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Petrography, geochemistry and petrogenesis of the Iskut-Unuk rivers volcanic centres, northwestern British… Hauksdóttir, Steinunn 1994

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PETROGRAPHY, GEOCHEMISTRY AND PETROGENESIS OF THE ISKUT-UNUK RIVERS VOLCANIC CENTRES, NORTHWESTERN BRITISH COLUMBIA By STEINUNN H A U K S D 6 T T I R B.Sc, University of Iceland, 1992 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL SCIENCES We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA November, 1994 0 Steinunn Hauksdottir, 1994 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. The University or British Columbia Vancouver, Canada Department of Date JO- A/oV DE-6 (2/88) Abstract The Iskut-Unuk rivers centres consist of eight Recent volcanic centres located within the Stikine volcanic belt, northwestern British Columbia. The centres include: Iskut River, Tom MacKay Creek, Snippaker Creek, Cone Glacier, Cinder Mountain, King Creek, Second Canyon and Lava Fork and comprise lava flows, pillow lava, cinder and ash. The volcanic rocks range in age from 70,000+30,000 to -150 years B.P. and are dominantly alkali olivine basalts; hawaiite is observed only at Cinder Mountain volcanic centre. The basalts are olivine and plagioclase porphyritic and contain rare resorbed clinopyroxene. The groundmass includes olivine, plagioclase, titanaugite, magnetite and locally ilmenite. Large plagioclase crystals with extremely diverse crystal habits and textures are abundant in lavas from Iskut River, Snippaker Creek, Cone Glacier and King Creek volcanic centres. Crustal xenoliths are most abundant at Lava Fork but also occur within the lavas from Iskut River, Snippaker Creek, Cone Glacier and King Creek. Olivine compositions within the basalts range from F055 to Fo 8 3 ; Cinder Mountain hawaiites contain Fo33.54. Clinopyroxene M G f s range from 46 to 76 and can contain up to 6 wt% Ti0 2 . The compositions of resorbed clinopyroxene phenocrysts indicates crystallization at slightly different magmatic conditions than the groundmass clinopyroxene. Based on textures and habits, plagioclase crystals are divided into 4 groups including: megacrysts, phenocrysts, sieved phenocrysts and groundmass. Megacrysts and phenocrysts range in composition from An 5 0 to An 7 0 . Groundmass laths of plagioclase range from An 3 8 to An 6 8 in composition. Sieved phenocrysts of plagioclase are either of magmatic origin (An50.7o) or they are xenocrysts as suggested by prominent dissolution surfaces (sieved), observed with Nomarski technique, and low An-content (An6^8). Most crustal xenoliths derive from granitic basement rocks; partial melting of xenoliths gives rise to glasses with compositions close to alkali feldspar. The chemical diversity observed within the centres cannot be explained by closed system processes involving the observed magmatic mineral phases. Two different hypotheses can explain this variation: i) source region processes including heterogeneous mantle melt or many separate partial melts and/or ii) assimilation of crustal material. With mass balance calculations the chemical variations of samples within Iskut River, Snippaker Creek and Cone Glacier volcanic centres, can be explained by fractionation of olivine (3.2-5.7%) and plagioclase (1.2-11.22%) and assimilation of granitic melt (3.5-6.2%). Cinder Mountain intermediate rocks are not derived from a basalt collected from the area, but the variation within the hawaiite flows is possibly related through coupled fractionation and assimilation processes. Table of Contents A B S T R A C T ii T A B L E O F C O N T E N T S iv L I S T O F F I G U R E S vii L I S T O F T A B L E S x A C K N O W L E D G M E N T S xii C H A P T E R 1. I N T R O D U C T I O N 1 1.1. R E G I O N A L G E O L O G Y 2 1.2. A C C E S S T O A R E A 5 1.3. P R E V I O U S S T U D I E S O F T H E I S K U T - U N U K R I V E R S C E N T R E S 6 1.4. S C O P E O F S T U D Y 7 C H A P T E R 2. T H E I S K U T - U N U K R I V E R S C E N T R E S 9 2.1 . I S K U T R I V E R 10 2.2. T O M M A C K A Y C R E E K 13 2.3. S N I P P A K E R C R E E K 13 2.4. C O N E G L A C I E R 15 2 .5 . C I N D E R M O U N T A I N 18 2.6 . K I N G C R E E K 21 2 .7 . S E C O N D C A N Y O N 2 2 2.8 . L A V A F O R K 2 2 C H A P T E R 3. M I N E R A L O G Y A N D M I N E R A L C H E M I S T R Y 27 3.1 . P E T R O G R A P H Y A N D G E N E R A L C H A R A C T E R I S T I C S 2 7 3.2. M I N E R A L C H E M I S T R Y 3 2 3.2. J. Olivine 3 2 3.2.2. Plagioclase 3 5 3.2.3. Clinopyroxene 4 0 3.2.4. Fe-Ti oxides 4 2 3.3. P L A G I O C L A S E ; H A B I T , T E X T U R E A N D C O M P O S I T I O N A L R E L A T I O N S H I P S 4 4 3.3.1. Implications of disequilibrium textures of plagioclase 55 3.3.2. Analyses of the Iskut-Unuk rivers centres 58 C H A P T E R 4. C H E M I C A L C H A R A C T E R I S T I C S O F I S K U T - U N U K R I V E R S C E N T R E S 60 4 .1 . M A J O R E L E M E N T S 6 0 4.2. T R A C E E L E M E N T S 6 6 iv 4.3. R A R E E A R T H E L E M E N T S 68 5. P E T R O G E N E S I S O F I S K U T - U N U K R I V E R S C E N T R E S 71 5.1. M A G M A T I C P R O C E S S E S W I T H I N T H E I S K U T - U N U K R I V E R S C E N T R E S 72 5.1.1. Iskut River 76 5.1.2. Snippaker Creek 83 5.7.3. Cone Glacier 89 5.1.4. Cinder Mountain 95 5.7.5. Lava Fork 102 5.2. D I S C U S S I O N 108 C H A P T E R 6. T H E R O L E O F A S S I M I L A T I O N O N T H E P E T R O G E N E S I S O F T H E I S K U T - U N U K R I V E R S C E N T R E S I l l 6.1. D E S C R I P T I O N O F C R U S T A L X E N O L I T H S F R O M T H E I S K U T - U N U K R I V E R S A R E A I l l 6.7.7. Chemical composition and melting mechanism of xenoliths. 113 6.2. A S S I M I L A T I O N O F C R U S T A L M A T E R I A L W I T H V O L C A N I C R O C K S F R O M I S K U T - U N U K R I V E R S A R E A 122 6.2.7. Crustal contamination of Lava Fork basalt 127 6.2.1.1. Isotopic data for Lava Fork volcanic centre 130 6.2.2. Crustal contamination of Snippaker Creek, Cone Glacier and Cinder Mountain basalts 132 6.3. S U M M A R Y 140 C H A P T E R 7. C O N C L U S I O N S 143 R E F E R E N C E S 147 A P P E N D L X A . P E T R O G R A P H I C D E S C R I P T I O N S O F I S K U T - U N U K R I V E R S S A M P L E S 163 A P P E N D L X B. R O C K P R E P A R A T I O N A N D A N A L Y T I C A L M E T H O D S 181 A P P E N D L X C . M A J O R A N D T R A C E E L E M E N T C H E M I S T R Y O F T H E I S K U T -U N U K R I V E R S C E N T R E S 186 A P P E N D L X D. E L E C T R O N M I C R O P R O B E A N A L Y S E S O F O L I V I N E 194 A P P E N D L X E . E L E C T R O N M I C R O P R O B E A N A L Y S E S O F C L I N O P Y R O X E N E 205 A P P E N D L X F. E L E C T R O N M I C R O P R O B E A N A L Y S E S O F O X I D E S 208 A P P E N D L X G . E L E C T R O N M I C R O P R O B E A N A L Y S E S O F P L A G I O C L A S E 211 A P P E N D L X H . E L E C T R O N M I C R O P R O B E A N A L Y S E S O F G L A S S E S 240 APPENDIX I. ESTIMATES OF ACCURACY AND PRECISION ON WHOLE ROCK ANALYSES 242 VI List of Figures Figure 1.1 Location and distribution of associated lava flows of the Iskut-Unuk rivers centres 3 Figure 2.1 Distribution of lava flows and pillow lava at Iskut River and Tom MacKay Creek volcanic centres 11 Figure 2.2 Distribution of lava flows at Snippaker Creek volcanic centre 14 Figure 2.3 Distribution of lava flows, pillow lava and pyroclastic rocks at Cone Glacier and Cinder Mountain volcanic centres 16 Figure 2.4 Photograph showing Cone Glacier lava flow including large plagioclase crystals and crustal xenoliths 18 Figure 2.5 Photograph of lava intruding layered hyaloclastite breccia at Cinder Mountain 19 Figure 2.6 Distribution of pillow lava and breccia at King Creek volcanic centre 21 Figure 2.7 Distribution of lava flow at Second Canyon volcanic centre 23 Figure 2.8 Distribution of lava flows, cinder and ash at Lava Fork volcanic centre 24 Figure 2.9 Volcanic bomb from Lava Fork containing crustal xenolith 26 Figure 3.1 Photomicrograph of complexely twinned and anhedral plagioclase from Cinder Mountain hawaiites 30 Figure 3.2 Photomicrograph of resorbed clinopyroxene from Tom MacKay Creek 31 Figure 3.3 Chemical variation of olivine from Iskut-Unuk rivers centres 33 Figure 3.4a Compositional range of feldspar from Iskut River, Tom MacKay Creek, Snippaker Creek and Cone Glacier on ternary Ab-An-Or diagram 36 Figure 3.4b Compositional range of feldspar from Cinder Mountain, King Creek, Second Canyon and Lava Fork on ternary Ab-An-Or diagram 37 Figure 3.5 Pyroxene quadrilateral showing clinopyroxene compositions in Iskut-Unuk rivers basalts 40 Figure 3.6 Al™ concentrations of clinopyroxene plotted against Ti 4 + 42 Figure 3.7a-d Nomarski photographs and chemical variation of plagioclase from Iskut River 49 Figure 3.7e-h Nomarski photographs and chemical variation of plagioclase from Iskut River and Tom MacKay Creek 50 Figure 3.7i-k Nomarski photographs and chemical variation of plagioclase from Snippaker Creek 51 Figure 3.71-0 Nomarski photographs and chemical variation of plagioclase from Cone Glacier 52 Figure 3.7p-s Nomarski photographs and chemical variation of plagioclase from Cone Glacier and Cinder Mountain 53 Figure 3.7t-y Nomarski photographs and chemical variation of plagioclase from King Creek and Lava Fork 54 Figure 4.1 Variation of alkalis vs. Si02 for Iskut-Unuk rivers centres 61 Figure 4.2 Variation of alkalis vs. Si02 for basalts and hawaiites for volcanic centres from Stikine and Anahim volcanic belts 62 Figure 4.3 Concentrations of compatible and incompatible trace elements for the Iskut-Unuk rivers centres plotted against solidification index 67 Figure 4.4 REE patterns for the Iskut-Unuk rivers centres basalts and hawaiite compared to REE patterns from Alligator Lake and Itcha volcanic centres 69 Figure 5.1 Q-type Pearce element ratio diagrams for Iskut River basalts using Zr and K as denominator 73 Figure 5.2 PER diagrams for basaltic rocks from Iskut River volcanic centre 78 Figure 5.3 Trace element concentrations for Iskut River basalts vs. S.I. index 80 Figure 5.4 Trace element ratios for Iskut River basalts vs. x-axis values from q-type PER diagram 81 Figure 5.5 REE patterns for Iskut River and Tom MacKay Creek basalts 82 Figure 5.6 PER diagrams for basaltic rocks from Snippaker Creek volcanic centre 84 Figure 5.7 Trace element concentrations for Snippaker Creek basalts vs. S.I. index 85 Figure 5.8 Trace element ratios for Snippaker Creek basalts vs. x-axis values from q-type PER diagram 86 Figure 5.9 REE patterns for Snippaker Creek basalts 88 Figure 5.10 PER diagrams for basaltic rocks from Cone Glacier volcanic centre 90 Figure 5.11 Trace element concentrations for Cone Glacier basalts vs. S.I. index 92 Figure 5.12 Trace element ratios for Cone Glacier basalts vs. x-axis values from q-type PER diagram 93 Figure 5.13 REE patterns for Cone Glacier basalts 94 Figure 5.14 PER diagrams for basalt and hawaiites from Cinder Mountain volcanic centre _96 Figure 5.15 PER diagram for hawaiites from Cinder Mountain 98 Figure 5.16 Trace element concentrations for Cinder Mountain rocks vs. S.I. index 99 Figure 5.17 Trace element ratios for Cinder Mountain rocks vs. x-axis values from q-type PER diagram 100 viii Figure 5.18 REE patterns for Cinder Mountain hawaiites and basalt 101 Figure 5.19 PER diagrams for basaltic rocks from Lava Fork volcanic centre 104 Figure 5.20 Trace element concentrations for Lava Fork basalt vs. S.I. index 105 Figure 5.21 Trace element ratios for Lava Fork basalt vs. x-axis values from q-type PER diagram 106 Figure 5.22 REE patterns for Lava Fork basalt 107 Figure 5.23 Trace element ratios from the Iskut-Unuk rivers centres 109 Figure 6.1 Photomicrograph of granitic xenolith in contact with basalt 114 Figure 6.2 Photomicrograph of schistose xenolith 115 Figure 6.3 Chemical compositions of xenoliths basement rock and granitic glasses from Lava Fork plotted on alkalis vs. silica diagram 118 Figure 6.4 Total MgO + FeO content of xenoliths and glasses plotted against Si02. 119 Figure 6.5 Alkalis vs. silica diagram of granitic and basaltic glasses from a granitic xenolith from Lava Fork volcanic centre 120 Figure 6.6 PER diagram for the Iskut-Unuk rivers centres 123 Figure 6.7 Slopes and norms for assimilation material on four different PER diagrams 126 Figure 6.8 Or-type PER diagram for Lava Fork basalt 128 Figure 6.9 143Nd/144Nd vs. 87Sr/86Sr for basalt, xenoliths and basement rocks from Lava Fork volcanic centre 131 Figure 6.10 Or-type PER diagram for Iskut River basalts 133 Figure 6.11 Or-type PER diagram for Snippaker Creek basalts 135 Figure 6.12 Or-type PER diagram for Cone Glacier basalts 136 Figure 6.13 Or-type PER diagram for Cinder Mountain basalt and hawaiites 138 Figure 6.14 Grams of crystals fractionated vs. assimilant added according to mass balance calculations 141 Figure LI Mean of replicate analyses of sample ICG-9 by GSC vs. a single analyses by McGill 246 Figure 1.2 Mean of replicate analyses of sample SH9360 by McGill vs. a single analyses by GSC 247 Figure 1.3 Major element analyses by GSC vs. analyses by McGill 248 Figure 1.4 Accepted vs. measured major element concentrations by GSC 249 Figure 1.5 Accepted vs. measured major element concentrations by McGill 250 Figure 1.6 Comparison of FeO analyses by GSC and UBC 253 ix List of Tables Table 2.1 General volcanological information on the Iskut-Unuk rivers centers 10 Table 3.1 Summary of petrographic characteristics of the Iskut-Unuk rivers centres 28 Table 3.2 Selected chemical analyses of olivine 34 Table 3.3 Selected chemical analyses of plagioclase 38 Table 3.4 Compositional variation of plagioclase phenocrysts/xenocrysts and groundmass 39 Table 3.5 Selected analyses of clinopyroxene 41 Table 3.6 Selected analyses of oxides 43 Table 3.7a Occurrences of different forms and textures for the three major crystal habits of plagioclase in the Iskut-Unuk rivers centres 45 Table 3.7b Occurrences of various textures of plagioclase in the Iskut-Unuk rivers centres 45 Table 4.1 Major and trace element chemistry of the Iskut-Unuk rivers centres. 63 Table 4.2 REE concentrations of representative samples from the Iskut-Unuk rivers centres 70 Table 5.1 Mineral vectors as slope and norm for three PER diagrams 75 Table 5.2 Mineral vectors of measured mineral compositions for PER diagrams of Iskut River lavas given as slopes and norms 77 Table 5.3 Mineral vectors of measured mineral compositions for PER diagrams of Snippaker Creek lavas given as slopes and norms 83 Table 5.4 Mineral vectors of measured mineral compositions for PER diagrams of Cone Glacier lavas given as slopes and norms 91 Table 5.5 Mineral vectors of measured mineral compositions for PER diagrams of Cinder Mountain rocks given as slopes and norms 97 Table 5.6 Mineral vectors of measured mineral compositions for PER diagrams of Lava Fork basalt given as slopes and norms 102 Table 6.1 Representative analyses of bulk xenoliths, xenolith glasses and basement rock 112 Table 6.2 Summary of displacement vectors for measured assimilation material from Lava Fork for or-type PER diagram 125 Table 6.3 Results from mass balance calculations for Lava Fork basalt 129 Table 6.4 Isotopic data for basalts, basement rock and xenoliths from Lava Fork 130 Table 6.5 Results from mass balance calculations for Iskut River basalts 134 Table 6.6 Results from mass balance calculations for Snippaker Creek basalts 135 Table 6.7 Results from mass balance calculations for Cone Glacier basalts 137 Table 6.8 Results from mass balance calculations for Cinder Mountain basalt and hawaiites 139 Table 6.9 Summary of tests applied to Iskut-Unuk rivers centres to evaluate the processes of the petrogenesis of the centres 142 Table C.l Whole rock XRF chemical analyses from the Iskut-Unuk rivers centres measured by McGill. 186 Table C.2 Major and trace element analyses from the Iskut-Unuk rivers centres measured by GSC 190 Table D Electron microprobe analyses of olivine 194 Table E Electron microprobe analyses of clinopyroxene 205 Table F Electron microprobe analyses of oxides ' 208 Table G Electron microprobe analyses of plagioclase 211 Table H Electron microprobe analyses of glasses 240 Table 1.1 Replicate analyses for Iskut-Unuk rivers rocks with calculated analytical precision 244 Table I.2a Reproducibility on major elements by the GSC of in-house standards 245 Table I.2b Reproducibility on major elements by McGill of in-house standards 245 Table I.3a Duplicate analyses of FeO measured at UBC 251 Table I.3b Duplicate analyses of H 2 0 measured at UBC^ 251 Table I.3c Duplicate analyses of C0 2 measured at UBC 251 Table 1.4 Wet chemical analyses on FeO, H 2 0 and C0 2 measured at UBC 252 Acknowledgments I wish to sincerely thank my supervisor, Kelly Russell, for his inspiring and excellent guidance throughout the study as well as his sense of humor for Scandinavians. The thesis has been greatly improved by comments from Kelly as well as my supervisory committee; R.G. Anderson, L A . Groat and G.M. Dippie. I also wish to thank my fellow graduate students at UBC for their support and discussions, especially Ben Edwards, Lori Snyder, Brian Leuck, Yao Cui and Nathalie Marchildon. I would like to extend special thanks to Jon Bjorn Skulason for his support and motivation. Chemical analyses were supported by the Geological Survey of Canada, where the effort of R. Theriault is appreciated. M. Raudsepp provided training for electron microprobe analyses and his tireless assistance is greatly appreciated. S. Horski supervised wet chemical analyses at UBC. The technicians at UBC, M. Baker, B. Cranston and Y. Douma are thanked for their assistance. Normative mineralogy was calculated using NEWPET provided by D. Clarke at Memorial University at Newfoundland. Error propagation for Pearce Element Ratio diagrams was performed by PRATIO provided by J. Nicholls at the University of Calgary and modified by Y. Cui. Mass balance calculations were done with a program written by S. Kwong and J.K. Russell. I appreciate the assistance of BC Hydro, especially E.G. Enegren, for allowing access to all information compiled during the Iskut Canyon and More Creek projects in 1979-1984. The field work component of this research was funded by the Geological Survey of Canada (Project 840046). Ancillary funding for this project was provided by Natural Sciences and Engineering Research Council of Canada, Geological Society of America Research Grant and in part by UBC Graduate Fellowship. Chapter 1. Introduction CHAPTER 1 Introduction Eight Recent volcanic centres, called the Iskut-Unuk rivers centres, are scattered in an area bounded by the Iskut and Unuk rivers in northwestern British Columbia; they are part of the Stikine Volcanic Belt (SVB) (Figure 1.1). The centres are named after their geographic locations: Iskut River, Tom MacKay Creek, Snippaker Creek, Cone Glacier, Cinder Mountain, King Creek, Second Canyon and Lava Fork centres and they comprise lava flows, pillow basalt, cinder and ash that mostly occupy topographic lows (e.g., stream valleys). The volcanic rocks of Iskut-Unuk rivers centres are generally olivine and plagioclase porphyritic (Grove, 1974; Hauksdottir et al., 1994). Abundant large plagioclase crystals (up to 3 cm in length) as well as extremely diverse crystal habits and textures of plagioclase characterize lava flows from Iskut River, Snippaker Creek, Cone Glacier and King Creek volcanic centres. Crustal xenoliths are common in these volcanic rocks from the area; they are found in lavas from at least five centres: Iskut River, Snippaker Creek, Cone Glacier, King Creek and Lava Fork (Hauksdottir et al., 1994). 1 Chapter 1. Introduction The Iskut-Unuk rivers centres comprise alkali olivine basalts and minor hawaiites, the rock types commonly observed in the small monogenetic centres of the SVB. Volcanism in the area of the centres spanned 70,000 to ~150 years B.P. (BC Hydro, 1985), which makes this group one of the youngest in Canada. The location of the Iskut-Unuk rivers centres within the SVB, close to large composite volcanic centres, and their young age make them an important, as yet unstudied, part of the volcanic belt. The petrographic complexity observed in these rocks also offers an opportunity to study possible processes of open magmatic systems involving basaltic volcanic rocks and crustal assimilation. 1.1. Regional geology The Iskut-Unuk rivers centres occur within the Boundary Ranges of the Coast Mountains near the boundary between the Coast and Intermontane physiographic belts (Figure 1.1). The Stikine Volcanic Belt (Souther, 1990a) includes scores of relatively small pyroclastic cones and related lava fields and extends north across the central Coast Mountains and into southern Yukon. Three large, compositionally-diverse, volcanic complexes are located within the volcanic belt: Level Mountain (Hamilton, 1981), Edziza-Spectrum Complexes (Souther, 1992) and Hoodoo Mountain (Edwards and Russell, 1994; Edwards et al., in press). Volcanic centres within the Stikine Belt generally occur along several short en 2 Chapter 1. Introduction Figure 1.1. Location with distribution of associated lava flows of the Iskut-Unuk rivers volcanic centres and Hoodoo Mountain volcanic complex in the southern part of the Stikine Volcanic Belt, northwestern British Columbia. Inset includes locations of other volcanic centres of the SVB (Souther, 1990a). Coordinates are for U T M zone 9. 3 ? Chapter 1. Introduction echelon segments. Souther (1990a) suggests that the southern part of the belt, where the Iskut-Unuk rivers volcanic rocks are located, is associated with north-trending extensional structures developed in response to shearing along the transcurrent boundary between the continent and the Pacific plate. The Iskut-Unuk rivers area is underlain in part by metamorphic and plutonic rocks of Stikinia: the largest component of a composite terrane that was accreted to the continental margin in the Jurassic (Monger, 1984). The Iskut-Unuk rivers volcanic rocks overlie a basement comprising Paleozoic Stikine assemblage, Upper Triassic Stuhini Group, Lower to Middle Jurassic Hazelton Group volcanic and sedimentary rocks and Middle to Upper Jurassic Bowser Lake Group sedimentary rocks that have been intruded by Devonian, Triassic, Jurassic and Tertiary plutons (Britton et al. 1989, Wheeler et al. 1988, Wheeler et al., 1991; Anderson, 1993). The stratigraphic sequence has been folded, faulted and metamorphosed during late Jurassic and Eocene times (Anderson, 1989; Anderson, 1993; Evenchick, 1991). The maximum post-Pleistocene extent of many glaciers in the Iskut-Unuk rivers area is marked by sharply defined lateral and terminal trimlines. Studies of the Neo-glacial history of the Stikine-Iskut area have revealed that glaciers expanded and advanced about 4000 and 600-500 C14 years BP as conditions were cooler and moister than today (Ryder, 1987). Glacier recession during the twentieth century has probably been more rapid and prolonged than at any other time during the past 4000 years and glaciers now are smaller than at any time during this interval (Ryder, 1987). The recent retreat of the glaciers and rapid uplift of rocks is 4 Chapter 1. Introduction reflected in the extreme rugged nature of the area. Seismic activity in the Iskut River region has been recorded since 1965 when seismographs capable of locating epicentres of earthquakes with magnitude >4 were installed. In 1981 and 1983 permanent and portable stations enabled the locations of epicentres of earthquakes greater than M=2 (BC Hydro, 1984). High levels of microseismic activity have been recorded in the area that possibly are related to active glaciers. Few small earthquakes were recorded during 1981 and 1982 up to 3.6 (M) in magnitude (BC Hydro, 1984). 1.2. Access to area The closest urban centre to the Iskut-Unuk rivers area is the town of Stewart 100 km to the south. The terrain is very rugged comprising steep mountains covered by glaciers or heavy vegetation up to 3000 feet requiring helicopters for access and travel around the area. The valleys are covered with fairly dense forest, making traversing in lower altitudes difficult. Exposure of the lava flows is therefore poor in valleys except where they are crosscut by big and very fast glacial rivers which also limit access to many locations. 5 Chapter 1. Introduction 1.3. Previous studies of the Iskut-Unuk rivers centres Most of the Iskut-Unuk rivers centres were first described by regional mapping programs of the Canadian Cordillera. Wright (1906) briefly described the two southernmost centres, Lava Fork and Second Canyon. Kerr (1948) provided more comprehensive descriptions of the Iskut River lava flows, complete with basic petrographic descriptions of the basalts. Grove (1974) visited and sampled most of the Iskut-Unuk rivers volcanic centres and published chemical analyses from six of the Iskut-Unuk rivers centres along with brief descriptions of the rocks. His compilation for the Unuk River-Salmon River-Anyox area also put the Iskut-Unuk rivers volcanoes into context by showing the distribution of all Recent volcanic rocks within the Iskut-Unuk rivers area and beyond (Grove, 1986). The most detailed mapping of Iskut-Unuk rivers volcanic centres derives from unpublished BC Hydro reports compiled between 1982 and 1984 as part of the Iskut Canyon and More Creek hydro-projects (BC Hydro, 1985). This work primarily addressed the Recent geological history of the area and provided 1:50,000 and 1:10,000 scale geological mapping, C 1 4 and K-Ar dating of Recent volcanic rocks, as well as diamond drilling of the Iskut River lava flows. Regional geological maps of the area (Britton et al., 1988, 1989; Read et al., 1989) include distributions of Recent volcanic rocks in the Snippaker and Unuk River areas. Elliott et al. (1981) and Brew (personal communication, 1990) describe lava flows and stratigraphic 6 Chapter 1. Introduction relationships from the Lava Fork centre, much of which has been summarized by Souther (1990b). Reconnaissance studies by Stasiuk and Russell (1990) of the Iskut-Unuk rivers volcanic centres provided more complete petrographic descriptions. Hauksdottir et al. (1994) revised field relationships and geological maps and extended the number of volcanic centres from six (e.g., Souther (1990b) to eight. Cousens and Bevier (in press) have compiled isotope and trace element data for four of the Iskut-Unuk rivers volcanic centres. 1.4. Scope of study This study provides an overview of field relationships and volcanological features of the Iskut-Unuk rivers centres, as well as mineralogical and chemical characterization of the volcanic rocks. These characteristics establish the nature of magmatic differentiation and elucidate some source-region processes of the volcanic centres. In particular, the abundant crustal xenoliths and diverse assemblages of xenocrysts suggest the possibility of extensive assimilation. In the first part of the thesis (Chapter 2), field relationships, rock types and distributions of volcanic formations of the Iskut-Unuk rivers volcanic centres are described. The second part (Chapter 3) deals with petrography and mineral chemistry of the rocks with an emphasis on disequilibrium textures commonly found in plagioclase crystals. The different textures are discussed along with a photographic atlas describing the features observed. The 7 Chapter 1. Introduction last part of the thesis (Chapters 4, 5 and 6) presents whole rock major, and trace, rare earth element and Sr-Nd isotopic compositions which help characterize the rocks and permit comparisons to other volcanic centres in the area. Explanations for chemical variations found within and between the volcanic centres are sought in i) magmatic differentiation (e.g., crystal fractionation), ii) assimilation and iii) source region processes. 8 Chapter 2. The Iskut-Unuk rivers centres CHAPTER 2 The Iskut-Unuk rivers centres The field descriptions presented in this chapter derive from compilation of fieldwork by Stasiuk and Russell (1990), Hauksdottir et al. (1994) and BC-Hydro's Iskut Canyon and More Creek projects during 1979-1984. In particular, BC Hydro's (1985) program provided extensive basic mapping and age determinations, which this study has adapted and expanded (Hauksdottir et al., 1994). Minor modifications to BC Hydro's maps for the volcanic material distribution also resulted from this work. The eight volcanic centres of the Iskut-Unuk rivers area are described in order from north to south: Iskut River, Snippaker Creek, Cone Glacier, Cinder Mountain, King Creek, Second Canyon and Lava Fork. Table 2.1 summarizes the general volcanological information for each of the centres including age, estimated surface area and maximum thickness of volcanic rocks (BC Hydro, 1985; Read et al., 1989; Hauksdottir et al., 1994). 9 Chapter 2. The Iskut-Unuk rivers centres Table 2.1. General volcanological information on Iskut-Unuk rivers centres. Centre Age (years) Method Rock type Vents Surface area (km2) Thickness (m)1 min. max. Iskut River 70,000±30,000 K-Ar Basalt 3 37.5 3 230 to 2555±60 C 1 4 Tom MacKay Creek Recent Basalt 1 0.4 ? 30 Snippaker Creek Recent Basalt 1? 6.2 2 24 Cone Glacier Recent Basalt 2 4.3 3 21 Cinder Mountain 33,000±24002 Basalt, 1 5.4 ? 154 Hawaiite King Creek Recent Basalt 1 1.3 ? 50 Second Canyon Recent Basalt 2 8.6 3 15 Lava Fork 360+60 C 1 4 , tree ring Basalt 2 21.9 0.5 10 to ~1503 "i 5 ^ Estimate of thickness of lava flows. Date from Copper King Creek lava flow. One flow is older than 360 years. 4 Estimate of basalt flow at Copper King Creek. 2.1. Iskut River Figure 2.1 shows the distribution of Recent lava flows along the Iskut River and the locations of three proposed volcanic vents which have produced both lavas and cinder. The estimated range in volume of Iskut River volcanic rocks is 0.12 to 8.6 km3 based on the minimum and maximum thickness of lava flows where they have filled up an ancient canyon formed by the Iskut River (Table 2.1). Today the river forms a canyon that dissects at least ten thick, subaerial lava flows; at least two other younger lava flows cover the eastern part of these flows (BC Hydro, 1985). Contacts between these younger lavas and underlying flows are partly marked by differences in vesicularity between the base of one flow and the top of the other. All of the flows observed are porphyritic with plagioclase and olivine phenocrysts, a 10 Chapter 2. The Iskut-Unuk rivers centres Chapter 2. The Iskut-Unuk rivers centres feature that makes separation of flows in the field difficult. The surfaces of Iskut River lava flows are vegetated and characteristically cindery, blocky and hummocky, preserving some flow structures. Flows at the base of the Iskut River volcanic centre are about 70,000 years old, based 14 on K-Ar dating; the overlying basalt flows are dated at 8730 years (C ) (BC Hydro, 1985; Read et al., 1989) (Table 2.1). Younger ash deposits represent possibly the most recent volcanic activity in the area, dated at 2555±60 (C14), but the youngest lava flows have not been successfully dated (BC Hydro, 1985). The youngest, and major vent exposed, lies to the southeast of the lava flows and is capped by a well-formed symmetrical cinder cone (BC Hydro, 1995). Two other vents are suggested by reddish to brown pyroclastic material which form small round mounds just east of windows of exposed basement rocks (Figure 2.1). Both vents are surrounded and almost engulfed by the two youngest lava flows fed by the main vent (BC Hydro, 1985). The main vent appears to have repeatedly erupted lava which dammed both Tom MacKay and Forrest Kerr creeks (BC Hydro, 1985). This inference is based on C 1 4 dating of plant remains in lake sediments associated with these ephemeral dams. These age determinations (BC Hydro, 1985; Read et al., 1989) suggest lava effusion occurred 3800, 5600 and 6500-6800 years ago; the Iskut River Canyon was eroded to its present configuration in the last 3600 to 3800 years (BC Hydro, 1985). 12 Chapter 2. The Iskut-Unuk rivers centres 2.2. Tom MacKay Creek A single flow unit composed of highly-weathered fragmented pillow basalt occurs in Tom MacKay Creek just east of the Iskut River lava flows (Figure 2.1). The pillow lava locally forms 20-30m high cliffs and maximum volume is estimated around 0.012 km3 (Table 2.1). Individual pillows are 20-40 cm in diameter, very vesicular, radially jointed and commonly have glassy rinds. These thick, restricted accumulations of pillow lava have probably resulted from subaqueous volcanic eruption possibly against or close to ice (BC Hydro, 1985). 2.3. Snippaker Creek Recent lava distributions within the lower part of Snippaker Creek drainage are shown in Figure 2.2 (Table 2.1). The lavas outcrop from stream level to approximately the 1000 foot contour and the maximum volume of lava is 1.5 km3. Representative samples were collected from three locations: i) the southern terminus, ii) close to the suggested vent area (BC Hydro, 1985) and iii) at the northern terminus where up to 6 flows, each at least 3-5 m thick, are exposed in a narrow, steep-sided canyon through the flow sequence. Contacts between flow units are marked by changes in vesicularity between flow tops and scoriaceous flow bases. Flows from the three localities are indistinguishable. They have grey, vesicular fresh 13 Chapter 2. The Iskut-Unuk rivers centres Figure 2.2. Distribution of lava flows at Snippaker Creek volcanic centre. Coordinates from U T M zone 9, map 104B/10, 1:50,000. 14 Chapter 2. The Iskut-Unuk rivers centres surfaces and are plagioclase and olivine porphyritic; phenocrysts range in size from 0.1 to 1 cm. Where the northern terminus of these flows abuts against lavas of the Iskut River lava flows they are indistinguishable in hand sample (BC Hydro, 1985) 2.4. Cone Glacier The Cone Glacier volcanic centre comprises two prominent cones and several lava flows (Figure 2.3; Table 2.1). Lava flows emanate from the Cone Glacier area, cover a portion of Snippaker Creek (to the west) and underlie Julian Lake and the King Creek drainage (to the south). Near the western terminus only 1-3 flows are exposed overlying till and fluvial deposits (BC Hydro, 1985). The maximum volume of lava flows and cinder erupted from both vents at Cone Glacier volcanic centre is close to 0.1 km3. Lava flow surfaces are blocky and heavily vegetated except above 3500 feet on the saddle immediately north of Cone Glacier. The recent retreat of Cone Glacier has left the lava exposed and striated. Cone Glacier takes its name from a 300 m high, well-exposed volcanic cone (west cone) of grey cinder, hyaloclastite and basaltic ash. On the northern side of west cone the lowest unit is pillow lava. The pillows are radially jointed, have glassy rinds and a concentric distribution of vesicles. Hyaloclastite breccia overlies the pillowed lava and consists of fragments of lava and glass in a brown-gold colored, devitrified basaltic glass matrix 15 Chapter 2. The Iskut-Unuk rivers centres 6275000 6265000 Figure 2.3. Distribution of lava flows, pillow lava and pyroclastic rocks at Cone Glacier and Cinder Mountain volcanic centres. Coordinates from U T M zone 9, map 104B/10, 1:50,000. 16 Chapter 2. The Iskut-Unuk rivers centres (palagonitized sideromelane). Most of the cone is made up of pyroclastic cinder representing subaerial eruptions. No flows are observed originating from the west cone. The majority of lavas that have reached the SnippakerCreek drainage to the west probably have a source to the east of west cone. Another well-dissected and nearly vegetation-free cone of red cinder and scoria (east cone), northeast of Cone Glacier, may be the source to the lavas in the Snippaker Creek drainage. North of Cone Glacier on the south side of Snippaker Creek a cliff provides exposure of up to seven different flow units. They are generally 2-3 m thick with scoriaceous and brecciated bottoms and tops. All of the lava flows are characterized by abundant, coarse (up to 4 cm long) megacrysts of euhedral glassy plagioclase (Figure 2.4) and also contain phenocrysts of olivine and smaller plagioclase crystals. Cinder and scoria derived from both west and east cones are mineralogically similar. Diverse crustal xenoliths are found in most of the lava flows; most are granitic. Commonly they are concentrated at the base of a flow and probably were incorporated into the lava after it erupted. Remnants of three lava flows are found on the eastern margin of east cone. The provenance of these lavas is somewhat ambiguous because they are equidistant to the Cinder Mountain volcanic centre (see below). Based on the abundant large plagioclase phenocrysts and the fact that these lavas occur at an elevation below or equal to the remnant of east cone, they lavas are interpreted as part of the Cone Glacier centre. 17 Chapter 2. The Iskut-Unuk rivers centres Figure 2.4. Photograph showing the characteristic megacrysts of plagioclase and crustal xenoliths (5-7 cm) of Cone Glacier lava flows. 