trend" of Barnes and Roeder (2001) and likely reflect the effect of exchange with Al-bearing clinopyroxene (see Discussion). 3.5.4 Olivine Clinopyroxenite Most olivine clinopyroxenite sampled in the Turnagain intrusion, and indeed in other Alaskan-type intrusions (Irvine, 1965), is devoid of chromite. A few samples of olivine clinopyroxenite from the Turnagain intrusion contain chromite, however the nature of the grains (small sizes, low abundances) appears to have allowed for more extensive subsolidus to post-magmatic compositional modifications compared to spinel grains from the previously described rock types. Chromite grains from olivine clinopyroxenite are relatively enriched in FeO (23-27 wt.%>), Fe203 (9.7-17.2 wt.%), Ti02 (0.9-2.1 wt.%) and V203 (0.22-0.54 wt.%), and depleted in A1203 (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 Fe3+/(Fe3++Cr+Al)<0.1 (Figure 3.7), and overlap with the analyses from the dunite sample 04ES-19-01-02. Spinel analyses from sample 05ES-05-01-01 are also distinct with high amounts of Ti02 (2.5-3.2 wt.%) and Fe3+/(Fe3++Cr+Al)>0.4 (Figure 3.7A, 3.8A), which indicates that all analyzed grains are ferritchromit in composition. This sample contains small (150 um) chromite grains entirely encased within cumulus diopside (Figure 3.4H), thus the ferritchromit composition of the spinels in this sample is likely the result of subsolidus reequilibration with the hosting clinopyroxene. With respect to trivalent cations, chromite grains from olivine 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 of clinopyroxene saturation and after the cessation of chromite crystallization. Chromite ceases to crystallize shortly after clinopyroxene saturation because Cr is compatible in clinopyroxene (e.g. Irvine, 1965; Findlay, 1969; Hill & 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. Ti02. 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. of spinel from two cumulus magnetite-bearing hornblende clinopyroxenites, both from drillcore, show contrasting compositions. Spinel from sample DDH05-84-19 is nearly pure end-member magnetite (Fe203 = 67.1-67.8 wt.%, Cr203 = 0.37-0.60 wt.%, A1203 = 0.06-0.18 wt.%), whereas magnetite from sample DDH04-47-49 shows slight Al enrichment (A1203 = 0.12-3.77 wt.%) and relative V enrichment (V203 = 0.22-0.73 wt.%), and exhibits relatively high Ti02 (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 composition of primary spinel grains may be changed or reset by syn- and post-magmatic processes (e.g. Roeder & Campbell, 1985, Power et al., 2000). In particular, reequilibration with interstitial melt and/or hosting silicate minerals and serpentinization can significantly change the composition of spinel (e.g. Roeder & Campbell, 1985; Sack & Ghiorso, 1991; Scowen et al., 1991; Roeder, 1994; Melinni et al., 2005). An important observation from this study is that spinel grains from chromitite schleiren, wisps, pods, and layers have the most Cr-rich, Al- and Fe3+-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 did not significantly interact with the hosting olivine or interstitial melt and thus preserved the highest temperature spinel compositions that crystallized from the most primitive (highest MgO) magmas. Chromitite sample 05ES-01-04-01 contains chromite with the lowest Fe# (0.30-0.35) consistent with the primary nature of these grains. In Figure 3.9, chromite analyses from most of the dunite, wehrlite, and olivine clinopyroxenite samples plot along vectors that converge towards the field of each of the chromitite compositions, which indicates that the compositions closest to the chromitite field have undergone the least amount of re-equilibration. The proximity of dunite, wehrlite, and olivine clinopyroxenite chromite compositions to those from chromitite samples, coupled with the region of Cr-Al-Fe space where sample-specific compositional vectors intersect, is consistent with derivation from a primary magma composition similar to that which precipitated the chromitites. Chromitite Dunite Wehrlite Ol cpxite ^05ES-01-01-01 •04ES-19-01-02 • 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 All chromite grains, except those from the chromitites, have undergone substantial compositional modification at high temperatures during cooling and interaction with evolved interstitial melt, enclosing silicates, or oxidizing fluids. The intersample change of chromite Fe# from chromitite to other lithologies at near-constant Fe3+, as exhibited by specific samples in Figures 3.6, 3.7, and 3.9, is likely the result of olivine+chromite fractionation - olivine depletes the melt in Mg during crystallization and chromite depletes the melt in Cr such that co-precipitating chromite will have progressively higher Fe# and lower Cr/Al. The spinel trends with intermediate slopes on Figure 3.9, which contains only core and intermediate position analyses (no rims)mostly from wehrlite and olivine clinopyroxenite, converge towards the chromitite field and exhibit intrasample variations toward higher Al and Fe3+ with increasing Fe#. These trends can be explained by equilibration with evolved interstitial melt: the melt with which these chromite grains were in contact (either directly or by diffusion through olivine) was likely relatively rich in Ca, Al, Ti, and Fe . Although the compositions of some samples in this trend may be related to their crystallization from a fractionated liquid, the dunite sample that parallels them did not and thus exhibits compositions related to re-equilibration with trapped melt. Chromite compositions with Fe3+/(Fe3++Cr+Al)>0.1, which also exhibit an increase in Fe# (Figure 3.7), appear to have been modified by subsolidus re-equilibration with enclosing or enveloping olivine and by oxidizing fluids. The chromite compositions from dunites 04ES-03-02-01 and 04ES-08-0T-01 overlap in the Cr-Al-Fe3+ ternary (Figure 3.9), extending parallel to the Cr-Fe join but are distinct with respect to Fe# (Figure 3.7A). Most of the spinel grains in these two samples occur along olivine grain boundaries, not inside olivine, and the increase in Fe3+/(Cr+Al+Fe3+) can be attributed to oxidation by fluids that locally precipitated magnetite (but did not involve serpentinization). The increase of chromite Fe# is the result of the exchange of Fe2+ from olivine to chromite during cooling; the spinel grains from these two dunite samples do not show enrichments in Al or Ti, thus the trend towards lower Fe# is best explained by exchange with olivine, in the absence of interstitial melt. The unusual spinel compositions from wehrlite sample 04ES-15-01-05 and olivine clinopyroxenite sample 04ES-01-04-01 - relatively high Al/Cr and low Fe3+ - may be attributed to their silicate mineralogy. These samples contain cumulus olivine and chromite surrounded by 2 cm-diameter Cr-rich (see Chapter 4) clinopyroxene oikocrysts. The volume ratio of 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 with 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 olivine clinopyroxenite samples that plot near the Fe3+ apex in Figure 3.6A are nearly pure magnetite in composition and likely reflect nucleation of magnetite around pre-existing chromite during serpentinization. Ferritchromit rims are recognized by individual spot analyses that plot further towards the Cr-Fe3+join 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 Al, and higher Fe compared to other analyses and reflect the Fe-rich and Cr-poor nature of the serpentinizing fluids from which these rims formed. It is unclear whether ferritchromit rims are products of nucleation or reaction with 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 with a core-to-rim order of formation of chromite —> ferritchromit —> magnetite. 3.6.4 Implications for the Redox State of the Turnagain Intrusion The low Fe3+ content of chromite grains from the chromitites in the Turnagain intrusion (Clark, 1978) is consistent with a low Fe3+/Fe2+ ratio (i.e. relatively low oxygen fugacity) in the parental magma (e.g. Parkinson & Arculus, 1999). However, most Alaskan-type intrusions appear to have formed from relatively oxidized arc magmas, with calculated AFMQ (log units of 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 will be dominantly dissolved as SO2, SO3, or SO4 " rather than sulphide (S2) and the magmas will not saturate in an immiscible sulphide liquid unless they are reduced to7O2 values below FMQ (Jugo et al, 2004; 2005). The presence of significant amounts of 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 view of the Cr-Al-Fe3+ ternary, all chromite compositions from this study are plotted by lithology, with the data density maxima (50% and 90%) of chromite compositions from other Alaskan-type intrusions from Barnes & Roeder (2001). The majority of chromite compositions from the Turnagain intrusion lie to lower Fe3+ values than the established compositional fields. The compositions from chromitites contain significantly less Fe3+ than other chromite compositions and higher Cr/Al, which suggests that the chromitites crystallized from magmas with a lower oxygen fugacity than the parental magmas of other Alaskan-type intrusions. The low Fe3+ field for other Alaskan-type intrusions on Figure 3.10 may represent compositions that result from re-equilibration with clinopyroxene as observed in this study. Although not shown on Figure 3.10, chromite compositions from chromitite in the Turnagain intrusion plot well within the boninite field (see Barnes & Roeder, 2001), which may indicate that the magmas parental to the Turnagain intrusion also originated from a mantle previously depleted by partial melting. Decompression melting at back-arc ridges segregates Pt alloys in the residue (lithospheric mantle) which, if remelted by slab-derived fluids, would generate a Pt-rich basaltic melt (Kepezhinskas & Defant, 2001; Batanova et al., 2005). The remelting of 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 of phyllite are observed in drillcore from the sulphide-mineralized zones of the Turnagain intrusion (Chapter 4) and reduction of the Turnagain parental magmas was likely achieved by the local assimilation of this graphitic, pyritic phyllite (Chapter 2 and 4). Assimilation of the pyrite-bearing phyllite also contributed additional S to the magma, thus increasingand allowing for early sulphide saturation. The relatively reducedJO2 of the Turnagain parental magmas not only lead to early sulphide saturation, but resulted in the crystallization of 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 of parental magmas to ultramafic rocks where only olivine is co-crystallizing, and thus may be used as an indicator of 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 of this study on spinel compositions in ultramafic rocks from the Turnagain Alaskan-type intrusion are 1) primary spinel compositions are relatively Fe3+-poor and Cr-rich compared to published results from other Alaskan-type intrusions, especially chromite from chromitite, 2) chromites from dunite, wehrlite and olivine clinopyroxenite exhibit intrasample trends that can be related to a variety of processes, including olivine fractionation, re-equilibration with interstitial melt, re-equilibration with coexisting silicate phases, oxidation, and serpentinization, 3) most intrasample re-equilibration trends can be interpolated to originate from the field of spinel compositions from chromitites, suggesting that all lithologies in the Turnagain intrusion crystallized from a similar parental magma, and 4) chromite compositions from chromitite are extremely Fe3+-poor, indicating their crystallization from a magma characterized by a relatively low oxygen fugacity compared to other Alaskan-type intrusions. The reduced nature of the parental magmas, attributed to the assimilation of graphitic and pyritic country rocks, appears to have promoted local sulphide saturation. Therefore the Fe3+ content of chromite from chromitites may be used as a reconnaissance exploration tool for assessing the relative redox state and sulphide mineralization potential of Alaskan-type intrusions. 