2.5. Cinder Mountain Cinder Mountain volcanic centre is located immediately east and northeast of Cone Glacier. The distribution of volcanic units shown in Figure 2.3 is an estimate because ice, snow, talus and minor vegetation obscure the rocks. Cinder Mountain lava flows and hyaloclastite breccia are mainly exposed on the south and west slopes of Cinder Mountain and as a single outcrop to the north near Copper King Glacier. 18 Chapter 2. The Iskut-Unuk rivers centres Hyaloclastite breccia is the most voluminous stratigraphic unit at Cinder Mountain found overlying basement rock at 5000 feet and is overlain and grades into hawaiite subaerial lava at the top of the mountain (6200 feet). The hyaloclastite is golden-brown colored and comprises basaltic fragments and basaltic glass in a matrix of palagonitized sideromelane. The hyaloclastite varies from basaltic rock fragment-dominated breccia with very little matrix to breccia that is dominantly basaltic glass fragments. These variations define the prominent 10-50 cm scale layering observed in the hyaloclastite. Basaltic dykes with chilled margins commonly cut the hyaloclastite breccia. Elsewhere massive basalt bodies apparently intrude the hyaloclastite and grade into pillow- like bodies with glassy rinds (Figure 2.5). These dykes Figure 2.5. Pillow like bodies within layered hyaloclastite breccia at Cinder Mountain volcanic centre. Outcrop is about 10 m in length. 19 Chapter 2. The Iskut-Unuk rivers centres are distinct from lavas erupted from the Cone Glacier centre in that they are light-grey in colour, very massive and have rare, small feldspar crystals. The breccia is more finely and regularly layered where the hyaloclastite breccia is in contact with basement rocks (plutonic and metamorphic rocks). The layers are characterized by internal planar and cross-laminations suggesting significant transport and reworking. Layering, commonly defined by variable glass content, dips up to 30° to the north, and probably reflects the paleoslopes along which the hyaloclastite debris was transported. Close to Copper King Glacier, near the head of Harrymel Creek, the remnant of a single flow is exposed. It overlies till and itself is overlain by an ablation moraine (BC Hydro, 14 1985). The flow forms a 15-20 m high wall of columnar jointed basalt. C dating of a sample recovered from the till-basalt contact gives a maximum age of 33,000 +2400 years (BC Hydro, 1985) (Table 2.1). The lack of megacrystic feldspar and xenoliths and overall paucity of phenocrysts suggests the lava was erupted from the Cinder Mountain centre. Souther (1990b) suggests eruption of the subaerial lava of Copper King Creek postdates failure of an ice dam retaining subglacial meltwater. 20 Chapter 2. The Iskut-Unuk rivers centres 2.6. King Creek The King Creek centre is dominated by pillow lavas and associated breccias. The lavas are exposed in a steep narrow creek south of Cone Glacier (Figure 2.6; Table 2.1) where they form a 40-50 m cliff. The pillow lavas and overlying breccias are exposed from stream-level to about 1070 m elevation (Stasiuk and Russell, 1990). Individual pillows are commonly N6263000 N6280000 Figure 2.6. Distribution of pillow basalt and breccia at King Creek volcanic centre. Coordinates from UTM zone 9, map 104B/7, 1:50,000. surrounded by scoriaceous breccia. A 1-2 m wide vertical dyke crosscuts the pillow lavas. As at Tom MacKay Creek, the restricted extent of thick pillowed lava and associated breccia suggest that the lava was erupted underneath or against ice. 21 Chapter 2. The Iskut-Unuk rivers centres 2.7. Second Canyon The Second Canyon centre comprises a single blocky lava flow, that is estimated to range from 0.03 to 0.13 km3 in volume; its eruption forced the Unuk River against its eastern bank (Figure 2.7). Subsequent dissection of the lava formed Second and Third canyons. The walls to these canyons are 15 m high cliffs of columnar jointed basalt lava (BC Hydro, 1985). The lava flow overlies fluvial sediments and the presence of a scoriaceous, flow-structured lava surface suggests that the eruption was post-glacial (BC Hydro, 1985). The source to this single flow unit is either a tree-covered cone located at the confluence of Unuk River and Canyon creek or on the slope immediately above Canyon Creek, about 4 km upstream from the same confluence (e.g., BC-Hydro, 1985; Stasiuk and Russell, 1990)(Table 2.1). 2.8. Lava Fork The Lava Fork volcanic centre includes basaltic cinder, ash and at least three lava flows, which are exposed at the confluence of Blue and Unuk rivers. Dissection by Unuk River at the southern terminus of the flows formed First Canyon (BC Hydro, 1985). The distribution of volcanic material shown on Figure 2.8 includes undifferentiated cinder and ash deposits as well as lava flows; maximum volume of lava is around 2.2 km3 (Table 2.1). A possible vent for the older flows is a tree-covered cinder cone located 4 km downstream of Blue Lake (BC Hydro, 1985) but the youngest flow erupted from a vent located on a ridge on 22 Chapter 2. The Iskut-Unuk rivers centres N6253000 N6246000 Figure 2.7. Distribution of Second Canyon volcanic centre lava flow. Coordinates from U T M zone 9, map 104B/7, 1:50,000. 23 Chapter 2. The Iskut-Unuk rivers centres N6233000 Figure 2.8. Distr ibut ion of lava f lows, cinder and ash at Lava Fork volcanic centre. Coordinates f rom U T M zone 9, map 104B/7, 1:50,000. 24 Chapter 2. The Iskut-Unuk r ivers centres the eastern side of Lava Fork valley. The lava flowed south, along the valley and southeast along Blue River valley, damming the river and forming Blue Lake. Near the main vent, the volcanic rocks overlie basement rocks, including foliated biotite-quartz-schist intruded by granodiorite. A layer of basaltic cinder and glassy ash covers the lava flows as well as the area to the east towards Leduc Glacier and Twin John Peaks (Grove, 1986). Near its source, the youngest lava flow has ropey pahoehoe surfaces and forms well-developed small lava channels and lava tubes. Spatter, cinder and ash are abundant around the vent. Downslope and away from the vent, the flow surface abruptly changes to aa and splits into two main streams (north and south forks). The lava streams form large channels with several generations of prominent levees. Accretionary lava balls are common on the flow surface of the north fork lava. They are approximately 5 m in diameter and consist of a red cinder breccia coated by massive flow material which itself exhibits radially-oriented irregular jointing. Xenoliths of basement rocks occur in both the interior and exterior portions of the lava balls. Crustal xenoliths are common throughout the lava and are primarily granitic rocks and metamorphic schist. The xenoliths are mainly angular, range in size from 1 to 30 cm in diameter, and resemble the basement rocks underlying the main vent area (Figure 2.9). The apparent degree of reaction between lava and xenolith varies between xenoliths which show considerable interaction with lava and are porous, granular and friable and those which show no signs of reaction (e.g., reaction rims). Commonly, the host basaltic melt has invaded the 25 Chapter 2. The Iskut-Unuk rivers centres latter xenoliths along thin fractures. Figure 2.9. Volcanic bomb from Lava Fork volcanic centre containing vesiculated and glassy granitic xenolith coated with quenhed basalt. C 1 4 dating of a partly charred conifer log from the surface of one of the flows yielded an age of 360 ±60 years BP. (Elliott et al., 1981). Grove (1986) argued for an age of 130 BP. based on C 1 4 dating of material associated with the lower flows. Tree-ring counts on living trees and observations of the lava flow surface give an estimate of 150 years for the youngest flow (BC Hydro, 1985). Living trees on the surface of the older flows give a minimum age of 350 years (BC Hydro, 1985). 26 Chapter 3. Minera logy and mineral chemistry CHAPTER 3 Mineralogy and mineral chemistry This chapter provides a petrographic description of the Iskut-Unuk rivers mafic and intermediate rocks and their mineral chemistry. The rocks are petrographically complex; phenocrysts show a variety of textures, habits and zoning patterns and the rocks contain abundant crustal xenoliths. The chapter is divided into three parts, including: i) descriptions of the minerals found in the rocks, ii) a summary of mineral compositions and iii) an analysis of the whole variety of populations of plagioclase in the Iskut-Unuk rivers rocks. 3.1. Petrography and general characteristics Recent volcanic rocks from the 8 centres within the Iskut-Unuk rivers area consist of alkali-olivine basalt and hawaiite. The basaltic rocks are petrographically similar; they are generally fine-grained, vesicular, plagioclase and olivine porphyritic. More detailed petrographic descriptions are provided in Appendix A. Table 3.1 summarizes the petrographic characteristics for each of Iskut-Unuk rivers centres. Lavas from all centres include 27 Chapter 3. Mineralogy and mineral chemistry phenocrysts of olivine and plagioclase and basalts from at least four centres also contain rare, partly resorbed clinopyroxene. The groundmass is always composed of plagioclase, olivine, clinopyroxene and oxides and hawaiites also contain apatite. Table 3.1. Summary of petrographic characteristics of the Iskut-Unuk rivers centres1. Centre Phenocrysts Ground mass Other OL PL CPX 2 OL + PL Titan Qtz+fsp Olivine Olivine + CPX augite3 xenoliths autoliths4 xenoliths Iskut River X X X X grm X X -Tom MacKay Creek X X X X grm - X -Snippaker Creek X X - X grm X X -Cone Glacier X X X X grm, vsc X X -Cinder Mountain X X - X - X - X King Creek X X X X grm, vsc - - -Second Canyon X X - X - - - -Lava Fork X X - X - X - -1 based on thin-section analyses. 2 only as inclusions in megacrystic plagioclase or rare resorbed crystals. grm = well developed cpx groundmass, vsc = vesicles coated with intergrown cpx and oxides, commonly as resorbed glomerocrysts. Olivine phenocrysts are generally euhedral to subhedral, up to 3 mm in size and comprise 3-20% of the rock. Inclusions of primary oxides and groundmass phases are common. Rare slightly sieved phenocrysts or glomerocrystic olivine are found in basalts from Iskut River, Snippaker Creek, Cone Glacier, Cinder Mountain and King Creek (Table 3.1). The origin of the resorbed crystals of olivine are somewhat problematic; they are probably autoliths representing early cognate crystals that have partially reacted to changes in physical and/or chemical conditions in the magma. At least one highly resorbed crystal was observed in the intermediate rocks from Cinder Mountain: embayed, anhedral and distinctly larger (4 mm) than other phenocrysts in the same sample. 28 Chapter 3. Minera logy and mineral chemistry Plagioclase is generally the most voluminous phase in the Iskut-Unuk rivers rocks, comprising 10-75% of modal volume and is always present as phenocrysts. Crystals show Carlsbad and/or Albite twinning but twinning of phenocrysts from Cinder Mountain hawaiites show distorted, multiple, narrow and discontinuous twin planes (Figure 3.1). Plagioclase phenocrysts in the intermediate rocks are commonly rounded and embayed. In sample (SH-35), a single xenocrystic plagioclase includes low temperature alteration minerals(carbonate and white mica). One of the main characteristics of the basaltic rocks is the presence of large (1 mm to 3 cm) plagioclase crystals and the wide variety of textures and habits they exhibit (see section 3.3) Clinopyroxene occurs in the groundmass of all lavas from the Iskut-Unuk rivers centres as small tabular, almost colorless grains in the groundmass or brown-purple pleochroic subhedral laths where it is well developed (Table 3.1). Iskut River, Tom MacKay Creek, Snippaker Creek, Cone Glacier and King Creek centres all contain one or more samples where the groundmass clinopyroxene is well developed, comprising 15 to 25% of the rock. The clinopyroxene is titanaugite, characterized by the distinct brown and violet color. In basalt samples from Cone Glacier and King Creek vesicles are commonly coated with intergrown dark colored titanaugite and dendrite oxides. Rare grains of partly resorbed clinopyroxene, up to 0.25 mm in size, occur in basaltic samples from four centres (Iskut River, Tom MacKay Creek, Cone Glacier and Cinder Mountain) (Figure 3.2). Clinopyroxene is also found as inclusions in megacrysts of plagioclase. These occurrences suggest a high-pressure cognate rather than a xenocrystic origin. 29 Chapter 3. Minera logy and mineral chemistry Figure 3.1. Photomicrograph of the characteristic complex twinning and anhedral form of plagioclase from Cinder Mounta in hawaiites. F ie ld of v iew is 2.63 mm. The groundmass always comprises olivine, plagioclase, clinopyroxene, Fe-Ti oxides and sometimes apatite. The texture of the basalts is always vesicular and ranges from intersertal to intergranular, depending on the presence or lack of glass. Where clinopyroxene is well developed it forms subophitic texture with plagioclase. The hawaiites show a subtrachytic texture with abundant small laths of plagioclase. All Iskut-Unuk rivers volcanic rocks contain magnetite and ilmenite in the groundmass; they make up 5-15% of modal volume (Table 3.1). A single rounded opaque 30 Chapter 3. Mineralogy and mineral chemistry Figure 3.2. Resorbed crystal of clinopyroxene from Tom MacKay Creek basalt Field of view is 2.63 mm. grain was observed in a sample from Iskut River (LR-3); the grain is 0.8 mm in diameter and probably is a xenocryst. Volcanic rocks from Second Canyon contain chromite in the groundmass. Apatite occurs as microphenocrysts in hawaiites from Cinder Mountain (Table 3.1). It is usually associated with magnetite but is sometimes found with olivine. The grains range is size from 0.1 to 0.2 mm. 31 Chapter 3. Mineralogy and mineral chemistry Quartz xenocrysts and crustal xenoliths of quartz and feldspar rich material are found in thin section and/or hand sample in all centres but two (Tom MacKay Creek and Second Canyon). This may reflect the fact that there is only a single sample for each of these centres. In thin section, the xenoliths are usually fine grained, rounded and highly resorbed. Quartz xenocrysts show reaction rims of clinopyroxene. 3.2. Mineral chemistry The following section shows mineral chemical compositions for the Iskut-Unuk volcanic rocks. Partial sets of mineral analyses are presented in Table 3.3. They are intended to show the quality of the analyses and some of the minor element compositions. Representative mineral analyses are listed for most of the different textural types found within each centre. 3.2.1. Olivine Olivine phenocrysts of the Iskut-Unuk rivers basalts range from Fo6i to Fog3 and olivine in the groundmass shows a similar range in composition (F055-81) (Table 3.2, Appendix D). The highest Fo contents (F080-83) are seen in Tom MacKay Creek, King Creek, and Second Canyon lava flows, and olivine phenocryst in hawaiites from Cinder Mountain are the 32 Chapter 3. Mineralogy and mineral chemistry least forsteritic (F033.54). A large sieved crystal from sample from Cinder Mountain, CM-21, shows reverse compositional zoning from core (F033) to the rim (F052) and is also more iron rich than other crystals from the same sample. The rim represents the same composition as found in the groundmass; the crystal is possibly xenocrystic. M g ( W t % ) Figure 3.3. Chemical variation of olivine compositions from Iskut-Unuk rivers centres. Olivine from Tom MacKay Creek, Second Canyon and King Creek basalts are generally more forsteritic (Fo77.83) than from Iskut River, Snippaker Creek and Lava Fork (Fo69.19). 33 Chapter 3. Mineralogy and mineral chemistry Table 3,2. Selected chemical analyses of olivine from Iskut-Unuk rivers volcanic rocks. Centre Iskut River Tom MacKay Creek Snipp. Creek Cone Glacier Cinder M Sampl IR-3 IR-8 SH-39 SH-33 SH-14 SH-26 SH-21 Grain MP9-i P9-i P6-i G-i SPll-i Pl-i Pl-r P3-i P7-i MPlO-i SPl-i SPl-r Si0 2 37.95 36.84 35.38 37.05 36.33 38.27 38.21 37.91 36.90 34.91 32.07 33.78 Ti0 2 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. A1203 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. Cr 2 0 3 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. FeO 22.77 25.45 19.07 19.95 18.96 22.71 21.82 19.32 27.54 37.33 51.36 40.20 NiO b.d. b.d. 0.11 b.d. 0.08 b.d. 0.08 b.d. b.d. b.d. b.d. b.d. MnO 0.36 0.36 0.28 0.25 0.26 0.32 0.28 0.27 0.40 0.66 1.25 0.68 MgO 37.69 36.58 41.89 40.56 41.36 38.19 39.53 41.49 34.41 26.37 14.49 23.96 CaO 0.27 0.17 0.20 0.31 0.27 0.22 0.25 0.24 0.20 0.41 0.34 0.32 Total 99.04 99.40 96.93 98.12 97.25 99.72 100.17 99.23 99.45 99.68 99.51 98.95 Fo% 74.41 71.76 79.45 78.04 79.25 74.75 76.09 79.03 69.17 55.39 33.28 51.26 Fa% 25.22 28.00 20;29 21.54 20.38 24.93 23.56 20.65 30.55 44.00 66.16 48.25 La% 0.38 0.24 0.27 0.43 0.37 0.31 0.35 0.33 0.28 0.61 0.55 0.49 P=phenocryst, MP=microphenocryst, SP=sieved phenocryst, G=groundmass, i=interior, r=rim Table 3.2. Continued Centre Cinder Mountain King Creek Second C Lava Fork Sampl SH-21 SH-35 KC-22 SC-23 SH-50 SH-54 Grain P2-i P12-i P12-r MP16-i P4-i G7-i P8-i GlO-i P6-i G l l - i P3-i Si0 2 34.06 35.09 36.15 33.57 38.89 37.03 38.27 38.62 38.27 37.42 38.25 Ti0 2 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. 0.12 b.d. A1203 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. Cr 2 0 3 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. FeO 39.51 27.90 30.66 34.23 17.55 23.41 18.01 18.80 20.09 23.00 21.57 NiO b.d. b.d. b.d. b.d. 0.18 b.d. 0.20 0.13 0.13 b.d. 0.06 MnO 0.61 0.41 0.53 0.68 0.27 0.30 0.19 0.21 0.25 0.27 0.26 MgO 24.72 34.72 32.35 28.95 42.75 37.83 42.62 41.82 41.11 37.76 39.57 CaO 0.27 0.25 0.27 0.38 0.22 0.32 0.24 0.34 0.21 0.36 0.24 Total 99.17 98.37 99.96 97.82 99.86 98.89 99.54 99.90 100.06 98.93 99.95 Fo% 52.52 68.68 65.04 59.79 81.04 73.89 80.57 79.50 78.25 74.15 76.32 Fa% 47.08 30.96 34.57 39.65 18.66 25.66 19.10 20.04 21.46 25.34 23.35 La% 0.41 0.36 0.38 0.56 0.30 0.45 0.32 0.46 0.29 0.51 0.33 34 Chapter 3. Minera logy and mineral chemistry Figure 3.3 shows all measured olivine compositions for the Iskut-Unuk rivers volcanic rocks plotted as wt% Ca and Mn vs. wt% Mg. The olivines from the Iskut-Unuk rivers lavas usually contain more than 0.1 wt% Ca which corroborates with the extrusive origin of the rocks as shown by Simkin and Smith (1970). Mn content of olivines from the Iskut-Unuk rivers volcanic centres is consistent with major element fractionation trends (Simkin and Smith, 1970). 3.2.2. Plagioclase Figure 3.4 shows the variation in plagioclase composition from the Iskut-Unuk rivers centres, subdivided into phenocrysts and groundmass. Plagioclase compositions range from high anorthite (An94,Or 0.i) to anorthoclase (An5.2, Or32). Phenocryst compositions are commonly more albitic than the groundmass. Table 3.3 lists select electron microprobe analyses of plagioclase from the Iskut-Unuk rivers centres (Appendix G). Table 3.4 lists the range of plagioclase compositions for each of the 8 centres divided into phenocrysts/xenocrysts and groundmass. The previous group includes: megacrysts, phenocrysts and microphenocrysts together with grains showing sieved textures. There are two types of sieved textures: i) 'sieved cores' where the sieved texture is in the core but the rim is solid, and ii) 'sieved interior' where the grain has a solid core with a mantle of sieved texture that is again overgrown by zoned plagioclase. The phenocrysts/xenocrysts generally range from Arus to An7o except for flows from Iskut River, Snippaker Creek and Cinder Mountain which are characterized by lower An-content and few crystals from Iskut River 35 Chapter 3. Mineralogy and mineral chemistry Figure 3.4 a. Compositional range of feldspar from Iskut River, Tom MacKay Creek, Snippaker Creek and Cone Glacier volcanic centres on ternary Ab-An-Or diagram. The solid line represents the solvus isotherm at 1000°C and 1 atm (Ghiorso, 1984). 36 Chapter 3. Mineralogy and mineral chemistry A n A n A b Second Canyon Lava Fork Or Figure 3.4 b. Compositional range of feldspar from Cinder Mountain, King Creek, Second Canyon and Lava Fork volcanic centres on ternary Ab-An-Or diagram. The solid line represents the solvus isotherm at 1000°C and 1 atm (Ghiorso, 1984). 37 Chapter 3. Mineralogy and mineral chemistry • 2 l<-> IS E 1 SH-33 V C O 2 53.98 29.02 0.48 0.08 b.d. b.d. 11.44 4.75 0.33 100.08 55.71 41.85 1.89 r- oo p T CN CN •d •d o Ov m CN 0 0 Os VO •<r 0 0 VO 6 CN m O N CN -~ d -d xi CN d Os OS VO i n ro CN •q-•^ r ON VO m •d •d m CO Ov VO CN 0 0 o as r-as P7 o m © ro © d xi x i CO d OS OS ON vo 0 0 CN d SH-39 u 1 O H 54.11 28.67 0.38 0.06 b.d. b.d. 11.28 4.85 0.53 99.88 54.27 42.20 3.04 U 1 •cr i n VD i n - •d ro o •n CN CN Ov VO o i n 5o C N m OV CN d d xi xi CN Ncr d as as SO vd CO — V VO CN CN o i n VO © •d •d CO i n o VO vo f~ SO 0 0 •q-CN ro i n VO m r-' CN d d xi x i OS i n d Ov Ov vd ON ro • Ov p */-! VO i n Ov 0 0 o •d •d O o CN VO O CN 0 0 O T)-m 6 CN i n Os CN o d xi x i ro d d o CN VO i n ro — V ro Ov co CN vo i n 0 0 -d •d i n Ov •cr m ro ro 0 0 r~ O vo NO i n O N OO ro i n 0 0 CN o d xi x i — •cr d Ov Ov tS i n ON ro OO CJ co 0 0 i n VD r-~ i n •a •a •d Ov CN VO Os SO Ov CN 0 0 m VO 1 oo vd i n vd CN d xi xi x i Ov i n d as Os i n ro 1 co VO O 0 0 ro i n Ov o •d •d 0 0 0 0 •cr p CN CN •q-ro r-ro i n !2 OO C N i n Os CN d d xi x i CN d d o CN VO i n ro — o 0 0 •q-i n OV ro -a •d i n OS r~ Os VO i n VO SO O m r- 0 0 VO 0 0 VO m vd CN O xi xi d Os i n d Os as <cr m ro t-l 0 0 ro O vo C N •d •d r- OS VO CN CN m r~- ON ro Os ro oo C M m © ro o d x> x i co CO d Ov Ov 3 CN ro — 9 o Ov ? o ro vo o •d •d OS oo ro ro ro O N m i n Ov P8- ro m 0 0 CN © d xi xi '—' •a d ov Ov m CN •<r 1 ro Ov 0 0 Ov •cr -d •d CO OV CN CN Ov CO ro Ov i n tN CN m OV CN d d xi xi ro ro d Ov OV VO ro ro — O l l/N. CN O m ro - •d •d 0 0 0 0 vo •cr vO CN vO i n CN ro m O m 1 ro i n Ov CN d d xi xi — •CT d Ov Ov 0 0 m Ov ro — Ov t-•cr •d •d vo T ro •cj- CN CO ro O ON <N ro ro 0 0 6 CN m Ov CN © d xi xi CN •cr d d o ON m 0 0 ro — SC6-r VO O 0 0 CO •d •d OV o 0 0 NCJ-ro ro o o 0 0 Ov o Ov SC6-r ro m Ov <N d d xi xi CN d d o 0 0 m 0 0 ro CI SC6-c ro Ov CN vo o •d •d © •3- 5- CN r--ro m o vo ro o SC6-c m SO CN d d xi xi 0 0 so d d o d i n i n C N ON VO CN VO CN •d •d VO O o <N VO OV CN CO VO ro oo ro P8 CN m Ov CN d d xi xi ro d Ov ON CN SO i n CO '— 1 u m ro CN VO •d •d •d ov CN CN O i n 0 0 0 0 ro ro 0 0 CL , "cr i n ro d xi xi x i o< d d Os Os ON i n d (L) "c Ot Grain o oo o 3 O CJ fcL, MgO BaO SrO CaO O r-l C3 O CN Total An% Ab% Or% 0 0 "3. 1 CO 0 0 so O •d •d o p CN m 0 0 ro m ON ON 0 0 ON ON oo C O i n 0 0 CN d d x i x i CN d ON ON m ON CO CN V CN 0 0 ON o CO •d •d •d m r-SO ro ro NO O N SO ON r-m CN 2; oo od m i n CN d x i x i x> vd d ON ON SO CO 0 0 m i n 0 0 ON t--SO p Os •d 0 0 ON ro ON vo r-ON CN •q-m 0 0 oo Ov 6 i n m CN d d d x i ON i n d ON ON 0 0 vd CO i vo O 0 0 r-o ro •d •d •d s r~ ON m ro O i n m r- o •cr P7 vd m CN d xi x i x i d i n d d o 0 0 •<r •cf CO V ro O i n o o •d •d C O CN SO ro ON CN SO 0 0 CO CO © CO ON vq P6- ro m Ov CN d d x i x i <N © ON ON as i n 0 0 CO — _ ^ ro ro r-vo m •d •d CO r~ i n so CO so CN CO ON O N 6 i n d CO d d x i x i CO ro © ©' o SO VO ro d o so Os CO o VO •d •d o ro © CN T ON •q-0 0 ON ON CN 2 i n d CO d d x i x i ro •cr © O N ON CN NO •^ r ro — l-H 1 t ~ Ov i n oo i n •d •d ON oq o vq vo VO r-m Ov © icT ON 0 Q d m d ro d d x i x i CO CO d ON ON SO VO ro d U i i n r~ i n o o CN •d •d -d ON oo CO i n ON i n p P-0 0 •«r i n © SI6 Os m i n CN d x i x i x i so r-' © © o CN CO vo m' as so 0 0 i n •d •d o CN 0 0 r~ o CN CO o r-co Ov rO oo P2 i n d ro d d x i x i ro C O d d o -cr vo ro ro V CN l> as SO VO o •d •d O ro CN CO 0 0 vo © © r-r~ o 0 0 P2- i n m CN d d x i x i d i n d © © © i n vd CN t-i I m •q-r-- o CN •d •d oo o © i n ro ro r-o ON o ro 0 0 sc: ro i n od CN — d x i x i CN © © © od i n ON ro — SC3-C so as m 0 0 o •d •d 0 0 VO ON i n VO VO vo vo p SC3-C 0 0 m i n <N d d x i x i t-: vd d d © SO CO ON i n CO o p co-co s •d •d SO CN ON i n r-CN CN VO CN SO •q- i n i n 6 ro i n ON CN d d x> xi CN "cr d d o 0 0 m Ov ro "~ C N 0 0 i n vO VO o •d •d Ov 0 0 •CJ" CO Ov Os 0 0 ON CN CO CO 6 r~ i n i n CN d d x i xi vd d od Ov r-^  CO vd i n u-i 2-r O N CO oo o C O so •d "cl-i n •d o 0 0 CN VO VO O N SO VO i n p I f r -SCI i n so d CN d x i d x i — r-~' i n d O i n CN so ro 2-c r~ ON o •d •d C O CO VO CN ON CN o m t> vq sci: CO i n ON CN d d x i x i CN d d o d VO ro 0 1 r-~ i n i n CO oo •d •d CO ON VO CN r- i n CN O i n ON 3ld ro i n Os CN d d x i x i — © © © 0 0 m ON ro 1 NO i n i n o i n •d •d o VO m CN CO 0 0 SO CN i n CN CN 2 CN m ON CN d d x i x i CN d Os ON VO vd ro — u 1 o CO O o o •d •d vO ON m ON ro CN vo Ov ' | •cl-0 0 i n ro m 2 CN m d ro d d x i x i CN ro' ©' ON as CO SO CO — Grain r-l o 0 0 m o o u b MgO BaO SrO CaO o C9 z o CN Total An% Ab% Or% 38 Chapter 3. Mineralogy and mineral chemistry Table 3.3. Continued Centre Cinder M. King Creek Sec. Can. Lava Fork Sample SH-35 KC-22 SC-23 SH-50 SH-54 Grain SC14-C SC14-r G-i SC6-r SC8-i SC8-r Pll-c Pll-r G-i MP2-i MP6-i G-i SC7-r G-i Si0 2 61.15 51.81 52.52 53.24 55.93 50.59 53.21 51.83 53.11 50.53 50.74 50.39 53.20 51.31 AI2O3 24.14 29.71 29.28 29.01 26.91 30.84 29.33 30.70 28.96 30.74 30.60 30.72 28.93 30.40 Fe 20 3 0.38 0.70 0.81 0.96 0.50 0.66 0.47 0.53 1.04 0.71 0.66 0.81 0.70 0.79 MgO b.d. 0.09 0.07 0.12 0.09 0.15 0.10 0.15 0.13 0.16 0.12 0.12 0.09 0.09 BaO b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. SrO b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. CaO 5.64 13.04 12.49 12.32 9.67 13.86 12.19 13.66 12.03 14.23 14.09 14.25 11.85 13.48 Na 20 7.47 4.04 4.43 4.23 5.64 3.29 4.39 3.46 4.44 3.24 3.44 3.42 4.66 3.70 K 2 0 1.46 0.25 0.29 0.26 0.47 0.17 0.30 0.20 0.29 0.20 0.19 0.18 0.35 0.23 Total 100.33 99.64 99.89 100.13 99.21 99.57 99.98 100.53 99.99 99.82 99.82 99.89 99.78 99.99 An% 26.90 62.80 59.64 60.15 46.95 68.53 59.11 67.06 58.42 69.24 68.02 68.46 56.89 65.56 Ab% 64.48 35.17 38.26 37.41 49.54 29.46 38.50 30.74 39.01 28.48 30.05 29.73 40.48 32.53 Or% 8.29 1.46 1.64 1.49 2.72 0.98 1.74 1.16 1.67 1.19 1.08 1.04 2.02 1.33 M=megacryst, P=phenocryst, MP=microphenocryst, G=groundmass, SC=sieved core, SI=sieved interior c=core, i=interior, r=rim Table 3.4. Compositional variation of plagioclase phenocrysts/xenocrysts and groundmass for all Iskut-Unuk rivers centres, including core, interior and rim compositions. Volcanic Iskut Tom Snippaker Cone Cinder Mountain King Second Lava centre River MacKay Creek Glacier Creek Canyon Fork Creek Basalt Hawaiite Phenocrysts A n 2 8 . 9 4 A n 4 5 _ 7 0 An5_64 An36_6s Ang.63 A n 3 9 . 5 0 AI145.70 AH66-70 An38_7o1 -all types Groundmass ArL47.65 An56 -68 A n 3 8 . 5 8 Aa, 5 . 6 7 Ari44.60 Ari45_48 A n 5 7 . 6 7 — Ari44.es 1 one composition found lower than Anj3. show a higher An-content. The groundmass ranges from An 4 4 to Ar^g and Tom MacKay Creek and King Creek centres both show a small range in groundmass composition (An56^g) but Snippaker Creek flows have more albitic groundmass feldspar (An38.58). 39 Chapter 3. Minera logy and mineral chemistry 3.2.3. Clinopyroxene Figure 3.5 shows all analyses of clinopyroxene from the Iskut-Unuk rivers centres plotted on a pyroxene quadrilateral. These compositions include both groundmass and rare partially resorbed (sieved) clinopyroxene. The range in composition is limited; the pyroxene is augite to salite, containing up to 6 wt% TiCV Table 3.5 lists representative chemical analyses of clinopyroxene from each centre (if present). CaMjgSi206 CaFeSi 20 6 Figure 3.5. Pyroxene quadrilateral showing the composit ion of cl inopyroxene in Iskut-Unuk rivers basalts. 40 Chapter 3. Minera logy and mineral chemistry Table 3.5. Selected analyses of clinopyroxene from the Iskut-Unuk rivers volcanic rocks Centre Iskut River SnC Cone Glacier King Creek L F Sample IR-3 IR-8 SH-33 SH-14 SH-26 KC-22 SH-54 Grain M2-i G l l - i SPl-r Gl - i G15-i G12-i G9-i G7-i GV15-i G8-i G8-i Si0 2 49.72 45.97 48.93 49.83 47.32 47.00 50.32 41.01 41.93 50.27 47.84 Ti0 2 1.22 3.75 1.58 1.53 2.99 2.32 1.55 5.39 5.10 1.60 2.72 A1 20 3 5.18 4.27 3.23 2.80 4.36 3.70 2.17 7.10 5.99 2.10 4.01 Cr 2 0 3 b.d. b.d. 0.07 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. FeO 8.56 12.61 8.59 8.59 10.90 11.60 9.64 14.61 16.09 9.39 10.59 NiO b.d. 0.06 b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. b.d. MnO 0.15 0.27 0.15 0.19 0.19 0.26 0.21 0.25 0.26 0.18 0.25 MgO 14.81 10.33 14.06 14.44 12.19 12.88 13.53 8.08 7.21 13.76 12.24 CaO 19.17 21.13 21.04 21.14 20.75 20.18 21.28 20.76 20.96 21.44 20.83 Na 20 0.58 0.61 0.43 0.40 0.53 0.51 0.44 0.65 0.70 0.40 0.58 Total 99.38 99.01 98.10 98.93 99.23 98.46 99.14 97.85 98.25 99.15 99.06 Mg# 75.52 59.36 74.47 74.98 66.60 66.44 71.46 49.62 44.41 72.32 67.32 M=megacryst, SP=Sieved phenocryst, G=groundmass, GV=groundmass, coating vesicles, i=interior, r=rim, SnC=Snippaker Creek, LF=Lava Fork Clinopyroxene occurring in the groundmass have MG# numbers ranging from 46 to 75 but for resorbed crystals from Iskut River MG# numbers are higher (75 to 76). Figure 3.6, shows the Al™ vs. Ti 4 + for different clinopyroxene populations. The clinopyroxene megacrysts plot separately with higher Al and generally lower Ti content. Si, Al and Ti proportions in clinopyroxene are controlled by chemical composition, temperature and pressure (Kushiro, 1960; Le Bas, 1962). Higher temperature and pressure favors Al over Ti in the tetrahedral site, indicating the phenocrysts have crystallized at different magmatic conditions from the groundmass grains of Iskut-Unuk rivers lavas. Titanaugite from the groundmass of King Creek basalt shows the highest Ti 4 + and Al™ content. 41 Chapter 3. Minera logy and mineral chemistry 0.4 0.3 h 0.2 h 0.1 0.0 0.00 o o o X A X X • • o • X * Iskut River phenocrysts Iskut River groundmass Cone Glacier groundmass Lava Fork groundmass King Creek groundmass Snippaker Creek groundmass 0.05 0.10 Cations T i 4 + (p.f.u.) 0.15 0.2 Figure 3.6. Al™ concentration of a l l cl inopyroxene analyses plotted against T i + 4 showing the different compositions of phenocrysts (open circles) and groundmass (see legend). Phenocrysts are a l l f rom Iskut R iver basalt. 3.2.4. Fe-Ti oxides Magnetite in the Iskut-Unuk rivers volcanic rocks generally range in composition from including 20 to 25% TiC"2 and 48 to 52% FeO. Table 3.6. includes samples of analyses of magnetite, ilmenite and chromite from the Iskut-Unuk rivers centres. 42 Chapter 3. Minera logy and mineral chemistry King Creek magnetite seems to be more oxidized as they contain higher portion of Fe203. AI2O3 content of magnetite ranges from 0.91% to 2.43. Compositions of ilmenites vary from including 44%Ti02 and 38% FeO (King Creek) to 29% Ti02and 24% FeO (Snippaker Creek). Ilmenite from Snippaker Creek also contains a high concentration of Fe203 (43%). Chromite from Second Canyon contains 3 to 14% AI2O3 and 2-19 wt% Cr203. Table 3.6. Selected analyses of oxides from the Iskut-Unuk rivers centres. Centre Iskut River SnC C M King Creek SeC L F Sample IR-8 SH-33 SH-35 KC-22 SC-23 SH-54 Grain 16 M7 19 M4 11 M2 13 M4 SI S5 M4 Si0 2 2.89 b.d. b.d. b.d. b.d. b.d. 1.49 b.d. b.d. b.d. b.d. Ti0 2 45.07 22.98 29.57 25.22 44.49 17.67 46.42 20.50 11.44 5.72 25.94 A1 20 3 0.60 1.97 0.68 1.70 0.27 2.43 0.96 2.01 7.55 14.38 1.61 Cr 2 0 3 b.d. 0.18 0.11 0.10 0.38 0.33 0.26 0.22 13.07 18.79 0.14 Fe 20 3 3.15 20.70 43.03 17.60 12.65 29.95 4.32 25.16 24.39 22.68 16.27 FeO 42.16 48.92 24.31 50.68 38.36 46.32 40.98 48.59 37.71 30.46 52.05 v2o5 0.44 0.88 0.73 0.62 0.74 0.81 0.78 0.76 0.51 0.40 0.52 NiO b.d. b.d. b.d. 0.08 b.d. b.d. b.d. 0.07 b.d. 0.06 b.d. MnO 0.62 0.48 0.63 0.68 0.64 0.57 0.58 0.55 0.55 0.49 0.75 MgO 0.78 2.91 1.56 2.63 1.04 1.35 1.53 1.40 3.36 5.23 2.12 ZnO b.d. 0.13 0.10 0.14 b.d. 0.13 b.d. 0.13 0.20 0.33 0.08 CaO 0.37 0.11 0.03 0.15 0.28 0.19 0.30 0.21 0.14 0.10 0.09 Total 96.08 99.26 100.75 99.60 98.85 99.75 97.62 99.60 98.92 98.64 99.57 T(°C) 1044°C M=magnetite, I=ilmenite, S=spinel, SnC=Snippaker Creek, CM=Cinder Mountain, SeC=Second Canyon, LF=Lava Fork Both temperature and oxygen fugacity dictate the Ti0 2 contents of coexisting cubic and rhombohedral oxides, magnetite and ilmenite (Buddington et al. 1955; Verhoogen 1962). Buddington and Lindsley (1964) developed a graphical Fe-Ti oxide geothemometer/oxygen barometer which is now replaced by the new thermodynamic model of Ghiorso and Sack (1991). Table 3.6 list the results of calculations made to determine crystallization temperature 43 Chapter 3. Minera logy and mineral chemistry (1044°C) and oxygen fugacity (log fo2 = -9.47) for King Creek pillow lava. Because of small grainsize, analyses of ilmenite often gave bad results (high SiC<2 values and high or low totals) and could not be used in the calculations. 3.3. Plagioclase; habit, texture and compositional relationships One of the more remarkable features of the Iskut Unuk rivers lavas is the diversity of plagioclase habit and texture. The habits include megacrysts, phenocrysts and groundmass laths and many lavas contain plagioclase phenocrysts that have prominent sieved textures. They also commonly exhibit euhedral to anhedral form, zoning, twinning and dissolution surfaces. Plagioclase crystals have been divided into at least four groups based on the diverse habits and textures: megacrysts, phenocrysts, sieved phenocrysts and groundmass laths. It is very common to find grains from all the different groups within the same thin-section. The form and texture related to the different crystal habits are listed in Table 3.7a, including how common these occurrences are. Megacrysts are most commonly euhedral, twinned and show multiple dissolution surfaces. They are generally composed of a large homogenous core with a narrow zoned rim. Sieve textures are not observed. Phenocrysts include the most diverse textures, showing signs of dissolution and commonly are strongly zoned. Groundmass laths 44 Chapter 3. Mineralogy and mineral chemistry are zoned and twinned, range from euhedral to subhedral but do not show any signs of dissolution. Table 3.7. a) Occurrence of different form and texture for the three major crystal habits of plagioclase in Iskut-Unuk rivers centres, b) Occurrences of various plagioclase textures in each of the Iskut-Unuk rivers centres. a) Euhedral Subhedral Anhedral Zoning Twinning Sieved Dissolution Habit surface Megacrysts Common Rare - Rare Common - Common Phenocrysts Rare Common Rare Common Common Common Common Groundmass Common Common Rare Abundant Abundant - -b) Iskut Tom Snippaker Cone Cinder King Second Lava Plagioclase River MacKay Creek Glacier Mountain Creek Canyon Fork texture group Creek Megacrysts X X X X - X - -Phenocrysts X X X X X X X X Sieved Phenocrysts X X X X - X - -Groundmass X X X X X X X X Plagioclase phenocrysts and groundmass are present in rocks from all centres (Table 3.7b). Megacrysts and sieved phenocrysts are found in most centres but both are absent in Cinder Mountain, Second Canyon and Lava Fork volcanic centres. Plagioclase crystals from Iskut-Unuk rivers rocks that show different textures and habits were etched with fluoboric acid (HBF4) for 3-4 minutes. They were then analyzed and photographed using Nomarski interference contrast microscopy to enhance surface features (Anderson, 1983; Pearce et al., 1987). Figures 3.8a to y show Nomarski photomicrographs of plagioclase grains. The photographic atlas is intended to show examples of the various textures of plagioclase within each centre. The quality of the photographs varies as the polish 45 Chapter 3. Minera logy and mineral chemistry of thin sections and overall appearance of the grains differs significantly. Every photomicrograph is accompanied by a diagram that shows the chemical variation within the crystal; the points of analyzes are labelled on the photos. The diagrams also show where dissolution features have been identified in the Nomarski images. Megacrysts typically have a large homogenous core and a narrow compositionally distinct rim commonly bounded by a dissolution surface (Figures 3.8 c, i, j, q). The megacrysts tend to be compositionally uniform from core to rim (An55 to An68); significant variation commonly occurs across a dissolution feature where the exterior portion shows reverse zoning. Phenocrysts as a group range in composition from Ariso to Ari69. These include both crystals with little chemical variation (3.8 k, n, r) or crystals with significant core to rim differences associated with disequilibrium surfaces (3.8 d, h, o, x). Reverse chemical zonation is recognized in all centres except Lava Fork and Cinder Mountain. An exception is a single .phenocryst from Iskut River with a very An-rich core (An93) and a zoned rim separated by a dissolution surface. The sieved phenocrysts are characterized by sieved interiors or cores. The location of the sieve texture may be a function of crystal orientation in thin section. The composition for the outermost rim for all sieved phenocrysts ranges from An5o to An7n (3.8 a, e, f, g, 1, m, p, s, t, u, v, y). The area within the core, sieved or not, is usually of lower An-content (An6-4s). For 46 Chapter 3. Mineralogy and mineral chemistry the few examples where this is not true, the sieved core is of similar composition as the rim (3.8 1, u, y). Groundmass laths range from An3s to Ari68 for all basalts. Groundmass plagioclase from hawaiite has a lower An-content (Arug). Phenocrysts (without sieved texture), megacrysts, and groundmass probably are cognate based on the relationship between texture and chemical composition. The sieved phenocrysts comprise low and high An-content cores, those with low An-cores probably being xenocrysts. Figure 3.8 a to y. Nomarski photomicrographs and chemical variation of plagioclase from Iskut River centre. For each grain analyzed, a photo and a diagram is represented. On the photo labels indicate analyzed points with electron microprobe. The diagram shows how the composition varies with distance from the rim. Solid lines between points represent dissolution features observed with the Nomarski setup. a) Boundary between the core and rim are denoted by inclusions which are within the anhedral core. They include melt inclusions and minor groundmass minerals and are weakly aligned. Field of view 0.83 mm. b) A sharp dissolution feature between anhedral core and zoned rim accompanied by a big change in composition. Crystal surface is uneven because of polishing. Field of view 1.65 mm c ) Megacryst with a large homogenous core and at least one dissolution feature within the rim. Field of view 1.65 mm. d) Phenocryst with complex growth-zones. Field of view 0.41 mm. e) Phenocrysts with a sieved interior containing aligned inclusions. A dissolution surface is observed at the outer margin of the sieved area. Field of view 1.65 mm. f) The sieved interior forms the boundary between core and rim where dissolution took place. Melt inclusions and irregular surface define the texture. Field of view 0.83 mm. g) Sieved interior between a homogenous anhedral core and relatively large zoned rim area. Interior texture formed by melt inclusions and irregularities in surface because of dissolution and difference in chemical composition. Inclusions are parallel to crystal surface. Field of view 1.65 mm. 47 Chapter 3. Mineralogy and mineral chemistry h) Irregular core of the phenocryst is clearly determined by the dissolution surface and some inclusions along it. Zoning is visible in the etched planes and crosscuts through rim and core. Field of view 0.83 mm. i) A megacryst with a sharp dissolution surface between a homogenous core and zoned rim. Field of view 0.41 mm. j) Megacryst with large core and zoned rim. Twin-planes revealed through the etching, crosscut both areas. Field of view 3.3 mm. k) The core of the phenocryst is anhedral with the outer margin showing signs of dissolution. The rim is finely zoned. Field of view 1.65 mm. 1) The majority of the grain is of interconnected inclusions forming sieved core with a fine zoned rim around. No signs of dissolution are observed between core and rim. Field of view 1.65 mm. m ) Melt inclusions are bound to the core by a dissolution surface and they are preferentially oriented along crystal faces. The outer perimeter of the core is rounded. Field of view 1.65 mm. n) Homogenous megacryst with fine growth zones around rim. Field of view 1.65 mm. o) Well developed growth zones form around an anhedral core that is outlined by a dissolution surface. Field of view 0.41 mm. p) A glomerocryst of at least two different crystals with a solid core and sieved interior. Disequilibrium texture formed after crystals formed, dissolving most of the crystals by partial dissolution. The core remains homogenous. Later overgrowth is zoned and mantles both grains. Field of view 1.65 mm. q) Megacryst with a homogenous large core and zoned narrow rim area. Twin-planes crosscut and disrupt the zoning of the rim which has at least one dissolution surface visible. Field of view 1.65 mm. r) Anhedral grain with at least one rounded dissolution surface within the rim. Field of view 1.65 mm. s) Sieved interior of melt inclusions somewhat aligned to crystal planes. Overgrowth occurred after sieved area formed as the growth zones form around irregular surface of the sieved area. Field of view 1.65 mm. t) Sieved core has variation in coarseness, the outer core is finer than the inner. No surface features indicate the boundaries. Inclusions are of melt and minerals found in the groundmass. Field of view 1.65 mm. u) The sieved core includes predominately melt inclusions and outer perimeters are rounded. Field of view 2.06 mm. v) The rounded sieved area encloses the homogenous core that is also anhedral. The overgrowth formed around the inclusion rich sieved area showing clear compositional zoning. Field of view 1.65 mm. x) The anhedral core of the phenocryst is separated from the zoned rim by a dissolution surface. Field of view 0.83 mm. y) Inclusion rich core, very much alike the groundmass immediately outside, overgrown by a more calcic plagioclase. Field of view 0.41 mm. 48 Chapter 3. Mineralogy and mineral chemistry 100 90 -80 -70 -60 . 50 -40 30 Iskut River IR-3 Sieved core 6 a ) 100 200 300 Distance from rim (microns) 400 100 90 80 70 60 50 K) 30 • • • •• • • • • 7 b) i i i i i i i i i Iskut River IR-3 Phenocryst 8 1 i i i i 50 100 Distance from rim (microns) 150 90 -80 -c) _J I I L_ Iskut River IR-7 Megacryst 4 V. 100 200 300 400 Distance from rim (microns) 500 100 90 80 70 c < 60 50 40 30 d) J _ I t _ i _ Iskut River IR-7 Phenocryst 8 . • I 50 100 150 200 250 Distance from rim (microns) 49 Chapter 3. Mineralogy and mineral chemistry 100 90 -80 -c < i£ 70 60 50 40 30 Iskut River IR-8 Sieved interior 6 I i I i I i I i I 0 50 100 150 200 250 300 350 400 450 Distance from rim (microns) 75 70 65 c£ 60 ^ 5 5 50 45 40 Tom MacKay Creek SH-39 Sieved interior 1 • • • • / • • 1 1 1 1 1 1 1 1 i i i 1 > i i 1 i i i 1 i i i 100 200 300 400 500 600 Distance from rim (microns) • 100 90 80 £ 70 < 60 50 40 30 Iskut River IR-8 Sieved interior 13 0 20 40 60 80 Distance from rim (microns) 100 75 70 65 ^ 60 d < 55 50 45 40 Tom MacKay Creek SH-39 ( Phenocryst 7 • - / • • ~ta) 1 1 1 1 i i i 1 i i i 1 i i i 50 100 150 200 Distance from rim (microns) 50 Chapter 3. Mineralogy and mineral chemistry 70 60 50 ^ 40 <! 30 20 10 0 ro 1 1 1 1 1 1 1 1 Snippaker Creek SH-33 Megacryst 3 i i 1 i i i ' I ' ' ' ' 0 50 100 150 200 Distance from rim (microns) 250 70 60 50 2? 40 d < 30 20 10 0 • • 7i) i i i , , i , Snippaker Creek SH-33 Megacryst 5 i 1 i i 1 i i 1 i i 300 600 900 1200 1500 1800 Distance from rim (microns) 70 60 50 ^ 40 <! 3 20 10 0 _ • • • / -/ • • -Snippaker Creek SH-33 7 k ) i i i i i i i i Phenocryst 10 > 1 i i > i 1 i i i i "0 50 100 150 Distance from rim (microns) 200 70 60 50 £ 40 <2 30 20 10 0 -• • • • - • -Snippaker Creek SH-33 "l>.. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Sieved core 12 i i i 1 i i i i 1 i i i i 1 i i i i 1 i i i i 50 100 150 200 250 300 350 400 Distance from rim (microns) 51 Chapter 3. Minera logy and mineral chemistry 70 60 50 40 30 V Cone Glacier CG-10 Sieved core 3 m) • i i i I i i i ' l i i i i i i i i i i 50 100 150 200 250 Distance from rim (microns) 70 60 50 P 40 h 30 • -• • • n) i i i 1 i i i 1 i i i 1 i i i Cone Glacier SH-26 Phenocryst 6 1 i i i 1 i > > 1 i i i 100 200 300 400 500 600 700 Distance from rim (microns) I o) Cone Glacier SH-14 Phenocryst 2 I • . I • • I • • I 20 40 60 80 100 120 140 Distance from rim (microns) 70 60 50 40 }0 P) Cone Glacier SH-14 Sieved interior 6 _i I I I I I i_ J I I I L _ l 1_ 100 200 300 400 500 Distance from rim (microns) 5? Chapter 3. Mineralogy and mineral chemistry s) Cinder Mountain SH-35 Sieved interior 4 100 200 300 400 Distance from rim (microns) 70 60 50 £ 40 <3 30 20 10 0 Cinder Mountain SH-35 Sieved core 14 t) _L _l ' ' ' ' I I I I L "0 100 200 300 400 500 Distance from rim (microns) 53 Chapter 3. Minera logy and mineral chemistry King Creek KC-22 Phenocryst 11 • • • -• • 1 1 1 1 1 1 1 1 1 1 1 i i i 1 i i i i 1 i i i i 50 100 150 200 Distance from rim (microns) 250 70 60 50 40 30 Lava Fork SH-54 Sieved core 7 — •• • • • - • "y) , i i i i i i i i 1 i i i i 1 i i i i 1 i i i i 50 100 150 200 Distance from rim (microns) 250 54 Chapter 3. Minera logy and mineral chemistry 3.3.1. Implications of disequilibrium textures of plagioclase The following processes have been suggested by various workers for the origin of sieved textured plagioclase phenocrysts: i) resorption of more sodic plagioclase and crystallization of more calcic composition (e.g. Kuno, 1950; Lofgren and Norris, 1981; Tsuchiyama, 1985; Nixon and Pearce, 1987; Bloomfield and Arculus, 1989, Kawamoto, 1992; Stimac and Pearce, 1992), ii) skeletal growth due to undercooling (e.g. Kuo and Kirkpatrick, 1982; Loomis, 1982; Kawamoto, 1992; Stimac and Pearce, 1992) and iii) rapid decompression with attendant mineral dissolution (e.g. Pearce et al., 1987; Nelson and Montana, 1992). Plagioclase phenocrysts are common in magmatic systems and they are resistant to solid state re-equilibration owing to the sluggish nature of CaAl-NaSi diffusive exchange at magmatic temperatures (Grove et al. 1984). This results in compositionally zoned plagioclase crystals which record the varying magmatic conditions. Normal zoning is promoted by rapid 5 5 Chapter 3. Minera logy and mineral chemistry cooling and contemporaneous crystallization of other phases and absence of volatiles whereas reverse zoning is favored where phenocrysts grow slowly, in melts where volatiles are concentrated (Loomis, 1982) or under changing pressure conditions. Disequilibrium textures and strong compositional zoning also commonly occurs with mixing of primitive and evolved magmas (Kuo and Kirkpatrick, 1982; Nixon and Pearce, 1987; Stimac and Pearce, 1992). The naturally occurring disequilibrium textures observed in these rocks have been duplicated by experiments (Tsuchiyama, 1985; Lofgren and Norris, 1981) where Ab-rich crystals are partially melted in a melt that is in equilibrium with more An-rich feldspar. Experimental work on plagioclase in the system Di-An-Ab revealed that plagioclase less calcic than the plagioclase in equilibrium with surrounding melt will show partial dissolution that takes place extensively along cleavages and twin planes of the crystal. If the plagioclase is more calcic than the plagioclase in the initial melt, it will produce overgrowth rich in albite. If the melt in which the plagioclase is immersed is undersaturated in regard to plagioclase, a rounded crystal is formed by simple dissolution (Tsuchiyama, 1982). Sieved zones resulting from resorption of plagioclase can be identified by several features: i) the outer perimeters of sieved zone have rounded forms, ii) laterally discontinuous zonation, iii) concentric zones in the inner core are truncated by a sieved zone and iv) inclusions are preferentially oriented along defects in crystal (cleavages, twin-planes or cracks) (Nixon and Pearce, 1987; Kawamoto, 1992). Resorption of plagioclase is 56 Chapter 3. Minera logy and mineral chemistry locally indicated by oscillatory zoning where the resorption surface is overlain by a Ca-rich zone. This feature is recognized by zoning profiles of the crystal and also rounding of corners that locally truncate inner zones (Nixon and Pearce, 1987). Studies have concluded that disequilibrium textures in plagioclase reflect both resorption and rapid growth (Stimac and Pearce, 1992; Kawamoto, 1992). The features characterizing rapid growth texture are mainly: i) many melt inclusions of irregular shapes that align with crystal faces of the host plagioclase crystal, ii) the part of the crystal containing inclusions is euhedral, iii) inclusions are elongate and iv) parts of different compositions have identical extinction angle (Kawamoto, 1992). Disequilibrium growth processes triggered by undercooling or supersaturation also generally result in change in partitioning of components between crystals and melt such that the newly formed plagioclase are more albitic relative to compositions in equilibrium with the bulk melt (Lofgren, 1974; Loomis, 1982). According to Nelson and Montana (1992), dissolution of plagioclase that shows remnants of an interconnecting network of channels is a consequence of physical and chemical changes in the magma. Alignment of the melt inclusions that crosscut grain-boundaries in glomerocrysts distinguishes dissolution of plagioclase from rapid cooling texture. 57 Chapter 3. Minera logy and mineral chemistry Decompression with mixing of different layers of magma can contribute to disequilibrium textures as observed in rocks from Mount St. Helens (Pearce et al., 1987). Other physical parameters such as temperature and H 2 0 content of the melt affect the An-content or resorption of crystals (Nixon and Pearce, 1987). Presence of water will assist decompression-induced resorption by reducing viscosity of the magma and enhancing increased ascent and diffusion rates (Nelson and Montana, 1992). 3.3.2. Analyses of the Iskut-Unuk rivers centres Disequilibrium (sieved) textures involving plagioclase are found in six of the eight volcanic centres of the Iskut-Unuk rivers area. The compositions of phenocrysts and megacrysts that show no sieved textures (An50 to An6a)are within the range expected for low pressure basaltic magma crystallization. The same compositions are observed for overgrowths of sieved crystals and all groundmass laths. Common dissolution features occurring in these crystals indicate a minor change in the physical of chemical conditions of the magma resulting in reverse zoning of the rims. Plagioclase showing sieved textures are diverse in composition; sieved cores and interiors generally show low An-contents (An6 to Arus). Exemptions are sieved crystals from Snippaker Creek, Lava Fork and Cinder Mountain some of which show little variation between core and rim compositions. The sieved areas are composed mainly of inclusions of 58 Chapter 3. Mineralogy and mineral chemistry glass with minor groundmass minerals and recrystallized plagioclase. Sieved areas (cores and interiors) have low An-content and commonly have rounded outer boundaries which truncate exiting zones; a xenocrystic origin is suggested for these plagioclase crystals. The xenocrysts are probably introduced to the magma during ascend through the crust or as it resides in a magma-chamber. Iskut River, Tom MacKay Creek, Cone Glacier, Cinder Mountain and King Creek basalts all contain xenocrystic plagioclase based on compositions and dissolution textures. The sieved crystals with compositions consistent with the magmatic phenocrystic assemblage, generally show coarser texture and contain more inclusions than xenocrystic plagioclase. They are found in basalts from Snippaker Creek, Lava Fork and Cinder Mountain centres. The texture of these plagioclase crystals is a result of rapid crystal growth due to undercooling or change in physical conditions; they are magmatic. The complexly twinned phenocrysts of Cinder Mountain hawaiites lack the sieved texture but commonly are anhedral indicating dissolution. The compositional range is typical of feldspars in a magma of intermediate composition. The complex twinning and anhedral form also distinguish the Cinder Mountain plagioclase from those of other centres. The plagioclase phenocrysts are possibly magmatic or they are xenocrysts from crustal rocks with disturbed inherited twinning which have undergone simple dissolution. 59 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres CHAPTER 4 Chemical characteristics of the Iskut-Unuk rivers centres 4.1. Major elements Major and trace elements analyses of samples collected from all of the Iskut-Unuk rivers centres were measured by Geochemical Laboratories at McGill University and GSC. Concentrations of 19 elements were determined by X-ray Fluorescence of fused sample powders. Ferrous iron and H20(T) were measured volumetrically in the Igneous Petrology Lab at University of British Columbia (Wilson, 1955) and by the Penfield method (Groves, 1951) respectively. All C0 2 determinations and a subset of FeO and H 2 0 determinations were made at the Geological Survey of Canada; both H 2 0 and C0 2 were determined using combustion followed by infrared spectrometry. Major and trace element compositions from the Iskut-Unuk rivers centres are listed in Table 4.1 with calculated CIPW normative mineralogy, using calculated Fe 2 + /Fe 3 + and no volatiles. The rocks of Iskut-Unuk rivers area are generally alkali-olivine basalts except for Cinder Mountain volcanic centre which also comprises hawaiite (Figure 4.1). The rocks 60 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres 0 s o + O 10 9 1 - # i ' i ' Iskut River i 1 i - o Tom MacKay Creek -- • Snippaker Creek Benmoreite - o Cone Glacier -- A - -$£ - + - © Cinder Mountain basalt Cinder Mountain hawaiite * King Creek Second Canyon , Hawaiite Mugearite Andesite -- EB Lava Fork m-A. & / --Basalt Basaltic Andesite -i A i 1 i i 1 40 44 48 52 S i O , (Wt. % ) 56 60 Figure 4.1. Total Alkali-Silica diagram with Iskut-Unuk rivers alkaline basalts and hawaiites plotted. Rock names according to the sodic series of silica-saturated rocks (Le Bas et al., 1986 ). Solid line represents division between alkaline and subalkaline compositions (Irvine and Baragar, 1971). are slightly nepheline or hyperstene normative with Lava Fork the only centre where all samples are Ne normative. Mg numbers [100*Mg/(Mg+Fe )] for basalts range from 40 to 54 but are lowest (22 to 27) for the intermediate rocks from Cinder Mountain. A single Cinder Mountain basaltic flow has a an Mg# of 34 which lies between basalts from other centres and the hawaiite. Major element compositions of the Iskut-Unuk rivers centres strongly resemble the 61 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres composition of other centres in the southern part of the Stikine Volcanic Belt (SVB) (e.g., Edziza (Souther, 1992)) and the Anahim Volcanic Belt (e.g., Itcha volcanic complex (Charland et al., 1993) (Figure 4.2). Centres of the northern part of SVB, in southern Yukon, are more Si-undersaturated and less evolved (Figure 4.2) (Eiche at al., 1987). The larger volcanic complexes (Edziza and Itcha) include more intermediate to felsic rocks compared to the smaller monogenetic alkali-olivine basalt centres. 10 0 s o + o CS 8 40 • O o • Iskut-Unuk basalt Edziza basalt Itcha basalt Alligator Lake basalt Iskut-Unuk hawaiite Edziza hawaiite Itcha hawaiite 15 £ 10 o - °° • o o o 1 * * 1 , 1 , 48 50 Si02(Wt.%) Dacite 45 50 55 60 SiO? (Wt. %) 65 70 Figure 4.2. Alkalis vs. S i 0 2 diagram of basalts and hawaiites from volcanic centres of Stikine and Anahim volcanic belts (Le Bas et al., 1986). The inset diagram shows M g O vs. S i 0 2 for the same volcanic centres. Labels are the same for both plots. Data are from this study and Souther (1992), Eiche at al., (1987) and Stout and Nicholls (1983). 62 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres Table 4.1. Major element chemistry of the Iskut-Unuk rivers centres Centre Iskut River T M C Snippaker Creek Sample IR-2 IR-3 IR-4 IR-5 IR-6 IR-7 IR-8 SH-37 SH-39 SH-01 SH-02 SH-31 SH-33 SH-34 Si0 2 48.95 48.84 47.99 48.02 49.09 48.80 47.98 48.90 48.01 48.63 48.48 48.37 48.50 47.67 Ti0 2 2.33 2.24 2.32 2.25 2.35 2.36 2.20 2.38 2.30 2.33 2.30 2.28 2.31 2.27 A1 20 3 16.32 16.78 16.87 16.93 16.29 16.38 17.04 16.35 15.55 16.74 16.84 16.81 16.78 16.06 Fe 20 3 3.67 3.95 2.36 2.39 2.66 3.10 2.16 3.47 3.26 2.68 2.31 2.93 2.99 5.69 FeO 8.11 7.74 9.47 9.31 9.01 8.71 9.37 8.40 8.50 9.00 9.40 8.70 8.80 6.70 MnO 0.19 0.18 0.18 0.19 0.19 0.19 0.17 0.18 0.18 0.18 0.18 0.18 0.18 0.19 MgO 6.14 6.38 6.74 6.94 6.14 6.36 7.01 6.15 7.82 6.13 6.26 6.40 6.29 7.32 CaO 8.93 8.79 9.19 9.39 8.95 9.09 9.32 8.97 10.01 9.27 9.33 9.45 9.19 9.58 Na 20 3.45 3.42 3.82 3.70 3.89 3.64 3.63 3.55 2.90 3.51 3.36 3.55 3.54 3.43 K 2 0 1.16 1.08 0.91 0.87 1.19 1.10 0.86 1.15 0.94 1.00 0.95 0.91 0.98 0.84 P2O5 0.45 0.49 0.41 0.38 0.46 0.45 0.36 0.47 0.38 0.41 0.40 0.38 0.41 0.37 Total 99.71 99.89 100.27 100.36 100.22 100.18 100.11 99.97 99.85 99.88 99.81 99.96 99.97 100.12 H 2Or 0.26 0.31 0.38 0.33 0.34 0.25 0.25 0.30. 0.70 0.30 0.20 0.10 0.10 0.20 CO-.' 0.30 0.20 0.10 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.10 0.20 0.20 0.10 MG# 36.99 45.20 41.57 42.71 40.52 42.20 42.79 42.27 47.92 40.52 39.97 42.38 41.68 52.21 S.I. 27.24 28.27 28.92 29.91 26.83 27.76 30.43 27.07 33.38 27.47 28.09 28.45 ,27.83 30.52 Trace elements Ba 501 474 327 298 455 438 291 475 253 347 372 277 378 285 Ce 92 53 49 38 73 95 74 41 47 62 77 86 57 60 Co 42 50 53 52 42 41 42 45 48 42 45 45 48 58 Cr 26 14 17 16 26 27 6 32 60 21 21 30 24 31 Cu 8 53 98 44 77 51 87 48 49 66 46 76 51 77 Nb1 24 24 23 18 24 21 20 23 23 22 18 21 21 25 Ni 57 54 56 110 47 50 48 46 65 39 42 51 42 49 Rb1 17 22 20 20 25 17 16 17 14 13 12 16 13 23 Sc 26 31 17 39 34 37 28 33 38 29 27 37 29 34 Sr1 610 660 650 650 610 620 650 610 580 630 630 640 620 600 V 234 216 227 227 226 239 213 230 253 228 227 217 225 244 Zn 113 110 106 102 110 108 105 109 96 108 105 106 107 104 Zr1 210 200 180 170 210 210 170 220 170 200 200 180 190 230 Normative mineralogy Or 6.86 6.38 5.38 5.14 7.03 6.50 5.08 6.80 5.56 5.91 5.61 5.38 5.79 4.96 Ab 29.19 28.94 27.53 27.17 30.55 30.80 27.18 30.04 24.54 29.70 28.43 29.74 29.95 29.02 An 25.62 27.25 26.20 27.02 23.48 25.11 27.67 25.29 26.64 26.97 28.07 27.25 27.01 25.95 Ne - - 2.59 2.24 1.28 - 1.91 - - - - 0.16 - -Di 12.78 10.64 13.68 13.96 14.66 13.89 13.26 13.13 16.62 13.37 12.80 13.98 12.97 15.16 Hy 6.52 8.31 - - - 0.19 - 3.91 5.06 1.52 2.77 - 1.44 3.25 Ol 7.96 7.26 16.11 16.24 13.85 13.68 16.86 10.18 11.48 13.16 13.50 13.93 12.98 7.73 Mt 5.32 5.73 3.43 3.46 3.85 4.49 3.14 5.02 4.73 3.88 3.35 4.50 4.87 10.33 Hm - - - - - - - - - - - - - -11 4.42 4.25 4.41 4.27 4.46 4.48 4.18 4.52 4.37 4.42 4.37 4.33 4.39 4.31 Ap 1.07 1.16 0.97 0.90 1.09 1.07 0.85 1.11 0.90 0.97 0.95 0.90 0.97 0.88 Ferrous iron and H 2Or determined by GSC for all SH-xx samples. FeO for other samples analyzed at UBC. Mg# = 100*MgO/(MgO+FeO). S.I. = 100*MgO/(MgCH-FeO+Fe2O3+Na2O)+K2O),1 Analyzed by GSC. 63 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres Table 4.1. Continued Centre Cone Glacier CM Sample CG-9 CG-10 CG-11 CG-12 CG-13 CG-14 CG-15 CG-18 SH-13 SH-14 SH-15 SH-22 SH-26 CM-19 Si0 2 48.55 48.36 49.00 49.05 47.85 48.54 48.34 47.64 49.35 47.95 47.82 47.06 47.26 49.64 Ti0 2 2.23 2.25 2.26 2.37 2.39 2.33 2.33 . 2.43 2.37 2.16 2.28 2.73 2.72 2.28 A1 20 3 17.06 16.88 16.93 16.56 15.82 16.91 16.72 15.83 16.38 16.21 16.12 16.21 16.33 16.05 Fe 20 3 3.62 2.16 3.88 4.34 2.46 4.32 4.31 2.40 4.25 8.20 6.02 5.34 6.95 4.85 FeO 7.87 9.43 7.70 7.58 9.26 7.47 7.57 9.49 7.70 4.10 6.30 8.20 6.70 8.34 MnO 0.18 0.18 0.18 0.19 0.19 0.19 0.18 0.19 0.19 0.18 0.18 0.20 0.20 0.25 MgO 6.34 6.55 5.87 5.62 7.38 5.96 5.98 7.39 5.77 7.61 7.31 6.30 6.32 3.07 CaO 9.48 9.41 9.14 8.64 9.32 9.27 9.23 9.35 8.60 9.61 9.63 8.78 8.84 6.46 Na 20 3.71 3.47 3.67 3.75 3.28 3.50 3.61 3.27 3.73 3.25 3.27 3.51 3.54 4.56 K 2 0 0.92 0.92 1.05 1.19 1.09 0.97 0.97 1.18 1.24 0.80 0.83 0.93 0.94 2.58 P2O5 0.38 0.39 0.41 0.46 0.46 0.41 0.41 0.47 0.47 0.34 0.36 0.42 0.43 1.53 Total 100.34 100.00 100.08 99.75 99.51 99.88 99.65 99.63 100.05 100.41 100.12 99.68 100.23 99.61 H 2Or 0.25 0.24 0.17 0.22 0.34 0.40 0.25 0.56 0.10 0.20 0.30 0.10 0.20 0.45 co2' 0.10 0.10 0.10 0.10 0.10 0.30 0.20 0.10 0.20 0.10 0.10 0.10 0.20 0.10 MG# 44.61 40.99 43.27 42.59 44.34 44.37 44.14 43.78 42.84 64.99 53.71 43.45 48.54 26.90 S.I. 28.22 29.07 26.49 25.00 31.43 26.81 26.65 31.15 25.43 31.76 30.81 25.95 25.84 13.12 Trace elements Ba 281 302 338 454 339 376 355 340 489 226 248 270 347 905 Ce 90 61 55 78 78 72 42 60 58 68 61 43 111 149 Co 44 40 35 39 42 37 39 48 32 46 46 50 55 25 Cr 25 31 20 18 36 27 26 29 18 28 29 10 13 0 Cu 50 62 47 47 45 57 29 46 41 67 39 70 42 59 Nb1 20 21 22 25 28 22 19 25 25 20 19 23 22 54 Ni 49 69 33 35 65 40 41 63 41 65 59 39 38 20 Rb1 18 17 16 28 17 16 20 17 23 17 13 11 12 36 Sc 31 27 36 36 44 34 30 32 28 43 35 32 33 31 Sr1 640 630 630 630 590 630 630 600 600 600 590 620 630 650 V 226 221 214 221 235 227 238 228 226 222 229 247 255 82 Zn 105 106 107 115 104 110 110 108 115 101 105 123 118 164 Zr1 180 180 200 230 210 200 200 210 230 180 180 200 200 420 Normative mineralogy Or 5.44 5.44 6.21 7.03 6.44 5.73 5.73 6.97 7.33 4.73 4.91 5.50 5.56 15.25 Ab 30.30 28.71 31.05 31.73 27.25 29.61 30.54 25.85 31.56 27.50 27.67 29.70 29.95 38.58 An 27.19 27.77 26.63 24.84 25.23 27.57 26.56 25.04 24.29 27.28 26.86 25.73 25.90 15.71 Ne 0.59 0.35 - - 0.27 - - 0.98 - - - - - -Di 14.07 13.41 13.00 12.15 14.67 12.71 13.37 14.91 12.38 14.15 14.70 12.15 11.98 5.26 Hy - - 3.06 4.90 - 5.41 2.81 - 5.60 8.82 6.35 3.23 5.89 1.09 Ol 12.40 16.02 9.28 7.24 16.48 7.21 9.01 16.72 7.14 2.50 5.76 9.48 4.73 8.83 Mt 5.25 3.13 5.62 6.29 3.57 6.27 6.25 3.47 6.16 7.58 8.72 7.74 10.08 7.03 Hm - - - - - - - - - 2.97 - - - -11 4.23 4.27 4.29 4.50 4.54 4.42 4.42 4.61 4.50 4.10 4.33 5.18 5.17 4.33 Ap 0.90 0.92 0.97 1.09 1.09 0.97 0.97 1.11 1.11 0.81 0.85 0.99 1.02 3.62 64 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres Table 4.1. Continued Centre Cinder Mountain K C SeC Lava Fork Sample CM-20 CM-21 SH-19 SH-21 SH-35 KC-22 SC-23 LF-24 LF-30 LF-31 LF-32 SH-44 SH-54 SH-601 Si0 2 49.30 50.07 49.70 50.18 47.37 49.35 46.06 46.44 46.41 46.48 46.77 46.46 46.44 46.47 TiOj 2.25 2.21 2.26 2.16 3.24 2.24 2.57 2.84 2.83 2.81 2.77 2.84 2.83 2.84 A1 20 3 15.92 16.09 16.04 16.04 16.04 16.55 14.89 16.94 16.86 16.92 16.90 16.92 16.97 16.94 Fe 20 3 4.95 3.85 3.18 3.25 3.46 2.77 4.30 4.92 3.62 2.72 2.67 2.59 4.90 3.28 FeO 8.15 9.12 9.80 9.80 10.00 8.50 8.28 7.91 9.16 9.91 9.86 10.10 7.90 9.40 MnO 0.25 0.25 0.25 0.26 0.21 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 0.18 MgO 3.05 2.94 2.99 2.81 5.21 6.00 9.25 6.50 6.52 6.62 6.71 6.52 6.56 6.55 CaO 6.27 6.29 6.32 6.17 8.31 8.56 10.24 8.95 8.89 8.87 8.81 8.87 8.91 8.88 Na 20 4.46 4.54 4.88 4.81 3.93 3.75 2.85 3.59 3.56 3.64 3.86 3.71 4.00 3.68 K 2 0 2.59 2.71 2.63 2.76 1.21 1.38 0.91 1.09 1.09 1.08 1.09 1.09 1.08 1.10 P 2 0 5 1.49 1.47 1.52 1.48 0.82 0.54 0.39 0.45 0.45 0.45 0.44 0.45 0.45 0.45 Total 98.67 99.54 99.57 99.72 99.80 99.82 99.92 99.80 99.57 99.69 100.05 99.73 100.22 99.77 H 2Or 2.01 0.91 0.40 0.50 0.30 0.53 0.62 0.20 0.23 0.25 0.18 0.10 0.20 0.10 co2' 0.60 0.10 0.10 0.10 0.20 0.10 0.30 0.20 0.20 0.20 0.10 0.10 0.20 0.20 MG# 27.24 24.38 23.38 22.28 34.25 41.37 52.78 45.12 41.57 40.04 40.51 39.23 45.37 41.05 S.I. 13.15 12.70 12.73 11.99 21.88 26.78 36.15 27.08 27.22 27.61 27.75 27.16 26.84 27.27 Trace elements Ba 881 960 938 932 346 609 156 191 220 213 217 188 188 203 Ce 145 144 158 144 87 92 80 71 92 76 103 47 98 52 Co 26 17 23 23 41 46 46 45 49 52 52 60 55 52 Cr 0 0 7 0 10 28 131 21 18 19 17 19 15 17 Cu 42 44 49 54 48 43 53 51 41 42 57 43 53 58 Nb1 55 59 58 60 35 27 24 26 24 26 24 25 27 26 Ni 18 10 11 10 36 44 154 56 54 76 64 56 51 67 Rb1 41 40 43 42 16 21 12 18 14 20 22 25 16 20 Sc 27 23 28 13 35 30 43 42 29 37 35 26 29 33 Sr1 620 640 640 660 560 650 550 690 680 690 680 670 690 690 V 61 64 79 52 239 213 250 222 244 230 222 225 222 227 Zn 164 168 167 170 134 112 105 104 106 107 109 109 110 106 Zr1 420 430 420 450 260 230 180 210 210 210 210 210 220 220 Normative mineralogy Or 15.31 16.02 15.54 16.31 7.15 8.16 5.38 6.44 6.44 6.38 6.44 6.44 6.38 6.50 Ab 37.74 38.41 36.49 37.33 32.23 31.73 21.90 27.78 26.35 25.12 25.01 24.74 26.57 25.64 An 15.78 15.53 14.10 14.03 22.56 24.26 25.15 26.89 26.81 26.65 25.57 26.30 25.17 26.48 Ne - - 2.60 1.82 0.55 - 1.20 1.41 2.04 3.07 4.14 3.60 3.94 2.96 Di 4.63 5.09 6.16 5.83 10.94 11.99 18.52 11.71 11.68 11.80 12.48 12.10 12.94 11.91 Hy 3.06 0.23 - - - 1.02 - - - - - - - -Ol 7.27 11.08 12.26 12.16 13.31 13.16 15.77 12.02 14.60 16.35 16.27 16.37 11.72 15.09 Mt 7.17 5.58 4.61 4.71 5.01 4.02 6.24 7.12 5.24 3.95 3.87 3.75 7.10 4.77 Hm - - - - - - - - - - - - - -11 4.27 4.20 4.29 4.10 6.15 4.25 4.88 5.39 5.37 5.34 5.26 5.39 5.37 5.39 Ap 3.53 3.48 3.60 3.51 1.94 1.28 0.92 1.07 1.07 1.07 1.04 1.07 1.07 1.07 65 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres Souther (1992) argues that the entire range of intermediate and felsic rocks in the Mount Edziza Volcanic Complex can be derived by crystal fractionation of a common alkali olivine basalt parent. Hawaiites from the Itcha Mountain Range likely formed by the combined processes of assimilation of crustal material and crystal fractionation (Stout and Nicholls, 1983; Charland et al., 1993). 4.2. Trace elements Trace element concentrations were measured at McGill University and by the GSC (Table 4.1 and Appendix C). Figure 4.3 shows concentrations of several incompatible and compatible elements plotted against solidification index: [S.I. = 100*MgO/(MgO+FeO+Fe^+Na20+K20)] (Kuno, 1957). S.I. values become smaller with increased fractionation. Nb, Rb, Zr and Ba are expected to behave incompatibly during differentiation of basaltic magmas. However, as seen in Figures 4.3a and 4.3e, Ba and Rb concentrations show considerable scatter and generally increase with decreasing S.I. Zr is the best behaved incompatible element and shows a steady increase with decreasing S.I. values. Strontium, compatible with basaltic plagioclase, should show a pattern indicating at least 66 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres 1000 34 32 30 28 26 24 22 20 18 16 14 12 S.I. /wfm mm I HI i • i 38 36 34 32 30 28 26 24 S.I. 22 20 18 16 14 12 Figure 4.3. Concentrations of compatible and incompatible trace elements plotted against S.I. Error bars denote Is due to analytical uncertainty. 67 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres weak compatibility; this is not observed. Strontium shows large variations in concentration where the highest content is from a basalt with moderate S.I. value and the intermediate rocks have concentrations well within the range of basalts. Nickel, due to the presence of phenocrystic olivine, is compatible and as expected Ni decreases with decreasing S.I. values (Figure 4.3f)-The general behaviour of the trace elements in the Iskut-Unuk rivers lavas is not entirely consistent with simple fractionation of olivine and plagioclase within a suite of basaltic magmas. The elements showing the inconsistencies are those generally associated with Ab-rich plagioclase and alkali feldspar. Any assimilation of material including these minerals would therefore result in distortion of gradual increase or decrease of the elements with fractionation. 4 .3. Rare earth elements Element concentrations for representative samples of basalts, hawaiite and crustal xenoliths are listed in Table 4.2 along with fractionation indices (Boynton, 1984). Additional analyses and descriptions of analytical methods are listed in Appendices B and C. 68 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres Rare earth elements patterns for the Iskut-Unuk rivers centres basalts and hawaiite are shown in Figure 4.4. The Iskut-Unuk rivers basalts are enriched in LREE compared to HREE and have very similar patterns showing the same degree of enrichment. The REE pattern for one of the intermediate rocks from Cinder Mountain is similar but has a significantly higher degree of REE enrichment. The (La/Yb)n ratio for basalts ranges from 5.81 to 7.30 and overall fractionation is higher for hawaiite (9.60). (La/Sm)n ratio is 2.03 to 2.49 for the alkali basalts and slightly higher for the hawaiite (2.69). La Ce Pr Nd Sm Eu Od Tb Dy Ho Er Tin Yb La La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb L u Figure 4.4. Rare earth element patterns for Iskut-Unuk rivers basalts and hawaiite. The inset shows the R E E patterns for basalts from Alligator Lake (Eiche et al., 1987) and basalts and hawaiite from Itcha Volcanic Complex (Charland et al., 1993). Chondrite values from Boynton (1984). 69 Chapter 4. Chemical characteristics of the Iskut-Unuk rivers centres Table 4.2. REE concentrations (ppm) of representative samples from the Iskut-Unuk rivers centres Sample SH-21 SH-33 SH-39a SH-39b IR-8 CG-12 SC-23 KC-22 LF-31 SH-41 SH-42 SH-39 Rock Hawaiite Basalt Basalt Basalt Basalt Basalt Basalt Basalt Basalt Xenolith Xenolith A La 63.92 20.30 17.99 17.92 18.37 24.03 19.06 28.01 22.85 9.87 31.23 0.07 Ce 140.82 46.12 41.02 40.72 40.19 53.85 43.79 61.55 51.83 21.25 58.50 0.7 Pr 17.48 5.98 5.3 5.35 5.31 7.04 5.82 7.87 6.81 2.62 6.29 0.05 Nd 72.86 25.58 23.18 23.32 23.11 30.39 25.59 32.22 30.10 10.40 21.91 0.14 Sm 14.96 6.18 5.52 5.63 5.44 7.05 5.86 7.08 6.55 2.90 3.93 0.11 Eu 4.79 2.01 1.92 1.94 1.90 2.30 2.80 2.27 2.28 0.27 0.94 0.02 Gd 14.75 6.21 5.74 5.65 5.78 7.02 6.15 6.89 6.57 2.89 3.41 0.09 Tb 1.90 0.86 0.81 0.79 0.76 0.93 0.79 0.96 0.89 0.46 0.44 0.02 Dy 11.03 5.15 4.88 4.82 4.73 5.74 5.89 5.66 5.11 2.69 2.51 0.06 Ho 2.01 0.96 0.87 0.92 0.87 1.09 0.85 1.08 0.98 0.50 0.47 0.05 Er 5.33 2.59 2.35 2.39 2.35 2.92 2.26 2.85 2.49 1.41 1.31 0.04 Tm 0.73 0.37 0.33 0.32 0.32 0.41 0.33 0.42 0.33 0.22 0.20 0.01 Yb 4.49 2.32 2.10 2.07 1.96 2.61 1.91 2.67 2.11 1.42 1.22 0.03 Lu 0.63 0.30 0.28 0.28 0.29 0.39 0.27 0.40 0.29 0.20 0.19 0.00 (La/Yb)„ 9.60 5.90 5.78 5.84 6.32 6.21 6.73 7.01 7.30 4.69 17.26 0.06 (La/Sm)„ 2.69 2.07 2.05 2.00 2.12 2.14 2.05 2.49 2.19 2.14 5.00 0.05 " Chondrite normalized values A Difference between duplicate analyses of SH-39. Volcanic rocks from Itcha Volcanic Complex show the same kind of pattern as seen for Iskut-Unuk rivers centres but are slightly more enriched (Figure 4 . 4 ) . The basalts from Alligator Lake are thought to be derived from two distinct parental magmas in the upper mantle. The REE profiles of both melts show a crossover between the LREE and HREE suggesting they were generated by different degrees of partial melting of a garnet bearing source (Kay and Gast, 1973; Eiche et al., 1987; Hanson, 1990). 70 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres CHAPTER 5 Petrogenesis of the Iskut-Unuk rivers centres Various degrees of melting of heterogeneous mantle is believed to be the most important process involved in the petrogenesis of small basaltic centres of the Stikine Volcanic Belt (Bevier, 1992). The petrogenesis of the Iskut-Unuk rivers centres has not been addressed previously, except for Cousens and Bevier's (in press) work which presented new Sr, Nd and Pb isotope data and preliminary interpretations concerning assimilation of asthenospheric melt by lithospheric mantle material. New petrographic, mineralogical and geochemical information is presented here and provides the basis for characterizing the petrogenesis of the Iskut-Unuk rivers centres. This section addresses the petrogenesis of the Iskut-Unuk rivers centres and evaluates the relative role of fractionation, assimilation and source region processes. The results indicate assimilation plays a big role in the petrogenesis of the volcanic centres is the area. The Iskut-Unuk rivers volcanic centres show many chemical similarities to other centres located within the southern Stikine Volcanic Belt (SVB) (Souther, 1992; Cousens and Bevier, in press) but are distinct chemically from volcanic centres in the northern part 71 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres of the SVB (Eiche at al., 1987). Various amounts of contamination by lithospheric mantle is thought to be responsible for the chemical differences between the northern and southern part of the volcanic belt (Eiche et al., 1987; Cousens and Bevier, in press). Rocks of intermediate composition are rare in the Recent volcanic centres of British Columbia and southern Yukon. The origins postulated are diverse and include: closed system fractionation (Souther, 1992), combined fractionation and assimilation of crustal material (Stout and Nicholls, 1983) or source region processes (Cousens and Bevier, in press). 5.1. Magmatic processes within the Iskut-Unuk rivers centres The following section elucidates the magmatic processes found at five of the Iskut-Unuk rivers centres which comprise lava flows and other volcanic deposits including; Iskut River, Snippaker Creek, Cone Glacier, Cinder Mountain and Lava Fork. One of the simplest processes that could be invoked to explain the observed chemical variation within each centre is closed system fractionation of from an homogenous melt involving the phases observed in the rocks. All centres contain olivine and plagioclase porphyritic lavas; several lavas also contain rare clinopyroxene phenocrysts. 72 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres 63 CS O o C O u to 0 0 d + OS o © + VO u •/-) v-> © ' i so S oo © I <L> UH CN 00 © + Ov © © ' bo vo 6250 6000 5750 5500 \ — 5250 5000 4750 4500 a ^ ^ I R - 5  O L r CPX — — IR-j> ' 1 1 lR-7 1 , 1 1 , 1 1 4500 4750 5000 5250 5500 5750 Si+Ti+Fe+Na/Zr 6000 6250 62 60 58 56 54 52 50 48 46 44 42 b I R - 8 ^ ^ -^IR-5 - .^^IR-4 — — O L - C P X SH-37 y ^ 1 . 1 . 1 . 1 . 