3.8 ACKNOWLEDGEMENTS We would like to thank Mati Raudsepp at the University of British Columbia for use of the electron microprobe and support during the research phase of this manuscript, as well as Caroline-Emmanuelle Morisset at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia, for her input into this manuscript. The authors are grateful to Hard Creek Nickel Corp. for continued field support for this project and to Jim Reed of Pacific Western Helicopters for his exemplary logistical support in the field. Special thanks to Tony Hitchins, Bruce Northcote, Chris Baldys, and Mark Jarvis (President) of Hard Creek Nickel Corp. for their generous support and interactions throughout the period of the principal author's M.Sc. thesis at UBC. Funding for this project was provided by a research grant from Hard Creek Nickel Corp. (formerly Canadian Metals Exploration Ltd.). 3.9 REFERENCES Ballhaus, C, Berry, R.F., & Green, D.H. (1991). High pressure experimental calibration of the olivine-orthopyroxene-spinel oxygen geobarometer: implications for the oxidation state of the upper mantle. Contributions to Mineralogy and Petrology 107 (1), 27-40 Barnes, S.J., & Roeder, P.L. (2001). The range of spinel compositions in terrestrial mafic and ultramafic rocks. Journal of Petrology 42 (12), 2279-2302 Batanova, V.G., Pertsev, A.N., Kamenetsky, V.S., Ariskin, A.A., Mochalov, A.G., & Sobolev, A. V. (2005). Crustal evolution of island-arc ultramafic magma: Galmoenan pyroxenite-dunite plutonic complex, Koryak Highland (Far East Russia). Journal of Petrology 46, 1345-1366 Carmichael, I.S.E. (1991). The redox states of basic and silicic magmas: a reflection of their source regions? Contributions to Mineralogy and Petrology 106, 129-141 Clark, T. (1975). Geology of an ultramafic complex on the Turnagain River, northwestern B. C.; unpublished PhD thesis, Queen's University, 454p. Clark, T. (1978). Oxide minerals in the Turnagain ultramafic complex, northwestern British Columbia. Canadian Journal of Earth Sciences 15, 1893-1903 Clark, T. (1980). Petrology of the Turnagain ultramafic complex, northwestern British Columbia. Canadian Journal of Earth Sciences 17, 744-757 Dick, J.B., & Bullen, 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., Mihalynuk, M.G., Gabrielse, H., Heaman, L.M., & Creaser, R.A. (2005). Mississippian volcanic assemblage conformably overlying Cordilleran miogeoclinal strata, Turnagain River area, northern British Columbia, is not part of an accreted terrane. Canadian Journal of Earth Sciences 42, 1449-1465 Findlay, D.C. (1969). Origin of the Tulameen ultramafic-gabbro complex, southern British Columbia. Canadian Journal of Earth Sciences 6, 399-425 Foster, F. (1974). History and origin of the Polaris ultramafic complex in the Aiken Lake area of north-central British Columbia; unpublished B.Sc. thesis, University of British Columbia, 66p. Gabrielse, H. (1998). Geology of Cry Lake and Dease Lake map areas, north-central British Columbia; Geological Survey of Canada, Bulletin 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, CD. (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, TA., 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 origin of arc picrites, New Georgia Group, Solomon Islands. Contributions to Mineralogy and Petrology 149, 685-698 Sack, R.O, & Ghiorso, M.S. (1991). Chromite as a petrogenetic indicator. Mineralogical Society of America - Reviews in Mineralogy 25, 323-354 Scowen, P.A.H., Roeder, P.L., & Helz, R.T. (1991). Reequilibration of chromite within Kilauea Iki lava lake, Hawaii. Contributions to Mineralogy and Petrology 107, 8-20 Takashi, A., & Adachi, M. (1995). Ilvaite from a serpentinized peridotite in the Asama igneous complex, Mikabu 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 CHAPTER 4 PETROLOGY AND METALLOGENY OF THE TURNAGAIN ALASKAN-TYPE INTRUSION AND ASSOCIATED NI-SULPHIDE MINERALIZATION 4.1 INTRODUCTION Alaskan-type intrusions are synonymous with Uralian-Alaskan-type and zoned ultramafic intrusions. The term "Uralian-Alaskan-type" originates from the two largest concentrations of these intrusions, in the Ural Mountains (n>15) of Russia (Taylor, 1967) and in southeastern Alaska (n=39) (Himmelberg & Loney, 1995). These intrusions are primarily composed of olivine- and clinopyroxene-rich cumulate rocks and may contain appreciable hornblende-and/or feldspar-bearing lithologies. Many of these intrusions are associated with 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 Ural Mountains (Garuti et al, 2003), in Columbia and Ecuador (Tistl, 1994), British Columbia (Findlay, 1969), Alaska (Himmelberg and Loney, 1995), and Australia (Barron et al, 1991) have been associated with past and present placer platinum-group metal (PGM) mining operations. Only a few Alaskan-type intrusions contain appreciable sulphide mineralization, including Salt Chuck, Alaska (Loney et al, 1987; Loney & Himmelberg, 1992), Duke Island, Alaska (Thakurta et al, 2004), and Turnagain, British Columbia (Clark, 1975; Nixon, 1998). The Turnagain Alaskan-type intrusion is a fault-bounded ultramafic intrusion (3.5 x 8 km) composed predominantly of dunite and wehrlite with minor amphibole-bearing phases, which are cross-cut by intermediate to felsic intrusions and dikes. There are two distinct styles of mineralization in the Turnagain intrusion: (1) Ni-(Cu)-sulphide mineralization that occurs in the most magnesian rock types (dunite and wehrlite) with minor local platinum-group element (PGE) enrichment, and (2) microscopic crystals of sperrylite (PtAs2) and stibiopalladinite (PdsSb2) of probable hydrothermal origin, which was discovered in 2004 within hornblende-clinopyroxene lithologies. Ni-sulphide was first discovered in 1956 along the Turnagain River and the property was staked by Falconbridge (Clark, 1975). In the 1990s, the property was acquired by Bren-Mar Resources (now Hard Creek Nickel Corporation) and is actively being explored today. The historic Ni-rich sulphide showing, the Horsetrail Zone, has been extensively drilled with over 100 diamond drill holes. Other showings and prospects in the intrusion have been explored as well and the current Ni resource (measured and indicated) is 428 Mt grading 0.17% Ni (http://www.hardcreeknickel.com), which represents an increase of 200% from the 2005 estimate. This study focuses on the petrology and geochemistry of the Turnagain intrusion to better constrain the emplacement and crystallization of 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 GEOLOGY OF THE TURNAGAIN 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 of the Turnagain intrusion are completely covered by 5-15 m of till, wheras east of the Turnagain River much of the intrusion is covered with up to 50 m of glaciofluvial gravels. Contacts between lithologies in the northern region of the Turnagain intrusion are generally observed, whereas most contacts in and around the Horsetrail Zone are inferred from drill core. Contacts in the western and southern areas are inferred from airborne and ground geophysics as well as recent drill core. The current geological map for the Turnagain intrusion, which is continuously updated based on results from new drilling in relatively unknown areas, is largely based on the efforts of Clark (1975) and Nixon (1998). The original mapping and petrographic investigations of Clark (1975; 1978; 1980) lead to a wealth of fundamental information about the Turnagain intrusion. Subsequent investigations by Nixon et al. (1989) and Nixon (1998) focused on the origin of the Turnagain intrusion with respect to regional geological interpretations, as well as the origin of associated Ni-(Cu)-sulphide and platinum-group element (PGE) mineralization. 4.2.2 Ultramafic Rocks 4.2.2.1 Dunite and Chromitite With the exception of hornblendite and diorite, the majority of the rocks exposed in the Turnagain intrusion are dominated by cumulus olivine and/or clinopyroxene. Dunite is volumetrically the most important lithology in the Turnagain intrusion and occurs in outcrop throughout the alpine regions of the intrusion, but is also observed in all major outcroppings in the Horsetrail Zone and the Cliff Zone (northeastern corner of 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). Most dunite is composed of large amounts of olivine (>90 vol.%) with small amounts of interstitial clinopyroxene, disseminated chromite, and locally interstitial phlogopite. Olivine grain size in dunite is commonly ~1 mm (Figure 4.4.1 A), however olivine as large as 2 cm across or larger has been observed. Uncommonly large olivine occurs in association with much smaller olivine (<1 mm) in a porphyroclastic texture, which is interpreted to represent the product of high strain at high temperature. Olivine (~1 cm) with irregular grain boundaries, as well 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 pm 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. Chromitite, observed in dunite from the alpine region of 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 mm in some cases, and is almost completely unimodal (99% chromite). The irregular distribution and habit of chromite in the chromitites suggests that these rocks were disrupted or deformed at high temperatures following 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 olivine clinopyroxenite are locally juxtaposed together in the northwestern part of the intrusion (Figure 4.1), with no fault or obvious intrusive relationship, which may indicate the presence of primary igneous layering. However, in the above example, ~3 cm-wide dunite dikes were observed cutting the olivine clinopyroxenite (Figure 4.3.IB). Continuous dikes (over 100 m) of olivine clinopyroxenite (up to 10 cm wide) have also been observed cutting dunite (Figure 4.3.2G, H). Clark (1975) noted deformation of igneous layering at the contact with dunite in the northwestern part of the Turnagain intrusion. Serpentinized dunite is common near major faults, although dunite typically contains only minor amounts (~10 vol.%) of serpentine minerals. Alpine dunite commonly contains small fractures filled with green, slickensided serpentine, and dunite from other parts of the intrusion is black due to an abundance of secondary magnetite. Black serpentine also contains traces of elemental carbon, graphite, and locally sulphide. Lizardite (green, well-foliated) is the most common serpentine mineral. Crysotile (fibrous and white) is only rarely found associated with serpentine veins/slips, and antigorite (massive meshes of interlocking needles) is generally only found in the Horsetrail Zone. 4.2.2.2 Wehrlite Most exposures of wehrlite occur in the northwestern alpine region of the Turnagain intrusion (Figure 4.1), around/within the Horsetrail Zone, and in the Cliff Zone. Phlogopite from a wehrlite in the Hatzl zone (far southeastern edge of the intrusion) was dated at 189±1.3 Ma by Ar-Ar geochronology (see Chapter 2 for details). Two types of wehrlite occur in the Turnagain intrusion. The most common type is composed of cumulus olivine (1-5 mm) and interstitial clinopyroxene (Figure 4.3.IC). It typically weathers to a light brown colour and is easily distinguished from dunite in alpine exposures. Locally, clinopyroxene forms oikocrysts 99 up to 2 cm wide (Figure 4.4.IC). Wehrlite also contains disseminated chromite (50-150 pm) and rare interstitial phlogopite. The other type of wehrlite contains what is interpreted to represent cumulus clinopyroxene (Figure 4.3.ID, 4.3.2E) and occurs in exposures in the northwestern part of the intrusion as well as in exposures east of the Turnagain River (Cliff Zone) (Figure 4.1). This cumulus clinopyroxene has an elongate, prismatic habit and is typically finer-grained than coexisting olivine, about 200 pm in diameter (Figure 4.4.ID), although locally clinopyroxene up to 3 mm in length can occur. Wehrlite dikes have been observed to cross-cut dunite. Both types of wehrlite commonly contain abundant serpentine (up to 85 vol.%) replacing olivine. 4.2.2.3 Olivine Clinopyroxenite and Clinopyroxenite Olivine clinopyroxenite and commonly pegmatitic clinopyroxenite are exposed in the northwestern part of the Turnagain intrusion (Figure 4.1) (clinopyroxenite is rarely exposed elsewhere and is generally only observed in drillcore). Interlayered olivine clinopyroxenite and wehrlite/dunite have been observed in recent drillcore from east of the Turnagain River, however layering is typically 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 volatile-rich residual melt, within olivine clinopyroxenite. Most olivine clinopyroxenite in the Turnagain intrusion is composed of cumulus olivine and clinopyroxene (both ~2 mm in diameter) with minor amounts of fine grained interstitial clinopyroxene. Olivine clinopyroxenite weathers grey in colour with small olivine grains weathering to a buff colour. Locally, modal banding has been observed (Figure 4.3.2F). A few examples of olivine clinopyroxenite occur without cumulus clinopyroxene (e.g. sample 05ES-02-01-01) and instead contain cumulus olivine within oikocrytic clinopyroxene (Figure 4.4.IC). Chromite is rare in olivine clinopyroxenite (see Chapter 2). Where present, chromite is fine-grained (<150 pm) and is commonly encased in cumulus clinopyroxene. Chromite in olivine clinopyroxenite also does not exhibit significant secondary magnetite growth on the rims of grains, as observed in dunites and wehrlites. Dikes of olivine clinopyroxenite and clinopyroxenite have been observed cross-cutting both wehrlite and dunite, and locally biotite occurs along the contacts. These dikes are commonly pegmatitic, and one such example contains clinopyroxene crystals up to 20 cm in length. Olivine is 100 typically completely serpentinized in olivine clinopyroxenite (Figure 4.4.2E), although unaltered cores may be preserved. Magnetite clinopyroxenite, an intermediate rock type between olivine clinopyroxenite and hornblende clinopyroxenite, has only been observed in drillcore from the east-central portion of the intrusion (Figure 1). Magnetite clinopyroxenite exhibits two types of magnetite: (1) cumulus (primary) magnetite crystals up to 5 mm in diameter coexisting with coarse (1-3 cm in length) clinopyroxene, and (2) round blebs of intergrown serpentine and secondary magnetite (up to 3 cm) in a matrix of small diopside crystals (~1 mm). Cumulus magnetite may exhibit modal banding and is interpreted to be comagmatic with its hosting clinopyroxene. The magnetite-serpentine blebs from the second type of magnetite clinopyroxenite are interpreted to represent clasts of dunite that were brecciated during the intrusion of their host clinopyroxenite. 4.2.2.4 Hornblende Clinopyroxenite Although outcrops of hornblende clinopyroxenite are scarce, it comprises a major portion (-10% of the surface area) of the Turnagain intrusion. Much of the hornblende clinopyroxenite in the intrusion occurs in the west-central portion of the intrusion in an area called the DJ-DB Zone, which is a zone that is prospective for PGE mineralization (Figure 4.1). However a prominent dike-like body (1.2 km long x 15 m wide), exposed at the southern margin of the interbanded wehrlite and olivine 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 cm long) and interstitial black amphibole (up to 2 cm long). Some samples contain abundant interstitial biotite, up to 35 vol.%. Magnetite crystals, typically 7 mm up to 1 cm in diameter, occurs in about 20% of all hornblende clinopyroxenite. Locally, magnetite in hornblende clinopyroxenite represents 5 vol.%) of the rock. Examples of this rock type in the DJ-DB Zone are commonly pegmatitic, consisting of large (up to 10 cm wide) equant clinopyroxene and abundant interstitial amphibole. Although typically unaltered, large amounts (up to 85 vol.%) of secondary brown amphibole were noted in hornblende clinopyroxenite adjacent to the large block of hornfels in the southern DJ zone (DDH05-84). 4.2.2.5 Hornblendite Hornblendite in the Turnagain in trusion is poorly exposed but makes up about 20 vol.% of the ultramafic lithologies. Hornblendite may contain coarse, equant clinopyroxene or interstitial plagioclase, and rarely biotite. There are three types of 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 DJ-DB Zone in the west-central portion of the intrusion. The other two types contain abundant (50-60 vol.%) cumulus amphibole, up to 1 cm in width, and 10-20 vol.% cumulus amphibole, respectively, with fine-grained interstitial hornblende matrices (<50 pm). Hornblendite commonly grades into hornblende clinopyroxenite or feldspathic hornblendite, which contains sub-rounded plagioclase grains 3-10 mm in length, rarely with irregular grain boundaries, within a matrix of hornblende crystals up to 2 cm long. Examples of hornblendite containing minor amounts of 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 of hornblendite are rare, and the most accessible outcrop of hornblendite is found as a splay of unknown length off the above mentioned hornblende-rich 'dike' (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 Ar-Ar (amphibole) and U-Pb (titanite) methods, and the obtained ages from this sample are 189±1.4 Ma and 190.3±4.6 Ma, respectively (see Chapter 2). Alteration in amphibole-bearing lithologies is distinct from that observed in olivine-bearing rocks in the Turnagain intrusion. Although 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 Diorite Diorite covers 10% of the exposed surface area in the Turnagain intrusion and occurs mainly in the central part of the intrusion (Figure 4.1). Although this unit is referred to as diorite, the central occurrence is actually a mixture of diorite, quartz diorite, and minor granodiorite, and contains an outer margin (-10 m thick) with significant amphibole (up to 95 vol.%). This margin may be easily confused for hornblendite (Clark, 1975). However, the presence of cumulus/porphyritic plagioclase helps to distinguish diorite from feldspathic hornblendite. It is 102 common for diorite to contain brecciated clasts of dunite, wehrlite, and olivine clinopyroxenite. In general, diorite contains 75 vol.% amphibole, 20 vol.% plagioclase, and minor amounts of quartz, biotite, apatite, and zircon. An outcrop of diorite from the northern margin of the central body (sample 04ES-00-07-01), near the contact with dunite, yielded a U-Pb (zircon) minimum age of 189.2±0.6 Ma (see Chapter 2). Diorite also occurs as thin (5-20 cm in width) dikes that are observed to intrude the more magnesian lithologies of the Turnagain intrusion. These dikes are typically felsic, with 5 vol.% amphibole, and also contain abundant quartz. One very coarse-grained leucocratic diorite (sample DDH04-57-12-89.2), with large cumulus crystals of amphibole and plagioclase (Figure 4.4.2G, H), yielded a U-Pb (zircon) age of 185.2±0.35 Ma (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 of the intrusion, or as xenoliths observed in drillcore. The hornfels unit is equigranular, with grain sizes typically between 0.5-1 mm, and is composed of approximately 45 vol.% epidote, 35 vol.% plagioclase, 10 vol.% amphibole, 5 vol.% quartz, and 5 vol.% biotite. The large block of hornfels in the northwest part of the intrusion contains pods and seams of two-mica granite not observed elsewhere that are interpreted to represent partial melts of country rock. Detrital zircons (subrounded to angular) are common in this lithology and one sample from the northwestern portion of the intrusion (sample 04ES-00-07-02) yielded a minimum U-Pb (zircon) depositional age of 301 Ma (latest Pennsylvanian-earliest Permian) with Precambrian inheritance (see Chapter 2). This unit commonly contains alternating 1-10 mm-wide bands of quartz- and chlorite-rich horizons, which 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 all 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 typically contain 0.5-1 vol.% disseminated sulphide. Sulphide abundances in the mineralized zones (Horsetrail Zone and associated satellite zones; 103 Figure 4.1) range from 2 vol.% up to 20 vol.% or more. These zones contain disseminated, blebby, minor net-textured and rarely semi-massive sulphide. The Northwest, Silesia, and Fishing Rock Zones (to the west, south, and east of the Horsetrail, respectively, Figure 4.1) are relatively small compared to the Horsetrail Zone, which is unconstrained at depth (T. Hitchins, pers. comm., 2004). The mineralization to the east of the Turnagain River, in an area called the Hatzl Zone, is currently unconstrained with respect to grade, tonnage, or spatial distribution. All of the zones were originally interpreted to be separate areas of sulphide mineralization, but new and proposed drilling results indicate that many of them are connected at depth. The typical sulphide assemblage within the mineralized zones consists of pyrrhotite (~90 vol.% of total sulphide) and pentlandite with trace amounts of chalcopyrite. Pentlandite is distinguished from pyrrhotite in hand sample and drillcore by its lighter colour and reflection of light from cleavage planes. Visual estimates of the nickel grade are inaccurate because the Ni content in pentlandite ranges from 10 to 45 wt.% (Hard Creek Nickel Corp. internal reports). Sulphide in clinopyroxene- and amphibole-rich lithologies, rocks that are not prospective for Ni, typically consists of varying proportions of pyrrhotite, pyrite, and chalcopyrite. Clark (1975) and H. Kucha (Hard Creek Nickel Corp. internal reports) studied the sulphide mineralogy in detail and also observed minor amounts of violarite, bornite, millerite, molybdenite, vallerite, mackinawite, and oxysulphides. Disseminated sulphides are typically fine-grained (0.1-0.5 mm) and occur throughout most of the olivine-rich lithologies of the Turnagain intrusion. Disseminated ore in the Horsetrail Zone is common near the margins of the zone, however it is low grade (<0.17% sulphide nickel) and represents the limit of currently economic sulphide mineralization. Serpentinized dunite and wehrlite proximal to the northern bounding fault, in the Highland Zone (Figure 4.1), contain ~0.5 vol.% disseminated pentlandite, similar in texture to sulphide shown in Figure 4.5C. These fine-grained pentlandite occurrences are interpreted to have formed by Ni-enrichment of primary sulphide during serpentinization. Blebby 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 typically surrounded by olivine grains and some sulphide is commonly present between olivine grains adjacent to the sulphide bleb. These blebs are interpreted to represent isolated droplets of sulphide liquid that crystallized in situ. Note that the bleb shown in Figure 4.5A is completely surrounded by magnetite, which 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 of sulphide in partially serpentinized rocks in the Turnagain intrusion. Occurrences of angular sulphide blebs (some up to 3 cm in width) have been noted in drillcore from all of the major mineralized zones. These blebs typically contain the same proportion of pyrrhotite and pentlandite as the more rounded blebs, however angular blebs are also observed in olivine clinopyroxenite, not just dunite and wehrlite. Olivine clinopyroxenite in the Turnagain intrusion does not contain contemporaneous Ni-rich sulphide mineralization, most likely 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 of sulphide, originally 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 Fishing Rock Zones or the Discovery showing (Figure 4.1), but is noted in local accumulations and horizons. This sulphide texture typically contains olivine grains of varying sizes within a sulphide matrix. Due to the amount of pentlandite present in such horizons (up to 10 vol.