1 , 1 , 1 1 • 44 46 48 50 52 54 56 Si + Ti + Fe + Na/K 58 60 62 Figure 5.1. Q-type Pearce element ratio diagrams for Iskut River basalts, using a) Zr and b) K as denominator. The line is through the sample with highest MgO content (IR-8). Vectors indicate displacement by fractionation of the different minerals observed in the rocks. 73 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres The Pearce element ratio diagrams (Russell and Nicholls, 1988; Stanley and Russell, 1989; Russell et al., 1990; Nicholls and Russell, 1991) can be used to test specific ideas for magmatic processes. They are an effective tool only if the common denominator is an element that is truly conserved during the differentiation process. The major elements most likely to be conserved in a basaltic system are K, P and Ti. Fe-Ti oxides are abundant in the rocks which may mean that Ti is not conserved. P is measured with less precision than both Ti and K, leaving as K the choice as conserved element. Should K not be conserved in the system, it is an indication of open system processes. One of the Pearce element ratio diagrams for Iskut River lava flows was duplicated using Zr and K as the denominator (Figure 5.1). Zirconium is expected to be absolutely conserved in most basaltic systems that behave as closed chemical systems. Both diagrams of Figure 5.1 show the same distribution of data whether using Zr or K as denominator. This is further justification for choosing K as conserved element. The axes used for plotting the Pearce element ratios, account for the stoichiometry of a variety of mineral phases. Data for each centre are plotted on three different diagrams. The first figure (two-phase) tests for sorting of olivine and plagioclase but any chemical affect resembling fractionation of clinopyroxene will pull the data off the model slope of one towards higher y-axis values (e.g., Figure 5.2a). The second Pearce-type diagram (three-phase) models the effects of sorting of olivine, plagioclase and clinopyroxene with a line of unit slope (e.g., Figure 5.2b). The third Pearce element ratio diagram (q-type) (Nicholls, 1990; Nicholls and Russell, 1991) tests for sorting of the three previous mineral 74 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres phases along with Fe-Ti oxides. The q-diagram has been successful in distinguishing different magma-batches in historic Kilauea eruptions using the intercepts of model sorting lines (Nicholls and Russell, 1991). In each diagram the model line is through the least fractionated sample, represented by the highest calculated MG# value (Mg#=100*Mg/(Mg+Fe2+)) (Wager and Deer, 1939), solidification index and petrographic indications. Error ellipses for each data point represents Is analytical error (Stanley and Russell, 1989; Nicholls, 1990) estimated from replicate analyses (Appendix I). Table 5.1 summarizes the effects of ideal stoichiometric mineral components on the three different Pearce element ratio diagrams. Each phase has a unique displacement vector on each diagram with a precise slope (m) and magnitude (n). The displacement vectors Table 5.1. Mineral vectors given as slope (m) and norm (n) for three Pearce-type ratio plots based on 8 O's. General Two phase Three phase Q-type Mineral Si Ti Al Fe 3 + Fe 2 + Mg Ca Na K Cr o m n m n m n An 2 2 1 8 1.00 2.83 1.00 2.82 1.00 2.82 Ab 3 1 1 3 1.00 4.24 1.00 4.24 1.00 5.65 Or 3 1 1 8 0.75 3.75 0.08 3.01 1.33 4.99 Fo 1 2 4 1.00 2.83 1.00 2.83 1.00 2.83 Fa 1 2 4 1.00 2.83 1.00 2.83 1.00 8.49 Mag 2 1 4 - 1.00 - 1.00 0.82 2.59 Usp 1 2 4 - 2.00 - 2.00 1.00 8.49 Ilm 1 1 3 - 1.33 - 1.33 1.09 7.89 Hm 2 3 - 0.00 - 0.00 - 0.00 Chr 1 2 4 - 1.00 - 1.00 0.82 2.59 En 2 2 6 0.50 2.98 0.50 2.98 1.18 4.12 Fs 2 2 6 0.50 2.98 0.50 2.89 1.09 7.89 Di 2 1 1 6 -1.00 3.77 1.00 3.77 1.00 3.76 Hd 2 1 1 6 -1.00 3.77 0.75 3.77 1.00 5.65 75 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres shown on the PER diagrams for each centre are calculated using measured mineral compositions, based on 8 oxygens. Trace element concentrations and ratios of incompatible elements are plotted against solidification index (Kuno, 1957) (e.g., Figure 5.3). Incompatible trace element values are expected to increase with decreasing S.I. and compatible trace elements with olivine or plagioclase should decrease. Ratios of these elements are plotted against x-axis values of q-type PER diagrams (e-g-, Figure 5.4). The resulting patterns constrain the magmatic processes although scatter in trace element data can result from the dependence of the exchange coefficients on temperature, pressure and bulk composition of the melt (Lemarchand et al., 1987). Lastly, concentrations of Rare Earth Elements, analyzed for each flow of the Iskut-Unuk rivers centres were measured by the Geological Survey of Canada and results are given in Appendix C. The pattern of normalized concentrations (Boynton, 1984) and the relative degree of enrichment within the centres can be helpful in the investigation of the petrogenesis of the centres. 5.1.1. Iskut River The basalts from Iskut River are olivine and plagioclase porphyritic and have a groundmass of olivine, plagioclase, clinopyroxene and Fe-Ti oxides. 76 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres Table 5.2. Mineral vectors for measured mineral compositions of the Iskut River lavas given as slope (m) and norm (n) on 8 O's basis as they appear in three Pearce-type ratio plots. Iskut River Two phase Three phase Q-type Mineral Si Ti A l Fe Fe Mg Ca Na K Cr o m n m n m n PI 2.40 1.60 0.60 0.30 8 0.96 3.29 0.97 3.30 1.01 3.84 Ol 0.98 0.57 1.44 4 1.03 2.81 1.03 2.82 0.99 4.37 Cpx xeno 1.85 0.22 0.27 0.82 0.76 6 -0.46 2.72 0.94 3.39 1.02 4.03 Cpx grm 1.78 0.20 0.41 0.60 0.88 0.05 6 -0.70 2.90 1.05 3.45 0.98 4.09 Mt 0.03 5.04 0.69 4.56 12.0 1.26 0.05 32 O O 2.04 O O 0.20 0.96 5.92 Dm 0.15 1.75 0.12 1.82 6 O O 1.23 O O 0.20 1.10 7.36 Table 5.2 lists the vector displacements for measured mineral compositions; they are shown as insets in figure 5.2. Clinopyroxene is represented by analyses from both rare phenocrysts as well as the groundmass. Figure 5.2a is a the Pearce element diagram testing for sorting of two mineral phases, olivine and plagioclase. A model line representing the sorting of those minerals is drawn through the sample containing the highest MgO concentration. The data do not fit the model line within associated analytical error (Is). The mineral displacement vectors (based on measured mineral compositions) show olivine and plagioclase to be co-linear with the model line (Table 5.2). The range of clinopyroxene, found as rare resorbed megacrysts and groundmass, is represented by the shaded area. Fractionation of these clinopyroxene compositions would induce the magma compositions to shift above the line of unit slope. The implication is that the Iskut River rocks are not related through simple fractionation of olivine and plagioclase. The deviations seen in Figure 5.2a could be an indication of clinopyroxene fractionation, however Figure 5.2b tests this possibility explicitly. This Pearce-type diagram tests for sorting of olivine, plagioclase and clinopyroxene because the displacement vectors are all 77 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres co-linear with the model slope of one. As seen in Figure 5.2b the model line does not fit the data within analytical uncertainty and causes rejection of the hypotheses involving fractionation of the three mineral phases. Finally the third PER diagram (Figure 5.2c) tests for sorting of all the common minerals found in basaltic systems: olivine, plagioclase, clinopyroxene and Fe-Ti oxides. In this figure comagmatic basalts related by any combination of these phases should be co-linear (Nicholls and Russell, 1991). In the case of the lavas sampled from the Iskut River they do not form a single line and thus are inconsistent with a closed magma system. This may suggest that the Iskut River rocks represent different batches of magma or result from other processes, including open system processes. Figure 5.3 shows the concentration of some trace elements as a function of calculated solidification index for Iskut River lava flows. Nb, Rb, Zr and Ba all behave incompatibly but the concentration of Sr and Ni decreases; consistent with olivine and plagioclase fractionation. In Figure 5.4 trace element ratios with Zr as denominator are plotted against the x-axis values from the q-type PER diagram. The incompatible element ratio data generally do not agree with a single closed system as the scatter exceeds analytical uncertainty. They cannot be distinguished by Nb/Zr and Ce/Zr but according to Sr/Zr, Rb/Zr and Ba/Zr the samples are roughly grouped into more mafic samples (IR-4, IR-5, IR-8) and more fractionated ones. 79 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres SI- S.I. Figure 5.3. Trace element concentrations for Iskut River basalts vs. S.I. index. Error bars represent Is. 80 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres 31 30 h 29 h 28 h N I-I C/3 OQ 27 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.6 2.4 2.2 2.0 1.8 1.6 a • m-8 I R - 6 « » I R - 2 , I , ^SH;37| 1 , 1 . 1 If, ^  J i L 1 . 1 , 1 i I i L J , I , I i I i L J , I , L 0.085 0.080 h i- 0.075 & 0.070 0.065 h 0.060 2 42 44 46 48 50 52 54 56 58 60 62 Si+Ti+Fe+Na/K 42 44 46 48 50 52 54 56 58 60 62 Si+Ti+Fe+Na/K Figure 5.4. Trace element ratios, with Zr as denominator, for Iskut River basalts plotted against x-axis values from q-type PER diagram. Error bars represent Is. 81 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres Figure 5.5 shows the patterns of normalized concentrations of Rare Earth Elements for the Iskut River basalts. The data separate into two groups (Figure 5.5); the samples show a very similar enrichment but samples IR-4,5 and 8 are slightly less enriched. A single sample from Tom MacKay Creek, located in the vicinity of the Iskut River lava flows, shows the same degree of enrichment as samples IR-4,5 and 8. Figure 5.5. R E E patterns for Iskut River and Tom MacKay Creek basalts, normalized to values from Boynton (1984). Data are listed in Appendix C. The mafic samples from Iskut River cannot be related to the more differentiated by fractionation of olivine, plagioclase and clinopyroxene (Figure 5.2). The two different groups could represent different magma batches, as different melts or portions of larger heterogeneous melt, or the magma has been contaminated to a various degree by the crust. too h -o Si g 10 •o e o -c 1 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 82 5.1.2. Snippaker Creek Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Basalts from Snippaker Creek comprise several olivine and plagioclase porphyritic lava flows with abundant clinopyroxene in the groundmass as well as olivine, plagioclase and Fe-Ti oxides. Rare and small crustal xenoliths of granitic composition occur in the basalts. Table 5.3. Mineral vectors for three Snippaker Creek Pearce-type ratio plots according to measured compositions given as slope (m) and norm (n). Snippaker Creek Two phase Three phase Q-type Mineral Si Ti Al Fe r~ 2 + Fe Mg Ca Na K Cr O m n m n m n PI 2.40 1.57 0.60 0.37 8 0.96 3.33 0.96 3.33 1.01 3.93 Ol 0.99 0.50 1.50 4 0.98 2.78 1.03 2.84 0.99 4.20 Cpx 1.81 0.08 0.22 0.35 0.68 0.86 6 -0.61 2.83 1.09 3.57 0.98 4.26 Mt 5.04 0.69 4.56 12.0 1.26 0.05 32 QO 2.04 oo 0.20 0.96 5.91 Um 1.08 1.69 0.99 0.11 6 OO 0.88 OO 0.09 1.09 4.10 Chemical compositions of five samples of Snippaker Creek basalts are plotted on a series of Pearce element ratios diagrams (Figure 5.6), following the methods discussed above. Specific mineral displacement vectors for Snippaker Creek basalts are given in Table 5.3; they are very similar to those computed for the Iskut River basalt mineral assemblage. Based on the analysis shown in Figures 5.6a,b and c it appears that the Snippaker Creek basalts cannot be related by simple fractionation. The data plotted on Figure 5.6a and b diverge significantly from the model line, implying that the data are inconsistent with sorting of olivine and plagioclase or olivine, plagioclase and clinopyroxene. Figure 5.6c 83 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres 21 < i SH-33 J , I i L J i I i L 32 31 30 29 28 27 S.I. 26 Figure 5.7. Trace element concentrations for Snippaker Creek basalts vs. S.I. index. E r ro r bars represent Is. 85 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres 32 30 -c/o 28 -26 3.50 v, 3.25 * 3.00 2.75 2.50 2.25 2.00 1.75 a j , i i J i I , L 52 54 56 58 60 Si+Ti+Fe+Na/K 0.07 62 64 56 58 60 62 Si+Ti+Fe+Na/K 64 Figure 5.8. Trace element ratios, with Z r as denominator, for Snippaker Creek basalts plotted against x-axis values f rom q-type P E R diagram. Error bars represent Is. 86 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres shows the data with a model line drawn through the highest mafic composition; this composition cannot generate the more fractionated samples by sorting of olivine, plagioclase, clinopyroxene and oxides as indicated by the fact that they plot off the unit line (Figure 5.6c). The most fractionated samples alone (SH-01, SH-33 and SH-02) fit a model line with unit slope and are possibly related through sorting of the associated mineral phases. Variations in concentrations of trace elements are shown in Figure 5.7. Ba, Zr and Nb all behave as incompatible elements with the exception of sample SH-34. Rb and Sr concentrations are fairly scattered where SH-02 has lower Rb concentration than other samples. Ni concentration is constant within Is analytical uncertainty for all samples. The S.I. and trace elements ratioed to Zr are shown as a function of the PER x-axis values (Si+Ti+Fe+Na/K) from Figure 5.6c (Figure 5.7). The incompatible element ratios are fairly constant for Snippaker Creek samples except for sample SH-34 which is aberrant in Sr/Zr and Nb/Zr ratios (Figure 5.8b and e). Rb/Zr shows lots of variation for the basalts where samples SH-02 and SH-34 have lower values than the rest. Figure 5.9 shows the patterns of Rare Earth Elements from Snippaker Creek basalts. Two of the samples (SH-02 and SH-34) have parallel patterns which crosscut the HREE patterns for other samples. This feature suggests the involvement of a phase such as 87 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres garnet which is capable of controlling the abundances of HREE (Hanson, 1990) or possibly assimilation. Otherwise the REE patterns from Snippaker Creek samples show very little variation of enrichment. La Ce Pr Nd Sm Eu Gd Tb Dy Ho E r Tm Yb Lu Figure 5.9. REE patterns for Snippaker Creek basalts, normalized to values from Boynton (1984). Sample SH-34 shows more enrichment for Tb, Dy and Ho than other samples. Data is listed in Appendix C. Major and trace element chemical compositions of Snippaker Creek basalts suggest the magmatic system of the centre is not closed, but possibly has been affected by source region processes and/or assimilation of crustal material. Two samples are not consistent to the trace element distribution of the other samples and they possibly represent a separate batch of magma or a lesser degree of contamination. REE patterns suggest a possible difference in degree of melting of a garnet-bearing source. 88 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres 5.1.3. Cone Glacier Cone Glacier volcanic centre comprises the largest number of lava flows of the Iskut-Unuk rivers centres; they appear to have originated from two vents located within 2 km of each other. The flows are olivine and plagioclase porphyritic with rare resorbed clinopyroxene phenocrysts. Granitic crustal xenoliths and xenocrysts of partly resorbed plagioclase crystals are common. Pearce element ratio diagrams, designed to test whether the Cone Glacier basalts are related through closed system fractionation are shown in Figure 5.10. Figure 5.10a tests for olivine and plagioclase sorting. The model line drawn through the sample containing the highest MgO does not fit the data from Cone Glacier within Is analytical error which implies that sorting of olivine and plagioclase alone does not describe the chemical variation within the volcanic centre. Mineral displacement vectors (Figure 5.10a) suggest that clinopyroxene fractionation could be involved. Figure 5.10b tests the data against the hypothesis of sorting of olivine, plagioclase and clinopyroxene but the addition of clinopyroxene fractionation is not suffice to explain the chemical variation (Figure 5.10b). The q-diagram comes very close to explaining the chemical variation within the Cone Glacier basalts (Figure 5.10c). Displacement vectors are co-linear with the model line which does not fit the 89 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Table 5.4. Mineral vectors for three Cone Glacier Pearce-type ratio plots according to measured compositions given as slope (m) and norm (n). Cone Glacier Two phase Three phase Q-type Mineral Si Ti Al r- 3 + Fe Fe Mg Ca Na K Cr O m n m n m n PI 2.40 1.57 0.60 0.37 8 0.96 3.29 1.00 3.35 1.00 3.87 Ol 0.99 0.50 1.50 4 0.99 2.04 1.03 2.06 0.99 4.31 Cpx 1.81 0.08 0.22 0.35 0.68 0.86 6 -0.61 3.09 1.09 3.40 0.98 4.26 Mt 5.04 0.69 4.56 12.0 1.26 0.05 32 OO 1.89 OO 0.20 0.96 5.91 Um 1.08 0.05 1.69 0.99 0.11 6 OO 0.81 OO 0.09 1.09 4.10 whole data set, leaving few samples that need further explanation. Figures 5.11 and 5.12 show trace element compositions and ratios of incompatible elements from the Cone Glacier lavas, plotted against S.I. index and x-axis values from q-type PER diagram, respectively. Concentrations of incompatible elements in Cone Glacier basalts generally increase with decreasing S.I. (Figure 5.11). Nb, Rb, Zr, Ba all behave similarly for the majority of the samples from Cone Glacier but at least two samples do not fit the general trend. These samples are from the western cinder cone and they are more enriched in Ba, Nb, Zr and Rb than other samples. Sr and Ni concentrations are fairly constant for the whole sample collection. All but 4 of the 13 samples show decreasing S.I. number with increasing fractionation (Figure 5.12). Two of the aberrant samples are from the west cone (CG-13 and CG-18) and the other two samples (SH-22 and SH-26) are from a stack of three flows located on the boundary between Cone Glacier and Cinder Mountain volcanic centres. Nb/Zr and Ce/Zr are more or less constant for Cone Glacier basalts when plotted against 91 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres a O . 3 cs CQ 550 500 450 400 350 300 250 650 IT 625 3 £ 600 575 550 80 IT a, 60 40 20 a 1-1 si •CO-13 SH CO-11 4 ITCO-15 fsH-14 , 4ct JSH-15 _l i I i I i I J i I , I . I J , I i L J i 1 . 1 , 1 . 1 J . l_ a a. 3 a 3 x> Pi a. a. N 33 32 31 30 29 28 S.I. 27 26 25 24 32 30 28 26 24 22 20 18 18 16 14 12 10 8 225 200 175 150 ^SH-15 f-SH-l.# j I , l _ j I i L ^CG-18 ^CO-13 H-13^  JCO-12 J , I , I , L f T T _J i I , L CO-15 J , L J i L I f J , I , I , L 33 32 31 30 29 28 S.I. 27 26 25 24 Figure 5.11. Trace element concentrations for Cone Glacier basalts vs. S.I. index. Error bars represent Is. 92 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres oo 35 30 h 25 20 3.50 3.25 3.00 2.75 2.50 2.25 2.00 PQ 1.75 1.50 •CO-18 #CO-13 CO-10 • •CO-9 CO-14 CO-11* •CG-15 SH-26«»SH-22 •CO-12 a i , i , i , i . i . i . i . i . i , ' t t 1 1 i . i i i i i i i i i i i i i i NJ N <L> o 0.10 0.08 0.06 0.04 0.14 0.13 0.12 0.11 0.10 0.6 0.4 0.2 0.0 lcO-12, Jn TcG-13 fCG-11 I . I . I CO-lOh CO-14 |cG-15tt C°-' SH-26^SH-22 S^H-15 SH-u4 1 . 1 , 1 •M + + Hi I , I . I . I . I i . i . i . i i . i . i . i . i . i 42 44 46 48 50 52 54 56 58 60 62 64 66 Si+Ti+Fe+Na/K 42 44 46 48 50 52 54 56 58 60 62 64 66 Si+Ti+Fe+Na/K Figure 5.12. Trace element ratios, with Zr as denominator, for Cone Glacier basaltic rocks plotted against x-axis values from q-type PER diagram. Error bars represent Is. 93 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres the x-axis values of the q-type PER diagram (Figure 5.10c) except for the two samples from west cone (Figure 5.12e and f). The Rb/Zr ratio decreases (Figure 5.10d) as Sr/Zr increases with x-axis values (Figure 5.10b) and Ba/Zr shows considerable scatter of generally decreasing values (Figure 5.10c). Figure 5.13 shows the REE patterns for Cone Glacier basalts; they show very similar patterns in terms of degree of enrichment; sample SH-14 with the lowest and SH-13 the highest. The patterns are similar to those observed for other Iskut-Unuk rivers centres. La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Figure 5.13. R E E patterns for Cone Glacier basalts, normalized to values form Boynton (1984). Data are listed in Appendix C. 94 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres According to the Pearce Element Ratio diagrams the chemical variation within samples from Cone Glacier volcanic centre are not explained by closed system processes, and possibly involves more than one magmatic system. With a closer look at trace elements and solidification index possibly three different unrelated units have been identified, likely the product of different batches or melts of magma; the majority were erupted from the east cone. Rb, Ba and Sr show a different degree of incompatibility when compared to Zr concentrations. This is possibly related to the abundant xenocrysts found in the flows. Possible explanations include source region heterogeneity or assimilation of crustal material or both. 5.1.4. Cinder Mountain The samples from Cinder Mountain include five intermediate rocks and one basalt, grouped together based on their spatial distribution (Figure 2.3). The basalt (Sample SH-35) is from an isolated flow in Copper King Creek with no identified vent. The remaining samples, all intermediate in composition were collected from an area close to the top of Cinder Mountain. The two rock types are petrographically and chemically different. The basalt is olivine and plagioclase porpnyritic and contains rare resorbed clinopyroxene crystals. Plagioclase xenocrysts commonly show sieved textures and at least one quartz crystal with a reaction rim of clinopyroxene. The groundmass includes olivine, plagioclase, Fe-Ti oxides and minor clinopyroxene. The hawaiite comprises anhedral often partially 95 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Table 5.5. Mineral vectors for three Cinder Mountain Pearce-type ratio plots according to measured compositions given as slope (m) and norm (n). Cinder Mountain Two phase Three phase Q-type Mineral Si Ti Al Fe 3 + Fe Mg Ca Na K Cr o m n m n m n PI 2.56 1.42 0.44 0.51 8 0.97 3.56 0.94 3.52 1.01 4.37 Ol 0.98 0.97 1.04 4 1.00 3.77 1.04 2.82 0.99 5.49 Cpx 1.81 0.08 0.22 0.35 0.68 0.86 6 -0.61 2.83 1.09 3.57 0.98 4.26 Mt 5.52 0.60 3.93 12.4 1.17 32 OO 2.01 OO 0.19 0.97 6.25 Ilm 1.08 0.05 1.69 0.99 0.11 6 OO 0.88 OO 0.09 1.09 4.10 resorbed phenocrysts of andesine and minor olivine in a groundmass containing mostly plagioclase with abundant magnetite and some apatite. Displacement vectors are based on measured mineral compositions and are shown graphically (Figure 5.14) and numerically (Table 5.5). Figure 5.14a shows that intermediate rocks from Cinder Mountain cannot be derived from the basalt by sorting of olivine and plagioclase. Figure 5.14b tests for 3-phase sorting (OL±PL±CPX) and shows the data plot below the model line. The q-type diagram shows that the chemical variation observed between the rock types cannot result from sorting of OL±PL±CPX±Fe-Ti oxides (Figure 5.14c). Lastly the intermediate rocks themselves cannot be explained by closed system fractionation of the observed minerals. Possibly other mineral phases are important in the system such as magnetite and apatite. This is tested by the Pearce type diagram in Figure 5.15 where the model line represents sorting of plagioclase and apatite. Clinopyroxene causes chemical variations with vertical trends and olivine and magnetite have no affect. The variation within the samples is not simply explained by the sorting of these minerals. 97 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres 7.5 6.0 6.5 7.0 7.5 A1 + 3.33P/K Figure 5.15. Pearce element ratio diagram for hawaiites from Cinder Mountain representing sorting of plagioclase, olivine, clinopyroxene, magnetite and apatite. Compared to the basalt (SH-35), the hawaiites show enrichment of the incompatible elements and within the group there is slight variation with decreasing S.I. (Figure 5.16). Ni shows the expected behaviour for a compatible element (Figure 5.16c). The ratios of incompatible elements over Zr suggest the two rock types are not generated from the same magma affected by closed system processes, as the values do not remain constant (Figure 5.17). Only Nb/Zr and Ce/Zr plot within Is analytical error for all samples but values for Sr/Zr are lower for the hawaiites and Ba/Zr and Rb/Zr are higher. The hawaiite samples alone exhibit variation exceeding analytical uncertainty for Rb ratios (Figure 5.17d). 98 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres 1000 900 ^ 800 h 5 6 700 h m 600 h 500 \-400 650 & 600 550 500 40 S 30 a , a g 20 10 0 a ASH-35 " i l l CM-1 CM-20' 21 •SH-21 9 i t s a . & a. Q. N 23 22 21 20 19 18 17 16 15 14 13 12 11 S.I. 10 23 22 21 20 19 18 17 16 15 14 13 12 11 10 S.I. Figure 5.16.. Trace element concentrations for Cinder Mountain rocks vs. S.I. index. Error bars represent Is. 99 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres 00. 24 22 20 18 16 14 12 2.00 1.75 1.50 1.25 2.25 * j 2.00 CQ -CM-20 -CM-19 -«%SH-19 t-H oo 1.75 1.50 a i i i i 1 . 1 , 1 , 1 , 1 . 1 , 1 , 1 0.12 0.10 0.08 h S H - 2 1 0.06 h u 0.04 0.15 0.14 0.13 0.12 0.4 0.3 0.2 lCM-21 TlcM-20 «SH-19 | f CM-19 20 22 24 26 28 30 32 34 36 38 40 42 44 46 Si+Ti+Fe+Na/K SH-35 | J , I , I , I , 1 , I 20 25 30 35 40 Si+Ti+Fe+Na/K 45 Figure 5.17. Trace element ratios, with Zr as denominator, for Cinder Mountain basalt and hawaiites plotted against x-axis values for q-type diagram. Error bars represent Is. 100 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres The Cinder Mountain samples show close to linear correlation between S.I. and x-axis values for the q-type PER diagram that represent the process involved (Figure 5.17a). The REE patterns for Cinder Mountain generally show enrichment in LREE compared to HREE. The samples of hawaiite exhibit similar amount of enrichment that is significantly higher than that for the single basalt from Copper King Creek displays (Figure 5.18).The difference in enrichment between the two rock types is higher for LREE than HREE. The patterns for basalt and hawaiites from Cinder Mountain are otherwise very similar; they are relatively flat, which is also observed for basalts from other Iskut-Unuk rivers centres. La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Figure 5.18. REE patterns for Cinder Mountain hawaiites and basalt (SH-35), normalized to values from Boynton (1984). Data are listed in Appendix C. 101 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres In conclusion, the intermediate rocks from Cinder Mountain volcanic centre are not differentiation products of basalt SH-35. A possible explanation is separate melts for the basalt and hawaiite or assimilation of crustal material by a basaltic parent. In addition the chemical variation within the hawaiites is not entirely explained by sorting of olivine ± plagioclase ± clinopyroxene ± Fe-Ti oxide + apatite. 5.1.5. Lava Fork Lava Fork volcanic centres is the youngest from the Iskut-Unuk rivers area and includes lava flows, cinder and ash. The 6 samples collected are from a single flow and one sample of cinder. The basalt is olivine and plagioclase porphyritic with olivine, plagioclase, Fe-Ti oxides and minor clinopyroxene in the groundmass. Crustal xenoliths are very common; they are partly digested, glassy and vesiculated. Lava Fork basalt is one of few from the Iskut-Unuk rivers area that lacks the characteristic megacrysts of plagioclase and sieve textured feldspars are rare. Table 5.6. Mineral vectors for Lava Fork basalt Pearce-type ratio plots according to measured compositions given as slope (m) and norm (n). Lava Fork Two phase Three phase Q-type Mineral Si Ti Al Fe3 + Fe 2 + Mg Ca Na K Cr o m n m n m n PI 2.38 1.58 0.62 0.38 8 0.96 3.30 1.00 3.36 1.00 3.90 Ol 0.99 0.51 1.49 4 0.68 2.89 1.03 2.84 0.99 4.23 Cpx 1.89 0.05 0.10 0.34 0.74 0.85 6 -0.71 3.09 1.02 3.59 1.00 4.35 Mt 5.43 0.33 4.34 12.5 0.99 32 OO 1.87 OO 0.15 0.97 6.26 Ilm 1.08 0.05 1.69 0.99 0.11 6 oo 0.88 OO 0.09 1.09 4.10 102 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres Figure 5.19 shows the three Pearce element ratio diagrams used to test for closed system fractionation of mineral phases observed and possible in the system. Displacement vectors show the affect fractionation of mineral phases have on the chemical variation of the samples plotted on the PER diagrams (Table 5.6). The model line is through the sample with the highest Mg# (SH-54) that also is most crystal rich. The data for the Lava Fork basalt do not fit the unit line for 2-phase, 3-phase or q-type PER diagrams (Figure 5.19). Most of the samples plot close together, within analytical error, except for two samples. Sample LF-32 is from unconsolidated ash, including a fair amount of accidental grains, increasing the Si0 2 content and sample SH-54 plots differently because of higher Na20 content than for other samples (Table 4.1). The investigation of analytical uncertainty, based on replicate samples, does not allow for the samples to be treated as chemically different. The increased Na20 for sample SH-54 is either caused by analytical uncertainty or it represents a very weak sign of assimilation of sodium rich material, like the crustal rocks and partial melts. Trace element distributions within Lava Fork rocks are plotted against the small variation in S.I. in Figure 5.20. Concentrations are constant within Is analytical uncertainty for all ratios except for Ba that decreases with fractionation. Figure 5.21a shows the relationship between S.I. and the x-axis values from PER diagrams. The trend of increasing S.I. with differentiation (x-axis values) is obscured by sample SH-54; its location indicates it is more primitive than is expected by the solidification index, possibly due to the elevated Na20 content. 103 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres S a PQ 350 300 250 200 a 6 Q. & oo 700 h 650 e 600 100 90 80 70 60 50 40 30 28.5 SH-44 SH-54+ 41 • Sll-60 1 4 IP LF-24| 4 L F-30 28.0 27.5 S.I. 27.0 27.0 Figure 5.20. Trace element concentrations for Lava Fork basalt vs. S.I. index. Error bars represent Is. 105 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres 30 a to 28 «LF-31 LF-24 .SH-44 SH-54* • SH-«0 # ' 26 <g 3.25 in 3.00 •3 1.50 1.25 1.00 47 1 48 48 Si+Ti+Fe+Na/K 0.080 0.075 0.070 h 0.065 49 48.5 48.0 47.5 Si+Ti+Fe+Na/K 47.0 Figure 5.21. Trace element ratios, with Zr as denominator, for Lava Fork basalt plotted against x-axis values for q-type PER diagram. Error bars represent Is. 106 Chapter 5. Petrogenesis of the Iskut-Unuk rivers centres The incompatible elements plotted against the x-axis values should ideally be constant. This is true for all but Rb/Zr where two samples (SH-54 and SH-60) have significantly lower values than the rest (Figure 5.21). The range of the enrichment of REE for samples of the Lava Fork basalt flow is very small, the only exception being higher Tb value for SH-54 than the rest (Figure 5.22). The pattern has the characteristic LREE enrichment over HREE as observed for other centres. La Ce Pr Nd Sm Eu Gd Tb Dy Ho E r Tm Yb Lu Figure 5.22. R E E patterns for the Lava Fork basalt, normalized to values from Boynton (1984). Data are listed in Appendix C. 107 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres The samples from Lava Fork are likely of the same chemical composition within analytical error and probably are related through closed system processes, involving the minerals observed in the rocks. However, a weak indication of contamination may be present in one sample, caused by assimilation of crustal material or source region heterogeneity. 5.2. Discussion The volcanism in the Iskut-Unuk rivers area is characterized by small, so-called monogenetic centres, where a single pulse of activity forms one or more pyroclastic cones and lava flows. Chemical variation within the centres of the Iskut-Unuk rivers area can generally not be explained by fractionation or sorting of the observed phenocryst assemblage, except possibly the Lava Fork volcanic centre. Other possible processes include: assimilation of crustal material (selective or bulk) or source region processes (e.g. various degree of melting or heterogeneous melt inherent from the mantle). Figure 5.23 introduces two diagrams for identifying the source region chemical characteristics of individual centres of the Iskut-Unuk rivers centres and provides a mean to compare the chemical diversity between centres. The two diagrams represent trace element ratios for all centres comprising more than one volcanic unit including the mean values of each centre with average analytical error (Is) plotted on the diagram. Cinder Mountain and Lava Fork 108 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres 0.16 T 0.14 N ^ 0.12 • Iskut River (IR) + Snippaker Creek (SnC) O Cone Glacier (CG) 0 Cinder Mountain (CM) O Lava Fork (LF) a L F O O O o • o CC*P*< o * O SnC o IR C M , 0.10 0.08 25 0.16 0.14 0.12 0.10 0.08 20 30 30 35 40 K/Zr 45 50 40 Ti/Zr 50 60 Figure 5.23. Trace element ratios from samples from the five volcanic centres of Iskut-Unuk rivers centres described in Chapter 5. The cross hairs denote Is average analytical error of the mean analyses for each o f the centres, a) Ratios of N b and K with Z r and b) ratios of N b and T i wi th Zr . 109 Chapter 5. Petrogenesis o f the Iskut-Unuk rivers centres plot separate from the rest of the data on both plots. The error bar for the Cinder Mountain data represents the hawaiites only; the Copper King Creek basalt plots separately. The data for Snippaker Creek, Cone Glacier and Iskut River are scattered and overlap. Sample SH-34 plots away from other Snippaker Creek basalts and appears to be chemically different as indicated in the discussion of the petrogenesis of the centre. For individual centres the time interval between eruptions has been small, based on the absence of soil from between lava flows. It is therefore unlikely that all the chemical variation observed within each centre can be attributed to many different magma-batches. One possibility is that inherent melt heterogeneity is responsible for the chemical diversity where the magma has not mixed in the chamber where it resided or in the conduit during ascend or the magma has been affected by crustal assimilation. According to field evidence (e.g., crustal xenoliths) and petrographic descriptions (e.g., xenocrysts of plagioclase) of the Iskut-Unuk rivers centres, assimilation of crustal material is possibly an important process. Assimilation of the material would likely affect the K and other element concentrations of the basalts and this may explain why crystal sorting of the observed phenocrysts is insufficient to explain the chemical variation. Potential bulk assimilants, glasses thereof and basement rock from Lava Fork volcanic centre have been sampled and analyzed. Tests of the role of assimilation in the petrogenesis of the Iskut-Unuk rivers centres are advanced in the next chapter. no Chapter 6, The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres CHAPTER 6 The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres 6.1. Description of crustal xenoliths from the Iskut-Unuk rivers area Crustal xenoliths are found in five of the eight Iskut-Unuk rivers centres. They are common in Cone Glacier and Lava Fork whilst they are rare and small at Iskut River, Snippaker Creek and King Creek. The xenoliths at Cone Glacier are commonly angular and embedded within the massive lava flows (Figure 2.4). They are generally granitic in composition and comprise mainly feldspar and quartz. Sometimes glassy basalt is found as veins within the coarse grained xenoliths. More diverse xenoliths are found at the bottom of one of the youngest flows from Cone Glacier. These were probably incorporated into the lava after it erupted and flowed over glacial-fluvial deposits from the Cone Glacier outlet. At Lava Fork crustal xenoliths are abundant and at least two types of xenoliths are found; they correspond to the basement rocktypes found in the area. Biotite-granite underlies most of the area as part of the Tertiary Coast Plutonic Complex and in the area of Lava Fork volcanic centre it has intruded a quartz-biotite schist. The xenoliths are glassy and variably vesiculated occurring as angular pieces within the massive flow or as larger basalt coated bombs i l l Chapter 6. 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The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres (Figure 2.9). Similar occurrence of basalt coated xenolith bombs has been described from Surtsey, Iceland (Sigurdsson, 1968). The partially reacted xenoliths lack mafic minerals, except for a schistose xenolith (SH-42) that contains Fe oxides. The crustal xenolith fragments found at Iskut River, Snippaker Creek and King Creek are much less abundant and smaller; they are generally granitoids, including mainly quartz and feldspar crystals. 