%), 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 all economic zones within the Turnagain intrusion. The difference between the two types of sulphide lies in their gangue-mineral content: semi-massive sulphide contains abundant silicate and other minerals (e.g. graphite), whereas massive sulphide does not. Both of these sulphide textural types typically have sharp contacts with surrounding rocks indicating that they may represent sulphide that was remobilized. Such horizons of massive and semi-massive sulphide are typically only 5 cm or less in width and are dominantly composed of pyrrhotite and minor chalcopyrite with trace amounts of pentlandite. Semi-massive and massive sulphides in the Turnagain intrusion therefore are rarely prospective for nickel. 4.2.5 Inclusions Xenoliths of country rock within the Turnagain intrusion are restricted to the mineralized zones, and these have only been observed in drillcore. No inclusions have been observed in areas of abundant outcrop (e.g. alpine dunite, Figure 4.2) or nearly continuous exposure. The inclusions within the Turnagain intrusion are, without exception, hornfelsed equivalents of 106 wallrocks. Figure 4.6 displays inclusions from six different drill holes within mineralized zones. The two most commonly encountered inclusions are metavolcanic wacke (MVwk) and metaphyllite (MPhy). The third type of inclusion, calc-silicate (CS), occurs as isolated inclusions (Figure 4.6E, F) or as interbeds within the other types of inclusions (Figure 4.6A). The metavolcanic wacke, described as the hornfels unit above (section 4.2.3.2), also occurs as smaller blocks within drillcore (Figure 4.6A-C). The inclusions of metavolcanic wacke are typically identical in mineralogy and texture to the larger blocks of hornfels. Rarely, the metavolcanic wacke inclusions are slightly coarser grained and contain small seams of two-mica granite (partial melt) that may cross-cut banding. It is uncommon, but noted, to observe interbeds of metavolcanic wacke and metaphyllite in the same inclusion (Figure 4.6B, C). Metaphyllite inclusions (MPhy) are texturally and mineralogically different from their "Road River" phyllite predecessors. Metaphyllite commonly contains brown-coloured areas that are mineralogically dominated by graphite and pyrrhotite with interlayered quartz (Figure 4.6B-D). Graphite and pyrrhotite wisps and seams (typically semi-massive sulphide), interpreted to represent partially digested inclusions of phyllite, were also previously observed by Clark (1975) within ultramafic lithologies. The lack of pyrite (FeS2) and the abundance of pyrrhotite (Fei.xS) indicate that sulphur was released into the host magma during contact metamorphism of the phyllite inclusions. Calc-silicate inclusions (CS) are typically white in colour and relatively small (as small as 2-3 cm in width). However, as noted above, they may occur as interbeds within either metavolcanic wacke or metaphyllite. Calc-silicate inclusions are fine-grained (<1 mm) and typically consist of a mixture of carbonate (calcite, magnesite), wollastonite, diopside, quartz, and locally grossular. Note that in Figure 4.6E and F the calc-silicate inclusions have a slight reddish colour indicating their high garnet content. Calc-silicate xenoliths typically do not display extensive digestion, incorporation into their host rocks, or redox halos. 4.3 ANALYTICAL TECHNIQUES 4.3.1 Mineral Chemistry The olivine, clinopyroxene, amphibole, and biotite contents of each sample, textural relationships with other phases, and relative degree of 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. For each sample, typically 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 with three spot analyses per grain (core, intermediate position, and rim). Representative analyses for olivine and clinopyroxene, and complete analyses for amphibole and biotite are found in Tables 4.1 to 4.4, respectively. Complete analytical results for olivine and clinopyroxene are listed in Appendices II and III. Garnet analyses are listed in Appendix IV. A total of 25 samples were selected for microprobe analysis, carbon-coated, and documented using the Philips XL-30 scanning electron microscope at the University of British Columbia, Vancouver, B.C. Quantitative analyses were carried out in wavelength-dispersion mode using the Cameca SX-50 electron microprobe with a beam diameter of 10 urn, an accelerating voltage of 15 keV, and a beam current of 20 nA with 20 s peak count-time and 10 s background count-time. A list of X-ray lines and elements considered, as well as their standards, can be found in Appendix V. Data reduction of all analytical results was undertaken using the "PAP" <)>(pZ) procedure of Pouchou & Pichoir (1985). A total of 354 points were analyzed (207 olivine, 91 clinopyroxene, 48 amphibole, 8 biotite, 9 garnet). Olivine and clinopyroxene were assumed to be stoichiometric. Ferric iron in olivine was assumed to be zero, and ferric iron in clinopyroxene was calculated using the stoichiometric technique of Lindsley (1983). In amphibole, ferric iron and other cation ratios were calculated using the method of Holland & Blundy (1994) and mineral names were assigned using the nomenclature of Leake et al. (1997). Chemical compositions of amphibole were calculated on the basis of 23 oxygens (16 cations ideal, with vacancy in A site). Biotite stoichiometry was calculated using standard techniques (22 oxygens, 16 cations, 2 OH ± CI ± F ideal). The term 'biotite' 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 of individual samples were taken in the field and any remaining weathered surfaces were systematically removed during sample processing. All samples were crushed using a hydraulic piston crusher between WC plates. A 100 gram aliquot of each crushed sample was powdered using the Fritsch Pulverisette planetary mono- and-multi mills in agate jars. no 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 Cr203 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 Cr203 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 Na20 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 A1,1V' 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 Al'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 Fe3* 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 Fe2* 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. %) Si02 49.54 49.73 49.90 53.33 52.74 53.79 50.74 51.37 50.77 Ti02 0.65 0.53 0.62 0.17 0.17 0.04 0.44 0.35 0.40 Al203 4.79 4.52 4.48 0.68 0.90 0.30 3.83 2.94 3.60 Cr203 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 Na20 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 Ar' 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 Fe3* 0.021 0.036 0.031 0.052 0.041 0.042 0.010 0.010 0.015 Fe2* 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. %) Si02 TiCb Al203 Cr203 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 Fe2^, 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 Nam 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. %) Si02 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 K20 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 Fe2*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 Fe2* (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 Ti02 1.31 1.54 1.56 1.53 1.10 1.15 Al203 14.89 15.27 15.12 15.14 13.85 14.30 Cr203 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 K20 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|(VD 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) of 23 whole rock powders, 3 blind duplicates, and one procedural duplicate (Appendix VI) were analyzed at Activation Laboratories Ltd. (Actlabs) in Ancaster, Ontario. For the major elements, a 0.2 g sample was fused in a graphite crucible after it was mixed with a combination of lithium 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 Jarrell-Ash Enviro II inductively coupled plasma optical emission spectrometer (ICP-EOS). Additional trace elements were analyzed by both the INAA (instrumental neutron activation analysis) and ICP-MS (inductively couple plasma mass spectrometry) methods. Internal calibration was achieved using a variety of international reference materials and independent control samples. For the INAA analyses, 1.5-2.5 g of sample was weighed into small polyethylene vials and irradiated with control international reference material CANMET WMS-1 and NiCr flux wires at a thermal neutron flux of 7 x 1012 ncm'V2 in the McMaster Nuclear Reactor. The samples were measured on an Ortec high-purity Ge detector linked to a Canberra Series 95 multichannel following a 7-day decay. Activities for each element were compared to a detector calibration developed from multiple international certified reference materials and decay- and weight-corrected. For the ICP-MS analyses, 0.25 g of sample was digested in HF, followed by a mixture of FINO3 and HCIO4, heated and taken to dryness. The samples were brought back into solution with HCI. Samples were analyzed using a Perkin Elmer Optima 3000 ICP. In-lab standards or certified reference materials were used for quality control. The normalizing values for the REE (chondrite) and extended trace elements (primitive mantle) are from McDonough & Sun (1995). 4.3.3 Platinum Group Elements The PGE concentrations of 21 whole rock samples, 3 blind duplicates, and 1 procedural duplicate were determined by the NiS fire-assay technique at Geoscience Laboratories (Sudbury, Ontario) following the procedures outlined in Jackson et al. (1990) and Richardson & Burnham (2003). Nickel, sulphur, sodium carbonate and sodium tetraborate are added to a 15 g aliquot of sample powder. This mixture is then fused for 1.5 hrs in a fire-clay crucible at 1050°C, after which the crucible is broken to recover the nickel sulphide button after cooling. The button, in order to remove the NiS 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. %) Si02 38.17 38.08 37.04 35.64 36.47 35.80 37.86 38.14 39.04 39.19 38.49 Ti02 0.04 0.01 0.01 0.01 0.03 0.04 0.03 0.02 0.09 0.03 0.05 Al203 0.32 0.05 0.03 0.07 0.22 0.61 0.17 0.15 0.37 0.18 0.33 Fe203* 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 Na20 0.02 0.03 0.01 0.04 0.04 0.02 0.03 0.05 0.03 0.06 K20 0.20 0.03 0.04 0.08 0.11 0.09 0.03 0.12 0.08 0.10 P2O5 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. %) Si02 38.20 37.07 42.85 50.62 51.23 48.99 49.04 47.14 38.53 41.93 53.56 49.67 Ti02 0.04 0.07 0.11 0.19 0.20 0.38 0.29 0.75 2.32 2.16 0.29 0.80 Al203 0.21 0.50 0.42 1.00 1.05 2.21 2.07 4.20 12.06 12.21 20.82 16.19 Fe203* 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 Na20 0.06 0.02 0.03 0.17 0.17 0.20 0.17 0.63 0.67 0.78 6.02 3.57 K20 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. Any Au or PGE that may have been dissolved during button dissolution are recovered by co-precipitation with tellurium. This produces a concentrate that contains Au and all PGE. The concentrate is vacuum-filtered and re-dissolved in aqua regia prior to analysis by ICP-MS. Osmium is not reported because, at the aqua regia re-dissolution stage, it may be lost as a volatile oxide. PGE concentrations in the samples, detection limits, duplicate results, and reference material values are reported in Table 4.6. The normalizing values for PGE (primitive mantle) are from Maier & Barnes (1999). 4.3.4 Sulphur Isotopes - Sulphide A total of 27 samples from sulphide-rich lithologies including 3 blind duplicates, sampled from drillcore and outcrop, were analyzed for their sulphur isotopic composition. Samples of massive sulphide were sampled using a scriber with a tungsten-carbide tip and all other samples were crushed using a steel hammer and base. Sulphide was then hand-picked using a binocular microscope to assure the lack of any attached silicate, oxide, or other phases. 534S was determined on separates that yielded appreciable sulphide. Most ultramafic samples contained pyrrhotite±pentlandite with trace amounts of pyrite, although some also contained chalcopyrite. Hornblende-rich samples typically contained pyrite and/or chalcopyrite (see Table 4.7). Sulphur was extracted online with continuous-flow technology, using a Finnigan MAT 252 isotope-ratio mass spectrometer, at the Queen's Facility for Isotope Research, Queen's University, Kingston, Ontario. All values are reported in units of per mil (%o), and were corrected using the NIST standard 8556. Sulphur is reported relative to Canon Diablo Troilite (CDT). Analytical precision for 834S is 0.3 %o. 4.3.5 Lead Isotopes - Sulphide A total of 16 sulphide samples from sulphide-rich lithologies, 2 duplicates, sampled from drillcore and outcrop, and the standard reference material NBS-981 were analyzed for their lead isotopic composition and the results are presented in Table 4.8. All 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 of 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 6N hydrochloric acid. Approximately 25-50 ng of 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 (%) 634S (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-silica gel emitter, and isotopic compositions were determined in peak-switching mode using a modified VG54R thermal ionization mass spectrometer at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. The measured ratios were corrected for instrumental mass fractionation of 0.10%/amu (Faraday collector) per mass unit based on repeated measurements of the N.B.S. SRM 981 Standard Isotopic Reference Material and the values recommended by Thirlwall (2000). Errors were numerically propagated including all mass fractionation and analytical errors, using the technique of Roddick (1987). All errors are quoted at the 2CT level. 4.4 RESULTS 4.4.1 Olivine Mineral Chemistry Olivine core compositions from olivine-bearing ultramafic rocks of the Turnagain intrusion become progressively less magnesian from chromitites (F091.96) through dunites (F089-92.5) and wehrlites (F085-90) to olivine clinopyroxenites (~Fo83-87) (Figure 4.7A, Table 4.1). The most Mg-rich olivine in dunite not associated with chromitite is F092.5, which is consistent with crystallization from a primitive parent magma in equilibrium with olivine in mantle peridotite, as originally proposed by Nixon (1998). Olivine grains from chromitites extend to more Mg-rich compositions (up to F096), however these are likely due to Fe-Mg exchange between olivine and neighbouring chromite during sub-solidus re-equilibration (Clark, 1978). The progressive decrease in the forsterite content of olivine with decreasing olivine abundance in the Turnagain cumulate rocks is consistent with progressive decrease in the Mg/Fe of the parent magma(s) due to continued olivine precipitation. There is a general positive correlation between the forsterite and Ni contents in olivine for all olivine-bearing lithologies in the Turnagain intrusion (Figure 4.7B). Three distinct groups can be identified within this trend. The first group contains the majority of the olivine core analyses, ranging from F091 and Ni = 3150 ppm down to F083.5 and Ni = 1000 ppm, and reflects progressive Mg and Ni depletion due to olivine crystallization. The second group consists of olivine grains enclosed within or adjacent to chromitite. These compositions extend to higher Mg (F096) and Ni (2750-4715 ppm) contents, and appear to reflect sub-solidus exchange between olivine and chromite as noted above. The third group consists of olivine core compositions that are distinctly depleted in Ni at a given Fo content, relative to the olivine 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 PB 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 Fo96 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 Ni depletion is consistent with the effect of sulphide liquid saturation and segregation in the parent magma(s) to these specific dunite, wehrlite, and olivine clinopyroxenite samples, with Ni being strongly partitioned into the sulphide liquid relative to coexisting olivine (e.g. sulphide/silicate liquid partition coefficient for Ni in basaltic melts is -800 (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 Mg# = Mg/(Mg+Fe2+). There are no systematic compositional differences between interstitial and cumulus clinopyroxene. There is also relatively little variation in clinopyroxene Mg# in wehrlite and olivine clinopyroxenite, and significant variation between olivine clinopyroxenite and hornblende clinopyroxenite (Figure 4.8A). The lower Mg# (0.84) of clinopyroxene from hornblende clinopyroxenite is consistent with its crystallization from more evolved magmas depleted in Mg due to abundant early olivine (and clinopyroxene) crystallization. The Al and Ti contents of clinopyroxene are also distinctive between the different lithologies of the Turnagain intrusion. The magnesian diopside grains in wehrlite and olivine clinopyroxenite are Al-poor (AI2O3 = 0.25-1.54 wt.%) (Figure 4.8B), whereas the lower Mg# of clinopyroxene grains from hornblende clinopyroxenites extend to higher A1203 (0.30-5.27 wt.%) and Ti02 (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). Amphibole is generally halogen-poor (Cl+F = 1-5% of OH site), contains a moderate amount of alkalis (Na+K = 0.315-0.908 c.p.f.u.), Ti (0.096-0.239 c.p.f.u.), and Al (1.213-2.480 c.p.f.u.), and has a compositional range between magnesiohastingsite and hornblende (based on the classification scheme of Leake et al, 1997) (Table 4.3). Small amounts of biotite (1-3 vol.%) are commonly observed in dunite and wehrlite, whereas hornblende clinopyroxenite may contain 10 vol.% biotite. Rare, but locally significant pegmatoidal biotite clinopyroxenite, observed both at surface and in drill core from the DJ Zone (Figure 4.1), may contain 50-60 vol.% 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 iHiitt 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 crystallized in place of hornblende. Biotite analyses in wehrlite are typically 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, which are largely controlled by the abundance and type of cumulus minerals, and the relative proportions of cumulus to intercumulus phases. There are four main lithological groupings: (1) high-Mg rocks (dunite and wehrlite), (2) intermediate-Mg rocks (olivine clinopyroxenite and hornblende clinopyroxenite), (3) hornblendites, and (4) dioritic rocks, represented by one sample (DDH04-57-12-89) in this study. 4.4.4.1 Group 1: High-Mg Olivine-rich Rocks These rocks are dominated by cumulus olivine and chromite with interstitial, and rarely cumulus, clinopyroxene. Their whole rock MgO contents range from 35 to 51 wt.% and they have a restricted range in Mg# (0.80-0.95), consistent with the presence of abundant cumulus olivine (>Fooo) and minor amounts of clinopyroxene. With respect to elements compatible in olivine or chromite, the high-Mg rocks contain significant Cr (500-5500 ppm) and Ni (800-3400 ppm) (Figure 4.10). The high-Mg rocks are also extremely poor in all elements not incorporated into olivine or chromite (e.g. Ca, Al, Ti, REE) to the extent that incompatible trace element abundances are generally at or below detection limits for nearly all of 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) with a (La/Yb)cn of 0.4-0.9. Wehrlites generally exhibit similar extended trace element patterns (Figure 4.1 IB). The single dunite sample (05ES-04-05-01) with trace element concentrations significantly above detection limits has distinctive LREE-enrichment relative to all other ultramafic samples from the Turnagain intrusion (Figure 4.11 A). This sample contains abundant 1-2 mm serpentine veinlets with minor rutile and chlorite, thus the distinctive chemistry is likely due to post-crystallization modification during fluid-rock interaction and serpentinization, which may have implications for minor LREE mobility in rocks of 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| + -^QOt^-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 Clinopyroxene-Rich Rocks Olivine clinopyroxenite and hornblende clinopyroxenite, like the high-Mg olivine-rich rocks, exhibit major element oxide contents that correlate with their clinopyroxene-dominant mineralogy. They have a relatively restricted MgO range (16-22 wt.%) and Mg# (0.75-0.85), both of which are lower than in the olivine-rich rocks, which is consistent with the presence of abundant cumulus clinopyroxene. Clinopyroxene-rich lithologies have relatively high whole rock A1203 (1-2 wt.%) and CaO (16-20 wt.%) contents (Figure 4.9) and exhibit moderate Cr enrichment (1200-3200 ppm) (Figure 4.10A). Note that, with 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 REE patterns show a concave-down shape similar to the high-Mg group ((La/Yb)cn = 0.3-2.0), but with higher REE contents (0.8-9 x chondrite La) (Figure 4.11 A). The clinopyroxene-rich rocks also have similar primitive mantle-normalized trace element patterns to high-Mg rocks, but again with higher overall abundances. Negative Ta-Nb and Zr-Hf anomalies are present where the abundances of these elements are above detection limits (Figure 4.1 IB). 4.4.4.3 Group 3: Hornblendites The whole rock hornblendite samples are characterized by moderate MgO contents (12-13 wt.%) with a relatively low Mg# (0.64) (Figure 4.9) and have significantly higher CaO (-13 wt.%), AI2O3 (-13 wt.%), and Ti02 (-2.4 wt.%) contents compared with high-Mg rocks. Incompatible trace elements are also enriched in hornblendites (10-30 x chondrite La) (Figure 4.11 A) compared with clinopyroxene-rich lithologies. The hornblendites, similar to the intermediate-Mg and high-Mg rocks, display concave-down REE patterns with (La/Yb)cn from 0.6-1.2. Note that the two analyzed hornblendite samples have sub-parallel REE patterns but distinctly different concentrations. The most REE-rich hornblendite (04ES-00-07-04) is an extremely fine-grained rock (grain size <1 mm) and thus has a composition closest to the original silicate magma (where the interstitial amphibole and other accessory phases represent the chilled melt). The other hornblendite (05ES-05-06-02) is coarse-grained and contains substantial large cumulus amphibole crystals resulting in dilution to lower incompatible element concentrations. The primitive mantle-normalized trace element patterns of the hornblendites are sub-parallel to the clinopyroxene-rich lithologies and olivine-rich 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 100 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 of sulphur isotopic compositions of sulphide separates from lithologies in the Turnagain intrusion and proximal host rocks is presented in Figure 4.14. Pyrite from the Road River phyllite has the most negative 834S 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 (834S = -10 %o to -1 %o), with dunite sulphide shifted to more negative values (834S = -9.7 %o to -3.4 %o) relative to wehrlite sulphide (534S = -8.4 %o to -1.1 %o). Sulphide separates from olivine 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; Ripley, 1999). There is no direct correlation between the presence of alteration associated with sulphide in dunite and wehrlite (see Figure 4.6) and its sulphur isotopic composition. 