6.1.1. Chemical compositions and melting mechanism of xenoliths Compositions of two xenoliths from the Lava Fork lava flow and a sample of granitic basement rock proximal to the volcanic centre are given in Table 6.1 and Appendix C and all glass analyses are found in Appendix H. Table 6.1 also has electron microprobe analyses of glasses and crystals from the partially melted xenoliths. The xenoliths are referred to as 'granitic' and 'schistose' xenoliths respectively, based on their protoliths. The 'granitic' xenoliths may derive from the biotite-granite which underlies the area surrounding the vent; it contains mostly quartz, plagioclase and alkali feldspar with up to 3% biotite. Glass within the xenolith is generally colorless and, it is at least as voluminous as the crystal phases. It is very rich in micro-vesicles and microlites and usually completely surrounds individual crystals (Figure 6.1). The most common crystals in the 'granitic' xenolith are either anhedral rounded quartz or relict feldspar crystals. Euhedral microlites of feldspar commonly nucleate around ancestral feldspars and form spherical masses. The xenoliths contain up 113 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Figure 6.1. Photomicrograph of the vesiculated 'granitic' xenolith (Sample SH-41) including glass and rounded crystals in contact with the basalt. Field of view 2.63 mm. to 50% vesicles, some of which are shared by the granitic and basaltic material. The boundary between the granitic and basaltic rocks is generally very sharp but locally the opaque basaltic glass has mixed with the granitic. Where the basaltic liquid invades the more viscous xenolith melt the glasses are variably colored (Figure 6.1). Individual crystals from the basalt can be found within the xenolith but are localized close to the boundaries. The second type of xenolith found in the Lava Fork area is probably derived from a quartz-biotite schist, also found in the area. The only sample collected of this kind is a basalt 114 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Figure 6.2. Photomicrograph of the 'schistose; xenolith showing the heterogeneity of the glass as biotite has dissolved. Rounded crystals are quartz. Field of view 2.63 mm. and light colored glass. The 'schistose' xenolith comprises about 30% vesicles and less glass coated xenolith bomb. In handsample the xenolith shows relict foliation defined by dark colored glass rich sub-millimetre bands alternating with coarser bands rich of quartz, feldspar than the granitic xenoliths. In the xenolith, glass is formed mainly at grain boundaries, especially adjacent to vesicles. It is very heterogeneous in color, from glassy to opaque and based on petrographic relationships the dark color is possibly due to dissolution of mafic minerals, such as biotite (Figure 6.2). With analyses by a scanning electron microscope common pseudomorphs of biotite were found to be composed of iron oxides. The crystals 115 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres within the xenolith are quartz and feldspar where the latter often shows signs of dissolution along cleavages; a feature also common within the granitic xenolith. Numerous studies in the past have tried to understand the nature of crustal assimilation and its affect on ascending mafic magma involving; 1) field and petrographic studies (Bowen, 1928; Holmes, 1936; Wyllie, 1961; Al-Rawi and Charmichael, 1967; Sigurdsson, 1968; Maury and Bizouard, 1974; Sato, 1975; Harris and Bell, 1982; Tindle and Pearce, 1983; McBirney et al., 1987; Geist and White, 1994), 2) trace element and isotopic studies (Pankhurst, 1969; Doe, 1969; Carter et al., 1978; Carlson et al., 1981) as well as 3) laboratory experiments (Watson, 1982; Watson and Jurevicz, 1984; Beard et al., 1993) and 4) theoretical modelling (Ghiorso and Charmichael, 1985, Nielsen, 1990). From petrographic observations of the xenoliths found in the Lava Fork basalt, the mafic minerals of the xenoliths are the first ones to react. This has been previously described from naturally occurring rocks. Sigurdsson (1968) describes acid plutonic xenoliths from Surtsey, Iceland which have undergone partial fusion during transport to the surface and, in which, dissolution of mafic minerals and some feldspar produced a salic liquid with anorthic plagioclase and tridymite residuum. The natural fusion of biotite-granite caused by intrusion of Tertiary basaltic andesite is described by Al-Rawi and Charmichael (1967). Here biotite is the first mineral to respond to the thermal metamorphism and the first liquid to form is at the boundaries of quartz and alkali feldspar. Alkali feldspar reacts before plagioclase but quartz is the most stable phase. Maury and Bizouard (1974) describe the possible melting mechanism 116 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres during contamination of a partially molten biotite gneiss in a basanite from France. They describe the same colour variation seen in Iskut-Unuk rivers xenoliths, due to melting of biotite. The colour fades progressively towards the clear glass and they suggest the genesis of the brown glass is from melting of feldspar and biotite and enriched in Si02by diffusion near quartz crystals and removal of alkalis. Their study concludes the main process responsible for element transfer between the two phases is that of Si, K and Na in the vapor phase. The breakdown of biotite in granitic rocks has been determined experimentally; biotite + quartz -» olivine + magnetite + liquid (Wones and Eugster, 1965; Luth, 1967; Yoder and Kushiro, 1969). Kaczor et al. (1988) also described granitic rocks where biotite has been replaced by Fe-Ti oxides, orthopyroxene and plagioclase. The mechanism of partial melting of granite observed by Le Maitre (1974) in rocks from Mt Elephant, Australia, shows the original mafic minerals in the xenoliths have been replace by dense aggregates of granular titano-magnetite or iron ore and cloudy brown glass. This is the same reaction seen in the schistose xenolith from Lava Fork. The glasses from the Iskut-Unuk rivers xenoliths generally have compositions very close to that of feldspars (Figure 6.3). They plot inside the triangle denoting the three feldspar end members and slightly towards higher Si02 in the alkalis vs. silica space. The granitic xenolith and basement rock are very close in composition including around 75% Si02 and 8-9% alkalis. The schistose xenolith has the same silica content as the basement rock but half the 117 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres amount of N a 2 0 + K 2 0 (4%); the difference is due to lower K content. The two samples of glass from this xenolith are also clearly different from the granitic glasses, with lower K 2 0 and higher SiCV Figure 6.4 shows the majority of granitic glasses from the 'granitic' xenoliths contain similar amounts of FeO + MgO as feldspars, except for few analyses where concentrations of 6 s fed + z 60 SiO. (Wt. % ) Figure 6.3. Chemical compositions of xenoliths, basement rock and granitic glasses from Lava Fork volcanic centre plotted as alkalis vs. silica (Le Bas et al. 1986; Irvine and Baragar, 1971). The triangle contains all feldspar compositions. 118 Chapter 6, The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres FeO + MgO are higher than expected for feldspars. The mineralogy of the granitic xenolith suggests the localized enrichment of mafic components in the glasses is probably caused by the .dissolution of the mafic minerals. Figure 6.5 shows that some chemical mixing has occurred between the basaltic and the granitic liquid. The diagram shows several analyses of basaltic and granitic glasses from the granitic xenolith, where the two are in contact. The feldspar end member triangle is the same o + O PH 12 10 k 45 A O • ffl 0 * i 1 1— Granitic glass Schistose glass Felspar crystals Basement rock Granitic xenolith Schistose xenolith • A A A A A A A A A f A A 50 55 60 65 SiCL(Wt. %) 70 75 o o 80 Figure 6.4. Total M g O + F e O content of xenoliths and glasses plotted against S i 0 2 content. A l so included are feldspar crystals for reference and basement rock sample. 119 Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres as plotted in Figure 6.3. Two of the basaltic glasses show normal compositions in the SiC>2 vs. alkalis space, and the majority of the granitic glass plots close to the albite-orthoclase tie-line. Several basaltic glasses have compositions between the two as the Si02 and K 2 0 contents are increased (Table 6.1). The geochemical effects on the basalt that is often linked to crustal contamination include increase in Si02 and alkalis (e.g., Watson, 1982). There are at least three potential 40 45 50 55 60 65 Si0 2 (Wt. %) Figure 6.5. A l ka l i s vs. s i l ica diagram of granitic and basaltic glass f rom a granit ic xenol i th f rom L a v a Fork volcanic centre. 120 Chapter 6, The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres styles of assimilation, reflecting the length and time scales of magma-host interaction, including; bulk assimilation, partial melt assimilation and selective assimilation (Watson, 1982; Huppert and Sparks, 1985; Groves et al., 1988). Selectivity is caused by the difference in chemical diffusivities where the alkali elements can attain chemical equilibrium with the host magma long before dissolution and homogenization of the assimilant is complete (Watson, 1982). After the xenolith has melted, the assimilation is controlled by liquid-liquid diffusion between the granitic melt and the basaltic magma. Previous studies, using experimental techniques, have focused on this element exchange between the two different liquids and they have shown the diffusivity of K to be higher from granite to basalt than that ofNa (Watson, 1982; Watson and Jurewicz, 1984; Beard et al., 1993). Hydrous fluids derived from dehydration reactions of crustal rocks could also be absorbed, resulting in selective contamination by elements that are enriched in the fluid phase (Patchett, 1980). Most common attempts to model the assimilation of basalts by crustal material involve the use of isotopes (Pb, Sr and Nd) and trace elements (e.g., DePaolo, 1981; Myers and Marsh, 1989; Glazner and Farmer, 1992; Brandon et al., 1993). These models often involve the decoupling of assimilation, fractionation and/or magma mixing (Groves et al., 1988) but assimilation is likely to be commonly associated with fractional crystallization (Bowen, 1928; DePaolo, 1981). One of the popular models is the "AFC" model of DePaolo (1981), emphasizing that the heat required to dissolve or melt country rock is likely to be provided by the heat of crystallization. The coupled assimilation-fractional crystallization causes chemical variations different from those produced by either process individually. Grove et al., (1988) 121 Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres suggested that the liquids generated by fractional crystallization are not necessarily those affected by assimilation, even though thermal budgets for each may be coupled, as heat and mass transfer are separated in space and time. Frequently disequilibrium textures of minerals occurring in the basalt are associated with assimilation processes (e.g., Harris and Bell, 1982) and even more commonly in cases of magma mixing (e.g. Wilcox, 1954; Kuo and Kirkpatrick, 1982). The characteristic sieved textures of plagioclase in the Iskut-Unuk rivers basalts is possibly caused by partial dissolution of xenocrysts of plagioclase in a basaltic melt (Tsuchiyama, 1985). In addition to the partly digested xenoliths, the abundance of sieved-textures plagioclase is further indication of the importance of assimilation in the petrogenesis of the volcanic centres. The following section deals with assimilation processes affecting the Iskut-Unuk rivers basalts. The main emphasis is on the chemical and mineralogical variations of the lavas but trace element and isotopic evidence will be introduced. 6.2. Assimi lat ion of crustal material wi th volcanic rocks from Iskut -Unuk rivers area The main part of this section deals with testing the affect of assimilation on the petrogenesis of the Iskut-Unuk rivers basalts. The most comprehensive collection of data, chemical and petrographical, for this study, is from Lava Fork volcanic centre. The discussion of assimilation of the Iskut-Unuk rivers centres will start by investigating Lava Fork 122 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres centre and follow with discussion of the other centres. It is concluded that the chemical variation within most of the Iskut-Unuk rivers centres is inconsistent with closed system fractionation. Figure 6.6 shows the same three PER diagrams used in Chapter 5, with all centres plotted on a single diagram. Model lines are through the samples believed to be the most primitive, using Mg#, S.I. or petrographic indications. The figure also plots compositions of the basement rock and xenolith from Lava Fork centre along with compositions of syenite, granite and diorite for further reference (Le Maitre, 1976). The location of the possible assimilants is consistent with the divergence from the model line towards higher y-axis values that all the centres have in common (Figure 6.6a). The intermediate rocks plot in the area between the basalts and xenolith and syenite composition and this trend is also observed in Figure 6.6b. Here the data fall of the model lines towards lower y-axis values, where the assimilants plot. The q-type diagram (Figure 6.6c) shows the model lines in a tight cluster with intercepts close to zero. A new PER diagram (or-diagram) has been designed for the purpose of detecting the affects of assimilation of granitic material on the chemical composition of the Iskut-Unuk rivers basalts. Rocks related by sorting of olivine, plagioclase and clinopyroxene will plot on a model line with the slope of one, but the chemical affects of alkali feldspar are perpendicular to that line. The chemical composition of glasses found within the crustal xenoliths have a large amount of normative orthoclase. Ti is used as denominator because the proposed assimilants contain very low concentrations of the element, making it close to conserved in the 124 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres system. Table 6.2 lists representative analyses of assimilation material with information on the associated affects of these phases in or-type diagram. The same samples will be represented graphically as displacement vectors in or-diagrams for individual centres. Table 6.2. Summary of displacement vectors based on 8 O's, for measured assimilation material from Lava Fork, for or-type Pearce element ratio diagram. Phase Granitic melt A Granitic melt B Basement SH-41 SH-42 x-axis displacement 2.99 3.00 3.31 3.32 3.26 y-axis displacement 2.93 0.49 0.27 0.11 1.16 slope (m) 0.98 0.16 0.08 0.03 0.36 norm (n) 4.18 3.04 3.32 3.32 3.46 Figure 6.7 provides a summary of slopes and norms generated by the various compositions of basement rock, xenoliths and melts (Table 6.1 and Appendix H) on the Pearce element ratio diagrams used in this thesis. Included are the affects these phases have on all three PER diagrams used for closed system fractionation testing as well as a simple PER diagram designed to test the role of assimilation of crustal material on the Iskut-Unuk rivers basalts. For each type of PER diagram, Figure 6.7 represents two plots; the displacements of y-axis vs. x-axis and the norm vs. the slope calculated on the basis of 8 oxygens. The vectors for 2 and 3-phase diagrams have slopes ranging from 0.4 to 1.2 but the norms for these vectors are mostly concentrated at 3.0 to 3.6 (Figure 6.7a and b). The opposite is observed for the q-diagram assimilation vectors where the slopes are fairly constant (1.0 to 1.3) but the norms vary from 2.7 to 4.0 (Figure 6.7c). The last two diagrams (Figure 6.7d) show the characteristics of the displacement vectors for the or-diagram explicitly designed to discriminate the phase believed to be involved with assimilation from the magmatic mineral phases. The vectors for the assimilants have slopes less than 1.0 and norms range from 3.0 to 125 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres 5 4 3 2 1 0 4 3 -"-> 2 <u 8 1 "S< ^ .2 0 on 'S 4 I >N 3 2 1 0 4 3 2 1 0 1 1 2 - p h a s e i --• • -• Granitic glass *• -— O Basement rock •fr Xenoliths 1 l a 3 - p h a s e — - • — - • * — 1 1 b - q - d i a g r a m * • — • — i 1 i c -- o r - d i a g r a m d --• • X -• *• 1 * * -o 0 x-axis diilacemert 6 5 4 3 2 5 4 3 2 5 4 3 2 5 4 3 2 • - r o Slope Figure 6.7. Slopes and norms for the assimilation phases on four different PER diagrams, represented as x-axis displacement vs. y-axis displacement and slopes vs. norms, a) 2-phase diagram, b) 3-phase diagram, c) q-diagram and d) or-diagram. 126 Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres 3.5. By this numerical summary of the displacement vectors of the assimilation material the advantage of the or-diagram over the others can be illustrated. The slopes are close to 0 and therefore at a great angle to the model line and assimilation affects should be more easily detected. The q-diagram is clearly not a good choice for this purpose as the vectors are almost collinear with the model line. The norms (vector lengths) also indicate that each of the different compositions of assimilation material will have very similar distance of displacement. 6.2.1. Crustal contamination of Lava Fork basalt The centre of Lava Fork has all the ingredients of a simple system: the samples are well constrained and show very small difference petrographically and chemically. The basalt contains abundant xenoliths, suggesting assimilation is an important process. Figure 6.8 shows the basaltic samples of Lava Fork plotted on an PER or-diagram and the model line is through sample SH-54, also used as parent for previous PER modelling. The remaining Lava fork basalt samples plot below the unit line at lower x and y-axis values and this can be assigned to the combined affects of fractionation of olivine, plagioclase and clinopyroxene with addition of assimilant (see displacement vectors). 127 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres 16 18 20 22 24 26 28 30 32 S i / T i Figure 6.8. Pearce element ratio diagram for testing for assimilation in the Lava Fork basalt, inset labels include sample numbers (bold), ratios of residuals for mass balance modelling (italic) and 8 7Sr/ 8 6Sr content of the samples. Displacement vector denote fractionation of OL, PL and CPX and addition of assimilation material. Mass balance calculations can be used to quantify the relative extent of fractionation and assimilation for Lava Fork basalt. The hypothesis to be tested includes SH-54 as parent and SH-60 as daughter, based on their relationship on the PER diagrams (Chapter 5). Petrography indicates the potential for fractionation of olivine and plagioclase; presence of xenoliths suggests assimilation. Chemical analyses of the observed minerals and the assimilants are used in the calculations. The mass balance calculations include the sums of squares of residuals (R2) and the ratio of R2 to the sums of squares of differences between parent and derivative (D2). 128 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Table 6.3 summarizes the results from mass balance calculations using SH-54 as parent to other samples, first with and then without assimilant. Higher values of residual means higher percent of the difference between parent and daughter cannot be described by the model. The residuals for the calculations, including olivine and plagioclase fractionation, are listed in Figure 6.8 showing the residuals range from 80-99% (Table 6.3). As indicated by the PER or-diagram the olivine and plagioclase fractionation alone does not account for the chemical difference between samples SH-54 and SH-60. Mass balance confirms this as 99% of the difference between the two samples remains unexplained (Table 6.3). When the assimilant is added to the phases, this fraction is 96%. The total chemical variation of the samples is close to analytical uncertainty and therefore cannot be explained by the calculations. Table 6.3. Results from Mass balance modelling for Lava Fork basalt, including grams fractionated or accumulated of each phase out of 100 gr. of magma and the residual based on the ratio of sums of squared residuals over sums of squared observed differences. Parent Daughter Ol (gr.)1 PI (gr.)' Assim. Assimilant R J (gr.)1 * P e 2 R z/D 2 SH-54 SH-60 0.087 0.145 0.130 0.99 SH-54 LF-24 -0.07 0.143 0.208 0.98 SH-54 LF-30 -0.099 -0.493 0.252 0.98 SH-54 LF-31 0.401 0.49 0.164 0.95 SH-54 LF-32 0.797 1.343 0.126 0.80 SH-54 SH-44 -0.145 -0.532 0.119 0.96 SH-54 SH-60 0.097 -0.104 0.344 GM 0.125 0.96 SH-54 LF-24 -0.065 0.013 0.178 GM 0.206 0.97 SH-54 LF-30 -0.088 -0.754 0.36 GM 0.246 0.96 SH-54 LF-31 0.414 0.203 0.398 GM 0.156 0.90 SH-54 LF-32 0.872 0.456 1.328 GM 0.039 0.25 SH-54 SH-44 -0.137 -0.742 0.287 GM 0.115 0.93 1 negative numbers = fractionation, positive numbers = addition, 2 GM = Granitic melt 129 Chapter 6, The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres It is therefore concluded that: 1) the system is not explained only by these phases, 2) the melt producing the lava flow was chemically heterogeneous or 3) the mass balance model cannot explain the small scale variations in the basalt, generally within analytical error. 6.2.1.1. Isotopic data for Lava Fork volcanic centre. Samples from Lava Fork volcanic centre, including basalt, basement rock and partly digested crustal xenoliths, were analyzed for Sr and Nd isotopes by the GSC. Table 6.4 lists values from the analyses along with their ratios. Table 6.4. Isotopic data for basalts, basement rock and crustal xenoliths from Lava Fork centre. Sample Rock- Rb Sr Sm Nd 8 7Sr/8 6Sr 1 ENd type (ppm) (ppm) (ppm) (ppm) " W W LF-31 Basalt 13.0 716.4 8.91 39.08 0.703305(12) 0.512905(5) +5.2 LF-32 Cinder 13.52 701.7 6.63 29.14 0.703299(12) 0.512906(8) +5.2 SH-54 Basalt 12.93 721.6 6.66 29.18 0.703345(25) 0.512894(6) +5.0 SH-60 Basalt 12.91 725.0 6.73 29.49 0.703289(13) 0.512907(8) +5.2 LF-28 Granite 121.4 106.2 3.74 18.17 0.708087(19) 0.512632(7) -0.1 SH-41 Xenolith 106.5 56.68 3.18 11.17 0.710297(15) 0.512697 +1.2 SH-42 Xenolith 9.54 291.4 4.17 22.51 0.704479(9) 0.512805(6) +3.3 SH-42 Xenolith 9.19 282.0 0.704477(14) 1 Bracketed values represent 2s analytical error The Lava Fork basalt shows little variation in "Sr/*6Sr, ranging from 0.703289 to 0.703345, higher than basalts from Edziza (0.7026-0.7029) but lower than Alligator Lake rocks (Souther, 1992; Bevier, unpublished data) (Figure 6.9). The 1 4 3Nd/ 1 4 4Nd for the Lava Fork basalt ranges from 0.512894 to 0.512907, and Figure 6.9 shows one sample (SH-54) 130 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres plot differently than the other three samples. This sample also contains higher Na content than other samples from Lava Fork (Figure 5.19).The lower 1 4 3 Nd/ 1 4 4 Nd and higher 8 7Sr/ 8 6Sr values for the Lava Fork samples than for the chemically similar rocks from Edziza, suggest a different source or contamination of the basalts from Lava Fork. According to Bevier (1992) and Glazner and Farmer (1992) elevated Sr ratios and lower eNd are generally attributed to 0.5131 i r 0,5130 0.5129 0.5128 h 0.5127 0.5126 1 1 Edziza i i i i i i i 1 1 1 ffl • i i i * Basement granite - | H r \ o Basaltic lava \ Alligator 0 Granitic xenolith \I11F Lake * Schistose xenolith -\ Stikinex \ Belt \ (""A \ \ Iskut \ w V I Granites -i I 1 , 1 , 1 , E i , i 0 1 , 1 , 0.702 0.703 0.704 0.705 0.706 0.707 0.708 0.709 0.710 0.711 ^Sr/^Sr Figure 6.9. M 3 Nd/ M 4 Nd vs. 8 7Sr/8 6Sr for basalt, xenoliths and basement rock from Lava Fork volcanic centre contamination by the ancient lithospheric mantle underlying the North American craton. This effect on astenospheric melts that are erupted through terrains at or near the craton is mainly observed within the northern part of the Stikine Volcanic Belt (e.g., Alligator Lake) but the 131 Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres volcanic rocks in the southern part erupted through Paleozoic and Mesozoic accreted terranes (e.g., Edziza). Figure 6.9 shows the schistose xenolith plotted within the area of Stikine rocks (adopted from Cousens and Bevier, (in press)), but the basement rock and the granitic xenolith have a considerably lower 1 4 3Nd/ 1 4 4Nd and higher 87Sr/86Sr ratios than Jurassic Iskut Granites (Causens and Bevier, in press). Unpublished data by Bevier and Anderson on the 87Sr/86Sr ratio of rocks from the Iskut area have not found as high ratios as found in the biotite granite or the granitic xenolith from the Lava Fork area. 6.2.2. Crustal contamination of Snippaker Creek, Cone Glacier and Cinder Mountain basalts. The role of assimilation of crustal material on the petrogenesis of Iskut River, Snippaker Creek, Cone Glacier and Cinder Mountain will be discussed in this section. Or-type Pearce element ratio diagrams were used to test for the affects of assimilation, using analyses of xenoliths and melts from the Lava Fork samples. Table 6.3 lists the displacement vectors for the different proposed assimilants including; basement rock, bulk xenoliths and xenolith melts. Figure 6.10 shows an or-diagram with Iskut River basalts plotted on it. PER diagrams and incompatible element ratios indicated at least three samples (IR-4, IR-5, IR-8) are 132 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres 16 18 20 22 24 26 28 30 Si/Ti Figure 6.10. Basaltic samples from Iskut River volcanic centre plotted on or-type Pearce element ratio diagram. different from other Iskut River basalts possibly as a result of open system processes. The or-type diagram shows that the three samples could be related through crystal fractionation of olivine, plagioclase and clinopyroxene but suggest that assimilation is important in the processes of the remaining samples. Mass balance calculations were performed to evaluate if the least (LR-8) and most (SH-37) evolved samples are cogenetic (a single magmatic system affected by open or closed system processes) and to estimate if and how important assimilation is in the system. 133 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Measured mineral compositions and analyses of the partial melt of a xenolith from Lava Fork are used for the calculations. Table 6.5 lists the results of the testing of two hypotheses, involving olivine and plagioclase and then olivine, plagioclase and assimilant listing the amount of fractionated phases and a ratio of R 2/D 2 (ratio of the unexplained to original difference). The parent material has the highest S.I. of the rocks occurring within the centre (IR-8) and the daughter the lowest (IR-6). With olivine and plagioclase alone, R 2/D 2 ratio is 0.33 (33%) but when the assimilation is taken into account, the ratio drops to 0.02, involving fractionation of 4.2% of olivine, 11.2% plagioclase and addition of 4.6% of assimilant. This does further support that open system processes are involved in the petrogenesis of Iskut River basalts and also suggests that the partial melt from granitic xenolith is possibly the assimilation material. Table 6.5. Results from Mass balance calculations for Iskut River basalts, including grams fractionated or accumulated of each phase out of 100 gr. of magma and the residual based on the ratio of sums of squared residuals over sums of squared observed differences. Parent Daughter Ol (gr.)1 PI (gr.) Assim. Assimilant 2 R 2 R 2 / D 2 (gr.) type IR-8 IR-6 -5.63 -11.015 0.950 0.33 IR-8 IR-6 -4.202 -11.222 4.614 GM 0.044 0.02 1 negative numbers = fractionation, positive numbers = addition,2 GM = Granitic melt Figure 6.11 shows the basalt samples from Snippaker Creek plotted on an or-diagram. The solid line is through the most Mg-rich sample, leaving the remaining samples consistent with the combined affects of fractionation and assimilation of crustal melts, according to the displacement vectors. Previous analyses suggest that sample SH-34 is possibly not related to the others, which is inconsistent with field relations; all the flows are close in time and space. This hypothesis was tested by mass balance calculations; sample SH-01 can be derived from sample SH-34 by fractionation of olivine and plagioclase and assimilation of granitic melt. 134 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Table 6.6. Results from mass balance calculations for Snippaker Creek basalts, including grams fractionated or accumulated of each phase out of 100 gr. of magma and the residual based on the ratio of sums of squared residuals over sums of squared observed differences. Parent Daughter 01 (gr.)1 PI (gr.) Assim. Assimiiant R 2 R2/D2 (gr.) < y p e SH-34 SH-01 -3.628 0.313 0.738 0.24 SH-34 SH-01 -3.152 -1.149 3.47 GM 0.187 0.06 1 negative numbers = fractionation, positive numbers = addition,2 GM = Granitic melt Table 6.6 lists the results from these calculations including the amounts of phases involved and residual of unexplained differences. When only plagioclase and olivine are used to explain the 135 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres chemical variation, the fit for the two samples is not very good (R2/D2=0.24) but with the assimilation material being added to the system the fit is significantly better (R2/D2=0.06). The calculations include 3.2% olivine and 1.1% plagioclase fractionated from the parent material and 3.5%) of granitic melt was assimilated. It is concluded that the samples from Snippaker Creek are related through open system processes including fractionation of olivine and plagioclase and the addition of partially melted granitic xenolith. The or-diagram, for testing for assimilation of Cone Glacier rocks, is shown in Figure 6.12. Again these data are consistent with a combination of fractionation and assimilation. The 16 18 20 22 24 26 28 30 32 Si/Ti Figure 6.12. Basalts from Cone Glacier volcanic centre plotted on or-type Pearce element ratio diagram. 136 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres unit line is through sample SH-14, which has the highest S.I. value, with most other samples plotting below the line. The displacement vectors indicate the slope and norm of analyzed compositions of possible assimilation material. Samples SH-22 and SH-26 are probably generated from a different magmatic system, as indicated by the incompatible element ratios (Chapter 5), and they fit a separate line with the slope of one. The same is observed for samples CG-13 and CG-18 that are generated from a magmatic system with separate chemical characteristics. Mass balance calculations were used to evaluate the hypothesis involving the basalts of Cone Glacier being related through fractionation of olivine and plagioclase coupled with assimilation of crustal material. Table 6.7 lists the two hypothesis tested along with the residual as constraint on the quality of the test. Based on Figure 6.12 sample SH-13 is probably not derived from sample SH-14 from sorting of olivine and plagioclase alone. Mass balance residuals indicate that 33% of the difference between the parent and daughter material cannot be explained by the fractionation model. When granitic melt is introduced to the system, the residual decreases to 0.08, with the proportions of 5.7% olivine, 9.5% plagioclase and 6.2% assimilant being involved. Table 6.7. Results from mass balance calculations for Cone Glacier basalts, including grams fractionated or accumulated of each phase out of 100 gr. of magma and the residual Parent Daughter Ol (gr.)1 PI (gr.) Assim. Assimilant R 2 R 2 /D 2 (gr.) type2 SH-14 SH-13 -7.084 -8.577 2.263 0.33 SH-14 SH-13 -5.675 -9.492 6.243 GM 0.545 0.08 1 negative numbers = fractionation, positive numbers = addition, 2 GM = Granitic melt 137 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres The basalt and hawaiite samples associated with the Cinder Mountain volcanic centre are plotted on or-diagram in Figure 6.13. The model line of Figure 6.13 is fitted through sample SH-19, and the inset vectors suggest the other hawaiite samples could be derived from it through the processes of fractionation of olivine and plagioclase and assimilation of granitic melt. 16 18 20 22 24 26 28 30 32 Si/Ti Figure 6.13. Basalt and hawaiites from Cinder Mountain volcanic centre plotted on or-type Pearce element ratio diagram. Table 6.8 lists the results from mass balance calculations for basalt and hawaiite samples from Cinder Mountain. The calculations include the basaltic sample as parent to the most evolved sample of hawaiite (SH-21), and within the intermediate suite the proposed 138 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres parent is based on Mg# and previous PER diagrams (CM-21). In both cases there is a considerable amount of the variation not explained by the model of fractionation of olivine and plagioclase or when assimilation is also considered. The fit is better if granitic melt is added to the system but a good statistical measure is needed to evaluate the results. In their attempt to model the origin of hawaiites from Itcha Mountain Range Stout and Nicholls (1983) concluded that a ratio of assimilated material to crystallized material of more than 1:2 will generally require heat from an external source. Energy calculations can be used to place further constraints on otherwise acceptable mass balance calculations. In the case of Cinder Mountain hawaiites, the mass balance calculations suggest assimilationxrystallization ratio of 1:1.85 is probably sufficient for fulfilling the heat budget required. Table 6.8. Results from mass balance modelling for Cinder Mountain basalt and hawaiites, including grams fractionated or accumulated of each phase out of 100 gr. of magma and the residual based on the ratio of sums of squared residuals over sums of squared observed differences. Parent Daughter Ol (gr.)1 PI (gr.) Assim. (gr.) Assimilant type 2 R 2 R 2 /D 2 SH-35 SH-21 -12.335 -17.61 9.955 0.42 SH-35 SH-21 -7.948 -18.378 14.198 GM 3.375 0.15 CM-19 SH-21 -1.557 -2.526 0.225 0.51 CM-19 SH-21 -0.888 -2.643 2.166 GM 0.077 .0.17 1 negative numbers = fractionation, positive numbers = addition, GM = Granitic melt The origin of intermediate rocks from Stikine and Anahim volcanic belts has been debated and various processes have been introduced. Souther (1992) argues that the entire range of intermediate and felsic rocks in the Mount Edziza Volcanic Complex can be derived by crystal fractionation of a common alkali olivine basalt parent. Curiously, the Itcha Mountain Range hawaiites are likely formed through the combined processes of assimilation of crustal material and crystal fractionation (Stout and Nicholls, 1983; Charland et al, 1993). 139 Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres Causens and Bevier (in press) suggest the hawaiites from Cinder Mountain represent a different partial melt as trace element mass balance calculations cannot tie their origin to the average basalt from the area. In this thesis the intermediate rocks cannot be related successfully to a basaltic parent but the variation within the hawaiites indicates assimilation is important in their origin. 6.3. Summary Figure 6.14 summarizes the results from mass balance calculations, showing the amount of crystal fractionation always exceeds the amount of assimilation suggested by the calculations. The ratio of fractionation vs. assimilation is close to 2:1; probably the processes do not require heat from an external source (Stout and Nicholls, 1983). Table 6.9 summarizes the various tests applied to the Iskut-Unuk rivers centres in order to evaluate the petrogenesis of the rocks. Closed system processes are rejected for all centres with the aid of three different Pearce element ratio diagrams, except, possibly for the Lava Fork centre. Trace element concentrations and ratios of incompatible elements also reject the closed system processes hypothesis for all centres, again Lava Fork is borderline as the total chemical variation is close to analytical uncertainty. The hawaiites from Cinder Mountain are also very close in composition and their trace element concentrations are similar. 140 Chapter 6. The role of assimilat ion on the petrogenesis of the Iskut-Unuk rivers centres 30 25 20 h £ 15 •55 10 o Iskut River • . Snippaker Creek A Cone Glacier O Cinder Mountain bas-haw Cinder Mountain haw-haw — o -A — O • 1 , 1 , 1 , 1 1 10 15 20 Crystal fractionation (gr.) 25 30 Figure 6.14. Grams of crystals fractionated vs. assimilant added according to mass balance calculations for Iskut River , Snippaker Creek, Cone Glacier and Cinder Mounta in . The sol id l ine represents ratios 1:1. The role of assimilation was tested by or-type PER diagram, specially designed to detect the affects of granitic melt in the basaltic and intermediate rocks. The assimilation affects are detected for all centres except Lava Fork, possibly because of questions regarding the analytical uncertainty of the chemical analyses. Relations between basalt and hawaiite from Cinder Mountain are not clear with this test as the denominator used for the diagram is not conserved. 141 Chapter 6. The role of assimilation on the petrogenesis of the Iskut-Unuk rivers centres Table 6.9. Summary of the tests applied to Iskut-Unuk rivers centres chemistry in order to evaluate the processes of the petrogenesis of the centres. Process Closed system Assimilation Test PER Trace elements PER Massbalance Iskut River R R - olivine 4.20 plagioclase 11.22 assimilation 4.61 Snippaker Creek R R - olivine 3.15 plagioclase 1.15 assimilation 3.47 Cone Glacier R R - olivine 5.68 plagioclase 9.49 assimilation 6.24 Cinder Mountain basalt to R R 7 olivine R hawaiite plagioclase R assimilation R hawaiite to ? - ? olivine R hawaiite plagioclase R assimilation R Lava Fork ? - ? olivine R plagioclase R assimilation R R = rejected, - = not rejected, The mass balance calculations are then applied to the centres where assimilation is strongly indicated by the PER diagrams, quantifying the fractionation and assimilation necessary. The amounts are listed in Table 6.9 for the four centres where the mass balance calculations accounts for up to 98% of the variation observed. This does not work for the basalt from Lava Fork volcanic centre, but comes close to explain the chemical variation of hawaiites from Cinder Mountain. 142 Chapter 7. Conclusions CHAPTER 7 Conclusions Based on the work in this thesis the following conclusions have been made: The Iskut-Unuk rivers centres comprise at least eight relatively small and short lived volcanic centres, that mostly comprise basaltic lava flows, cinder and ash; one centre (Cinder Mountain) includes hawaiite. Petrographically the basaltic rocks from the area are very similar; they contain abundant and common megacrysts and phenocrysts of plagioclase and phenocrysts of olivine and rare partially resorbed clinopyroxene and olivine autoliths. The groundmass is generally composed of plagioclase, olivine, titanaugite, Fe-Ti oxides and/or glass. Xenoliths of crustal material and xenocrysts of feldspar are abundant in the basaltic lavas and the latter show characteristic disequilibrium textures due to resorption. The hawaiite lavas comprise olivine and plagioclase phenocrysts in a groundmass of olivine, plagioclase, Fe-Ti oxides and apatite. The chemical compositions of the Iskut-Unuk rivers basalts are very similar; all are 143 Chapter 7. Conclusions alkali-olivine basalts. They are within the compositional range of other alkali basalts from the southern part of the Stikine Volcanic Belt and, with them, are chemically distinct from basalts from the northern SVB. Hawaiite from Cinder Mountain volcanic centre has similar chemical composition as other intermediate rocks from within the SVB volcanic belt. Mineral compositions within the basalts show little range within and between centres. Olivine compositions generally range between Fo 7 0 . 8 3 ; phenocrysts within the hawaiites are less forsteritic. Clinopyroxene is titaniferous augite and has Mg# that vary from 45.7 to 75.0. All centres contain magnetite and/or ilmenite and Second Canyon basalt also contains chromite. Most of the centres contain both magmatic and xenocrystic plagioclase phenocrysts. Magmatic plagioclase range from An 6 0 to An 7 0 whilst xenocryst compositions range from An 3 5 to An 5 5 . Rare grains of An 1 2 and An 9 3 are also found. The xenocrystic origin of some plagioclase is further supported by the textural evidence, especially where sieved textures have resulted from partial dissolution of the crystal in the basaltic magma. Phenocrysts of andesine from the intermediate rocks also show signs of disequilibrium, e.g., rounded form and disturbed discontinuous twinning, but their compositions suggest a magmatic origin. Crustal xenoliths in the area are common and generally granitic in composition. They contain mainly quartz and feldspar and lesser quantities of mafic minerals. Partial melting of the xenoliths gives rise to glass with compositions close to alkali feldspar. Textural and chemical characteristic of glasses in the xenoliths suggest biotite is the first phase to react, giving rise to formation of Fe-oxides and heterogeneous granitic glass, commonly with 144 Chapter 7. Conclusions enrichments of Mg and Fe. Alkali feldspar and plagioclase are next to dissolve, but quartz is the phase most resistant to the thermal affects of the basaltic magma. The basaltic glass immediately adjacent to the granitic melt of the xenoliths shows increase in alkali contents, especially K, as well as in Si02, suggesting diffusion is an important process in the contamination. Chemical variations within each volcanic centre have been tested against closed system processes using Pearce element ratio diagrams. It is concluded that the chemical diversity observed within individual centres cannot be explained solely by closed system fractionation of phenocryst assemblages. Lava Fork is an exception but shows little chemical variation. Incompatible element ratios support the idea that open system processes have contributed to the chemical variations within the Iskut-Unuk rivers centres. Field evidence, including: partly melted crustal xenoliths and xenocrysts of sieved plagioclase, and chemical characteristics of the Iskut-Unuk rivers centres, suggestive of open system processes, indicate the importance of assimilation on the petrogenesis of the Iskut-Unuk rivers centres. With mass balance calculations the chemical variations of samples within Iskut River, Snippaker Creek and Cone Glacier volcanic centres, can be explained by fractionation of olivine (3.2-5.7 %) and plagioclase (1.2-11.22 %) and assimilation of granitic melt (3.5-6.2 %). 145 Chapter 7. Conclusions Cinder Mountain intermediate rocks cannot be derived from the basalt from Copper King Creek according to PER diagrams but variations within the hawaiite flows are possibly related through coupled fractionation and assimilation processes. Lava Fork basalt samples are from the same lava flow and are chemically homogenous except for one sample that is relatively enriched in Na20. This is possibly caused by assimilation but mass balance calculations, using olivine and plagioclase fractionation with assimilation of granitic melt fail; possibly indicating the lack of sensitivity of the mass balance method for the variation observed. Sr and Nd isotope analyses of biotite-granite, a sample of the basement from the Lava 87 86 Fork area, contains unusually high Sr/ Sr ratio. One of the basaltic samples from Lava Fork contains significantly different Sr and Nd ratios than the rest of the samples; a strong indication of assimilation of crustal material. This study concludes that assimilation plays an important role in the petrogenesis of the Iskut-Unuk rivers centres along with fractionation of mainly olivine and plagioclase. 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Wones, D.R. and Eugster, H.P. 1965: Stability of biotite: experiment, theory and application. American Mineralogist, v.50, 1228-1272. Wright, F.E. 1906: The Unuk River mining region of British Columbia; in Geological Survey of Canada, Summary Report of the Year 1905, 68-74. Wyllie, P.J. 1961: Fusion of Torridonian sandstone by a picrite sill in Soay (Hebrides). Journal of Petrology, v.2, 1-37. Yoder, H.S. and Kushiro, I. 1969: Melting of a hydrous phase: phlogopite. American Journal of Science, v.267, 558-582. 162 Appendix A. Petrographic descriptions Appendix A. Petrographic descriptions and visually estimated modes of geochemical samples from the Iskut-Unuk rivers volcanic centres. Minerals are grouped as phenocrysts, groundmass or other and are listed in order of decreasing modal volume within each group. Sample: IR-1 Centre: Iskut River UTM location: 6285950N, 401800E Volume Phase Mineral Description 13 27 60 Phenocrysts plagioclase Groundmass Vesicles Other olivine plagioclase olivine clinopyroxene oxides glass up to 1.7 mm, sub-euhedral, megacrysts, zoned phenocrysts and crystals with sieved core, up to 0.3 mm, sub-euhedral, minor melt inclusions, subhedral laths. small tabular crystals. Texture porphyritic, interstitial, vesiculated. Rock name basaltic cinder and bombs Sample: IR-2 Centre: Iskut River UTM location: 6286450N, 401950E Volume Phase Mineral Description 50 40 10 Phenocrysts Groundmass Vesicles Other plagioclase olivine plagioclase olivine clinopyroxene oxides glass up to 2 mm, sub-euhedral, zoned phenocrysts and sieved crystals, up to 0.8 mm, sub-euhedral, minor melt inclusions, subhedral laths. small tabular crystals. Texture porphyritic, interstitial, vesiculated. Rock name basaltic cinder and bombs Sample: IR-3 Centre: Iskut River UTM location: 6289200N, 400650E Volume Phase Mineral Description 25 Phenocrysts plagioclase olivine up to 4.5 mm, sub-euhedral, megacrysts, zoned phenocrysts and sieved crystals, up to 1.5 mm, sub-euhedral, minor melt inclusions. 163 Appendix A. Petrographic descriptions clinopyroxene rare anhedral resorbed tan colored phenocrysts and inclusions within megacrysts and phenocrysts of plagioclase. 60 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass 15 Vesicles Other rounded xenoliths of quartz and/or feldspar rich material commonly rimmed by fine clinopyroxene crystals. Texture porphyritic, interstitial, vesiculated. Rock name basaltic lava flow. Sample: IR-4 Centre: Iskut River UTM location: 6289200N, 400650E Volume Phase Mineral Description 10 Phenocrysts plagioclase up to 0.5 mm, sub-anhedral, megacrysts and zoned phenocrysts. olivine up to 0.3 mm, sub-euhedral. clinopyroxene rare up to 0.3 mm phenocrysts. 40 Groundmass glass sideromelane. 50 Vesicles Other Texture vitrophyritic, interstitial, highly vesiculated. Rock name basaltic cinder and ash. Sample: IR-5 Centre: Iskut River UTM location: 6289200N, 400650E Volume Phase Mineral Description 25 Phenocrysts plagioclase up to 2.5 mm, sub-anhedral, megacrysts, zoned phenocrysts and very common sieved crystals. olivine up to 2.0 mm, subhedral and minor inclusions. 55 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass 20 Vesicles Other Texture porphyritic, intersertal, vesiculated, subtrachytic. Rock name basaltic scoriaceous lava flow. Sample: IR-6 Centre: Iskut River U T M location: 6287050N, 398850E 164 Appendix A. Petrographic descriptions Volume Phase Mineral Description 30 50 20 Phenocrysts Groundmass Vesicles Other Texture Rock name plagioclase olivine plagioclase olivine clinopyroxene oxides glass up to 4.5 mm, sub-anhedral, megacrysts and sieved crystals, up to 0.8 mm, eu-subhedral, minor oxide inclusions, subhedral laths. small tabular crystals. xenoliths of fine grained quartz and/or feldspar. Resorbed glomerocrysts of olivine, plagioclase and clinopyroxene. porphyritic, vesiculated and intersertal. basaltic lava flow. Sample: IR-7 Centre: Iskut River UTM location: 6286450N, 396950E Volume Phase Mineral Description 40 Phenocrysts crystals. 50 Groundmass 20 and Vesicles Other plagioclase 0.5 to 2.5 mm, eu-anhedral, zoned phenocrysts and sieved olivine up to 0.8 mm, subhedral, weathered. plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass rounded and resorbed xenoliths of mainly fine grained feldspar oxides. Texture Rock name porphyritic, vesiculated, intersertal, subtrachytic. basaltic lava flow. Sample: IR-8 Centre: Iskut River UTM location: 6285000N, 394700E Volume Phase Mineral Description 15 with 65 Phenocrysts plagioclase Groundmass plagioclase 10 Vesicles Other olivine plagioclase olivine clinopyroxene oxides glass 0.25 to 3 mm, eu-anhedral, megacrysts, phenocrysts and crystals sieved core. up to 1 mm, eu-subhedral. subhedral laths abundant colored aligned crystals commonly enclosing groundmass laths. 165 Appendix A. Petrographic descriptions Texture Rock name porphyritic, vesiculated, subtrachytic, subophitic. basaltic lava flow. Sample: SH-37 Centre: Iskut River UTM location: 6287170N, 400220E Volume Phase Mineral Description 40 Phenocrysts crystals. 40 Groundmass 20 Vesicles Other plagioclase up to 2.0 mm, eu-subhedral, zoned phenocrysts and sieved olivine up to 3 mm, eu-anhedral, few megacrysts show resorption. plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass glassy and vesiculated xenoliths of mainly fine grained quartz showing minor blending with basalt. Texture Rock name porphyritic, vesiculated and intersertal. basaltic lava flow. Sample: SH-39 Centre: Tom MacKay Creek UTM location: 6285420N, 404130E Volume Phase Mineral Description 20 Phenocrysts plagioclase 30 Groundmass 50 Vesicles Other olivine clinopyroxene plagioclase olivine clinopyroxene oxides glass up to 1.3 mm, eu-subhedral, megacrysts, zoned phenocrysts and sieved crystals, up to 1.5 mm, eu-subhedral. few 2.5 mm highly resorbed grains, subhedral laths well developed, brown colored fibrous bundles, tachylite. Texture Rock name porphyritic to vitrophyric, vesiculated, intersertal basaltic pillow lava. Sample: SH-01 Centre: Snippaker Creek UTM location: 6277520N, 385940E Volume Phase Mineral Description 70 Phenocrysts plagioclase up to 7 mm, eu-anhedral, megacrysts, phenocrysts with sieved core and crystals with sieved interior. olivine up to 3 nun, eu-subhedral, weathered. 20 Groundmass plagioclase subhedral laths olivine clinopyroxene well developed, colored, up to 0.5 mm subhedral crystals. 166 Appendix A. Petrographic descriptions 10 Vesicles Other oxides Texture Rock name porphyritic, vesiculated, intergranular, subophitic. basaltic lava flow Sample: SH-02 Centre: Snippaker Creek UTM location: 6277520N, 38S940E Volume Phase Mineral Description 70 Phenocrysts 20 Groundmass 10 Vesicles Other plagioclase up to 5 mm, eu-subhedral, megacrysts, phenocrysts and sieved crystals. olivine up to 2.5 mm, subhedral. Rare as inclusions in megacrystic plagioclase. plagioclase subhedral laths, olivine clinopyroxene well developed, colored, up to 1 mm subhedral laths, oxides Texture Rock name porphyritic, vesiculated, intergranular, subophitic. basaltic lava flow. Sample: SH-31 Centre: Snippaker creek UTM location: 6272820N, 386670E Volume Phase Mineral Description 70 Phenocrysts inclusions. 20 Groundmass 10 Vesicles Other plagioclase up to 4.5 mm, sub-anhedral, megacrysts, zoned phenocrysts and minor sieved crystals, olivine slightly colored, up to 1.0 mm, subhedral, glass and oxide plagioclase subhedral laths olivine clinopyroxene well developed, colored, up to 1.5 mm subhedral laths, oxides Texture Rock name porphyritic, vesiculated, intergranular, subophitic. basaltic lava flow. Sample: SH-33 Centre: Snippaker creek UTM location: 6272970N, 390820E Volume Phase Mineral Description 75 Phenocrysts plagioclase up to 5.0 mm, eu-subhedral, megacrysts, phenocrysts and crystals with sieved core. 167 Appendix A . Petrographic descriptions olivine up to 1.5 mm, subhedral. Rare crystals show resorption texture. 15 Groundmass plagioclase subhedral laths olivine clinopyroxene well developed, colored, up to 0.5 mm subhedral laths. oxides 10 Vesicles Other Texture porphyritic, vesiculated, intergranular, subophitic. Rock name basaltic lava flow Sample: SH-34 Centre: Snippaker creek U T M location: 6272970N, 390820E Volume Phase Mineral Description 75 Phenocrysts plagioclase up to 4.5 mm, subhedral, megacrysts, phenocrysts and crystals with sieved core. olivine up to 2.5 mm, subhedral, highly oxidized. 15 Groundmass plagioclase subhedral laths olivine clinopyroxene well developed, colored, up to 0.3 mm subhedral laths. oxides 10 Vesicles Other Texture porphyritic, vesiculated, intergranular, subophitic. Rock name basaltic lava flow Sample: CG-9 Centre: Cone Glacier U T M location: 6269900N, 397500E Volume Phase Mineral Description 70 Phenocrysts plagioclase up to 15 mm, eu-subhedral, very common megacrysts, zoned phenocrysts and sieved crystals. olivine slightly colored, up to 1.3 mm, eu-subhedral, weathered. Common as inclusions in megacrysts of plagioclase. clinopyroxene rare resorbed crystals often as inclusions in resorbed plagioclase. 15 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides 15 Vesicles Other Texture porphyritic, vesiculated, intergranular, felty. Rock name basaltic lava flow Sample: CG-10 168 Appendix A . Petrographic descriptions Centre: Cone Glacier U T M location: 6269900N, 397500E Volume Phase Mineral Description 45 Phenocrysts 45 Groundmass 10 Vesicles Other plagioclase up to 10 mm, eu-subhedral, megacrysts, zoned phenocrysts and sieved crystals, olivine up to 1 mm, eu-subhedral, weathered. clinopyroxene rare, colored, resorbed crystals up to 1.3 mm as inclusions in megacrystic plagioclase. plagioclase subhedral laths, olivine clinopyroxene fairly well developed, colored laths. oxides glass Texture Rock name porphyritic, vesiculated, intergranular, felty. basaltic lava flow Sample: CG-11 Centre: Cone Glacier U T M location: 6269900N, 397500E Volume Phase Mineral Description 75 Phenocrysts plagioclase olivine glomerocrysts glomerocrysts of dominantly 10 Groundmass plagioclase 15 Vesicles Other reaction rim of up to 10 mm, eu-anhedral, megacrysts, phenocrysts and sieved crystals. up to 2.5 mm, eu-subhedral, weathered. Common as with plagioclase also rare resorbed olivine. subhedral laths, olivine clinopyroxene small tabular crystals, oxides xenoliths of high birefringence resorbed mineral with fine grained quartz and/or feldspar. Xenocrysts of quartz with clinopyroxene. Texture Rock name porphyritic, vesiculated, intergranular, felty. basaltic lava flow Sample: CG-12 Centre: Cone Glacier U T M location: 6269900N, 397500E Volume Phase Mineral Description 75 Phenocrysts sieved 10 Groundmass plagioclase olivine clinopyroxene plagioclase olivine clinopyroxene up to 9.0 mm, eu-anhedral, megacrysts, zoned phenocrysts and crystals. slightly colored, up to 1.5 mm, eu-anhedral, weathered, up to 1.3 mm, inclusions in plagioclase. subhedral laths small tabular crystals. 169 Appendix A. Petrographic descriptions 15 Vesicles Other oxides glass Texture Rock name porphyritic, vesiculated, intergranular, felty. basaltic lava flow Sample: CG-13 Centre: Cone Glacier UTM location: 6269650N, 397500E Volume Phase Mineral Description 55 20 25 Phenocrysts Groundmass Vesicles Other Texture Rock name plagioclase up to 4.5 mm, eu-subhedral, megacrysts, zoned plagioclase and sieved crystals. olivine up to 2.5 mm, eu-subhedral, opaque inclusions. plagioclase subhedral laths. olivine clinopyroxene well developed, colored, up to 1 mm subhedral laths. oxides glass vesicles are coated with intergrowth of dendrite oxides and dark brown titanaugite. porphyritic, vesiculated, intersertal, felty. basaltic pillow lava. Sample: CG-14 Centre: Cone Glacier UTM location: 6269850N, 398350E Volume Phase Mineral Description 15 65 20 Phenocrysts plagioclase Groundmass Vesicles Other olivine clinopyroxene plagioclase olivine clinopyroxene oxides glass up to 5.0 mm, sub-anhedral, megacrysts, zoned phenocrysts and sieved crystals, up to 2.0 mm, subhedral, weathered, few rounded and resorbed crystals, subhedral laths. small tabular crystals, Texture Rock name porphyritic, vesiculated, subtrachytic, intergranular. basaltic lava flow. Sample: CG-15 Centre: Cone Glacier UTM location: 6270150N, 398350E 170 Appendix A. Petrographic descriptions Volume Phase Mineral Description 15 Phenocrysts 70 Groundmass 15 Vesicles Other plagioclase eu-anhedral, megacrysts, zoned phenocrysts and minor sieved crystals. olivine up to 3.5 mm, sub-anhedral, weathered. Rare resorbed crystals. plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass Texture Rock name porphyritic, vesiculated, subtrachytic, intergranular. basaltic lava flow. Sample: CG-16 Centre: Cone Glacier UTM location: 6270300N, 398500E Volume Phase Mineral Description 15 minor 70 15 Phenocrysts plagioclase Groundmass Vesicles Other olivine plagioclase olivine clinopyroxene oxides glass up to 2.5 mm, eu-anhedral, megacrysts, zoned phenocrysts and sieved crystals. up to 3.0 mm, eu-anhedral, weathered, subhedral laths minor tabular crystals. Texture Rock name porphyritic, vesiculated, intersertal. basaltic lava flow. Sample: CG-17 Centre: Cone Glacier UTM location: 6270300N, 398500E Volume Phase Mineral Description 15 50 35 Phenocrysts Groundmass Vesicles Other plagioclase olivine plagioclase olivine clinopyroxene oxides glass up to 5.5 mm, eu-anhedral, megacrysts and phenocrysts. up to 0.4 mm, eu-subhedral, highly oxidized, subhedral laths. well developed colored subhedral laths, tachylite. Texture vitrophyric to porphyritic, vesiculated and intersertal. Rock name basaltic cinder. 171 Appendix A. Petrographic descriptions Sample: CG-18 Centre: Cone Glacier UTM location: 6269800N, 397300E Volume Phase Mineral Description 50 30 Phenocrysts plagioclase Groundmass 20 Vesicles Other up to 3.0 mm, eu-anhedral, megacrysts, phenocrysts and sieved crystals. olivine up to 2.5 mm, sub-anhedral. clinopyroxene resorbed, 2.5 mm, anhedral, commonly in relation with resorbed megacrysts of plagioclase. plagioclase subhedral laths, olivine clinopyroxene rare small tabular crystals. oxides glass Texture Rock name porphyritic, vesiculated, felty and intersertal. basaltic pillow lava. Sample: SH-13 Centre: Cone Glacier UTM location: 6269960N, 397620E Volume Phase Mineral Description 40 Phenocrysts plagioclase olivine clinopyroxene 55 Groundmass 5 Vesicles Other plagioclase olivine clinopyroxene oxides up to 9.0 mm, eu-anhedral, megacrysts, zoned phenocrysts and sieved crystals, up to 1.5 mm, eu-anhedral, weathered. few grains up to 1.3 mm, sub-anhedral, resorbed. Also occur as inclusions in plagioclase. subhedral laths. small tabular crystals. Texture Rock name porphyritic, vesiculated, intergranular. basaltic lava flow. Sample: SH-14 Centre: Cone Glacier UTM location: 6269900N, 397550E Volume Phase Mineral Description 40 Phenocrysts plagioclase up to 6.0 mm, subhedral, megacrysts, phenocrysts and sieved crystals. olivine up to 3.0 mm, sub-anhedral, weathered with rims of oxides. 35 Groundmass plagioclase subhedral laths. olivine clinopyroxene well developed, colored, up to 0.5 mm subhedral. 172 Appendix A. Petrographic descriptions oxides 25 Vesicles Other Texture porphyritic, vesiculated, intergranular, subophitic. Rock name basaltic lava flow. Sample: SH-15 Centre: Cone Glacier UTM location: 6269900N, 397550E Volume Phase Mineral Description 40 50 10 Phenocrysts Groundmass Vesicles Other plagioclase up to 5.5 mm, eu-subhedral, megacrysts, phenocrysts and sieved crystals. olivine up to 2.0 mm, eu-subhedral, minor glass and oxide inclusions, weathered, plagioclase subhedral laths, olivine clinopyroxene small tabular crystals, oxides Texture Rock name porphyritic, vesiculated, intergranular, felty. basaltic lava flow. Sample: SH-22 Centre: Cone Glacier UTM location: 6269810N, 398580E Volume Phase Mineral Description 25 65 10 Phenocrysts plagioclase Groundmass Vesicles Other up to 5.0 mm, eu-subhedral, megacrysts, zoned phenocrysts and sieved crystals. olivine up to 2.0 mm, eu-subhedral, minor inclusions. plagioclase subhedral laths olivine clinopyroxene up to 0.5 mm subhedral tabular crystals, oxides Texture Rock name porphyritic, vesiculated, intergranular. basaltic lava flow. Sample: SH-26 Centre: Cone Glacier UTM location: 6269810N, 398580E Volume Phase Mineral Description 15 Phenocrysts plagioclase up to 6.0 mm, eu-anhedral, megacrysts, zoned phenocrysts and sieved crystals. olivine up to 2.5 mm, eu-subhedral, minor inclusion, weathered. 173 Appendix A. Petrographic descriptions 75 Groundmass 5 Vesicles Other plagioclase subhedral laths olivine clinopyroxene up to 0.5 mm, subhedral tabular crystals, oxides Texture Rock name porphyritic, vesiculated, intergranular. basaltic lava flow. Sample: CM-19 Centre: Cinder Mountain UTM location: 6270200N, 399900E Volume Phase Mineral Description 40 Phenocrysts weathered. 45 Groundmass 15 Vesicles Other plagioclase olivine plagioclase olivine magnetite apatite oxides up to 2.0 mm, sub-anhedral, phenocrysts. up to 0.5 mm, eu-subhedral, melt and oxide inclusions, subhedral laths up to 0.5 mm, eu-subhedral. associated with magnetite, beige colour. xenoliths of resorbed feldspar. Texture Rock name porphyritic, vesiculated, intersertal, subtrachytic. hawaiite scoriaceous lava flow. Sample: CM-20 Centre: Cinder Mountain UTM location: 6270200N, 399900E Volume Phase Mineral Description 40 55 Phenocrysts Groundmass 5 Vesicles Other plagioclase olivine plagioclase olivine magnetite apatite oxides up to 7.5 mm, sub-anhedral, phenocrysts. up to 1.5 mm, eu-subhedral, melt and oxide inclusions. subhedral laths up to 1.0 mm, eu-subhedral. up to 0.25 mm, associated with magnetite. Texture Rock name porphyritic, intersertal, subtrachytic. hawaiite lava flow. Sample: SH-19 Centre: Cinder Mountain UTM location: 6270030N, 400380E Volume Phase Mineral Description 174 Appendix A. Petrographic descriptions 70 Phenocrysts 29 Groundmass 1 Vesicles Other plagioclase olivine plagioclase olivine magnetite apatite oxides up to 5.0 mm, sub-anhedral, phenocrysts. up to 0.8 mm, eu-subhedral, melt and oxide inclusions. subhedral laths up to 0.3 mm eu-subhedral. up to 0.2 mm with olivine and magnetite. Texture Rock name porphyritic, intersertal, trachytic. hawaiite lava flow. Sample: SH-21 Centre: Cinder Mountain UTM location: 6269370N, 400120E Volume Phase Mineral Description 70 29 Phenocrysts Groundmass 1 Vesicles Other plagioclase olivine plagioclase olivine magnetite apatite up to 4.0 mm, sub-anhedral, phenocrysts. up to 0.5 mm, eu-subhedral, melt and oxide inclusions. subhedral laths up to 0.3 mm, eu-subhedral. up to 0.1 mm. Texture Rock name porphyritic, intersertal, subtrachytic. hawaiite dike. Sample: SH-28 Centre: Cinder Mountain UTM location: 6269810N, 398580E Volume Phase Mineral Description 45 50 Phenocrysts Groundmass Vesicles Other plagioclase up to 0.5 mm, anhedral, phenocrysts. olivine up to 0.3 mm, subhedral. glass palagonite glass. Texture Rock name vitrophyritic, vesiculated. hyaloclastite. Sample: SH-35 Centre: Cinder Mountain UTM location: 62774330N, 403140E Volume Phase Mineral Description 65 Phenocrysts plagioclase olivine up to 3 mm, eu-anhedral, phenocrysts and sieved crystals. Rare carbonate and possible mica alteration, up to 0.3 mm, eu-subhedral. Few resorbed crystals. 175 Appendix A . Petrographic descriptions 30 Groundmass 5 Vesicles Other clinopyroxene plagioclase olivine clinopyroxene magnetite apatite oxides glass quartz rare resorbed phenocrysts. Also occur as inclusions in plagioclase phenocrysts. subhedral laths. fairly well developed, subhedral crystals. up to 0.3 mm eu-subhedral. rare, in association with sieved plagioclase. xenocryst with overgrowth of clinopyroxene. Texture Rock name porphyritic, intergranular, felty. basaltic lava flow. Sample: KC-22 Centre: King Creek U T M location: 6261150N, 398000E Volume Phase Mineral Description 45 Phenocrysts 40 Groundmass oxides. 15 Vesicles Other plagioclase up to 5.0 mm, subhedral, megacrysts, phenocrysts and sieved crystals. olivine up to 1.3 mm, eu-subhedral, minor inclusions, clinopyroxene rare resorbed phenocrysts. plagioclase subhedral laths olivine clinopyroxene lightly colored, up to 2.0 mm, subhedral laths, intergrown with oxides glass vesicles coated with intergrown dendrite oxides and dark colored clinopyroxene. Texture Rock name porphyritic, vesiculated, intergranular, subophitic. basaltic pillow lava. Sample: SeC-23 Centre: Second Canyon U T M location: 6251100N, 395800E Volume Phase Mineral Description 30 40 30 Phenocrysts Groundmass Vesicles Other plagioclase olivine plagioclase olivine clinopyroxene oxides up to 0.8 mm, eu-subhedral, phenocrysts. up to 2.5 mm, eu-subhedral, minor inclusions. subhedral laths. minor subhedral tabular crystals. Texture porphyritic, vesiculated, intergranular. 176 Appendix A . Petrographic descriptions Rock name basaltic lava flow. Sample: LF-24 Centre: Lava Fork U T M location: 6253800N, 385300E Volume Phase Mineral Description 35 30 35 Phenocrysts Groundmass Vesicles Other plagioclase olivine plagioclase olivine clinopyroxene oxides glass up to 1.0 mm, eu-subhedral, phenocrysts. up to 0.8 mm, eu-subhedral, weathered, subhedral laths. small tabular crystals. Texture Rock name porphyritic, vesiculated, intersertal. basaltic lava flow. Sample: LF-25 Centre: Lava Fork U T M location: 6254150N, 385800E Volume Phase Mineral Description 20 10 70 Phenocrysts Groundmass Vesicles Other plagioclase olivine plagioclase olivine clinopyroxene oxides glass up to 2.0 mm, eu-subhedral, phenocrysts. up to 0.8 mm, eu-subhedral, weathered, subhedral laths. small tabular crystals. Texture Rock name porphyritic, vitrophyritic, vesiculated. basaltic cinder. Sample: LF-26 Centre: Lava Fork U T M location: 6254800N, 383350E Volume Phase Mineral Description 10 20 70 Phenocrysts Groundmass Vesicles Other plagioclase olivine plagioclase olivine clinopyroxene oxides glass up to 1.0 mm, eu-subhedral. up to 0.8 mm, eu-subhedral, weathered. subhedral laths. small tabular crystals. 177 Appendix A. Petrographic descriptions Texture Rock name porphyritic, vitrophyritic, vesiculated. basaltic cinder. Sample: LF-27 Centre: Lava Fork UTM location: 6254150N, 385800E Volume Phase Mineral Description 25 5 40 5 22 1 2 Major Accessory plagioclase alkali feldspar quartz biotite chlorite oxides epidote sphene muscovite subhedral, sericitized. subhedral. subhedral. show foliation. Texture Rock name holocrystalline, hypidiomorphic, granular, f i n e grained foliated biotite-quartz granodiorite. Sample: LF-28 Centre: Lava Fork UTM location: 6254150N, 385800E Volume Phase Mineral Description 35 20 40 2 1 1 1 Major Accessory plagioclase alkali feldspar quartz biotite chlorite oxides muscovite sericite saussurite subhedral, sericitized. subhedral, perthite. subhedral, undulatory extinction, chloritized. Texture Rock name holocrystalline, hypidiomorphic, granular, medium grained biotite granite. Sample: LF-29 Centre: Lava Fork UTM location: 6254150N, 385800E Volume Phase Mineral Description 40 10 15 15 20 1 Major Accessory plagioclase alkali feldspar quartz hornblende biotite apatite subhedral, saussuritized. subhedral, perthite. subhedral, undulatory extinction. eu-subhedral eu-subhedral. 178 Appendix A . Petrographic descriptions sphene epidote oxides Texture holocrystalline, hypidiomorphic, granular. Rock name medium grained hornblende, biotite granodiorite. Sample: LF-30 Centre: Lava Fork U T M location: 6255950N, 383400E Volume Phase Mineral Description 30 Phenocrysts plagioclase up to 1.5 mm, eu-subhedral. olivine up to 1.5 mm, eu-subhedral, weathered. 50 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass 20 Vesicles Other Texture porphyritic, vesiculated, intersertal. Rock name basaltic lava flow. Sample: LF-31 Centre: Lava Fork U T M location: 6255850N, 383350E Volume Phase Mineral Description 30 Phenocrysts plagioclase up to 1.5 mm, eu-subhedral. olivine up to 1.5 mm, eu-subhedral, weathered. 50 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass 20 Vesicles Other Texture porphyritic, vesiculated, intersertal. Rock name basaltic lava flow. Sample: SH-44 Centre: Lava Fork U T M location: 6255500N, 384600E Volume Phase Mineral Description 20 Phenocrysts plagioclase up to 1.5 mm, eu-subhedral. olivine up to 1.5 mm, eu-subhedral, weathered. 55 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides 179 Appendix A. Petrographic descriptions glass 25 Vesicles Other xenoliths of quartz rich material. Texture porphyritic, vesiculated, intersertal. Rock name basaltic lava flow. Sample: SH-54 Centre: Lava Fork UTM location: 6254030N, 384480E Volume Phase Mineral Description 50 Phenocrysts plagioclase up to 1.5 mm, eu-subhedral. olivine up to 1.5 mm, eu-subhedral, weathered. 35 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass 15 Vesicles Other Texture porphyritic, vesiculated, intersertal. Rock name basaltic lava flow. Sample: SH-60 Centre: Lava Fork UTM location: 6255250N, 384000E Volume Phase Mineral Description 15 Phenocrysts plagioclase up to 1.8 mm, eu-subhedral. olivine up to 1.0 mm, eu-subhedral, weathered. 75 Groundmass plagioclase subhedral laths. olivine clinopyroxene small tabular crystals. oxides glass 10 Vesicles Other Texture porphyritic, vesiculated, intersertal. Rock name basaltic lava flow. 180 Appendix B. Rock preparation and analytical methods Appendix B. Sample preparation and analytical methods. Powder preparation Samples selected for geochemical analyses were processed at the facilities of Department of Geological Sciences at the University of British Columbia. Rock samples of approximately 6 cm2 were crushed to less than 1 cm in jaw crusher. Rock chips were cleaned and sorted by hand to ensure that no weathered surface was included. The chips were then pulverized in a steel shatterbox with tungsten carbide rings to approximately 200 mesh. The powder was sieved through 200 mesh nylon fiber and placed in a plastic container. These procedures were repeated until at least 0.3 litre of powder was obtained. Samples were submitted to commercial analytical laboratories after being homogenized by shaking. Analytical methods Major and trace elements were determined at Geochemical Laboratories at McGill University, Quebec. All 19 elements were determined by x-ray Fluorescence, fusion method. The same suite of samples was analyzed by the Geological Survey of Canada by x-ray fluorescence fusion method for major elements. 181 Some FeO determinations were made in the Igneous Petrology Laboratory at the University of British Columbia. A maximum wt% of FeO was estimated for each sample by the Wilson titrimetric method. About 0.5 grams sample were weighed accurately and placed into 50 ml polypropylene beakers. Accurately weighed ammonium meta-vanadate was added to the beakers in slight excess to the amount of FeO expected, where 0.1 g of N H 4 V 0 3 is needed for a 0.5 g sample including 12% FeO. The samples are dissolved in 10 ml of 48% H F acid and added to each sample is 30 ml of cold H 2 S 0 4 . The contents are washed into a 500 ml conical flask containing 50 ml of saturated boric acid diluted to about 150 ml with water. Up to 10 drops of barium diphenilamine is added to produce a distinct purple colour. The solution is now titrated with ferrous ammonium sulphate solution until solution turned apple green. Blanks were also run as standards. The FeO amount in the samples was calculated by: %FeO in sample = 61.42 . (V - v'T) R t where v' = wt of ammonium meta-vanadate. t = titre of standard R = wt of sample V = wt of vanadate with sample T = titre of sample Appendix B. Rock preparation and analytical methods 182 Appendix B. Rock preparation and analytical methods Some H20(T) analyses were made in the Igneous Petrology Laboratory at University of British Columbia. Total water content of the powdered samples was estimated by Penfield method. A clean 9 inch long Penfield glass tube with an internal diameter of 4 mm and with a glass bulb at closed end is heated while using a glass tube connected to a filter pump to remove superficial water. Using a thistle funnel, 1.000 g of 200 mesh rock powder is placed in the bulb which is then heated for about 5 minutes with a bunsen while turning the tube slowly. Water will evaporate from the sample and condense in the tube. The tube containing the water is then removed from the sample by melting the glass. The tube is weighed cold, containing the water and after the water has been removed by a filter pump. For roughly half of the samples total C0 2 measurements were made at the Igneous Petrology Laboratory at the University of British Columbia using volumetric methods by Shapiro (1960). Approximately 1.000 g of 200 mesh sample powder is transferred to the bottom of a carbon dioxide tube and 2 ml of 3% mercuric chloride solution is added. Motoroil (S.A.E. No. 10) is added to oil level mark previously determined by calibration and the tube is tilted to completely displace air from the side arm. With the side arm vertical 2 ml of HC1 is added to the solution and the tube is placed in a clamp attached to a support with the lower part of the tube through a hole in an asbestos cover. The tube is then heated until the aqueous phase has boiled for 2.5 minutes and the cooled by allowing tap water to flow down the outside for 15 sec. The C0 2% is estimated by holding the tube against previously calibrated scale. 