4.4.7 Lead Isotopic Compositions The range of lead isotopic compositions of sulphide separates from various lithologies within, and proximal to, the Turnagain intrusion is: 206Pb/204Pb = 18.11-19.16 , 207Pb/204Pb = 15.53-15.72, 208Pb/204Pb = 37.91-38.72 (Table 4.8). There is no apparent correlation between the lead isotopic composition of a sulphide separate and its host lithology. 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 Cordilleran shale curve (Godwin & Sinclair, 1982), which is interpreted as a mixing line (Figure 4.15 A). The Pb isotopic composition of most of the sulphide separates is shifted towards more radiogenic values relative to mantle values, indicating a greater contribution of Pb from crustal sources. 4.5 DISCUSSION 4.5.1 Parent Magma Characteristics The petrology and geochemistry of rocks from the Turnagain Alaskan-type intrusion indicate that it was formed by the emplacement and crystallization of Mg-rich, primitive, hydrous magmas in an arc setting. The primitive nature of the parent magmas is constrained by the Mg-rich olivine compositions (up to F092.5) in dunite that has not re-equilibrated with chromite. The hydrous nature of 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 5MS (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 |2a 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 of the intrusion, 3) the late appearance of plagioclase as a cumulus phase relative to clinopyroxene and hornblende (e.g. Gaetani et al, 1993), and 4) the presence of a fine- grained hornblendite dike (sample 04ES-00-07-04) that intruded wallrocks of the Turnagain intrusion. Sub-parallel trace element patterns, especially the rare earth elements (REE), indicate a genetic association between the different ultramafic rock types of the Turnagain intrusion. The range in concentrations reflects the relative abundances of cumulus olivine (and spinel), which both contain extremely low abundances of incompatible trace elements, cumulus and interstitial clinopyroxene, hornblende, and accessory minerals that crystallized from an evolved interstitial melt. The arc geochemical signature for the Turnagain parent magmas is based on combined trace element and Nd isotopic (see Chapter 2) characteristics of the analyzed samples. The prominent negative high field strength element (HFSE) anomalies (Figure 4.1 IB), specifically Nb and Ta, is typical of arc-derived magmas, reflecting (for example) the retention of the HFSE in refactory minerals such as rutile during subduction and magma genesis (e.g. Ryerson & Watson, 1987). Additionally, the most radiogenic Nd compositions of samples from the Turnagain intrusion (Chapter 2) fall within the general range of Paleozoic arc-derived mafic volcanic rocks from the northern Canadian Cordillera (eNd = +4 to +7; Piercey et al, 2006). 4.5.2 Sequence of Crystallization The relative order of crystallization and emplacement in the Turnagain intrusion is dunite —> wehrlite —* olivine clinopyroxenite —> hornblende clinopyroxenite —* hornblendite —• diorite. The entire sequence of rocks crystallized and cooled down to ~350°C at 190±1 Ma, based on the combined results from U-Pb and Ar-Ar geochronometry (Chapter 2). Cross-cutting relations and ferromagnesian silicate Mg/(Mg+Fe2+) (e.g. Fo0nVine, Mg#cpx, Mg#hbi) are consistent with the sequential crystallization and emplacement of ultramafic and mafic lithologies in the Turnagain intrusion. Dunite (~Foai) cumulates are cross-cut by wehrlite dikes, wehrlite (-Fogy) is cross-cut by olivine clinopyroxenite dikes, olivine clinopyroxenite (-Fogs, Mg#cpx = 0.92) is cross-cut by hornblende clinopyroxenite dikes, hornblende clinopyroxenite (Mg#cpx = 0.81, Mg#nbi = 0.65) is cross-cut by hornblendite dikes, and hornblendite (Mg#hbi = 0.60) is cross-cut by diorite. Later lithologies typically cross-cut all 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 of dunite dikes cutting olivine clinopyroxenite (Figure 4.3.IB), near the contact between these two lithologies in the northwestern part of the intrusion (Figure 4.1). These "dikes" are interpreted to represent fractures within the olivine clinopyroxenite through which primitive melts were injected. The primitive melts dissolved clinopyroxene and precipitated olivine, similar to dunite dikes observed in ophiolites (Kelemen & Dick, 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, Alaska; Irvine, 1974). Combined with trace-element and PGE results, the chemical and lithological constraints on the evolution of the Turnagain intrusion imply that all 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 of a magmatic feeder system to an arc volcano. The relationship between Alaskan-type intrusions and basaltic volcanic rocks has been discussed since some of the earliest studies of these intrusions (e.g. Findlay, 1969; Irvine, 1974; Clark, 1975). This association has typically been spatial, as belts of basaltic volcanic rocks have been observed to be broadly sub-parallel to belts of 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; Nixon et al, 1997), Columbia (Tistl 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). Arc ankaramite and picritic ankaramite have been observed as volcanic rocks near, or intruded by, Alaskan-type intrusions in southern Alaska (Irvine, 1974) and the Kamchatka Peninsula, Russia (Batanova et al, 2005), and as dikes cross-cutting Alaskan-type intrusions in New Zealand (Mossman et al, 2000; Spandler et al, 2003) and central Mexico (Hernandez, 2000). Arc ankaramite dikes, with a whole rock CaO/Ai203>l, share three key characteristics with Alaskan-type intrusions: mineralogy, crystallization sequence, and zonation. Ankaramite dikes are typically composed of olivine and clinopyroxene phenocrysts set in a groundmass containing hornblende and minor plagioclase. The crystallization sequence in the ankaramite dikes is olivine —> clinopyroxene —> hornblende —• plagioclase, similar to that in many Alaskan-type intrusions. Finally, 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 of the Turnagain and other Alaskan-type intrusions should occur as olivine+clinopyroxene-phyric basalts in the field, characterized by primitive mineral compositions, and as such may potentially be found in any arc mafic volcanic formations of Early 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 of abundant sulphide, predominantly pyrrhotite and pentlandite, in the Turnagain intrusion is unusual for Alaskan-type intrusions. Basalts generated in subduction zone settings (arc basalts) typically contain 900-2500 ppm sulphur, higher than mid-ocean ridge basalts at comparable FeO (Wallace, 2005). The speciation of dissolved S in arc magmas is important in the genesis of magmatic sulphide in the Turnagain intrusion. Sulphur may exist in multiple valence states (S2", S°, S4+, S6+) depending on the relative oxygen fugacity (/O2) of its hosting magma. The relative oxygen fugacity and sulphur content of basaltic melts, illustrated in Figure 4.16, are critical factors in assessing the development of sulphide saturation (e.g. Jugo et al., 2004; 2005). At7D2 values at or below the reference oxygen buffer fayalite + O2 <->• magnetite + quartz (FMQ), the dominant sulphur species in basaltic liquids is sulphide (S2") (Figure 4.16A), where AFMQ is the J02 relative to FMQ. Magmas with a relatively high fd2 (greater than AFMQ = 0 to +1) will have S dominantly speciated as sulphate (S042~), and as such need significantly more S (approximately an order of magnitude more) to become sulphate-saturated (Figure 4.16B). This is consistent with the observations that most arc magmas are relatively oxidized (e.g. Ballhaus et al., 1991; Carmichael, 1991; Parkinson & Arculus, 1999; Rohrbach et al, 2005), and the general absence of magmatic sulphide deposits associated with most arc plutonic and volcanic rocks. As documented in this study, the Turnagain intrusion contains abundant localized sulphide mineralization (pyrrhotite+pentlandite), thus requiring that the7D2 of the parent magmas was relatively low, especially compared with other typical arc magmas (Figure 4.16). This reduced nature of the parent magmas is consistent with the extremely low ferric iron content and Fe3+/SFe (e.g. Parkinson & Arculus, 1999) of chromite from chromitite in the intrusion (Figure 3.10; Chapter 3). In addition, relatively early sulphide saturation in the crystallization sequence of 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' -3-2-101234 oxidation state (AFMQ) B ? 1.00 c a> c o u 3 0.10 Q. 3 (0 0.01 basalt trachyandesite CCO (hydrous)' IJ 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/02 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 of crystallized mss inclusions in chromite grains (Figure 3.3D, Chapter 3) and Ni-depletion of olivine in some dunite and wehrlite samples (Figure 4.7B). Sulphide separates from the Turnagain intrusion display S34S values from +1 %o (mantle-like; e.g. Ripley, 1999) down to -9.7 %o (Figure 4.14), shifted in the direction of pyrite from the enclosing graphitic phyllite (-17.9 %o). Many of the analyzed sulphide separates exhibit highly radiogenic Pb isotopic compositions (Figure 4.15), consistent with the incorporation of crustal Pb, and some whole rock ultramafic samples exhibit low 8Nq 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, which may have aided in achieving sulphide saturation. Inclusions of graphitic, pyritic phyllite are observed in drillcore from areas proximal to or within the sulphide-mineralized zones of the Turnagain intrusion (Figure 4.6). The pyrite in these inclusions has been completely converted to pyrrhotite, which is indicative of the prograde reaction 2 FeS2 <-> 2 FeS + S2. The phyllite inclusions released sulphur and carbon into the surrounding mafic liquid during heating and partial assimilation, with the graphite acting as a reducing agent, possibly following reactions such as C032"(meit) *-> C02(g) + 02~(meit) (Nixon, 1998) or C(S) +0(meit) CO(g). The fact that partially digested phyllite with remnant graphite is still present in many ultramafic rocks from the mineralized zones indicates that the magmas proximal to these inclusions may have had a jOi near the CCO buffer (carbon-carbon monoxide) (AFMQ = -1 at upper crustal pressures and hydrous conditions; Parkinson & Arculus, 1999). Therefore the phyllite inclusions acted as both a sulphur source and a reducing agent, thus allowing 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 likely generated from the fluid-fluxed partial melting of a peridotitic mantle wedge (e.g. Spandler et al., 2003; Green et ah, 2004; Batanova et al, 2005). The parental magma generated in this setting was hydrous, likely volatile-rich (S, Cl), and primitive, as defined by the high forsterite content of olivine (F092.5). This magma ascended through the mantle lithosphere and overlying crust with relatively minor interaction, based on the highly magnesian olivine compositions, the mineral assemblage of the hornfelsed volcanic wacke 144 (epidote + plagioclase ± amphibole ± biotite), and the whole rock Nd isotopic compositions of the various lithologies (Chapter 2), until it reached the upper crust. The intrusion was emplaced and crystallized within a tectonically active environment, perhaps explaining the presence of 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 of Alaskan-type intrusions along major structures (Nixon et al, 1997; Krause et al., 2006). The magmas differentiated and cooled in a relatively short interval of time at 190 Ma, producing the entire range of lithologies present in the Turnagain intrusion, with periodic injections of primitive melt, as evidenced from the near-constant Pt/Pd ratio and possibly the dunite dikes. Stoping of roof- and wall-rocks, as observed by hornfelsed inclusions of phyllite and volcanic wacke, introduced significant amounts of local crustal material that were partially incorporated into the magma. Metasedimentary inclusions are only observed within or near areas containing abundant sulphide. The pyrite-rich graphitic phyllite, the dominant host rock enclosing the intrusion, released S and C into the surrounding magma during heating. Many Alaskan-type intrusions are typically 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 composition of the host rocks of the Turnagain intrusion is distinct from those that host other Alaskan-type intrusions, and thus the key factor that promoted locally abundant sulphide mineralization in Turnagain intrusion was this distinctive package of pyritic and graphitic phyllites. 