183 Appendix B. Rock preparation and analytical methods Some H20(T), C02(T) and FeO determinations were conducted by the Geological Survey of Canada, analytical chemistry section, Quebec. Ferrous iron was determined by the Wilson Method (titrimetric) and H20(T) and C02(T) were determined using combustion followed by infrared spectrometry. The same sample suite was also analyzed for REE and trace elements by the Geological Survey of Canada by ICP/MS method. A selected suite of representative samples from each centre was analyzed for REE at the University of Saskatchewan. Replicates of analyses made comparison of different laboratories possible. Further discussion on precision and accuracy estimates is in Appendix I. Electron microprobe analyses Mineral compositions were measured using Cameca SX-50 electron microprobe at the University of British Columbia. Operating conditions were 15 kV and 20 nA with a peak counting times of 20 seconds. Background concentrations were counted for 10 seconds. Analyses of olivine and pyroxene involved a focused, 2\x spot-fixed beam and calibration of standards included: albite (Na, Al), forsterite (Mg), fayalite (Fe), diopside (Ca, Si), chromite (Cr), rutile (Ti), nickel-olivine (Ni) and rhodonite (Mn). Fe-Ti oxides were analyzed with a 184 Appendix B. Rock preparation and analytical methods focused lp. spot-fixed beam and calibrated against the following standards: hematite (Fe), albite (Al), rutile (Ti), diopside (Si, Ca, Mg), chromite (Cr), vanadium-metal (V), nickel-olivine (Ni), gahnite (Zn) and rhodonite (Mn). Analyses of plagioclase were made with a focused 5u, spot-fixed beam to reduce loss of Na. Standards included: fayalite (Fe), diopside (Mg), orthoclase (K, Si), albite (Na), SrTi03 (Sr), anorthite (Ca, Al) and barite (Ba). Analyses for olivine, clinopyroxene, Fe-Ti oxides and plagioclase are listed in Appendices D , E, F and G. Glass was analyzed with a focused 15u. spot-fixed beam and operating conditions of 15 kV and 5 nA. Peak counting times were 20 seconds except for F where it was 60 seconds. Background concentrations were counted for 10 seconds but 30 seconds for fluorine. Calibration of standards includede; diopside (Mg, Si, Ca), albite (Na, Al), orthoclase (K), rutile (Ti), fayalite (Fe), apatite (P) and halite (CI). Analyses of glasses are listed in Appendix H. 185 Appendix C . Who le rock chemical analyses Appendix C . l . X R F chemical analyses f rom Iskut-Unuk rivers centres measured by M c G i l l Univers i ty Centre Iskut R i v e r T M C S n i p p a k e r C r e e k Sample IR-2 IR-3 IR-4 IR-5 IR-6 IR-7 IR-8 SH-37 SH-39 SH-01 SH-02 SH-31 S i O z 48.95 48.84 47.99 48.02 49.09 48.80 47.98 48.90 48.01 48.63 48.48 48.37 T i 0 2 2.33 2.24 2.32 2.25 2.35 2.36 2.20 2.38 2.30 2.33 2.30 2.28 A 1 2 0 3 16.32 16.78 16.87 16.93 16.29 16.38 17.04 16.35 15.55 16.74 16.84 16.81 F e 2 0 3 3.67 3.95 2.36 2.39 2.66 3.10 2.16 3.47 3.26 2.68 2.31 2.93 F e O 8.11 7.74 9.47 9.31 9.01 8.71 9.37 8.40 8.50 9.00 9.40 8.70 M n O 0.19 0.18 0.18 0.19 0.19 0.19 0.17 0.18 0.18 0.18 0.18 0.18 M g O 6.14 6.38 6.74 6.94 6.14 6.36 7.01 6.15 7.82 6.13 6.26 6.40 C a O 8.93 8.79 9.19 9.39 8.95 9.09 9.32 8.97 10.01 9.27 9.33 9.45 N a 2 0 3.45 3.42 3.82 3.70 3.89 3.64 3.63 3.55 2.90 3.51 3.36 3.55 K 2 0 1.16 1.08 0.91 0.87 1.19 1.10 0.86 1.15 0.94 1.00 0.95 0.91 P2O5 0.45 0.49 0.41 0.38 0.46 0.45 0.36 0.47 0.38 0.41 0.40 0.38 Total 99.71 99.89 100.27 100.36 100.22 100.18 100.11 99.97 99.85 99.88 99.81 99.96 M G # 36.99 45.20 41.57 42.71 40.52 42.20 42.79 42.27 47.92 40.52 39.97 42.38 S.I. 27.24 28.27 28.92 29.91 26.83 27.76 30.43 27.07 33.38 27.47 28.09 28.45 Trace elements B a 501 474 327 298 455 438 291 475 253 347 372 277 Ce 92 53 49 38 73 95 74 41 47 62 77 86 C o 42 50 53 52 42 41 42 45 48 42 45 45 C r 26 14 17 16 26 27 6 32 60 21 21 30 C u 8 53 98 44 77 51 87 48 49 66 46 76 N i 57 54 56 110 47 50 48 46 65 39 42 51 Sc 26 31 17 39 34 37 28 33 38 29 27 37 v- 234 216 227 227 226 239 213 230 253 228 227 • - 217 Z n 113 110 106 102. 110 108 105 109 96 108 105 106 Normative mineralogy O r 6.86 6.38 5.38 5.14 7.03 6.50 5.08 6.80 5.56 5.91 5.61 5.38 A b 29.19 28.94 27.53 27.17 30.55 30.80 27.18 30.04 24.54 29.70 28.43 29.74 A n 25.62 27.25 26.20 27.02. 23.48 25.11 27.67 25.29 26.64 26.97 28.07 27.25 Ne - - 2.59 2.24 1.28 - 1.91 - - . _ 0.16 D i 12.78 10.64 13.68 13.96 14.66 13.89 13.26 13.13 16.62 13.37 12.80 13.98 H y 6.52 8.31 - - - 0.19 - 3.91 5.06 1.52 2.77 . O l 7.96 7.26 16.11 16.24 13.85 13.68 16.86 10.18 11.48 13.16 13.50 13.93 M t 5.32 5.73 3.43 3.46 3.85 4.49 3.14 5.02 4.73 3.88 3.35 4.50 H m - - - - - - - - . _ _ _ 11 4.42 4.25 4.41 4.27 4.46 4.48 4.18 4.52 4.37 4.42 4.37 4.33 A p 1.07 1.16 0.97 0.90 1.09 1.07 0.85 1.11 0.90 0.97 0.95 0.90 Ferrous iron and H 2 0 T determined by G S C for al l SH-xx samples. FeO for other samples analyzed at U B C . Mg# = 100*MgO/ (MgO+FeO) . S.I. = 100 *MgO/ (MgO+FeO+Fe 2 O 3 +Na 2 O)+K 2 O) . 186 Appendix C . Who le rock chemical analyses Appendix C . l . Continued, Centre Snipp. Creek Cone Glacier Sample SH-33 SH-34 C G - 9 C G - 1 0 CG-11 C G - 1 2 C G - 1 3 C G - 1 4 C G - 1 5 C G - 1 8 SH-13 SH-14 S i 0 2 48.50 47.67 48.55 48.36 49.00 49.05 47.85 48.54 48.34 47.64 49.35 47.95 T i 0 2 2.31 2.27 2.23 2.25 2.26 2.37 2.39 2.33 2.33 2.43 2.37 2.16 A 1 2 0 3 16.78 16.06 17.06 16.88 16.93 16.56 15.82 16.91 16.72 15.83 16.38 16.21 F e 2 0 3 2.99 5.69 3.62 2.16 3.88 4.34 2.46 4.32 4.31 2.40 4.25 8.20 F e O 8.80 6.70 7.87 9.43 7.70 7.58 9.26 7.47 7.57 9.49 7.70 4.10 M n O 0.18 0.19 0.18 0.18 0.18 0.19 0.19 0.19 0.18 0.19 0.19 0.18 M g O 6.29 7.32 6.34 6.55 5.87 5.62 7.38 5.96 5.98 7.39 5.77 7.61 C a O 9.19 9.58 9.48 9.41 9.14 8.64 9.32 9.27 9.23 9.35 8.60 9.61 N a 2 0 3.54 3.43 3.71 3.47 3.67 3.75 3.28 3.50 3.61 3.27 3.73 3.25 K 2 0 0.98 0.84 0.92 0.92 1.05 1.19 1.09 0.97 0.97 1.18 1.24 0.80 P2O5 0.41 0.37 0.38 0.39 0.41 0.46 0.46 0.41 0.41 0.47 0.47 0.34 Total 99.97 100.12 100.34 100.00 100.08 99.75 99.51 99.88 99.65 99.63 100.05 100.41 M G # 41.68 52.21 44.61 40.99 43.27 42.59 44.34 44.37 44.14 43.78 42.84 64.99 S.I. 27.83 30.52 28.22 29.07 26.49 25.00 31.43 26.81 26.65 31.15 25.43 31.76 Trace elements B a 378 285 281 302 338 454 339 376 355 340 489 226 Ce 57 60 90 61 55 78 78 72 42 60 58 68 Co 48 58 44 40 35 39 42 37 39 48 32 46 C r 24 31 25 31 20 18 36 27 26 29 18 28 C u 51 77 50 62 47 47 45 57 29 46 41 67 N i 42 49 49 69 33 35 65 40 41 63 41 65 Sc 29 34 31 27 36 36 44 34 30 32 28 43 V . 225 244 226 221 214 221 235 227 238 228 226 222 Z n 107 104 105 106 107 115 104 110 110 108 115 101 Normative mineralogy O r 5.79 4.96 5.44 5.44 6.21 7.03 6.44 5.73 5.73 6.97 7.33 4.73 A b 29.95 29.02 30.30 28.71 31.05 31.73 27.25 29.61 30.54 25.85 31.56 27.50 A n 27.01 25.95 27.19 27.77 26.63 24.84 25.23 27.57 26.56 25.04 24.29 27.28 N e - - 0.59 0.35 - - 0.27 - - 0.98 - -D i 12.97 15.16 14.07 13.41 13.00 12.15 14.67 12.71 13.37 14.91 12.38 14.15 H y 1.44 3.25 - - 3.06 4.90 - 5.41 2.81 - 5.60 8.82 01 12.98 7.73 12.40 16.02 9.28 7.24 16.48 7.21 9.01 16.72 7.14 2.50 M t 4.87 10.33 5.25 3.13 5.62 6.29 3.57 6.27 6.25 3.47 6.16 7.58 H m - - - - - - - - - - - 2.97 11 4.39 4.31 4.23 4.27 4.29 4.50 4.54 4.42 4.42 4.61 4.50 4.10 A p 0.97 0.88 0.90 0.92 0.97 1.09 1.09 0.97 0.97 1.11 1.11 0.81 187 Appendix C. Whole rock chemical analyses Appendix C. l . Continued. Centre Cone Glacier Cinder Mountain K C SeC L F Sample SH-15 SH-22 SH-26 CM-19 CM-20 CM-21 SH-19 SH-21 SH-35 KC-22 SC-23 LF-24 Si0 2 47.82 47.06 47.26 49.64 49.30 50.07 49.70 50.18 47.37 49.35 46.06 46.44 Ti0 2 2.28 2.73 2.72 2.28 2.25 2.21 2.26 2.16 3.24 2.24 2.57 2.84 A1203 16.12 16.21 16.33 16.05 15.92 16.09 16.04 16.04 16.04 16.55 14.89 16.94 Fe 20 3 6.02 5.34 6.95 4.85 4.95 3.85 3.18 3.25 3.46 2.77 4.30 4.92 FeO 6.30 8.20 6.70 8.34 8.15 9.12 9.80 9.80 10.00 8.50 8.28 7.91 MnO 0.18 0.20 0.20 0.25 0.25 0.25 0.25 0.26 0.21 0.18 0.18 0.18 MgO 7.31 6.30 6.32 3.07 3.05 2.94 2.99 2.81 . 5.21 6.00 9.25 6.50 CaO 9.63 8.78 8.84 6.46 6.27 6.29 6.32 6.17 8.31 8.56 10.24 8.95 Na 20 3.27 3.51 3.54 4.56 4.46 4.54 4.88 4.81 3.93 3.75 2.85 3.59 K 2 0 0.83 0.93 0.94 2.58 2.59 2.71 2.63 2.76 1.21 1.38 0.91 1.09 P2O5 0.36 0.42 0.43 1.53 1.49 1.47 1.52 1.48 0.82 0.54 0.39 0.45 Total 100.12 99.68 100.23 99.61 98.67 99.54 99.57 99.72 99.80 99.82 99.92 99.80 MG# 53.71 43.45 48.54 26.90 27.24 24.38 23.38 22.28 34.25 41.37 52.78 45.12 S.I. 30.81 25.95 25.84 13.12 13.15 12.70 12.73 11.99 21.88 26.78 36.15 27.08 Trace elements Ba 248 270 347 905 881 960 938 932 346 609 156 191 Ce 61 43 111 149 145 144 158 144 87 92 80 71 Co 46 50 55 25 26 17 23 23 41 46 46 45 Cr 29 10 13 0 0 0 7 0 10 28 131 21 Cu 39 70 42 59 42 44 49 54 48 43 53 51 Ni 59 39 38 20 18 10 11 10 36 44 154 56 Sc 35 32 33 31 27 23 28 13 35 30 43 42 V 229 247 255 82 61 64 79 52 239 213 250 222 Zn 105 123 118 164 164 168 167 170 134 112 105 104 Normative mineralogy Or 4.91 5.50 5.56 15.25 15.31 16.02 15.54 16.31 7.15 8.16 5.38 6.44 Ab 27.67 29.70 29.95 38.58 37.74 38.41 36.49 37.33 32.23 31.73 21.90 27.78 An 26.86 25.73 25.90 15.71 15.78 15.53 14.10 14.03 22.56 24.26 25.15 26.89 Ne - - - - - - 2.60 1.82 0.55 - 1.20 1.41 Di 14.70 12.15 11.98 ' 5.26 4.63 5.09 6.16 5.83 10.94 11.99 18.52 11.71 Hy 6.35 3.23 5.89 1.09 3.06 0.23 - - - 1.02 - -Ol 5.76 9.48 4.73 8.83 7.27 11.08 12.26 12.16 13.31 13.16 15.77 12.02 Mt 8.72 7.74 10.08 7.03 7.17 5.58 4.61 4.71 5.01 4.02 6.24 7.12 Hm - - - - - - - - - . - -11 4.33 5.18 5.17 4.33 4.27 4.20 4.29 4.10 6.15 4.25 4.88 5.39 Ap 0.85 0.99 1.02 3.62 3.53 3.48 3.60 3.51 1.94 1.28 0.92 1.07 188 Appendix C . Who le rock chemical analyses Appendix C . l . Continued, Centre L a v a F o r k Sample L F - 3 0 L F - 3 1 L F - 3 2 SH-44 SH-54 SH-60 1 S i 0 2 46.41 46.48 46.77 46.46 46.44 46.47 T i 0 2 2.83 2.81 2.77 2.84 2.83 2.84 A 1 2 0 3 16.86 16.92 16.90 16.92 16.97 16.94 F e 2 0 3 3.62 2.72 2.67 2.59 4.90 3.28 FeO 9.16 9.91 9.86 10.10 7.90 9.40 M n O 0.18 0.18 0.18 0.18 0.18 0.18 M g O 6.52 6.62 6.71 6.52 6.56 6.55 C a O 8.89 8.87 8.81 8.87 8.91 8.88 N a 2 0 3.56 3.64 3.86 3.71 4.00 3.68 K 2 0 1.09 1.08 1.09 1.09 1.08 1.10 P 2 0 5 0.45 0.45 0.44 0.45 0.45 0.45 Total 99.57 99.69 100.05 99.73 100.22 99.77 M G # 41.57 40.04 40.51 39.23 45.37 41.05 S.I. 27.22 27.61 27.75 27.16 26.84 27.27 Trace elements B a 220 213 217 188 188 203 Ce 92 76 103 47 98 52 Co 49 52 52 60 55 52 Cr 18 19 17 19 15 17 C u 41 42 57 43 53 58 N i 54 76 64 56 51 67 Sc 29 37 35 26 29 33 V 244 230 222 225 222 22.7 Z n 106 107 109 109 110 106 Normative mineralogy Or 6.44 6.38 6.44 6.44 6.38 6.50 A b 26.35 25.12 25.01 24.74 26.57 25.64 A n 26.81 26.65 25.57 26.30 25.17 26.48 Ne 2.04 3.07 4.14 3.60 3.94 2.96 D i 11.68 11.80 12.48 12.10 12.94 11.91 Hy - - - - - -• 01 14.60 16.35 16.27 16.37 11.72 15.09 M t 5.24 3.95 3.87 3.75 7.10 4.77 H m - - - - - -11 5.37 5.34 5.26 5.39 5.37 5.39 A p 1.07 1.07 1.04 1.07 1.07 1.07 189 Appendix C . Who le rock chemical analyses Appendix C,2. Major and trace element analyses from Iskut-Unuk rivers centres measured by Geological Survey of Canada 1 Centre Iskut River T M C Snippaker Creek Sample IR-2 IR-3 IR-4 IR-5 IR-6 IR-7 IR-8 SH-37 SH-39 SH-01 SH-02 SH-31 Si0 2 49.30 48.70 47.90 48.00 49.30 48.40 48.20 48.70 47.70 48.30 48.50 48.40 Ti0 2 2.27 2.16 2.24 2.17 2.28 2.27 2.12 2.29 2.21 2.23 2.22 2.19 AI2O3 16.30 16.50 16.60 16.70 16.30 16.10 16.80 16.20 15.40 16.60 16.50 16.60 Fe 20 3T 12.80 12.60 12.90 12.80 12.80 12.80 12.60 12.80 12.80 12.80 12.90 12.70 Fe 20 3 4.10 3.90 2.70 2.70 2.90 3.20 2.50 3.50 3.40 2.80 2.50 3.00 FeO 7.80 7.80 9.20 9.10 8.90 8.60 9.10 8.40 8.50 9.00 9.40 8.70 MnO 0.18 0.17 0.17 0.18 0.18 0.18 0.17 0.18 0.17 0.17 0.18 0.17 MgO 6.25 6.47 6.74 6.99 6.17 6.36 7.04 6.13 7.83 6.17 6.34 6.43 CaO 8.97 8.80 9.15 9.30 8.90 9.03 9.30 8.93 9.90 9.21 9.28 9.40 Na 20 3.50 3.40 3.50 3.20 3.40 3.50 3.30 3.40 2.90 3.40 3.40 3.40 K 2 0 1.18 1.08 0.93 0.86 1.19 1.09 0.86 1.16 0.91 0.98 0.95 0.91 P203 0.45 0.47 0.41 0.38 0.46 0.45 0.37 0.48 0.38 0.40 0.40 0.38 H 2 0 0.10 0.30 0.40 0.30 0.40 0.30 0.20 0.30 0.70 0.30 0.20 0.10 C02 0.30 0.20 0.10 0.20 0.20 0.20 0.2Q 0.20 0.20 0.20 0.10 0.20 Trace elements 2 Ba 3 501 474 327 298 455 438 291 475 253 347 372 277 Sr3 610 660 650 650 610 620 650 610 580 630 630 640 Ce 55 54 47 46 55 53 43 56 43 49 49 45 Dy 5.7 5.8 5.1 4.9 5.9 5.7 4.8 6.0 5.0 5.7 5.4 5.2 Er 2.8 2.8 2.4 2.4 2.8 2.9 2.3 2.9 2.3 2.6 2.6 2.6 Eu 2.4 2.3 2.2 2.1 2.3 2.3 2.1 2.4 2.1 2.3 2.3 2.2 Gd 7.1 7.0 6.1 6.0 7.2 7.0 6.0 7.3 6.2 6.7 6.5 6.4 Ho 1.1 1.1 0.97 0.94 1.1 1.1 0.88 1.2 0.96 1.1 1.0 1.0 La 24 23 20 19 24 23 19 25 18 21 20 19 Lu 0.39 0.40 0.33 0.32 0.41 0.41 0.32 0.42 0.33 0.39 0.38 0.37 Nd 31 31 27 26 32 30 25 32 25 28 29 26 Pr 7.2 7.1 6.3 6.0 7.3 7.1 5.8 7.5 5.7 6.5 6.5 6.1 Sm 6.8 6.9 6.3 6.1 6.9 6.7 5.7 7.4 6.0 6.7 6.6 6.3 Tb 1.1 1.1 0.93 0.92 1.1 1.0 0.89 1.1 0.93 1.1 0.99 0.98 Th 2.2 2 1.6- 1.6 2.1 2.0 1.6 2.2 1.5 1.7 1.7 1.6 Tm 0.45 0.46 0.37 0.38 0.45 0.44 0.36 0.47 0.38 0.44 0.42 0.40 Y 28 28 26 24 29 28 24 29 24 27 27 26 Yb 2.6 2.6 2.2 2.2 2.6 2.6 2.0 2.7 2.2 2.4 2.5 2.3 Cs 0.14 0.17 0.14 0.14 0.19 0.16 0.07 0.18 0.13 0.06 0.04 0.08 Ga 21 21 22 21 21 22 21 22 21 22 21 21 Hf 5.1 4.9 4.5 4.3 5.2 5.0 4.1 5.6 4.9 5.4 5.1 4.4 In 0.17 0.08 0.19 0.08 0.08 0.08 0.07 0.17 0.08 0.19 0.08 0.17 Nb 25 24 23 22 26 26 21 27 23 24 23 22 Rb 16 15 13 11 17 15 11 17 12 12 9.6 12 Ta 2.0 1.7 2.5 2.3 3.6 2.5 0.87 1.3 1.2 2.2 1.0 2.6 Tl 0.02 0.03 0.03 0.03 0.04 0.03 0.03 0.05 0.03 0.04 O.02 <0.02 U 0.72 0.63 0.58 0.51 0.79 0.74 0.49 0.74 0.53 0.55 0.27 0.49 Zr3 210 200 180 170 210 210 170 220 170 200 200 180 'major elements maesured with XRF except for FeO and H20 measured volumetrically, e^lements measured with ICP-MS 3 trace elements measured with XRF 190 Appendix C. Whole rock chemical analyses Appendix C.2. Continued Centre SnC Cone Glacier Sample SH-33 SH-34 CG-9 CG-10 CG-11 CG-12 CG-13 CG-14 CG-15 CG-18 SH-13 SH-14 Si0 2 48.70 47.70 48.44 48.40 48.90 49.10 48.20 48.80 48.40 47.60 49.60 47.70 Ti0 2 2.22 2.20 2.14 2.18 2.17 2.30 2.30 2.25 2.28 2.35 2.27 2.08 A1203 16.80 15.80 16.84 16.80 16.70 16.20 15.70 16.70 16.40 15.60 16.30 16.00 Fe203T 12.90 13.30 12.52 12.70 12.50 12.90 12.90 12.80 12.90 13.00 12.90 12.90 Fe203 3.10 5.90 3.90 2.30 4.10 4.60 2.60 4.80 4.70 3.00 4.30 8.30 FeO 8.80 6.70 7.70 9.40 7.60 7.50 9.30 7.20 7.40 9.00 7.70 4.10 MnO 0.17 0.18 0.17 0.17 0.17 0.18 0.18 0.17 0.17 0.18 0.18 0.17 MgO 6.35 7.36 6.43 6.55 5.93 5.69 7.45 6.05 6.04 7.43 5.81 7.65 CaO 9.17 9.60 9.38 9.33 9.07 8.67 9.31 9.28 9.26 9.34 8.55 9.60 Na 20 3.50 3.20 3.40 3.50 3.60 3.80 3.30 3.40 3.40 3.10 3.60 3.10 K 2 0 0.97 0.82 0.91 0.91 1.05 1.20 1.11 0.96 0.97 1.16 1.25 0.78 P2O5 0.40 0.36 0.38 0.39 0.41 0.46 0.46 0.42 0.41 0.47 0.47 0.33 H20 0.10 0.20 0.10 0.20 0.10 0.20 0.30 0.30 0.20 0.60 0.10 0.20 C02 0.20 0.10 0.10 0.20 0.10 0.10 0.1Q 0.30 0.20 0.10 0.20 0.10 Trace elements 2 Ba3 378 285 281 302 338 454 339 376 355 340 489 226 Sr3 620 600 640 630 630 630 590 630 630 600 600 600 Ce 48 43 44 46 50 56 54 50 50 54 58 40 Dy 5.4 5.2 5.4 5.5 5.7 6.0 5.6 5.5 5.6 5.6 6.0 4.8 Er 2.6 2.5 2.5 2.6 2.7 3.0 2.6 2.7 2.7 2.7 2.9 2.4 Eu 2.2 2.1 2.3 2.3 2.3 2.5 2.4 2.3 2.4 2.5 2.4 2.1 Gd 6.7 6.3 6.3 6.4 6.8 7.5 6.9 6.7 7.1 7.2 7.3 5.9 Ho 1.0 0.98 1.0 1.0 1.0 1.2 0.98 1.0 1.1 1.0 1.2 0.93 La 20 18 19 20 21 24 23 22 21 24 25 17 Lu 0.37 0.34 0.35 0.36 0.37 0.42 0.36 0.37 0.39 0.38 0.43 0.33 Nd 27 25 26 27 28 32 31 29 29 31 33 24 Pr 6.4 5.7 5.9 6.2 6.7 7.5 7.3 6.8 6.7 7.5 7.8 5.5 Sm 6.5 6.0 6.1 6.3 6.7 7.4 7.1 6.7 7 7.1 7.5 5.6 Tb 1.0 0.93 1.0 1.0 1.0 1.1 1.0 1.0 1.0 1.0 1.1 0.87 Th 1.6 1.4 1.6 1.5 1.7 2.0 1.8 1.6 1.6 2.0 2.0 1.4 Tm 0.43 0.38 0.40 0.40 0.43 0.46 0.41 0.42 0.43 0.41 0.47 0.38 Y 26 25 26 26 27 30 27 28 27 27 30 24 Yb 2.3 2.3 2.3 2.4 2.5 2.7 2.4 2.5 2.5 2.5 2.7 2.1 Cs 0.07 0.08 0.09 0.11 0.12 0.14 0.13 0.11 0.07 0.21 0.10 0.08 Ga 21 21 21 21 21 22 21 22 22 21 23 21 Hf 5.1 4.7 4.4 5.0 4.8 5.4 5.3 4.8 4.6 5.0 5.5 4.2 In 0.17 0.08 0.07 0.07 0.14 0.08 0.09 0.08 0.08 0.17 0.18 0.08 Nb 23 21 22 22 24 28 28 24 24 30 28 20 Rb 12 11 12 12 15 18 16 13 13 19 17 10 Ta 1.2 1.0 1.1 1.4 1.3 1.6 L7 1.2 1.4 1.5 1.4 1.8 TI 0.03 <0.02 0.03 0.03 0.02 0.03 0.05 0.03 <0.02 0.04 0.03 O.02 U 0.40 0.65 0.52 0.48 0.60 0.67 0.66 0.56 0.58 0.64 0.70 0.48 Zr3 190 230 180 180 200 230 210 200 200 210 230 180 191 Appendix C. Whole rock chemical analyses Appendix C.2. Continued Centre Cone Glacier Cinder Mountain K C SeC LF Sample SH-15 SH-22 SH-26 CM-19 CM-20 CM-21 SH-19 SH-21 SH-35 KC-22 SC-23 LF-24 Si0 2 47.90 47.00 47.00 49.70 49.30 49.90 49.70 49.90 47.60 49.10 45.80 46.60 Ti0 2 2.19 2.63 2.60 2.20 2.14 2.12 2.19 2.08 3.15 2.16 2.51 2.75 A1203 15.90 16.00 16.10 15.80 15.80 15.90 16.00 15.80 15.90 16.20 14.60 16.60 Fe203T 13.10 14.70 14.60 14.30 14.00 14.00 14.20 14.30 14.70 12.30 13.70 13.90 Fe203 6.10 5.60 7.20 5.50 5.20 4.20 3.30 3.40 3.60 3.20 4.80 5.20 FeO 6.30 8.20 6.70 7.90 .7.90 8.80 9.80 9.80 10.00 8.20 8.00 7.80 MnO 0.17 0.19 0.19 0.25 0.24 0.24 0.24 0.25 0.21 0.17 0.17 0.17 MgO 7.37 6.37 6.39 3.08 3.04 2.94 3.04 2.86 5.33 6.06 9.44 6.61 CaO 9.60 8.76 8.79 6.38 6.21 6.25 6.32 6.13 8.30 8.49 10.30 8.88 Na20 3.20 3.50 3.40 4.60 4.20 4.40 4.60 4.50 3.70 3.40 2.80 3.50 K20 0.82 0.92 0.92 2.56 2.59 2.71 2.63 2.74 1.21 1.33 0.89 1.09 P2O5 0.36 0.42 0.42 1.54 1.49 1.48 1.53 1.47 0.82 0.53 0.39 0.45 H20 0.30 0.10 0.20 0.30 1.70 0.60 0.40 0.50 0.30 0.40 0.50 0.20 C02 0.10 0.10 0.20 0.10 0.60 0.10 0.10 0.10 0.20 0.10 0.30 0.20 Trace elements 2 Ba 3 248 270 347 905 881 960 938 932 346 609 156 191 Sr3 590 620 630 650 620 640 640 660 560 650 550 690 Ce 43 49 50 150 150 150 150 160 71 61 45 54 Dy 5.0 5.9 5.7 11 11 11 11 11 7.5 6.0 4.9 5.3 Er 2.5 2.8 2.8 5.2 4.9 5.1 5.0 5.2 3.6 3.1 2.3 2.5 Eu 2.1 2.5 2.4 5.6 5.3 5.6 5.4 5.4 3.2 2.5 2.4 2.6 Gd 6.1 7.3 7.2 16 15 15 15 15 9.5 7.8 6.6 7.1 Ho 0.96 1.1 1.1 2.2 2.0 2.1 2.1 2.2 1.5 1.2 0.94 1 La 18 21 21 58 56 57 58 62 31 28 19 23 Lu 0.35 0.40 0.39 0.70 0.66 0.70 0.69 0.71 0.51 0.45 0.29 0.33 Nd 24 28 29 75 73 75 74 78 41 34 27 31 Pr 5.8 6.5 6.7 18 18 18 18 19 9.7 8.4 6.2 7.3 Sm 6.1 6.9 6.9 16 15 16 16 16 9.8 7.8 6.2 7.3 Tb 0.94 1.1 1.1 2.2 2.1 2.2 2.2 2.2 1.4 1.1 0.99 1.1 Th 1.4 1.7 1.7 4.9 4.9 5.0 4.9 5.2 2.2 2.3 1.7 1.9 Tm 0.38 0.45 0.44 0.81 0.77 0.79 0.78 0.81 0.56 0.51 0.36 0.39 Y 25 28 28 52 50 52 51 53 37 30 24 26 Yb 2.3 2.5 2.5 4.5 4.5 4.5 4.5 4.8 3.4 2.9 2.0 2.3 Cs 0.08 0.10 0.08 0.18 0.28 0.27 0.44 0.32 0.09 0.21 0.13 0.16 Ga 21 24 23 27 26 28 26 27 23. 21 21 23 Hf 4.4 4.8 5.0 9.4 9.0 9.5 9.5 10 6.4 5.4 4.5 5.2 In 0.09 0.15 0.09 0.10 0.12 0.13 0.20 0.13 0.11 0.09 0.08 0.09 Nb 21 25 25 >50 >50 >50 >50 >50 38 31 25 30 Rb 11 12 12 37 40 43 39 39 16 20 13 16 Ta 1.5 1.8 1.5 4.0 3.7 3.6 3.8 3.8 2.2 1.4 1.4 1.6 Tl <0.02 <0.02 <0.02 0.02 0.08 0.07 0.08 0.06 0.03 0.08 0.04 0.18 U 0.50 0.52 0.55 1.60 1.60 1.70 1.80 1.70 0.73 0.83 0.78 0.65 Zr3 180 200 200 420 420 430 420 450 260 230 180 210 192 Appendix C. Whole rock chemical analyses Appendix C.2. Continued Centre Lava Fork Sample LF-28 LF-30 LF-31 LF-32 SH^4 SH-54 SH-60 SH-41 SH-42 Si0 2 75.00 46.70 46.50 46.60 46.70 46.40 46.30 75.70 74.60 Ti0 2 0.10 2.74 2.71 2.67 2.76 2.75 2.73 0.06 0.36 A1203 13.20 16.90 16.60 16.60 16.90 16.80 16.70 13.10 12.60 Fe 20 3T 0.50 13.80 13.90 13.70 13.90 13.90 13.80 0.30 2.80 Fe 20 3 0.10 3.90 2.80 3.00 2.70 5.10 3.40 0.00 2.00 FeO 0.40 8.90 10.00 9.60 10.10 7.90 9.40 0.00 0.70 MnO 0.01 0.17 0.17 0.17 0.17 0.17 0.17 0.01 0.02 MgO 0.11 6.59 6.71 6.79 6.62 6.64 6.59 0.04 0.84 CaO 0.69 8.85 8.85 8.72 8.84 8.89 8.80 0.68 2.92 Na 20 3.70 3.70 3.70 3.50 3.70 3.50 3.70 3.50 3.70 K 2 0 4.57 1.10 1.09 1.08 1.09 1.08 1.09 5.08 0.59 P2O5 0.03 0.45 0.45 0.44 0.45 0.45 0.45 0.02 0.06 H 2 0 0.20 0.10 0.10 0.10 0.10 0.20 0.10 0.50 0.50 C02 0.20 0.20 0.20 0.10 0.10 0.20 0.20 0.20 0.20 Trace elements 2 Ba3 540 220 213 217 188 188 203 110 410 Sr3 110 680 690 680 670 690 690 58 300 Ce 20 55 53 54 54 56 54 24 60 Dy 0.89 5.4 5.3 5.2 5.2 5.5 5.5 3.1 3.5 Er 0.43 2.5 2.5 2.5 2.4 2.6 2.6 1.6 2.1 Eu 0.24 2.6 2.5 2.4 2.5 2.6 2.5 0.3 1.0 Gd 1.3 6.9 7.1 6.7 6.6 7.1 7.1 3.3 3.8 Ho 0.16 1.0 1.0 0.99 1.0 1.0 1.0 0.61 0.72 La 10 24 23 24 23 23 23 10 31 Lu 0.07 0.35 0.33 0.34 0.33 0.36 0.34 0.29 0.43 Nd 7.8 32 . 31 31 30 31 31 12 22 Pr 2.2 7.3 7.3 7.3 7.1 7.3 7.2 2.9 6.6 Sm 1.6 7.4 7.1 7.4 6.8 7.3 7.0 3.3 4.1 Tb 0.18 1.0 1.0 1.0 1.0 1.1 1.0 0.54 0.6 Th 13 2.0 1.9 1.9 1.9 1.9 1.9 22 15 Tm 0.08 0.40 0.38 0.36 0.37 0.38 0.38 0.30 0.40 Y 5 27 26 26 26 26 26 19 21 Yb 0.49 2.2 2.2 2.2 2.3 2.3 2.2 2.0 2.6 Cs . 1.5 0.17 0.16 0.19 0.15 0.14 0.16 2.6 0.22 Ga 17 23 23 22 23 23 23 19 12 Hf 2.3 5.8 5.1 5.2 5.2 5.7 5.2 2.1 5.8 In <0.05 0.09 0.15 0.09 0.09 0.08 0.09 <0.05 O.05 Nb 7.2 30 29 29 29 30 29 19 22 Rb >50 16 16 16 16 15 15 >50 11 Ta 1.0 1.3 1.6 1.8 2.1 1.9 1.8 3.2 1.5 Tl 0.64 0.05 0.10 0.06 0.05 0.03 0.03 1.0 0.11 U 2.20 0.71 0.66 0.70 0.66 0.67 0.64 25 4.6 Zr3 57 210 210 210 210 220 220 39 350 193 Appendix D . Electron microprobe analyses of olivine I * 73 s IS 3 i J 1^ C u U CJ "B. c E '|3 "O T3 X> VO o CN r- I—1 CN ON CN 00 © ' © ' —I © ' CN ON © r- •n ON o co r- CN 00 © ' © ' >-i © ' 00 ON © o CN 00 CN ON o © ' © ' •O • • ON 00 rt ON vo ON r- o 00 © rt NO CN © m' X xi xi NO © ' © ' rt' © ' 00 ro CN CO ON rt 00 T3 •d •d m rt T3 ND CO oo VO r- © rt NO X X X vo X> ©' NO ©' ON ro CN CO ON T3 X T3 X> >n rt •d r-ro ro © 00 NO NO vo CN xi © NO ro © 00 ON rt © •d vo CO vo rt © CN © rt CN X> © NO CO © ON ON NO 00 NO ON CN 00 © CN CO CN co' © © r-' © ' © NO 00 _ © 00 CO rt CN »-H o rt CN X © ' r> CO © ON ON rt ON •d •d •d CO •d CN CO © © CN r^  oo io' xi xi xi rt X) © r»' ©' r--' CO CN ro ON NO 00 •d •d •d rt NO •d rt ro no 00 00 NO 00 iri xi xi xi vo X © ' vo © ' r-' ro CN ro ON -a x vO ON •d r-ro CN O 00 00 rt in CN xi o NO ro © 00 ON °, -d -d -d xi x xi CO NO ro •d ON ro ON CN CO CO CN X © ' CO © ON ON IO ON •d •d •d r> r~ •d NO ro ON NO CN rt © X xi xi CN xi ©' r-' © ON CO CN ro ON d d 5 ? o o ? ° M o c I Ti-cs O T3 CJ Vi CS X c o oo ro rt © rt © ON O © © ON © 00 O ON O © © © O tv3 H < rt ^H rt ~H rt CN CN © NO CN vo r- NO 00 © © © i-H © CO ON " rt © © NO © © © ' © © © ' —' © ' CN 00 ON m co © oo —i vo oo r-© © © © © rt © © NO © © © ©' —iI © IO rt VO CN NO CN © © rt © © © © © ' rt vo r— "o NO © NO O ~* © ' CO CO t- CN rt rt r— NO © NO rt © CN vO r- © r~ i—< © i-H i © rt ON © I ON i NO © © rt © © © © ' © © © © ' ^ © CN m © CN ON 00 00 r—4 © CN 00 CN rt CN 00 © 00 NO © vO © CO ON O i ON i >o 1 © rt © © © ' © © © © —1 © CN ON NO vO CN VO CO © rt 00 CO VO 00 00 o 00 © rt © CN ON © • ON « 1 © rt © © © © © © © —^i © CN CN CO NO 00 oo NO NO 00 CN © CN VO CN VO ON © ON <o © rt © ON O i OS i •O 1 o rt © © © ' © © © ' © —1 © CN CN ON VO NO 00 CO rt NO ON © ON 00 VO NO NO 00 00 © 00 CN © © © ON © i ON i vo © © rt © © O o O © © ' © ~- © CN 00 00 IO ro CN ON © © rt 00 CN NO ro NO NO © VO © ON © NO ON i i ON © VO 1 o rt © © © © © © o -1 © CN _ © CN ON rt t-~ NO © I-H < 00 CN VO rt © rt © ON © VO ON © i ON i VO 1 © rt © © © ' © ' © © © —' © ' CN 00 r- rt ro VO ro OO CO o rt CN t—i VO NO r~ © r- 00 © VO © rt ON O i ON • LO © rt © © © o © o o" © ' CN CN ON NO NO VO ro © CN © CN NO OO — VO CN r- o r- 00 © VO o vO ON O i ON VO 1 © rt © © © © © ' © © ' © ' CN NO 00 vo NO VO oo NO 00 r—i © 00 © VO © rt © o © ' © —! © CN rt NO vO NO 00 ON NO © © r~- © ON vo o rt © ON O © © — 1 u £ z S S u ON NO © CO ON © " © ' CN NO ON rt rt CO ON © © ' r-- CN VO Ov r--rt CN CN ON © © ' r- CN rt ON NO rt <—* ro ON © © ' NO CO NO © rt © CN oo" © ' CN rt © NO rt CO CN oo" © ' r~ CN ON rt OO ON CN ^H r-' © ' CN © 00 CN rt CN CO CO NO © ' CN o ON © CN CN © ' r~ CN t-H 00 ON 00 CN CN NO © ' r~ CN 00 NO NO <—1 VO CN i—< oo' © ' r- CN ro NO © CN 00 © ' CN r~ VO r~ ON NO CO CO VO © ' CN CN 00 rt CN ro rt VO © ' CN 5^ o x 5? O ca CS UH ti, CS e a 3 2 so II O o o c 1) X o, T3 CJ o o e CJ SS o, o cu .11 194 Appendix D. Electron microprobe analyses of olivine .22 CS lo <u OJ .9-1 l«3 T3 <U 3 _C c o O Q >< •3 c I1 CL, NO o OO ~ . NO' 8 -q WO 00 CN NO O CN| O CO CN © ©' r> ©' CN CO T-j r- © — i oo wo X co — i ro CN <N * •* CN © o r» © WO T3 13 T3 00 wo T3 CO CN 00 CN © CN NO W0 00 X> X> xi CN X> © ' © ' © CN CO 1—1 CN wo ~. r-- X) T3 xi T3 X> § -q -q t^ ' x> x> co 0 0 -a NO ~ od J= CO CN -a oo * CO CN ~ od - 0 CO T3 X) T3 x> 13 xi T3 xi W0 i-H NO CN •*»• t> w CO CN 00 CN xi © od © ' CN CN CO CN 00 CO T3 CO 00 CN wo CO wo' <N xi ©' wo ro ©' CN CN r- •q" CN CO oo v-i CN CN NO NO CO CN xi © r-' ro © ON ON wo <N NO © wo CN wo CN © CN 00 NO_ © CN © ©' © t ©' CN CN CN 00 00 © OO CN ro wo vi (N (N © ©' CN ro © © © r- CN CO CN CN CN CN r-CN CN xi © 00 ro ©' ON CN o CN T3 CN CN © NO CN © CN CN xi ©' od ro © ©' © T3 xi W0 " NO' - ° CO T3 xi T3 xi T3 xi •a xi NO CN 00 © NO CN NO ro r-CN od © © ' © CN 00 ro wo CN CN r- ro CN © ' © © © NO © r-CN •* NO CN OO © © © WO CN 00 © W0 CN NO WO ro CN © ' © ' d •3-© ,£> A o o 0 n o O o c o _H CN NO ro NO WO © o 00 wo r -00 00 ro © © 00 © co CN 1 1 CN 1 KO © © © © © © ' © © ' © t—t © CN © © NO CN © CO CN I—t CO CO © CN I—< 00 00 © © © CO CN 1 1 CN ' wo © © © © © © © © © © CN © o oo wo WO CN V~l wo 00 CN ON CN o t~~ © o CN 1 1 CN 1 © o © © ' d © ' © ' — . © CN r> NO CN NO ro CO NO NO NO NO NO °^ . . ON © CN © © CN 1 1 ON i © Tt; © © © © © © © CN CN CN NO r - © CO OO 00 CN NO r~ CN CN . ^° o © CN CN 1 1 CN 1 W0 © © ON © ' © ' © © © — 1 CN (VI © CN CN ro 00 . CN ro NO 00 CN CN CN © r- © © ON 1 1 CN 1 WO • © © © © © © © — © CN r- ro ro CN NO 00 00 r- wo CN wo 00 CN CN ro © © CN CN 1 1 CN 1 -<t © o i n © CN © © ' © O © — 1 © CN CN CN NO CN ro © © © © CN NO r- WO CN CN © © CN © I—( ON 1 1 CN © o uo © © © © © © © »—< © CN CN CN ro ON CN CN NO NO NO CN CN CN © oo © CN CN ' 1 CN 1 1 © © CN © © © © ' © —< CN CN 00 r- CN CN ro ro oo 00 WO 00 CN CN CN © ON © © ON ' 1 CN 1 © © o © ' © © © © CN wo — NO O CN 1 © CN r-© c75 H < WO NO OO 00 ND © —I CN © © © © © — > © E O0 CJ NO r- WO ro wo NO CN WO CN ro © © © © NO © © NO © © d © © ' © CN NO CN rN (N NO ro NO © O © o © © NO © © d © © © CN CN NO WO CN wo 00 NO ro © © ON © © © W0 © o © © o o CN £ z S 2 <3 >o 1—< wo CN CO r-NO CN ©' CN CO r -WO CO CN r -VO CN © wo NO OO © CN 00 r -CN ©' wo 00 00 CO •<*•' CN © wo CO WO CO © CO od CN © © NO 00 © CN CO co' NO CN © oo r- WO CN CN t-' r~ CN © CN © NO WO WO CO NO r~ co' CN © WO CO ON ro •"*•' CN © 00 CN 00 CN CN CN ©' wo CN 00 ro CO CN © CN d NO 00 ro NO od r~ CN ©' NO © ro CO CN ©' CN ©' © WO CO od CN ©' Fo% cd 195 Appendix D. Electron microprobe analyses of olivine et lo cu c o IO O H 3 a o CJ D .* •3 c u , ex e E g S -q c-' * ro § -q r-' - ° ro •a xi T3 xi S -q NO - 0 - ° ro ro vO XI VO CO •a -a xi xi £ -q CO T3 Xi •a x> Ov ~ r-- X> -a -a xi xi T3 xi 'O "U XJ xi xi xi •a -a xi xi ON ^ ro T3 T3 Xi Xi T3 xi •a -a xi xi g -q -q on- X) X> O O H < ON O •q 00 cs cs cs CS cs WO 00 CS cs xi d ON ro d 00 Ov r-00 00 o r-CS-CO wo cs 00 wo © cs d d d Tt d ON ON wo © NO o Tt CO CO o cs cs o W0 wo' cs d d r-' ro d ON ON NO •q •* CO OO ON Tt cs ON c~ Tf cs xi d NO ro d oo' Ov r-wo NO o wo CS ro © cs T* d cs d d d Tt d oo' ON o wo o cs ON 00 cs Tt Ov od d d Tf d od ON 00 ro wo cs wo ro Tl-tS Tf 00 d d cs Tt d Ov Ov (S CO •q cs ON Tf Tl-tS ro cs ON xi d Tf d ON Ov r-CS o wo CS r-00 TI-CS NO © 00 d d Tt d ON OV ro CS •q W0 <s p-cs CS cs to od xi d cs Tf d ON Ov ro wo •q NO cs Tt ON r-CN O ON ON' xi d d Tt d od ON Tf Tf *q ro rs cs o ts TI-CS 00 xi d cs Tt d ON Ov CS ro •q ro cs W0 Ov cs cs wo 00 xi d Tt d OV ON o r- cs ro TI-CS O ON o o Tt o ON Ov FeO n O O O CJ "ro o H 3 o Tf c o T3 CJ </} ro XI c o ro U w H < ro ro cs CO NO cs NO CN oo © Tf © Tf Tf 1 © WO © © d © ' © ' cs' ON NO © © NO to f—< NO CO r- *—H wo © © NO © CO Tf © © WO © © d © © —' © ' cs' o Tf NO r- Tt © NO © wo © © NO © Tf wo © © Tt o © d © ' © ' rt © ' cs' o NO , ( 00 WO o CO NO r-wo © r- © CO wo 1 © Tf o © d d © ' CS CO Tf CO wo cs © r—< wo CO oo wo © o NO © cs Tf © © WO © o © © ' © ' •—< © ' cs' W0 _ W0 CO 00 ro © ts Tf NO wo ON © © © <—H © cs Tf © © NO © © © © © d CN CN NO Tf c- NO Tf ts ts W0 oo NO WO ON © © cs © CO ro © o NO © © © © © © ' ts Tf Ov Tf NO ro 00 wo r--I NO cs ^ — © © © CO Tf • © NO © © © ' © ' © ' CN CN Tf NO NO ON Tf CS WO © NO OO Ov © © © [—< ro © © NO © © © © © 1—1 d cs' r- Tf ts CS Tf ts WO ro NO Ov © cs © ts ro 1 © NO o o © ' © ' ~* © ' ts r- r- CS Tf © Tf wo r- wo CN © 00 © cs Tf 1 o WO © © © © © CN CN Tf Tf oc W0 WO o Cv © cs © ro ro I © NO © © © © ' © ' CN wo cs WO Tf wo © NO ND CN © I-H © ro © NO © © © ' © — ' © CN © Tf © ON NO ON Tf ro NO W0 NO WO — © O CN © cs Tf © o wo © © C © © ' d cs a £ z 2 2 o wo c-Tf ON ro wo r~ CO cs ©' CO C S CO Tf wo CO r- ts C S ©' NO CS CN Tf CO cs' r-r-' cs ©' r~ WO ON © Tf CO cs t-r-' cs ©' Tf CO CN cs r» ro r-' r-' cs ©' CN © 00 CN CS ON ON ©' CO CO Tf CO cs ro © 00 ON © ro © WO NO ro ro CN © CN ©' r-© © NO ro ro ©' 00 ON © CS CS Tf ro © ' oo ON ©' © NO CO © r-ro od cs © © NO ND cs © 00 ON © ' 00 © CS NO ro ' oo ON © ' Tf ro wo ro ro ON © © 5^ a% o ro a% [X, 196 Appendix D . Electron microprobe analyses of olivine .a ca IO <u e o I U T3 C J a c o U Q x •3 c « , "5. c E -5 to O T3 T3 •a x T3 X> •a x i x •a x i T3 x i T 3 X> T3 -a Xi X> T3 X •a TS x i x i •a xt x i x T 3 x i T3 T3 X> X O _ H < o o o ON •q © CO 00 rt CS 00 r-co CS X- d r-' CO © ON ON co !-—I ON r t r t r t CO 00 r> d co d d CN CO © ON NO cs ON O NO cs 00 r- cs r-cs rt-' CS ©' d r-' ro d ©' © co CO •q CN CO 00 ON cs r t rt' CS x i d NO CO ©' ON" ON Tf T3 ON CO m <n CS cs r t CS m' cs X d NO* ro ©' ON ON o r t © C O r t •n © CS © ON r t CS X) © r-' ro © ON ON m ON •q C O © © cs i n ON CO CN x i © r-' ro ©' 0 0 ON ON •q rt rt r t r t m cs m r t ©' CO x i © cs' CO © ON ON m •q C O Vi © © 0 0 cs 0 0 r~ o' CO X) © cs ro d ON ON 0 0 NO •q rt C O r t ON © cs CS NO C O CN X d r-' ro d ON' ON rt ON •q NO cs ON NO cs NO rt C O CN X ©' r~ C O ©' ON ON r-co T3 r~ C O cs ON cs ON 0 0 «n CN X © NO ro ©' 0 0 ON N O o 0 0 O ro i n 0 0 rt 0 0 CN CS d © ON ro © 0 0 CN r-~ 0 0 o CN CN IT) © © cs © rt cs cs d ©' ON ro d 0 0 CN FeO O % o c 2 o o 2 u o H c C J o r t C o T3 C J Vi C O X (S O .9877 • i .9877 • .5256 9900 .4807 ,0067 ,0196 © © © © -H © CS .9872 i i .9872 ,6852 .0025 ,0113 .3149 0600 ,0228 © © © © © © cs ,9874 • i ,9874 5318 0019 0057 4759 0059 0212 © © © © © — © cs .9946 • i .9946 • ,5377 ,0072 4570 0059 0079 © © © © © CS ,9786 i i .9786 ,5671 8800 4541 0064 0364 © © © © © CS ,9861 i - i .9861 • ,5373 9900 .4734 .0055 0228 © © o © o cs 9943 • i ,9943 i 5314 0070 4631 0900 0075 © © © © © CS ,9858 i i ,9858 l 6889 0101 3193 0074 0257 © © © © © cs .9874 • i 9874 i ,7010 0122 3007 0082 0221 © © © © © CS ,9861 i i ,9861 ,5214 ,0075 .4890 ,0055 ,0234 © © © © — 1 © cs ,9858 i i ,9858 l ,5284 ,0058 ,4829 ,0059 0230 © © © © I—1 © cs .9840 • i ,9840 .5684 .0085 ,4424 ,0084 ,0277 o © © © © CS .9776 • i .9776 i ,4868 ,0016 ,0069 ,5399 ,0051 ,0405 © © © © © © cs .9738 • i ,9738 i .4920 ,0016 .0049 .5452 ,0056 ,0494 © © © o © © cs bo P < Sum Cr + CN C J fe „ c z 2 2 o Sum N O _ CO •n *—' CO CO N O " © ' r- CN VI © m r t »—i r t m' r t © ' SO CO © O N CO r t CS CO VO © r- cs co 00 © 00 00 CO CS N O © ' r- CS CS r- cs r - O N CO r-' © r- cs 00 m © N O cs ro N O ' d r~ cs r t r~ © —-1 m CO CO N O © ' CN i n 00 r-r t ro •n r t © N O ro cs 00 r~- oo r t r t rt" © N O ro N O N O 00 00 cs CO i n © r~ CN ON ON i n CS CO N O © CS CO i n CS r t r t 00 © ' CS O N N O m r- O N CS «n ro © ' rs r t O N r~-N O © cs i n rt © ' CN s? O co C3 fe fe •J 197 Appendix D . Electron microprobe analyses of olivine CO u .a OS lo <u a o IO -a D S3 _£ C o U D x *5 c CD I 1 00 1-4 r-H^ co' cu CO oo CS 00 1 p CU oo o "a, c S "S CO O XI xi xi •a xi x> •a xi XI xi Tf CO •o xi X) xi XI xi XI xi XI xi VO XJ CO XI XI Xi Xi X) XI xi xi XI xi X) x> 0 0 X! oo ^ wo' -° co XI xi XI XI xi xi X) XI xi xi XI xi XI X) o o _ co i - < o o © xi wo 00 00 Ov 00 CO 00 co Tf xi d d CN ©' oo' Ov © CN xi 00 VO VO OV CN CO wo OS © Tf xi d CO CN ©' oo' OS vo CO xi wo CN Ov Tf Tf CO wo i-H WO xi *" Tf © Ov OS o CN xi 00 Ov Ov VO wo CO 00 so Tf xi d 00 ©' Os' OS VO CN xi CO vq 00 Tf CO Tf wo W0 r-' CO xi d VO CN ©' Os' Ov CO CO xi VO VO co <—1 Tf 00 VO r-' CO x> ©'" vd CN ©' Ov OS r-CN xi Ov Tf Ov wo CO 00 t~-ov CN xi d CN CO ©' 00 Ov 00 1—t vo O wo CN Ov Tf CN CN 00 co' CN d d 00 CO ©' Os' OS O VO xi VO CO wo CN OS Tf CN xi d r-' CO ©' OS Ov WO CN xi CO © CN © Tf CN xi d CO ©' d © t-; xj Ov Tf © WO oo CN W0 00 ro CO xi d Ov CN © Ov Ov oo CO xi VO CO wo W0 CN CN © Ov CN xi d CO CO ©' ' © Tf CO xi Tf CN © CN wo r-' CN xi d Tf CO © Ov Ov Tf wo xi o Tf Tf © CN wo Tf r-' CN xi d Tf CO © Ov OS FeO o iz O e Is o i-o CO H < VO CO Ov wo i—< I-H «-H « vO VO . CN CN i-H © 1 © OS © © © ' © © CN CN 00 © © © Tf VO WO © vo c- i-H CO r-H CO OS 1 © © © © © © ' © CN VO Tf © r~-oo CN CO *-H WO . co VO I-H CN CO p vq © © -1 © © ' © CN CO Ov CN Tf wo Tf CO 1—H Tf wo CO I-H CN ; • © 00 © © * " * © ' © © CN Tf CN I-H CN oo CN W0 00 CO 00 00 i-H ——* I-H CN 00 © © © ' © © ' CN CO OO oo CO CN CN wo © CN 1—H 00 i-H i-H i-H CN 00 © © © © © ' —< © ' CN Tf © OS I-H Ov Os OS VO i-H CN © i-H VO © CO © © © ' © —< © ' CN CN CO Tf CN ro wo 00 i-H wo Tf vo WO © © © © © CN wo © © WO © © © ' © ' © ' — 1 © ' CN CN Ov Os I-H CN 00 ro wo © Tf , © r- © CO WO 1 © Tf © © © ' © ' rt © ' CN Tf Ov OS wo CN vo WO W0 © ro , o © CN wo p Tf © © © ' © © ' CN Tf wo WO ro r~ 00 Tf 00 CN P-H r-H © I-H r~ 1 © CN © © © ' © ' —' © ' CN ro VD _ © ro 00 OS VO vO , o Tf © CN VO °. CO o © © © ' -1 © CN CN Tf wo VO t--ro Ov 00 wo VO i-H © 00 © vq © CO © © © ' © ' -' © ' CN Ov , , ro VO O 00 Ov oo wo CN •—• © © ~H vq © ro © © © © ' © CN a OO Os _ © i-H CN VO vd co' © ' Tf wo VO wo OS CN CN Tf »-H 00° © WO Tf 00 VO WO CN ^H wo co' vd © ' CO VO vo 00 vO vq p- wo -H r-' © ' Tf wo CO CN WO wo 00 vO wo' co' © wo Tf Ov © CO © vo wo Tf © ' wo Tf © wo WO CN CO Tf vd CO © ' vo CO t 00 wo ~H ro Tf wo © ' CN OS OS 00 oo CN CN vd © ' CN Ov Tf r-CN Tf CN co' vd © ' r- CN OS © vo Ov Tf © ' 00 d V0 CO W0 wo © oo 00 CO vd CN © ' VO ro f- wo 00 I—1 wo CN Os' © © ' VO ro CN © 00 00 ov CN 00 © ' © ' vo ro ov N? o CS CS _-) 198 Appendix D. Electron microprobe analyses of olivine 'S3 e 3 o IS u •a 3 c o U Q •a I 1 OH CJ E '5s 13 x>. •a x> 13 - a 13 x> •a xi cs VO •a c n Tt oo Tt TI-CS c s r~ r> cs xi © Tt cn d r-' ON cn 00 13 c s vi Ti-en CS TT r-H r-cn xi o ' f-H cn d ON 13 c n un TI-CS Tt no cs cn X d ro d ON ON P fl rX * ~ A . cvi X -d 13 WO ON •a NO r-vo r> r-cs v> Tt X Xi TT xi d cs' cs d ON ON xi 13 X cs' - 0 CO •a xi 13 X) 13 xi 00 Tt 13 Tt 00 c s c s ON cs Tt ON Tt X> d CO c s d t-i ON 00 r-13 ON r-00 CO m CO Tt ON ON CO xi d Tt' c s d r-' ON o NO NO o CO NO 00 NO cs Tt ON CO d d Tt c s d ON ON CO Tt 13 oo 00 00 Tt ON CS v> o ON CO xi d Tt cs d 00 ON O cs 13 13 13 ro 00 13 O OO NO v i cs Tt 00 CO X) X> xi CS X) d d 00 CO Tt cs ON 13 xi ro' -° CO •o ^ ; -° o< CO -a xi o oo — i 00 NO ro d Tt ©' cs HO NO NO ro Tt cs ro ON CO xi d vi cs © ON ON •a xi 13 13 X X 13 X> © cs Tt ON VI cs cs CO ON ro xi d Tt CS © ON ON © Tt NO 00 cs NJ NO cs VI ON' X> © Tt © 00 CO cs ON NO *d *d -ft NO CS CO © VI © NO t- cs CS Tt xi xi X) ON © ' © Tt © ' ON CO ro CS ON ^ ^ O O - . f - N O O n r-H _ Tt ON © © Tt CO ro NO ON NO ON ^ , NO CO o r-H © NO ON 1 1 CN NO I © Tt © © © © ' d © ' © ' CN v> VI © Tt © r-ON ON cs cs © CS Tt , Tt V) cs ~H ON ON 1 1 ON 1 I © CO © © © © © © ' © CN CO ro cs Tt 00 © Tt NO NO cs cs v, CS CN r- r- CO 00 Tt ON 1 i CN 1 1 © cs © © © ' © ' © ' © © CN CS CS © 00 r^ ro f—c r—t —« oo 00 VN 00 50 cs r-H 00 © ro ON 1 CN 1 © I © ON © © © © © © ' © ' CN 00 00 ro © Tt r~ ro ro © OO ON oo VI VI ro cs CS © 00 ON 1 1 CN 1 © I © © © © © d d © CN 00 00 © NO Tt © © ON CN • oc ON OO VI vi i-H NO l-H ON 1 • CN 1 CN © © © © © ' © ' © © — 1 © CN © © VI CN rs CN OO 00 VI —— VI © 00 r-H r- , r- VI o r-H NO © Tt ON 1 1 CN 1 CN o © © © © © ' ° © o © © ' CN CS CS vi 00 ro rs Vl V) V, r-H 00 CN Tt NO NO NO CS NO © NO ON 1 1 CN 1 CN 1 © © © © © ' ° © ' © d CN © — © © Tt CN CO 00 3c V, © VI OO r- vi cs Vl © CO ON 1 ' CN 1 © © CN © © © ° — © ' © © ' CN ro CO r- 00 NO NO 00 Tt Tt cs CN Tt CN NO NO NO •—( r- © NO ON 1 1 ON 1 CN 1 © © © © © c © —1 d CN Tt Tt V r- CO r-CS CS •—' V) oo r- CN r- r- Tt r-H 00 o Vl ON 1 1 CN 1 1 © © o © © © ' © © ' ~ © ' CN CS CN NO NO 1-- NO Tt Tt NO Vl r- r~ 00 X ro NO o CN CN 1 1 CN 1 ON 1 © © © © © ° d © d CN ro CO CN 1> NO NO O oo Vl 00 r- Tt r-H NO © Tt ON 1 1 CN 1 CN 1 © © © © © o © ' © ' d CN CS cs CN OO OO cs , , © © — Tt o oo NO 00 V o r—H NO o CO CN 1 1 CN 1 CN o © o © © © ' © ' © '—' d d CN g 0CJ co \— < co Cr Fc z U Su NO © ON Tt CO 00 NO ©' ro © ' CN CO © NO CO NO NO CO © ' Tt CO © ON VI CO NO NO ro © ' V) ON Tt NO Tt oo' Tt ©'VI ©' CN r~ CO 00 VI Tt ON Tt ON Tt © ' CO ON Tt V) Tt VI VI r-' Tt ©' Tt 00 Tt CS Vl Tt ©' CN CS NO CN VI Tt cs' VI r> Tt ©' Tt CO r-CN CN ro r~' Tt CN v> ©' © Vl ro © Tt cs Vl r> Tt ©' cs Tt CN CN NO ro ro Vl NO Tt ©' cs © CN VI OO CO ro VI NO Tt © ro NO Tt ON CO Tt CN V) NO Tt © CS V) 00 © Tt CS Vl r> Tt ©' Fo% ^? ox CO UH 55 C3 rJ 199 o ON r- Tt cs o fl H ND cs cs 00 rO © CS © ' ON Tt ON Tt 00 co CO Tt r-© rs m cs NO r~-' © ' © cs' © ' ON Tt ON ro ND © cs ON CS *-* cs NO cs m 00 © ' © cs © ' ON '~H Tt ON r- © co CS cs NO ON r-H cs CO cs Tt r-° © ' © cs © ' ON , ™ H Tt ON Tt r—( © Tt r-H >—1 TI- cs CO r-' © © CS' © ' ON r-H Tt ON r~ ON co r-H cs ON cs NO © © ' rs* © ' ON ~ Tt ON r- © m CO CS -H oo rs © t--' rO © rs © ON Tt ON co • 00 m oo cs rs ND ON ro 00 Tt X © ' 00 © ' r~ ro cs ON in 00 00 00 Tt in NO ON CO m NO' © NO © ' r-' ro rs ON vo 00 ON m m 00 Tt m cs o ON X) © rs © CO fS ro ON Tt ro in ON CS ON fl Tt m CS —' ON X © cs © ' 00 rs ro CN NO rr-J r-i m r- NO ND ro cs CN © ' X © rs © ' CN co ro CN m NO m CN Tt NO m ro Tt ro xi © ON © ' ON ro CS CN O CS in 00 ON Tt r- cs ro r~-' x" © Tt © CO rs CO CN O O o c o W) o "53 Fe 2 S rS CS u To Appendix D . Electron microprobe analyses of olivine 4) 41 I U '53 •w c 3 O IS 1-41 ' 1 T3 CJ 3 C a o U Q x •3 e cj I1 CJ E '3 W rt GO O H - fl fl xi oo- x xi x CO S3 fl fl 00 X X CO •a x i T3 T3 x i X> -a xi <n fl. oo' X •a xi x -a -a xi xi T3 xi -a x T3 T3 X) xi -a x § fl .x x O _ O O n t-H u c o Tt c o •a CJ cyi CO X c g cd "3 M H < r-H CS NO m r~ Tt in NO CO 00 . © CO © CO CO • © NO © © ©' © ' r-H ©' cs' ON NO © CO m cs 00 r—H m ON NO r—1 r- © © >-H © r—< co © © NO © © © ' o' © ' —' © ' CS m Tt NO 00 CS Tt r-H CS m © NO NO ON © © CO © CO CO © © NO © © © ' © ' © ' © ' cs' m © © cs 00 m CS in 00 NO NO 00 © © r^ © CO © © NO © © © ' © ' © ' rt © ' cs CO Tt NO Tt oo m © cs CO © m cs 00 © © CS © r-H CO © © NO © © © ' o' © ' —«' © ' cs' Tt ro m ro f-© cs Tt ro >n r~ © © ro © ro © © NO © © ©' ©' —«' © ro NO 00 ON r-ON CO NO NO NO NO , © CO © ro 1 © NO o © © ' © ' — © ' cs ro m CS NO NO NO cs r-H r-H ro r-H OO ' © cs © © © ' • © ' © ' cs NO 00 © 00 NO 00 l-H Tt oo r—l NO HH 00 00 ' © r-H © © © ' © © cs 00 CS 00 m CO rs r-H ON ON r-H Tt © in NO ' © ro © © © © © ' cs CO © r- r-Tt © m oo oo ON H Tt © m NO ' © CO © © © ' © ' © ' cs © cs cs cs -H oo ON T~H rH © cs NO © CO © © © ' © © ' cs _ m 00 CS NO m CO ON m —H cs © cs r- © cs © © © ' © ~ © ' CS NO 00 Tt ON ON CN r~ CO CO © r-H © NO © Tt © © © © ' © cs E 00 U £ 2 2 f c3 £ 3 C/3 © cs NO © CO © ' ON © ' 00 r-H 00 © cs r- ON CO © ' oo' © ' 00 —* © © © Tt CO ro © ' ON © ' 00 —~* ( 00 m r-H CO © ' ON © ' 00 NO m ON r~ ON cs © ' oo' © ' 00 00 CO ON cs Tt CS •—I 00 © ' 00 )__ Tt Tt CO CO ro .