4.6 CONCLUSION The origin, emplacement, and crystallization of the Turnagain Alaskan-fype intrusion in north-central British Columbia are constrained by 1) the high fersterite content (F092.5) of olivine from the central dunite, 2) the progressively decreasing Fo content of olivine, Mg# of 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 (REE) patterns between ultramafic lithologies, 5) the presence of phlogopite in early olivine cumulates (dunite, wehrlite), the presence of late, primary hornblende in clinopyroxene-hornblende cumulates, and the absence of early plagioclase, and 6) high field strength element (HFSE) depletions, especially Ta and Nd, in all ultramafic rocks. These results indicate that the Turnagain parent magmas were primitive melts generated in the mantle, within 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 of zones within the Turnagain intrusion, is variable in tenor and texture. A number of features constrain the origin of the sulphide-rich zones: 1) olivine from select dunite and wehrlite samples exhibits Ni-depletion, 2) the 834S values of sulphide separates span a wide range, from mantle-like values (0±1.1 %o) down to light values (-9.7 %o), with the most magnesian rocks (dunites) systematically shifted to lighter 834S values, 3) the Pb isotopic compositions of the sulphide separates indicate the presence of a significant component of radiogenic Pb derived from upper crustal rocks, and 4) partially digested inclusions of graphitic phyllite found in the mineralized zones contain pyrrhotite instead of pyrite. These results indicate that the sulphide mineralization in the Turnagain intrusion occurred as a result of assimilation of local upper crustal material, specifically the hosting Road River phyllite, which contains significant graphite and pyrite (834S = -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 (SO42"), which is typical of most arc-derived magmas. The reduced nature and the addition of crustal sulphur allowed for sulphide saturation to occur in the regions of the Turnagain intrusion where the majority of graphitic phyllite inclusions occur, and where the addition of crustal S was needed to saturate in earlier lithologies. The composition of the country rocks was critical in allowing the Turnagain Alaskan-type intrusion to host magmatic Ni-sulphide mineralization. 146 4.7 ACKNOWLEDGEMENTS I am grateful to Hard Creek Nickel Corp. for continued field support for this project and to Jim Reed of Pacific Western Helicopters for his exemplary logistical support in the field. Special thanks to Tony Hitchins, Bruce Northcote, Chris Baldys, and Mark Jarvis (President) of Hard Creek Nickel Coro. for their generous support and interactions throughout the period of my M.Sc. thesis at UBC. Thanks to Mati Raudsepp at the University of British Columbia for guidance in the use of the electron microprobe and support during the research phase of this manuscript, Janet Gabites at the Pacific Centre for Isotopic and Geochemical Research (UBC) for processing the sulphide Pb isotopic analyses, and Andrew Greene for input into this manuscript. Thanks also to Reza Tafti of the Mineral Deposits Research Unit (UBC) for support during the research phase of this manuscript as well as Dr. Akira Isiwatari for mailing 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 Nickel Corp. 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Ultramafic and Related Rocks, John Wiley and Sons, New York, 97-121 Thakurta, J., Ripley, E.M., & Li, C. (2004). Mineralogic and sulfur isotopic studies of Cu-Ni mineralization in the Duke Island Complex, Alaska. Abstracts with Programs - Geological Society of America 36, 515-516 Thirlwall, M.F. (2000). Inter-laboratory and other errors in Pb-isotope analyses investigated using a 207Pb-204Pb double spike. Chemical Geology 163, 299-322. Tistl, M. (1994). Geochemistry of platinum-group elements of the zoned ultramafic Alto Condoto Complex, Northwest Colombia. 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 Wallace, P.J. (2005). Volatiles in subduction zone magmas: concentrations and fluxes based on melt inclusion and volcanic gas data. Journal of Volcanology and Geothermal Research 140,217-240 Zartman, R.E., & Doe, B.R. (1981). Lead-isotope evolution. U. S. Geological Survey Professional Paper P 1275, 169-170 CHAPTER 5 SUMMARY AND CONCLUSIONS 5.1 SUMMARY AND CONCLUSIONS This comprehensive study of the Turnagain Alaskan-type intrusion in north-central British Columbia, Canada, is based on the combined results of field relations, petrography, mineral (spinel, olivine, clinopyroxene, and amphibole) chemistry, whole rock major and trace element geochemistry, neodymium isotopic geochemistry, sulphide sulphur and lead isotopic geochemistry, and Ar-Ar and U-Pb geochronology. The major goals of this study included 1) constraining the age and source of the parent magmas to the Turnagain intrusion, 2) evaluating the origin and petrogenesis of the intrusion, and 3) identifying the mechanism(s) responsible for the genesis of 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 of cumulate dunite (~Fo0iiVine = 91), wehrlite (~Fo0iiVine = 87), olivine clinopyroxenite (~Fo0iiVine = 85, Mg#cpx = 0.92), hornblende clinopyroxenite (Mg#cpx = 0.81, Mg#hbi = 0.65), hornblendite (Mg#nbi = 0.60), and diorite. This intrusive sequence and their relative order of emplacement is constrained by cross-cutting relationships. Olivine, clinopyroxene, and amphibole chemistry suggest that all lithologies crystallized from a progressively fractionating parent magma. Trace element geochemistry, especially the rare earth elements, of whole rock ultramafic samples indicates a genetic relationship between all lithologies, and corroborates their relationship by crystallization from a progressively evolving liquid. All lithologies in the Turnagain intrusion, based on the similarity of Ar-Ar (phlogopite, hornblende) and U-Pb (zircon, titanite) geochronological results, were emplaced and crystallized in a short time interval at 190±1 Ma. The presence of irregularly distributed chromitite schleiren in the central dunite, which may have formed by gravity flows in a upper crustal magma chamber, is consistent with the emplacement of the Turnagain intrusion in an active tectonic setting. The hydrous nature of the Turnagain intrusion, based on the presence of early interstitial and late cumulus hydrous phases and late plagioclase, indicate that the parent magmas were generated in a subduction zone setting and the high forsterite content of olivine in dunite (maximum of F092.5 in olivine that did not re-equilibrate with chromite) requires that the parent magmas were in equilibrium 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. All disseminated chromite, due to its 154 relatively small volume proportion in dunite, wehrlite, and olivine clinopyroxenite has been compositionally modified by olivine and clinopyroxene fractionation, oxidation, re equilibration with silicate phases, and equilibration with interstitial liquid. Each of these processes is clearly delineated on chromite compositional plots that establish post-crystallization processes based on inter- and intra-sample trends. Primitive chromite compositions (Cr/(Fe3++Cr+Al) = 0.90, Fe2+/(Fe2++Mg) = 0.3, Fe3+/(Fe3++Cr+Al) = 0.75) in the Turnagain intrusion occur in chromitite and are the most primitive spinel compositions observed in Alaskan-type intrusions to date. The ferric iron content of chromite from chromitite, and the Fe3+/SFe, in the Turnagain intrusion is extremely low and reflects the relatively low oxygen fugacity (/02) of the parent magmas. The relatively reduced nature of the Turnagain intrusion may have been an intrinsic property of its parent magmas, however the majority of arc-derived plutonic rocks are relatively oxidized (AFMQ = +1 to +3.5, e.g. Carmichael, 1991). Therefore^ reducing agent added to the magmas was required to lower the /O2 enough to allow the parent magmas to saturate in sulphide (e.g. Jugo et al., 2004; 2005). Thus the ferric iron content and Fe3+/SFe of chromite from chromitite in Alaskan-type intrusions could be considered as a possible exploration tool for evaluating the sulphide mineralization potential of Alaskan-type intrusions. Sulphide in the Turnagain intrusion occurs in localized areas of dunite and wehrlite as disseminated to semi-massive pyrrhotite and pentlandite with other minor phases (e.g. violarite, molybdenite). Hornfelsed inclusions of wallrocks have been intersected in drillcore within the sulphide-mineralized zones. The inclusions are dominantly volcanic wacke, graphitic phyllite, and lesser quartzite and marble. The inclusions of graphitic phyllite are the most important in the context of sulphide mineralization in the Turnagain intrusion because they contain sulphide and graphite. The graphitic phyllite 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 localized Ni-sulphide mineralization in the Turnagain intrusion is therefore the result of the interaction between sulphur- and graphite-rich fluids released from the graphitic phyllite inclusions and the primitive, hydrous parent magmas. Assimilation of crustal material is also demonstrated by systematic variations in sulphide sulphur and lead, and whole-rock neodymium isotopic compositions. Sulphur isotopic analyses of sulphide separates (534S = +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 (206Pb/204Pb = 18.11-19.15 , 207Pb/204Pb = 15.53-15.72 , 208Pb/204Pb = 37.91-38.72) indicate that much of the lead in sulphide originated from an upper crustal source. Finally, 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). Finally, the Turnagain intrusion, which ascended through and stalled in graphitic phyllite and volcanic wacke, was dated by Ar-Ar and U-Pb geochronology at 190±lMa, which has implications for the tectonic history of this part of northern British Columbia. The wallrocks were previously assigned to the paleo-passive margin of Ancestral North America by Gabrielse (1998) as the undifferentiated Road River and Earn Groups, with an overlying volcanic/sedimentary package of "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 minimum depositional age of 301 Ma for the volcanic wacke was determined by U-Pb dating of detrital zircon. The volcanic wacke also contains zircon grains with numerous Precambrian inherited cores. The lithological characteristics, age, and REE chemistry of the volcanic wacke are similar to the Lay Range Assemblage/Harper Ranch Subterrane of Quesnellia and the Klinkit Group of Yukon-Tanana. Inclusions of "Road River" phyllite and volcanic wacke in two Early Jurassic arc-derived intrusions (the Turnagain intrusion and Ring Complex to the southeast) requires that the wallrocks were situated in crust above a subduction zone, and the only known subduction zones of Early 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 with the Stikine terrane) may have been part of a super-terrane after -360 Ma (e.g. Simard et al., 2003; Nelson & Friedman, 2004; Nelson et al., 2006). Alaskan-type intrusions are well-documented in Quesnellia (e.g. Nixon et al., 1997), but none have been described to date in Yukon-Tanana. If Alaskan-type intrusions were to be found hosted in the Klinkit Group, the proposed genetic association between Quesnellia and Yukon-Tanana would be further supported. 5.2 REFERENCES Carmichael, I.S.E. (1991). The redox states of basic and silicic magmas: a reflection of their source regions? Contributions to Mineralogy and Petrology 106, 129-141 Erdmer, P., Mihalynuk, M.G., Gabrielse, H., Heaman, L.M., & Creaser, R.A. (2005). Mississippian volcanic assemblage conformably overlying Cordilleran miogeoclinal strata, Turnagain River area, northern British Columbia, is not part of an accreted terrane. Canadian Journal of Earth Sciences 42, 1449-1465 Gabrielse, H. (1998). Geology of Cry Lake and Dease Lake map areas, north-central British Columbia; Geological Survey of Canada, Bulletin 504, 147p 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 Nelson, J.L., & Friedman, R. (2004). Superimposed Quesnel (late Paleozoic-Jurassic) and Yukon-Tanana (Devonian -Mississippian) arc assemblages, Cassiar Mountains, northern British Columbia: field, U-Pb, 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, CF. (2006). Paleozoic tectonic and metallogenetic evolution of pericratonic terranes in Yukon, northern British Columbia and eastern Alaska. In: Colpron, M., and Nelson, J.L. (ed.) Paleozoic Evolution and Metallogeny of Pericratonic Terranes at the Ancient Pacific Margin of North America. Geological Association of Canada, Special Paper 45, 323-260 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 157 Piercey, S.J., Nelson, J.-A.L., Dusel-Bacon, C, Simard, R.-L., Roots, CF, (2006). Paleozoic magmatism and crustal recycling along the Ancient Pacific Margin of North America, Northern Cordillera. In: Colpron, M., and Nelson, J.L. (ed.) Paleozoic Evolution and Metallogeny of Pericratonic Terranes at the Ancient Pacific Margin of North America. Geological Association of Canada, Special Paper 45, 281-322 Simard, R-L., Dostal, J., & Roots, CF. (2003). Development of late Paleozoic volcanic arcs in the Canadian Cordillera: an example from the Klinkit Group, northern British Columbia and southern Yukon. 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 V203 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 Fe203 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 FeJ** 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 Fe/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. %) Si02 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 Al203 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 Cr203 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 V203 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 Fe203 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 Fe"* 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 Fe"* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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. %) Si02 0.03 0.06 0.02 Ti02 0.76 0.94 0.79 Al203 8.73 8.99 8.98 Cr203 54.61 54.66 54.58 v2o3 0.18 0.14 0.10 Fe203 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 FeJ** 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 Fe^* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 V203 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 Fe203 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 FeJr* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 FeJ'* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 V203 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 Fe203 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 Fe"* 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 Fe"* 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 Mi 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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 Fe"* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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. %) Si02 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 Ti02 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 AI2O3 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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 NI 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 FeJT* 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. %) Si02 0.00 0.02 Ti02 0.91 0.96 Al203 12.76 11.86 Cr203 40.57 43.47 v2o3 0.20 0.14 Fe203 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 Fe"* 0.345 0.321 Fe"* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 v2o3 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 Fe203 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 Fe"* 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 Fe"* 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 V203 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 Fe203 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 Fe"* 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. %) Si02 0.01 0.02 0.05 0.01 TiOj 0.04 0.05 0.08 0.14 Al203 0.04 0.06 0.18 0.15 Cr203 0.37 0.42 0.37 0.38 V203 0.89 0.86 0.91 0.93 Fe203 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 Fe"* 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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 Ca 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. %) Si02 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 Cr203 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. %) Si02 39.23 40.44 40.18 40.31 40.52 40.36 40.10 40.19 39.94 40.43 Cr203 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 Ca 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 oc 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. %) Si02 54.46 52.28 Ti02 0.07 0.09 Al203 0.92 0.90 Cr203 0.47 0.61 FeO* 2.38 2.79 MnO 0.06 0.03 MgO 16.92 16.59 CaO 24.49 25.03 Na20 0.37 0.41 Total 100.15 98.73 Cations (p.f.u.) Si 1.964 1.956 Ti 0.005 0.004 Al"v) 0.036 0.044 Al|v" 0.014 0.004 Cr 0.017 0.021 Fe" 0.004 0.019 Fe" 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 Na20 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 Al"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 Al,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 Fe" 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. %) Si02 53.50 53.99 54.78 54.27 54.42 Ti02 0.24 0.24 0.08 0.12 0.06 Al203 1.16 0.86 0.25 0.36 0.41 Cr203 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 Na20 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 Al"V| 0.043 0.036 0.042 0.042 0.026 Ar" 0.006 0.012 0.010 0.011 0.004 Cr 0.016 0.012 0.016 0.012 0.014 Fe" 0.019 0.011 0.013 0.017 0.009 Fe" 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 Na20 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 Ar" 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 Fe" 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 Fe" 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. %) Si02 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 Ti02 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 Al203 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 Cr203 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 Na20 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 Al,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 Fe" 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. %) Si02 51.23 51.40 50.74 51.37 50.77 51.77 51.26 51.25 Ti02 0.43 0.35 0.44 0.35 0.40 0.36 0.42 0.42 Al203 3.07 2.77 3.83 2.94 3.60 2.98 3.17 3.24 Cr203 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 Na20 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 Al,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 Fe" 0.016 0.004 0.010 0.010 0.015 0.009 0.005 0.006 Fe" 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. %) Si02 35.15 35.07 35.09 35.07 34.98 35.11 35.18 34.86 Ti02 0.05 0.23 0.44 0.07 0.44 0.03 0.32 0.58 Al203 0.00 0.03 0.03 0.01 0.01 0.03 0.01 0.03 Cr203 4.43 7.66 8.31 3.50 8.21 0.92 8.02 9.17 Fe203 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 Na20 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 Fe3+ 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: Ca3Fe3+2Si3012 Uvarovite: Ca3Cr2Si3012 APPENDIX V: List of X-ray lines and mineral standards for EPMA Electron-probe micro-analyses of garnet were done on a fully automated CAMECA SX-50 instrument, operating in the wavelength-dispersion mode with the following operating conditions: excitation voltage, 15 kV; beam current, 20 nA; peak count time, 20 s; background count-time, 10 s; spot diameter, 10 pm. Data reduction was done using the 'PAP' (|>(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the following standards, X-ray lines and crystals were used: albite, NaKa, TAP; almandine, MgKa, TAP; almandine, AlKa, TAP; diopside, SiKa, TAP; ruble, TiKa, PET; grossular, CaKa, PET; magnesiochromite, CxKa, LIF; synthetic rhodonite, MnKa, LIF; almandine, FeKa, LIF. Biotite: excitation voltage, 15 kV; beam current, 10 nA; 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 'PAP' <j)(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the following standards, X-ray lines and crystals were used: synthetic phlogopite, FKa, TAP; albite, NaKa, TAP; anorthite, AlA^a, TAP; synthetic phlogopite, MgXa, TAP; synthetic phlogopite, SiKa, TAP; scapolite, C\Ka, PET; synthetic phlogopite, YLKa, PET; diopside, CaKa, PET; rutile, TiKa, PET; synthetic magnesiochromite, CxKa, LIF; synthetic rhodonite, MnKa, LIF; synthetic fayalite, FeKa, LIF; barite, BaLa, PET. Olivine: excitation voltage, 15 kV; beam current, 20 nA; peak count time, 20 s; background count-time, 10 s; spot diameter, 5 pm. Data reduction was done using the 'PAP' (|)(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the following standards, X-ray lines and crystals were used: albite, NaKa, TAP; kaersutite, AlKa, TAP; olivine, MgKa, TAP; olivine, SiKa, TAP; orthoclase, YJCa, PET; diopside, CaKa, PET; rutile, TiKa, PET; synthetic magnesiochromite, CxKa, LIF; synthetic rhodonite, MnKa, LIF; synthetic fayalite, FeKa, LIF; synthetic Ni2Si04, NiKa, LIF. APPENDIX V (continued): List of X-ray lines and mineral standards for EPMA Clinopyroxene: excitation voltage, 15 kV; beam current, 20 nA; peak count time, 20 s; background count-time, 10 s; spot diameter, 5 (am. Data reduction was done using the 'PAP' (|)(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the following standards, X-ray lines and crystals were used: albite, NaKa, TAP; kaersutite, AlKa, TAP; diopside, MgKa, TAP; diopside, SiKa, TAP; diopside, C&Ka, PET; ruble, T\Ka, PET; synthetic magnesiochromite, CxKa, LIF; synthetic rhodonite, MnKa, LIF; synthetic fayalite, FeKa, LIF; synthetic Ni2Si04, NiKa, LIF. Amphibole: excitation voltage, 15 kV; beam current, 20 nA; peak count time, 20 s (40 s for F, Cl); background count-time, 10 s (20 s for F, Cl); spot diameter, 5 um. Data reduction was done using the 'PAP' <))(pZ) method (Pouchou & Pichoir 1985). For the elements considered, the following standards, X-ray lines and crystals were used: synthetic phlogopite, ¥Ka, TAP; albite, NaKa, TAP; kyanite, AlA^a, TAP; diopside, MgKa, TAP; diopside, SiKa, TAP; scapolite, ClKa, PET; orthoclase, KJCa, PET; diopside, CaKa, PET; rutile, TiKa, PET; synthetic magnesiochromite, CrKa, LIF; synthetic rhodonite, MnKa, LIF; synthetic fayalite, FeKa, LIF; synthetic Ni2Si04, Nlrv«, LIF. 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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