—1 00 © ' 00 ON m NO r- NO m ON CN © ' m CO © CO wo ON m NO cs © ' m Tt CO r~ oo 00 ro m' ro © ' NO ro ON ON ro NO 00 Tf m CO © ' NO CO Tt r> oo © m ro m' Tt © ' NO CO 00 NO NO oo NO Tf © ' OO © ' NO CO 00 NO NO NO CN ro 00 © ' © NO CO s? •s? 5? o CS cs UH PH rJ 2 0 0 Appendix D . Electron microprobe analyses of olivine I i<3i co: CN OO o W I ' l l X) CJ 3 _g C o U Q •3 c ° . I1 O. C E '« co a 00 co •a x> ON o WO wo T-H wo 1-H CN VO CN r-' © © CN © ' x i wo o CO o Tt vo vo CN CN CN CN VD X) X) vd i—i d d CO Tf d oo' Ov XI X) XJ XI X i X> XI X) X) x i XI X) x i x i X! XI x i x i X3 X! X> x i XI Xi XI XI x i x i TO -a x i x i XI XI x i x i XI x i XI x i CN 00 OV o wo CN oo vq CN CN CN Tt r-' d © CN Tt © Ov OV VO O wo 1-H CN 00 CO CN © CO r-' i-H d ©' CO Tt ©' OV Ov Tt CN 00 i-H © © CN © CN r-' d ©' co' Tt ©' Ov Ov VO CN x i 00 CN 00 00 CN Tf CN OV x i ©' Tt © OV Ov CN o CO CN CN © CN CN CN Tt r-' d ©' CO Tt ©' OV* Ov VD CN CN ro p CN ro VO r-' d ©' ro Tt ©' Ov Ov p oo o OO CN 00 U0 Tt CO r-vq CO CN d © r»" ro © 00 Ov VO Tt x i wo CN wo r- r-CN ro Ov CN CN x i ©' 00 ro ©' oo' Ov Tt x i © CO ro OO CN CO Ov 00 CO CN x i ©' r-' ro © oo' Ov i-H ro VD O CN CN © Tt CN W0 ro OO O © CN Tt © OV Ov WO WO 00 CN WO t— CN CN vo 00 o © CN Tt O Ov Ov © Tt Ov 00 CN CN CN ro ro r- © © ro Tt © OV OV c cj o Tt e o XI CJ .9812 1 1 .9812 • .3794 0021 0054 6402 0058 0329 © © © © © © CN .9821 I I .9821 • ,3584 0042 0051 6580 9900 0323 © © © © © © CN .9840 1 1 ,9840 i .3823 0018 0053 6324 0062 0280 © © © © © © CN .9807 1 I .9807 • .3654 .0031 .0045 ,6562 .0058 ,0350 © © © © © © CN .9851 1 .9851 i ,3698 .0034 .0039 ,6444 0058 0274 © © © © © © CN .9749 I .9749 • 4175 0062 6155 0078 0470 © © © © —• o CN ,9883 1 .9883 • .3682 0021 0050 6403 0061 0218 © © © © © —, © CN .9834 1 .9834 • .3768 ,0024 .0048 .6409 0058 0306 © © © © © © cs .9899 1 .9899 • .5115 .0016 .0064 .4853 .0095 0144 © © © © © © CN .9816 I .9816 .4956 .0055 .5243 0075 0329 © o © o —* © CN .9824 I .9824 i .5195 • .0067 ,4959 .0091 0312 © © © © —1 © CN .9880 .9880 i .3937 .0013 0048 6141 9900 0204 © © o © © —• © CN .9908 .9908 , .3739 .0037 .0059 6236 0061 0130 © © © © © — * © CN .9833 I .9833 .3654 .0029 .0042 .6512 . 0061 0298 © © © © © o CN co b Sum Cr + CJ P_ Ni Mn Mg Ca Sum 00 Ov ro r - as CN ©' oo oo' 1-H © VO Ov CN r~ CN CO 00 r^' d 00 CN OV © CO ©' 00 00 ©' Ov vq CN © 00 CN 00 00 ©' i-H Tt CO OV CN OO 00° ©' vO VO Tt 00 CO OV r~-© CN ©' CN Tt OO CN © CO 00 oo' ©' © CN VO oo CN oo 00 1-H ©' ro © Ov Tt 00 Tt Tt WO CN ©' 00 WO Tt CO wo Tt CN © Ov 00 VO vq WO Tt ro r- wo CN ©' ro Tt WO CO CO ©' oo Ov © ' Tt © VO vq o ro 00 oo' © ro VO VO © © CO OO oo' ©' Fo% N? CO P H CM - J 201 Appendix D. Electron microprobe analyses of olivine 03 • S3 © wo I X CO CN o O o f-H O e •a c o u , *> CO CN • CJ co •a CJ 3 C e 0 CJ Q •3 1 CJ C E °j3 w ,fe CO O T3 X>° X! X> X) xi X ) xi X J X ) X ) X> 00 CN xi ON 00 00 CN o NO Cs xi d d Tt d ON ON 00 00 o wo CN NO 00 CN O WO ON d d d Tf d ON ON ON o CO WO CN - CN NO O © CN d d Tf d d O xi T3 o CO T3 NO CN r-NO CN Tf ND xi xi CN xi d ON CO d ON ON X> xi -a xi CN X) 00 ON 00 O CN NO CN <—' - H xi d ON d ON CN CO ON wo CN 1 oo CO ""*•*! CN NO CO wo x> d as d ON CN CO ON ON W0 od ••=> CO X I X J TO xi xi ^ xi NO ~ 00 - ° CO xi ON ^ r~-' x. XJ xi X) xi xs xi XJ xi X I xi XI xi £ -a -q od •=> CO O Q co H O CO 00 CN W0 CN CN ro 00 CO r-' d d CN Tf d ON ON o 00 CO CN CN 00 Tf ro O ON od d d Tf d ON ON o o CN ON CN NO Tf CN Tf WO od d d CN Tf d ON ON CO ro Tf CO CN ro CN ro 00 ON CN d d ON ro d 00 ON O Tf f—< ro CN ON CN O Tf od d d Tf d ON ON oc 00 r- ON CN NO CN CN 00 © r-' d d CN Tf d ON ON Tf 00 - r- CN CN CN CN ON r- o o CN Tf o 00 ON Tf o Tf 00 r-00 wo CN ro r--d d d CN Tf d ON ON o O o O O a to £ z £ S CJ o Tf c o co [- < E OO a Tf CN wo 00 © < Tf CO WO wo CO © r- © Tf i © wo © © d © —' © ' CN ON Tf wo 00 OO ON CN WO wo wo 00 CN © © t- © Tf O o wo © © d d © —' © CN 00 NO Tf CN 00 OO CN CN WO oo wo Tf CO O © f» © CN Tf o © wo © © d d © © ' CN _ ON Tf , CO WO NO r- CO NO © CO © 1—1 Tf 1 © W0 © © d © © ' CN 00 © © CN © 00 NO Tf oo t -WO © Tf © Tf • © W0 © © d © © CN o Tf ON NO ON wo WO NO 00 WO NO © ro © • — • Tf i © wo © © d © *—' © CN Tf Tf ON wo 00 © CN CN WO wo 00 WO oo O © T--I © 1—1 ro o © NO © p d d © —* © cvi 00 SO wo ON CN © CN CN Tf r- ON O O © ON © TT © © wo © © d © © — © CN WO CN CN CN W0 r~ NO Tf Tf © ND 00 o © CO © ro ro © © NO © © d © ' © ' — © CN o © CN © CN 00 CO r- ON Tf NO © © ro © CN Tf © © wo © ' © d © © —' © CN NO Tf ro wo wo CN wo ^ H 00 CN CN © © © © CO © © NO © © d © ' © © CN Tf Tf CN CO CN ND WO CO Tf p- NO ND oo © O co © CO ro © © NO © © d © © -— © ' CN Tf r- Tf CN ro Tf CN co CN ND C N CO © o CN © ro © © NO © © d © d — © ' CN ro ON ON ND ON SO NO CN CO ND NO SO co © © ro © ro ro © © NO © © d © © © r-j + a 00 E Fc z s s cd CJ CO wo CN NO Tf ON CN 00 r~ CN © CO CO oo CO ON CN od CN © wo CN NO Tf ON CN od r» 1—1 CN © NO WO © co NO r» CO CN ©' 00 CN 00 Tf NO l> CN CN ©' Tf Tf ro CO Tf NO ro CN © © wo NO © Tf Tf ©' 00 CN © © wo Tf © NO Tf ON © CN © W0 © CN CO © 00 ON © CN ro ro CN WO Tf NO ro CN ©' NO 00 ro © Tf ON ON © © © © © ro © CO CN © CN WO — ro © 00 CN © ro ND ro © Tf ro d 00 ON © Fo% N? 03 U- 03 —1 202 Appendix D . Electron microprobe analyses of olivine > c U OJ E '55 oo O 73 X x> 73 T3 X 73 X •a x i •a x -a -a x i x i 73 73 X X> -a TS x xi 73 73 X X v> oo l-H Tt Tt CO o CS cs CN d © ' OS d v> cs CO cs *-H CS CO cs d d d d r—I 00 V) o CS -H CS d d d d r-co 73 CO cs m Tt CO o r-NO CS x i d v i CO d OS ON 73 T3 m cs 73 r-ro ON 00 cs Tt © x i X Tt cs X) d NO CO d ON ON 73 X r-H • CO oo *rH NO 73 CN CO rH o d x ' d d d d cs Tt o Tt oo CO 00 CS Tt o cs CS cs d d d d d ON CO NO ^ NO d 73 73 X X 00 cs 73 CS ON CO 00 Tt 00 Tt ON cs X> d cs CO d ON Os ON cs 73 o 73* 00 CO NO OS V) r-H m cs r-H CO OS r-~' d x i X CO x i d d 00 CO cs CO Os o CO 73 73 VI VI © Tt no r—l Vl CO 00 V) 00 NO d x i X OS x i d cs d 00 CO cs CO ON cs CS 73 *"0 o 73 NO NO CO Tt l-H © cs r> ro ON t-~' d x i X CO x i d r-' © ' od CO cs ro Os T? A. oo' -° CO 73 X OS -° CO 73 X VI CO 00 Vl vi NO © r^ cs © CS '—< r-H © © © d © CS Tt © CO NO © cs V) CS Tt 00 d cs © ' © ' © Tt d ON ON O Tt oo © oo CS CO NO Tt CS VI ON ©' CS d d © Tt © ON ON ^ O O o r - , O O o W H < C J S Z S r l U c <u o Tt C5 o 73 cs r-NO rs ON ro Tt CS r-- r-cs cs ON ro oo cs 00 © ON © © ' © ' W H < Tt NO NO Tt ON r-H Tt CS NO Tt 00 © © r-H © Tt © © VI © o © ' © ' © rt © ' cs CS 00 Tt CS r-© ro Tt VI NO ON V) © o Vl © l-H Tt © © Vl © © © ' © ' © © ' CS ON OS VI oo © r~ l-H Tt © cs Tt © © V, © r-H Tt © © v. o © © © ' © ' © cs' © _ NO Tt r~- r-H OS Vl 00 © l—H © r—l v i 1 © Tt © © © ' © ' rt © CS ON Tt •v^- © f -00 00 CS 00 CO © NO © V) 1 © Tt © © © ' © ' —1 © ' cs' ON © © o Tt V) Os no Tt Tt © Tt © © Tt © VI © © © d © rs NO Os CS VI Tt l-H Vl r-H NO ON Tt © © NO © r-H Tt © p no © © © ' © © ' © ' cs' OO ON OO 00 Tt Tt rH © ro NO r-H l—H rH © NO 1 © CO © © © ' © ' © ' cs CO Tt _ CO r-H © NO VI © CS cs . © NO r-H © V) ' © Tt © © ©' © — 1 © CS Vl © © CS 00 00 cs Tt CO Tt © CO o NO 1 © CO © p © ' © ' — " © ' cs Tt ,_, CO Vl OO NO r~ o CS © © 00 i-H i-H VI 1 © Tt o o © © ' —' © ' cs NO NO CS ON © Tt Tt cs NO r-H cs no o © Tt © i-H Tt © © VI © o © ' © ' © — 1 © cs ro ON v> oo r-00 —H no f- Vl 00 ro © © no o © Tt © © Vl © © © ' © © — © cs NO cs ro NO 00 cs r-H NO Tt NO o Tt o © NO © CS Tt © © Vl © © © © ' d 1-1 © ' cs E 3 |H oo O N C OJ) (2 z 2 2 © r- CO CO CO CO v i Tt © ' r - cs rs r- t CO co CO r-' cs' © ' r- cs cs CO VI CO CO CO t~-' cs' © ' r> cs NO NO 00 CS CS Tt © ON © ' r- CS 00 cs © r- oo Tt cs NO d cs cs cs VI v. cs cs r-' cs' © ' r- cs © OS NO © CO CS © ' CS Os cs © 00 Tt v i CO © ' NO CO _ cs Tt © VI co' NO' © cs NO © Tt no NO cs d ND CO Vl Tt r-H *—' CO Vl Tt v i © ' r~ cs NO OS Vl OS NO CO NO CS © r~ cs CS ON ON oo 00 CS r-' r-H © ' CS NO CO r- ON CO r—l d CS s? s? 6s-O ca ca UH tin r J 203 Appendix D . Electron microprobe analyses of olivine i<2 > 13 CJ a c c o O D x •3 (3 u . °-\ CJ "S, e E |3 OQ O T3 T3 •°' * -° CM C N _ j : r- vo cs r~ wo *-! o ro vo C N O O O O ' o 13 13 xi xi 13 •°' wo CN VO VO Tt 00 W0 Tt- o CO Ov CN O O wo O 13 xi -q 5? X) CN 00 C N wo r-~ C N ov d ro r- wo o C N - H C N C N C N 13 -° o o o o o CN Tt VO VO Tf Tf - H ro ro ro wo vo r- Tf ^  Tf o ro vo ro r--' d d Tf d CN ro _: r- vo vo r- Tf — . W O O C N W0 C N x> X) ^ C N O O OV O 13 13 13 xi xi xi 13 xi W0 Tf OV ro vo CN _; vo vo r~ N-i V ro o C N x> X) CN wo C N r- C N O O Ov O b o s CO P < ° w o o ? ° M o u £ 2 S £ o o co E- < 00 Ov ro _ © © wo WO CO • - H wo Tf Ov 00 O © © © © Ov Tf o o WO © o d d d © -1 © CN CN Tf VO CN CN wo i—< r~ •—H OV CN Ov vo o © CN © F—» Ov wo o © Tf © © d d d © © ' CN o CN WO VO © Tf 00 vO Ov O oo VO © CO © CN Ov Tf i © wo © © d d © ' - ' © CN ,_ CN Tf Tf Ov CN CN CN wo ro WO Ov VO © Ov Tf O © Tf © •——< Ov Tf O © wo © © d d d © rt © CN 00 00 vo VO oo 00 Ov Tf wo 00 VO oo Ov © © © Ov W0 1 © Tf © © d d © — 1 © CN Tf r- Tf WO r- 00 CN o Tf oo CN 00 VO Ov —< o © 00 © — H Ov VO o © ro © © d d d © rt © CN WO , , ro wo VO CN CN 00 • — i wo © VO CS Ov VO O © ro © i——< OV Tf o © wo © © d d d © ' © CN Ov Tf Tf CN 00 Tf W0 00 00 OV 00 © © © © Ov Tf 1 © wo © © d d © — ' © CN VO ro ro © CN CN © o ro — H vo t ~ VO Tf Ov vo © © ro © i — i Ov Tf © © wo © © d d d d © CN 3 >-' co O 2 I f u © wo wo Tf CN CO wo' Tf" © r- CN ro — vo ro ro co —i 00 © r~ cs O wol CN CO VO CO © r- CN Tf Tf wo CN CO | CN CN VO © OV VO Ov Ov VO CN CO VO CO CN wo o vo CN Tf Tf OV VO Tf od ©' ©' VO CO CN WO CO CO CO CO VO CO © t~- C N CO © ' N ? V* Nr ©^ QV O 0 3 03 [i, fc, J 204 Appendix E . Electron microprobe analyses of clinopyroxene u u > i i a a o c CJ u E '3 oo O o co ON NO CN o NO ON •d CN CN NO. ON CO ON © m © ON t> rt CN r t ©' © X ©' r-H ©' CN ©' oo' ON C O IT! O CO CN r-H •d CO •d © CO N O r-H © © P ~ Tt N O © C O rt CN CO x> x i © ' CN CN ©' ON ON CN CO ON ON NO CO T3 o ON •d ON ON i n r~ CO m CO CN r-° rt CN r t X> ©' x i ©' CN ©' CN © ' O N O N CO so CO m © C O •q ON m ON r-H r t Tt r t © Tt CO O N ON' r t CN x' C O x i © ' rt" r-H r-H CN © ' oo' ON CO ON C O m CO CN © ON m •d m N O © r t © CO Tt © C O Tt *-* CO ©' 00 x i o' Tt CN ©' oo' ON CN oo CN t> m -d CN CN CN 00 <n ON in O N © NO Tt m' X ON x i ©' Tt 00 © ' NO ON ON C O CO ON CN •a CO m NO o m CN NO NO r> NO CO NO rt ©' m x i ON ©' ©' m' r-i ©' NO ON S O ON m ON CN •d r- -q CO CN NO ON 00 m CN NO NO rt CN r t X X d r-H d CN ©' oo' ON r~ ON m r-CN •q NO NO o r-CN CO CO CO NO © m' rt CO rt x i CN ©' d d CN © ON ON CO CN ON © •q CO •d 00 ON 00 00 m © NO in r t rt m' X 1 ' x i d d ©' CN ©' 00 ON NO rt m r~ ON •q ON m •d oo r> 00 © r~-m P~ Oi rt r t x i C O x i d rt ON d od ON O m CN CN C O •d CN •d NO O O ON ON Tt m ON rt r t x i C O x i d r t 00 © od ON CN r-CN CN C O NO m d m OO P- 00 m oo CO ON rt m x i C O x i o rt ON © ON ON CO m CN rt © -d CN m -q m CN - o ON m m © ON rt m x i od x i o m oo © ON ON NO O © rt •q r-CN -6 m NO ON r~ CO ON rt ' 1 in X C O x i d rt ON d 00 ON CO CO m © ON CN •q oo q' 00 CN 00 CO © m >n rt rt ON rt in X od xi d r t ON d od ON n o bo d H m o < m q O O CJ UH O Z O a O 00 o ca O q ca z "ca o H s CJ 1+ SO c o T3 CJ <J: ca x io c o U .8149 .1851 .0080 .0775 ,0022 ,3517 ,0071 ,6839 8605 0371 0280 © © © © © © © © © Tt 1098 ,1399 .0008 .0663 ,3563 1 9600 6938 8615 ,0350 0233 © © © © © © © © Tt .8075 .1925 .0039 .0858 • ,3481 ( ,0063 ,6940 ,8491 0389 0261 © © © © © © © © Tt .8819 .1181 .0064 .0436 i ,2715 1 ,0062 ,8133 ,8556 ,0296 0261 © © © o © © © © Tt .8661 .1339 .0113 .0454 ,0022 ,2741 1 ,0050 7995 8599 0319 0295 © © © o © © © © © r t .7988 ,2012 ,0542 ,0375 ( ,2982 1 ,0072 8591 7558 0447 0568 © © © © o © o © Tt .8181 ,1819 ,0520 ,0272 i ,3091 ,0020 0081 8760 ,7375 0456 0575 © © © © © © © © © r t .8152 1848 ,0028 ,0858 • 3804 0076 6428 8648 0384 0226 © © © © © © © © r t .7846 ,1954 0000 ,1096 i 4093 0020 0089 5978 8787 0457 0318 © © © © o © © © © r t 7547 2290 0000 1222 3807 i 0059 6301 8649 0426 0300 © © © © © © © © r t .8572 ,1428 ,0771 ,0325 ,2699 i 0053 8271 7678 0412 0209 © o © © © © © © r t .8597 .1403 .0730 .0316 i ,2740 ,0053 ,8321 7642 0393 0195 © © © © © © © © Tt .8533 ,1467 .0808 .0341 i ,2667 ,0049 ,8229 .7656 ,0419 0169 © © © © © © o © r t .8531 ,1469 ,0756 .0314 i ,2665 i ,0078 ,8427 ,7578 0401 0218 — © © © © © © © o Tt 8507 ,1493 ,0788 .0283 i ,2604 i 0049 ,8394 .7732 ,0374 ,0225 — 1 © © © © © © © © Tt .8541 ,1459 .0885 ,0297 i ,2572 i ,0058 ,8306 ,7663 ,0403 ,0183 © © © © © © © © Tt bo > < < H Cr + "cj U H c z S eo s Ca Na Sum 00 CJ > oo _c cs o CJ > a E •a c 3 O rH OD I! a o o c CJ "5. T 3 CJ > CH G O c? o O c CJ X CH 00 •£ E 1 205 Appendix E . Electron microprobe analyses of clinopyroxene co co \d eu l i u .a °CJ lo CO c C/3 c 1) U SO CN i oo ON O 3S oo CN 5 CN 0 1 CN 5 'T CN 5 i CN 5 as 00 £ '« OO O 40.67 6.05 6.75 b.d. 15.73 b.d. 0.23 7.43 20.44 0.75 98.06 wo NO Tt Tt ON NO •q wo wo NO ON NO 00 wo ©' vo' r-' X> CO x i d oo' d CN d r-' ON © ON CO o NO •q WO CN 00 o NO WO NO WO 00 Tf vo' r-' X> Tt x i d 00 d CN d r-' ON Tt Tt ON o © r- •q CN CN r~ 00 NO O CO NO Tt 00 Tf vo r-' X> CN x i d oo' CN d NO ON ON NO wo ON Tt T3 r-CN *q NO CN ON ro CN CN Tt O 00 Tf CN CN X) - x i d CN d CN d ON CN co wo wo r-- •q Tt NO •q CN CO WO 00 CN Tt Tt Tt d WO CN x> ON x i d CO CN d ON ON ON CN ON NO p •q" 00 o •q 00 CN t -H 00 Tt 00 Tt 00 ro 00 vo Tt CO wo x> CN t-H x i d ^ H ON d oo' ON o r- CN 00 o p •q t-H •q CO CN wo r~ Tt Tt Tt o 00 ON Tt ro x> d x i d CN d CN d 00 ON wo ro WO Tt OO NO •q o CN •q ON CN WO NO ro r-ON ON Tf 1—H CN x> ON x i d Tt d CN d ON 'r-WO WO CN •q 00 •u CNl CN o NO o ro wo CN CN Tt CN Tt x i d x i d CN d CN d 00 ON WO 00 ON p o WO •q o p •q <N Tt O WO Tt WO CO O wo Tf-CO Tt Xi x i d CN d CN d 00 ON ON NO Tt CN 00 Tt •q WO oo •q WO O NO CN OO Tt wo NO ro CO Tt Tt wo x i x i d d d CN d C-' ON ,ON Tt O NO •q o •q 00 ON 00 W0 ro wo z WO Tt CO Tt X>' X)' o CN o CN o 00 ON o o CN CO o l> •q o NO *q NO CN 00 00 00 wo NO Tt Is-' Tt CN ro x i ^ H x i d CN d CN d 00 ON ! ON Tt Tt wo ro NO •q CN 00 o wo (N wo Tt ro ro WO ON ON NO Ti-CN Tt x i d d d CN d CN d r~' ON ro Tt O ON NO •q CN •q NO CN CN Tt Tt CO WO ro Tt CN ro x i x i d — d CN d od ON o O0 o p o fN < o fN \-> U o UH o O c s O 00 s o C 3 u O CN ro z "ro o H .6326 .3191 0000 .1828 1 .5282 .0079 .4446 .8792 0588 0531 45.70 o © © © © © © © Tt 45.70 .6248 .3365 0000' .1725 1 .4576 1 .0052 .5109 .8976 .0522 ,0573 52.75 o © © © © © © © Tt 52.75 .6397 .3348 0000' .1620 1 .4887 1 .0083 ,4814 8895 0502 0544 49.62 —1 o © © © © © © © Tt 49.62 .6477 .3345 0000' .1547 1 .4253 1 .0074 5297 9036 0492 0523 55.47 © © © © © © © © Tt 55.47 .8855 .1138 0000' .0627 1 .3649 , .0085 ,7036 .8394 0314 0097 65.85 © © © © © © © © Tt 65.85 .9046 .0954 .0015 .0442 .3050 1 9900 .7635 .8631 0326 0165 71.46 © © © © © © © © Tt 71.46 .7529 .2284 0000' .1073 1 .3910 1 .0093 ,6812 8227 0627 0556 63.53 © © © © © © © © Tt 63.53 .8900 .1100 .0247 .0520 1 .3216 1 .0075 .7230 8449 0328 0065 69.21 © © © © © © © © Tt 69.21 .8855 .1145 .0063 .0417 1 .2939 1 .0063 ,8094 .8396 0270 0241 73.36 © © © © © © © © Tt 73.36 .8140 .1860 .0070 .0744 1 .3472 1 .0072 .7292 8278 0393 0320 67.75 © o © © © © © © Tt 67.75 .7809 .2059 .0000 .0901 I .3573 1 .0089 ,6972 .8636 .0406 0445 66.11 © © © © © © © © Tt 66.11 .7234 .2548 .0000 .1257 I .3909 1 .0052 .6232 8800 0412 0443 61.45 © © © © © o © © Tt 61.45 .7820 .2106 0000' .0885 I .3570 1 .0059 .7043 8547 0395 0425 66.36 © © © © © © © © Tt 66.36 .8160 .1686 0000' .0674 I .3750 1 .0085 .7422 .8353 0384 0513 66.44 © © © © © © o © Tt 66.44 ;7984 .2016 .0094 .0738 1 .3467 .0024 ;0080 7182 8426 0384 0396 67.44 « © © © o © © © © o Tt 67.44 .8308 .1692 .0019 .0843 I .3638 i .0084 .6747 .8454 .0393 0178 64.97 o © © © © © © © Tt 64.97 OO > < < P Cr + CJ fc Z Mn 60 s Ca Na Sum 60 2 206 Appendix E . Electron microprobe analyses of clinopyroxene '•a > T3 1) g •a C o O PL]' •3 c f c o u U 00 O 00 o CN O i M > o 1) "5. c £ '3 « .t co O co ON '—' Tf wo ON r~ CN Tt 00 l> Tt CN —i r- o f~ o o CN NO — d —< CN WO ON r~ Tt Tt Tt O d -H rs WO o ON ON CO ON •q T? -q X) £> co uo ^ ON O NO © NO' v i Tt CO O ON —< ON o NO o o c o H < O O u o o £ z ro o o CN Tt Tt CO wo © ' ro d CN d 00 ON wo CN Tt CN CO 00 00 WO Tt o d CN d CN d ON ON 00 NO Tt Tt o Tt WO d CO CN d ON ON ON 00 Tt WO CN ON Tt r~ 00 d CO CN d oo'' ON o CO CO Tt NO Tt o 00 wo r-d r-° d CN d r--ON NO CN CN NO ON o WO CN d d CN d oo' ON MnO o O re O re Z 2 o c I ND e o T3 re .o e o :8898 .1033 0000' .0505 .3430 .0101 .7428 .8508 .0331 .0233 68.41 o o o o o o o o Tt 68.41 .8280 .1720 .0084 .0781 • .3384 .0079 .6972 .8530 ,0429 .0259 67.32 © o o o o © o o Tt 67.32 .9029 .0936 0000' .0456 • .2973 ,0058 ,7766 .8693 ,0297 0208 72.32 o o o o o o © o Tt .9147 .0853 .0059 .0419 • .2999 ,0062 ,7622 .8636 .0357 0153 71.76 o o o o o o o o Tt .6533 .2672 0000 1839 • .5468 ,0102 ,4474 ,8854 ,0623 .0564 45.00 i-H o © o © o o © o Tt .6807 .2830 0000' .1539 .5395 .0088 .4310 .9001 .0545 .0514 44.41 o o o o o o o o Tt 44.41 CO > <! < p Cr + <N CJ _ e. Z £ 60 £ Ca Na Sum Mg# 207 Appendix F. Electron microprobe analyses of oxides u •4-* i J c cj "S. C 6 '53 rt rt T3 pO CN CN o r- © © vo 00 VO rt 00 © oo VO CO vq rt WO OV CO WO CN ©' r-' ©' wo ©' ©' ©' CN ©' ©' Ov OV b.d. CN rt 00 VD r> wo Tt OV Ov CO CO •d CO VO CN vq © Os © WO rt b.d. wo" CN ©' r-' ©' wo © X ©' CN ©' ©' Ov OV b.d. CN CN p- oo CN Ov CO 00 00 Tt 00 © CN SO vq CN CN VO © Os SO b.d. wo' CN ©' r-.' ©' V O ©' ©' ©' CN ©' ©' OS OS b.d. p CO r-VO CN CN 00 © vo 00 CO VO © CO VO r-vo © VD © 00 CO b.d. wo CN ©' r> ©' wo ©' ©' ©' CN ©' ©' OS Os •d NO o Tt 00 © VO t-© VO CO •d CO VO Tt CN •d VD t> X wo CN ,—1 ©' r»" wo ©' x' ©' CN xi ©' od Os f- CN Tt •d r~ r- VO CO T3 rt VO CO Tt CO t -H wo © wo' CN *~* xi r-' ©' wo ©' X © CN ©' ©' od Os b.d. CN V O Tt oo © rt 00 00 © rt •d oo vq rt CO rt © Os CO b.d. WO CN ©' r-' wo ©' xi ©' CN ©' ©' Ov OV b.d. p Ov CO © vO rt 00 .00 CN rt •d © VD CO l/O CN o 00 W 0 b.d. wo CN © r-' ©' wo ©' X © CN ©' © od Os •d r-wo 00 VD CO © r -H CO O wo T3 CO VO VO wo © CO © CN wo X> ON CN ©' ©' CO rt rt CN ©' X ©' ©' ©' © o VO VD o Ov CN CN Ov © 00 wo •d VO VO CO Tt r- vo © © CN 43 00 CN © © rt rt CO CN ©' xi © © ©' © •d oo Ov r-Ov 00 © CN Ov oo VD 00 rt Os CO VD © rO CN CN ©' ©' CN 00 rt © xi © CN ©' ©' Ov Os Ov 00 © © VO •d vO VD wo T3 CN VD 00 r~ •d r-co Os CN wo Tt d X CO CN rt © xi ©' ©' X © vri OS •d o VD Ov CO r^ rt Os VO •d 00 wo CN CN VD Os 00 X CO CN ©' Ov Os rt ©' X © CN © © OS r-00 r-© © rt Ov rt oo w-i T3 © VD rt OS © rt r-CN rD CO CN © Ov © wo ©' xi © ^ © © oo Os •d CN © vo Ov Ov 0 0 Os © in •d WO CN OV o CN Tt X CO CN © © CN Os rt © xi ©' CN © ©' Os OS •d r-r- Ov Ov © CN © VD. Ov SO r-r-- OV © CO wo 0 0 0 0 d rt SO VO X> CN CN © © CN 0 0 rt ©' © ©' CN X ©' od Ov rs o G O d H o < d l-H o m o CM CJ UH O CJ tL, O > O z o c s O 0 0 2 O c N o ca O o H a o Tt JS l T^  fl *cj 1 •4> ca c^j + U H % T3 U H c -i> W " C J PH T 3 C ca c cj 0 0 o c o T3 CJ 3 U ca o c o CJ a T3 C ca H • c 0 0 ca wo wo vo 00 wo C O C N © wo r-00 W O © r t © C N OS © OS SO 00 Tt © C O © Tt © C O r-Os wo' ©' ©' C O C N ©' ©' ©' ^ ©' © co' C N 1 C O Os wo OS r-OS C O © C N Tt 00 r~ r-Tt Tt © VO wo C O rt wo © 00 C N © VO r-OV wo' ©' ©' co' C N ©' ©' ©' ©' co' C N 1 Tt C O W O Os © SO wo VO © 00 00 © Tt C O C O Ov © 00 r~ W O p-rt © OS © © OO Os wo © ©' C O C N © © ©' rt ©' © co' C N © C N W 0 r-Ov W O © VO © wo C N Ov © OS C O Tt r t o VO wo W O SO C N C N © o\ © C N 00 OS W 0 © ' ©' co' C N © ©' ©' ' ©' ©' C O C N 1 00 Os W O 00 00 r t Os © C N C N OS VO C O vo 00 wo 00 00 OV W O © r-H r-OS wo' ©' ©' co' C N © © ©' © co' C N C O C O so 00 Ov rt 1 wo Tt 00 © C N vq C N VO W O C N © C O © rt © VO VO Os W 0 © ' ro' C N ©' ©' 1—H ©' ©' co' C N 1 wo C N © W O Os © VO Tt Ov Os r-m 00 OS SO in C N © © C O © C N C N © r—H 00 OS wo © © ' C O C N © © ' © ' ©' C O C N W 0 oo W 0 W O 00 Tt C O C N © C O Os 00 Tt © VD C O C N r -H wo © C N © •n wo © C N C O © r-Os wo © © ' C O C N © ' © ' © ' © C O C N C N © rt © r t © o C N C O vq Tt C N © r t C N o r-C N © rt © © C N © © © © © © ' © ' © ' © ' © ' © ' © ' rt 1 © oo © C O wo © wo © © C O Ov vq ro OV Ov VD C N © 00 C N © © VO © © C O © © OS Ov Os © ' © ' © ' ©' © ' © ' © ' ©' C O r t VO © © 00 VO C N Tt o ro VD W O r~-00 Ov © Ov r-C N 00 C N © W O C O © OS wo OS wo © ' © ' Tt ~* © ' © ' © ©' co' C N Os Tt Ov rt VO C O © C N C N Os 00 wo © C N © © vo © © C N © 00 Os OS © © © ' -1 © ' © ' © ' © ' C O © C O © Os r t VO C N © © © C O 00 00 Tt C N 1 r> rt W 0 rt Ov VO Tt o W O © C N r-OS wo © © rt C N © © ' © © ' © ' C O C N VD C O C O VO C N o Ov wo ro vq Tt W O r -H C N W O rt VO 00 wo © wo rt © Tt VO Ov W 0 © ' © rt C N © © ' © ' © ' © ' C O C N oo wo p wo so rt rt © OS VO W 0 W O Os Os C O oo VO C N C N C N wo © 00 C O © wo r-Os wo © © ' rt © ' © © ' © co' C N co © © Os VD t-rt © Os W O wo t— r-Os Ov 00 C N © C N C O C O VO C N r t rt © ds W 0 OS wo © ' © rt - © ' © ' © ' © ' C O C N iy5 p < VH o + C J U . rt O U H > z c 2 0 0 2 c N ca £ G O 208 Appendix F. Electron microprobe analyses of oxides c CS o u CU CJ "a, c B 'js oo O x i x i co r - wo CO wo co wo O r -T t x i Tt SO co' V) 00 r--' cs OS ro d x i © Ov T t SO r -wo CO CS so OS SO r -T t x i Tt wo OS co' co' CS cs W0 Tt d X i © ' wo © ro l - H OS wo o cs SO WO so Tt © CO W0 CN cs co" 00 c~-' Tt d © ' © ' T t T t wo wo •> p OS CO r » wo CO x i wo wo - r - ' co' Tt cs ro d x i © ' r -r -W0 00 SO CO r -sO o Tf x j wo co wo oo' SO cs Os' CO d x i © Os 00 i—« OS OS r -cs r -sO 00 x i cs wo 00 CN' d SO cs SO Tf d x i © o wo o cs cs SO OS wo W0 © W0 W0 © ' CS cs d wo CS 00 Tt d © ' © ' Tt cs ro Os Tt cs CO Os cs 00 wo x i W0 © ' cs d Tt CS od Tt d x i © ' Tt cs SO wo cs cs OS Tt OS t-H CO Tt x> SO wo wo Tt "—' d Tt d Tt d x i © ' cs Tt SO OS so CS CS ro 00 Os Os Tt x i oo wo SO Tt © ' d Tt d Tt d x i © ' r ~ SO ro Tt CO ro WO Os cs ro CO so x i r-WO r - ' CN d Os cs SO Tt d x i © ' f -o cs CO cs SO Tt CO Tt Tt x i wo r - ' cs d ro wo' Tt d x i © ' SO OS cs cs CS O 00 CO Tt o SO x i 00 Tt SO cs d d ro wo Tt d x i © ' © cs © ' © cs —i —i 00 — cs © CS d © © os ~ - H -I xi 0-© ro Tt — i —<" © ' SO 00 r o —i ^ H ' © s^  Tl wo ^ - i r o _ j © wo r o wo ro Os ro <—' •—' — ' © ' © t-H SO CS cs © cs Os 00 wo SO so Tt Tt 00 Tt cs CO SO ro Tt x» SO © Xi cs Tt © © cs 00 © x i © ' —< x i © ' XJ __ Tt CO oo Tt © Tt W0 cs OS W0 t-H 00 so XI sO Tf XI r-H x i T t CS © ' SO d W0 d X) © ' CS x i © XI xi T f cs CO WO OS © Os Tf W0 Tf x i . Tf SO Tf ro t -© —I © ' r-~' © ' © x i © ' cs © © ' d d ° . S ° o o o 9 ^ o o © r-' Os C _o cs o Tf CS _» cs Xt CJ CS r-i ™ CJ U H X! C3 CJ + CJ U H XI c C CJ 60 5? o cs CO e o X) CJ c o CS "3 CJ -73 o c" o CJ a X) c CS CJ a 60 CS r o 00 Os c s CS 00 CS SO 00 © W0 OS SO CO T f CS c s wo 00 SO wo r o Tf © f -co © © 00 OS cs' •—' •—1 wo OS ©' ©' " — 1 ©' ©' r o c s SO cs 00 00 c s © r -o t-~ Tf OS © t—< r-c s t - H 1 CO CO CS c s CS Tf CS © wo sO © Tf T f OS Tf r-H ©' Tf ©' ©' " ~ l ©' © co' CS 1 00 © OS CS Os © c s r-co Tf W0 © CO r~ OS CS © CO CO r-H wo CN 00 c s © Os © © SO 00 Tf —* ©' Tf ©' © O ©' © co' CS © SO Tf T t T t wo wo WO OS T f c s SO © SO Os © r o r o CS CO Tf c s Tf © CO T f © 00 SO OS cs' cs' c s wo" OS ©' © ©' ©' co' c s 1 CS CS © SO Os r-00 00 00 00 r -c s 00 so © 1 SO CS © CO Tf cs © © wo © wo Os co' t - H •*"' WO Os' ©' ©' ^ ©' © CO c s 1 OS CO cs c s Tf T t r o c s © © OS Tf SO OS CO WO T f 00 1 c s CO © t-~ so Os Tf © ©' wo ©' ©' © ©' CO c s 1 CO SO wo © wo o Tf © SO OS c s © Os Tf © 00 CO 00 SO 00 c s © SO © wo SO Os Tf ©' ©' wo CN t - H ©' © ©' ©' ©' ©' CO c s 1 wo wo o 00 SO r -WO © © SO ( - H CO © CS WO T t T f SO © SO © Tf © © 00 Tf Os Tf ©' ©' CS © ©' ©' ©' ©' ro' c s Tf Os © CS CO Tf OS © OS © © c s r -Tf c s © Tf CS © 00 1 © c s © Os OS Os ©' ©' ©' © - 1 ©' ©' ©' ©' co' i Os SO r ~ WO © © t - H © wo SO r-CO SO cs © WO c s © SO 1 so © © © © ©' © © ©' © ©' ©' Tt i 00 cs Os r -Tf 00 iS © r o so SO © wo Tf 00 W0 t - H CO Tf wo Os WO 00 cs © © SO © Os Tf Os r o ©' ©' SO ©' ©' ©' ©' © co' CS i r ~ cs 00 wo i - H 00 Tf SO © 00 wo © c s CO SO OS CS 00 r o WO CO © © © l> wo OS ro ©' ©' o " ©' ©' ©' ©' © co' c s i 00 CS oo wo 00 Tt SO © 00 wo Os wo © Tf wo wo c s c s Tf SO WO 1 Tf SO © wo Tt Os r o © ©' SO *—' ©' ©' ©' © r o c s i CS © SO © wo © Tf 00 Tt cs r o so wo cs © 00 c s © OS © 1 wo © o © © ©' ©' ©' ©' ©' ©' ©' Tf © W0 © Tf WO CO © 00 r -r-_ SO t - H SO Os wo SO SO 00 © 1 00 r o © Os r -OS W0 ©' ©' CO CS ©' ©' ©' CO c s © OS wo SO r o wo CS © CO 00 SO W0 © CO so I-H wo Os © OS CS © cs cs © SO OS o © ©' CO CS ©' © ©' ©' CO c s OO p < VH CJ + m CJ U H + CN CJ U H >' 2 S 00 c N CS U e 3 00 209 Appendix F. Electron microprobe analyses of oxides —1 T3 CJ o u UH' X •3 c 1 1 . c & CS o u CJ ISO in GO r t GO CJ 6 "53 oo O cs VO 00 r t V 0 VO r-»-H r t r> CN •d CO r-CO p- © r-H CO 00 WO cs ~ d vd m d X! © ' CN ©' ©' 00 Ov vo VO VO wo m 00 CN CN m rt •d m VO F-H CN vo CN ov Ov 00° cs d Ov rt m d x i © CN ©' ©' r-' OV r t OV H—< VO r t i—c P~ cs in o CO •d m p~ CN 00 © Ov © VO CO wo cs *™H d vo' f-H CN m d X ©' CN © ' © Ov Ov r» OV Ov VO VO Ov vq rt vq 00 CN © p- © CN CO m VD wo' cs r-H d m' <n d x i © CN © ©' od Ov Z2 r t r t •d -d in vq CN rt VO CN •d VO VO CO vq ro OV © Ov CO ©' cs in cs vd rt d x i ©' ©' © VD Ov m p~ Ov m 00 o cs r t p~ CN rt CO T3 p~ rt Ov •d 00 © 00 d cs d in cs r-' rt d x i © X ©' od Ov CO wo cs r t CO r-00 CN m CO T 3 OV VD © CO - r t <n r-m' cs d VO vn d X ©' CN ©' ©' od ^v VO r—< m cs r t r-H cs r t o © CO CN •d 00 VD CO ro •d CO rt CO ©' CO d r-' wo m d X ©' CN x' ©' P-' Ov vO vo Ov 00 cs Ov r~ VO VO rt •d Ov P- © CN © CN m © r t © r t CS d d 00 d m d x i © CN © ' ©' Ov Ov CS cs CO ©v VD 00 CO p~ oo rt -d VO p-CN CN - rt © P~ rt r t cs d d OV d m ©._ x i d CN © © od Ov cs p~ 00 CO Ov p-00 vq vo rt p-CN VD o OV rt CO CN ro CO © m m' r t od CS CN d CO d d © ' m' ©' ©' od ov >n cs r-in CO cs m CN rt VO rt OV © Ov rt r t OV •d CO CO p~ cs' cs VO od od vd rt d © © ' ro X ©' vd Ov Ov p~ 00 m rt rt VD rt 00 VO rt d rt m rt rt m © © 00 m r t VO CS Ov d rt d X d ro © d 00 Ov Ov 00 CS r> m 00 O VO rt CN vo rt T 3 in rt p- Ov © Ov © VD d Ov r-' r-' p-CO d x i © ' ro © ' ©' 00 Ov r- Ov CS cs CO -d p~ V0 <N rt d p~ m CO Ov m © rt VO m r-' cs m od x i d <n d x i d CN © © in OV o H co q < m q u co q CJ UH O CJ UH d > O Z O c s o s o e N o ca U 2 O H s ca o r t CN •a CJ -a + m CJ CN CJ UH T3 c ca r ) ™ CJ UH C CJ 60 O CN C o -a CJ C/l ca x c o CJ c T3 c ca cj C 00 ca s .698 vo m CO © Ov CN p-WO p~ r t Ov © CO 00 OV CO OV p-ro © CN CO © © 00 Ov •n ©' ©' CO CN © ©' ©' ©' © CO CN . jVo VO r t WO wo CO © Ov OO wo r t CO CO VO 00 p-OV wo CO © oo CO © P-OV VO © ' © ' CN CO © ' © ©' © ' d co' CN 00 WO WO CO CO © 00 OV in in OV r-© p-00 OV CN OV p~ © 00 CN © © 00 OV m ©' ©' co' CN ©' ©' ©' ©' © co' CN . / /4 Ov 00 wo p-ro © Ov rt 00 vo p-VO Ov © wo r- © p-Ov 00 CN © 00 r t © VO p-OV m o' ©' CO CN ©' ©' ©' ©' © CO CN .oil Ov W0 Ov Ov 00 VO oq Ov © CN r t P~ Ov CN © OV CN © CN VD OV r t ©' in ©' © © ©' ©' CO CN .DOO VO wo Ov i-H © CO CN p-VD CN 00 wo © © 00 in vo 00 i VO CN © CO r-OV rt ©' ©' wo d © © ©' CO CN .0/0 wo Ov r t © ro © r t wo p-© vo VO OV © ro P- r t © r t CN © r t r t © OV P-OV m ©' ©' ro CN ©' ©' ©' ©' co' CN © r t r t ro ro © VO vo vo VO CN P~ OV © CN P~ VO CO © i CN r t © r t P-OV vo ©' © '-"1 CO ©' ©' ©' CO CN ov 00 CO rN r t © P~ CN 00 r t •n CO 00 OV r—C P-Ov r t r t © vO © VO p~ Ov m ©' ©' rt CN © © ©' ©' ©' CO CN .4/i f VO CN CO OO ro © rt rt CO in Ov rt VO CO CN Ov VO oo Ov r t CN © CO © oo p-Ov m ©' © r t CN © ©' ©' ©' © CO CN Ov P~ i' r t r t vq © P-P~ VO © OO Ov CN p~ © CO © rt r> ro P-VO © OV CN © CO oo Ov r t r t rt VD ©' ©' ©' CN ©' ©' CO CN .840 © r t CN CN OO 00 rt P~ P^  Ov CN CN VO CN CN © © CN Ov Ov VO © r t © p~ OV rt CN ~™ - © ©' ©' ©' ro CN © Ov i r t CN CN ro wo p-00 CO CN P~ OV P~ OV CO P~ rt o CO O wo VO Ov CO CN CN rt Ov © ©' ~" ©' ©' CO CN .318 CO r t CN wo OV Ov 00 rt P~ VD 00 r t oo © Ov in OV © P-CN © Ov r-©v CN CO CO co oo © ©' © ©' co' CN .012 W0 CO 00 VO CO Ov © p^  r t r t CN CN r t WO 00 CN © r t rt © Ov wo 00 VO CN ©' d © ©' CO CN oo E-i < WH o + m CJ UH + CN CJ UH _ c > i z s 00 2 c N ca U Sum 210 Appendix G . Electron microprobe analyses of plagioclase NO oo V vo 00 V vO 00 oo OH u. 00 PH Ul 00 OH tH 00 OH ' T 00 > OH a CO 1 s E l • CM 00 OH i W 00 OH 00 OH _ ^ 00 OH , M 00 OH 00 0-O oo OH V oo OH <u •+—» c o, S ain CJ 03 VH CJ OO a Ov 00 CN r-CN OV UO o oo' uo' o' d UO CN Tf o Ov Tt Ov uo XI 00 uo' d xi UO CN CO VO OV CN Tt o r-' vd o' d uo CN t-- 00 VO UO 00 OV Tt vd © d UO CN r- vO VO CO OV t> uo l-H CN oo" d d UO CN CO uo CN VO VO H^ CN Ov d d uo CN CN OV CN CN —H VO VD l-H CN Ov d d UO CN —i C N uo r-~ Tt CO Tt CO o o r-VO CN •a xi xi xi 2 -a d - ° X) X! X) xi TO T3 Xi Xi T3 T3 Xi X>' Tt 00 00 CN Tt Tt Tt CO T3 TO XI X) X)' Xi Xi Xi UO H^ uo CN CN Tt uo' d Tt CO T3 xi TO T3 X) X> TO xi TO xi TO T3 T3 XJ X) Xi T3 T3 Xi Xi CO H^ Tt OV 00 CN Tt co' d Tt CO 00 00 i-H xi Tt Tt xi Tt CO XJ TO TJ xi xi xi XJ XI XI Xi Xi Xi XI XI XI XI xi xi xi xi xs xi XI XI XI Xi Xi X)' £ xi xi xi xi Tt uo' - ° X. X> Tt CO © Tt Ov CO OV VO uo CO od vd d d o o CO CN Tt Tt Ov Tt 00 vd d d © o Tt Tt CN CO 00 vd d d o CO CN r-CO uo Ov 00 —-j Tt d oo' Ov CO NO 00 o VO CN OV CO CN Tt d Ov Ov Ov u-i r~ CN •> CN VO CN CN Tt d d o VO © o Tt CN VD Ov CO Tt d Ov Ov Tt CO OV XI 00 od d xi od Ov VO o xi Ov oo 0 0 VO 0 0 d xi Ov Cv C O uo C N Ov t> XI Ov od d X)' r-' Ov C O 0 0 C N 0 0 C O od" * d od Ov u-i U 0 0 0 U 0 od d x> od —' Ov 0 0 uo p r-Ov d X> 0 0 * -— Ov 0 0 U O © 0 0 r- "O U O 0 0 d X) Cv —— Cv C N o o 0 0 ' o I - H Ov d xi Cv —- Cv Ov C N VO XI vq Ov* d xi Ov CV Q S oo < ca UH CQ oo CJ o CN 03 Z I 00 e o X) C J on ca x> CJ c/i 03 03 CX| O Tt vo vo r- Cv r- Tt o VO — i o vo CO o o CN —•' d d VO 00 00 »-H CO Ov H^ VO -H VO CO © CN —i d o o ro O 00 r— uo ro ro OV OO - H o uo ro O O CN —•' d d Tt O VO Ov C V Tt Tt Tt r- vo Tt O CO — o © CN - H o o oo vo vO vo — 1 Tf Tf U 0 co oo •—c 00 CN O o o CN - H © © Tf ro uo ro 00 oo ro uo 00 Tf UO 00 CN O o o CN - H © © CO 00 CN CN t~~ OV CO uo CN —<* Ov r-—H Tf Ov 00 O 00 CN* —•' CO O i — i 00 CN O o o d d C N o O Tf Tf OO VO C N o P Cv o C N — d - H VO VD — H Cv © 0 0 C N — Cv vo C N C N Ov OO . © oo • C N — ' U 0 Tf VO Ov o VO o — 0 0 o C N — 1 d Tf 0 0 o o Cv 0 0 O 0 0 1 C N — O ro VD u-i VO C N O Cv C N — NO 0 0 Tf u-i C N O CV • C N — r-ro C N uo C O p Cv 1 C N I I I uo Tf Tf Ov CN Tf OV Tf © UO CO Ov Tf UO © ON d d d Tf CN CN ro NO r- VO CN CN Ov uo Tf ON CO uo o ON d d d Tf' CO Tt o UO CO t> i-H ^ H o uo Tf © Tf uo © © d d © ' uo' Tf <-- Tf UO 00 © uo Tf I—1 ro oo uo Tf © ON d d © ' Tf Tf o Tf CO i> UO r-I-H VO I-H 00 VO CO © ON d d © ' Tf ro NO i> uo t—I U 0 uo uo t-H r- i-H © NO ro © © © ' © ' © ' uo' © UO —' r- —i Tf CO vo —< vo co © © ' © ' © ' uo Tf ^ H © OO CN Tf °^ . CN ON © 1 ON © ' © ' Tf' NO © OO UO CN CO CO © CN © 1 © © © uo' Tf oo 00 UO 00 T-H uo . CN CN © 1 CN © ' © ' Tf ON _ Tt uo —4 CN Tf CN CN © ' CN © ' d Tf NO NO ON © CO CO Tf r- , ON Ov © 1 CN © ' © ' Tt CN © © CN uo CN Ov © ' CN © © ' Tf 00 r-NO uo ro C N ON © ' C N © ' © ' Tf © uo 00 —4 CN Tt © ON © ' © © ' © ' uo' oo < CJ U H 03 i_ 03 03 oa oo CJ z CN uo © ro CO CN Cv CO uo uo CO CN 00 NO Tf CN ON CO uo" uo Tf nm Tf Tf OO © ©' Tf uo' uo Tf Tf CN Tt NO NO © Tf UO Tf ro 00 uo © CO uo NO NO ro — 1 r-Tf uo i—H uo uo ©' NO iS ro ^ CN Tf CN Tf 00 CO CN NO uo' CO — 1 © Tf © NO co' ON vd 1 U 0 00 uo CN ON l> 1 00 CN CN CO Ov NO 1 © CN ON CO OV NO ' uo f~ UO CN CN Cv r-' 1 CO i—H 00 CO CN NO 1 NO CN Tf ro NO ON r~- ro ON © CN iS CN CN CN Tf UO U 0 VO U 0 OO uo Tf uo U 0 ON Tf ON UO ON © ' CN © ' d Tf v» vo . o t OV i v C X> T-< < o o •c CU 00 C J * I— o C J O oo TO" C J > C J Ts. II 00 X! e 3 o 60 II a £? o o c C J ex o o o c C J C J xi ig 0H £ > ii C J 3 60 O « % 2 J1 211 o v o . SO cn O CO rt CN r t © d o 00 Os rt r t SO Os ©' wo d Os' OS CN NO CN CO CN SO OS CN f-H rt d OS OS 00 r-CN r -CN CO i n l-H rH r—( r t d d o r -o <n r-CN rt wo CN rt d d © 00 r t i—< SO r t CN OS 00 cn cn d Os' OS so r t cn rt CN CO CO O CN rt d d o r -CN rt SO wo CN CN Os CN cn d 00 OS r-H sq cn r - CO O r ~ r t d Os' OS OS SO >n SO CN CN CN CN rt d d o oo rt rt CN Os CN 00 CN rt d Os OS SO rt vo CN 00 CN o CO CN rt d d © Os r t cn o CO OS o CN rt d d o O i n cn CO 00 CN r-co CN rt d d o OS © 00 rt CO CO r -o CN rt d d © 00 CO CN rt CN SO CN CN rt d d o Appendix G . Electron microprobe analyses of plagioclase a a a a a a a CJ "p. C G ' r t rt r t oo O CO 00 r -r t r t r-CN wo OS CN d d CN O OS o OS © vo <n r-CN d © r t r t CO r-o SO cn CN <n Os CN d ©' o sq 00 00 wo © co' vo oo' CN d ©' cn wo SO 00 cn en vo Os' CN d © vo CN CN so CN r t 00 CN f-H WO Os' CN ©' OS r~ r t r- i—< CN WO OS CN d ©' OS r t CO CN Os rt CN wo Os' CN d ©' Os r t CN 00 Os wo 00 © CO wo 00 CN d © SO SO OS r~ SO wo © rH CN WO Os CN d © o sq SO W0 rt wo © CN W0 OS CN d © cn © 00 wo SO © »-H cn wo OS CN d © ' r t 00 r t wo CO wo 00 © CN WO OS CN d © ' Os r> Os r-Os wo 00 © CN" WO Os CN d © ' so O 00 CO CO wo OS CN d © ' o SO Os r -so r t CN wo Os CN d © ' JO X •a -a J=' X X JO T3 T3 JO JO T3 T3 JO JO* X X T3 T3 X> X* -a -a X* x i T3 T3 X* X* •a -a x x* xi xi T3 T3 xi xi T3 X o %t GO <! CJ fe ca ca m GO o z c sU , 00 M o 00 c o X CJ _cs °o o '5b| ca <H o c o CN Os rt NO CN CN W0 OS r- CN © CO wo © © CN* -* © © ' CN 00 Os r t © wo cn NO OS 00 CN © r t r t © © CN* © ' © ' r- OS SO NO CN f-H © 00 00 OS CN © cn wo © © CN © ' © cn CN r-- wo r- f-H wo NO CN rt CN © r t wo © © CN — 1 © ' © ' OS _ , r t OS W0 f-H r- 00 f-H WO CN © r t wo © © CN © ' © ' Os CO OS CN SO 00 OS r t Os rt f-H CO wo © © CN* -* © ' d OS _ wo wo Os i-H SO Os SO CN © CO wo O © CN* —' © © ' CO rt CN r t CO f-H Os © CO © r t wo © © CN* — © ' © ' WO CN CO WO I-H r t © WO cn rt CN © r t WO © © CN* —1 © ' © ' r-H CN © wo SO f-H ON so 00 OS f-H © CO W0 © © CN " © ' © r- 00 WO W0 CN rt 00 NO Os 00 i-H © CO wo * © © CN* © ' © CN © WO Os © NO Os CN © CO WO O O CN* -1 © © ' r ~ CN © r -SO Os 00 WO OS r ~ f-H o CO W0 © © CN* —1 © © ' Os W0 © W0 00 00 © W0 oo 00 CN © CO wo © © CN* — ' © ' © r t wo WO r_ f-H wo so ON f-H wo CN © r t WO © © CN —1 © ' © ' CO © NO CO rH WO 00 OS i-H © CO wo © © CN © ' © + < 00 GO Fe I-H NO r-H ON f-H CN 00 f-H 00 © NO CO © © d © ' © ' WO* OS NO cn © CN © r-OS 00 CN © r t r t © p © ' © ' © WO CO CN wo © r t f-H cn cn i-H r- f-H © SO co © © © ' © ' © ' wo' wo CN CO f-H r t 00 r t r» f-H f-H © WO r t © © © © © " wo © r- r-cn © wo CN 00 © f-H © wo r t © © © ' © ' © ' wo' rt in CQ co U NO © © ON NO f-H r-H o NO CO © © © ' © ' © ' wo" ON CO r~- OS NO © 00 © © ON rH r-H NO CO © © © ' © ' © ' wo' 00 CO WO OS f-H CO rt O © CN r-H NO NO CO © ON © ' © ' © r t NO NO WO CN WO NO f-H wo NO f-H CN © WO r t © © © ' © ' © ' wo' CO © CN CO NO wo wo ON l-H NO rH ON NO CO © OS © ' © ' © ' r t © © r - CO 00 rt NO f-H © ' © NO CO © © © ' © ' © ' W0 00 r - r t CO CO CN NO NO © C- f-H ON NO co © ON © ' © ' © ' ^rt 00 r t CO ,_ NO ON r- CO © r ~ r-H © NO CO © © © ' d © ' wo' CN CN CO wo NO © NO wo © OO r-H © NO CO © p © © ' d wo WO CN CN wo r> rt ON CO 00 ON r-H © wo CO © © © ' © © ' wo © OO r_ NO CN r-H rt wo CN r-H o N O CO © © © ' © ' © wo CS CS -H 6 rj u 0O © WO 00 NO ©' SO r-~' cn *~ 1 r t ON CN r-rH r-00 r t r> r t CN NO ON r t 00 r t cn ©' NO NO* cn f—( NO wo Os OS 00 NO* WO ©' r t f-H Os 00 r> NO SO wo r~-' wo ON cn r~ NO wo Os CO wo NO cn © CO r t CO 00 ON WO 00 cn ^ r t © CO WO co' NO r t CO r t © 00 CN cn NO wo r t CN wo r t OS CO wo NO NO CO Os rt © CN NO NO ©' NO t-' CO CN rt ON CN r t vq ©' NO r-' CO CO ON WO ©' NO r-' cn CN r> CN NO ©' NO r - ' CO r~ ro © © ON od WO ON ro r t CN NO ON cn ND NO CO N? O N . a < N? o 212 00 © SO 00 OS Tt Os © cn vo oo' CN © ' d r~ VO CN © vo cn cn vo OS CN © ' d o OS OS 00 t--Tt m OS-CN © d Tf sq cn T * so SO cn f-H CN in os' CN d © in c- © in r-CN Tf © ' Tf' ©' OS Os 00 00_ SO Tf SO CN Tf SO Tf © OS OS SO t-00 CN o OS cn cn ©' Os' OS Appendix G . Electron microprobe analyses of plagioclase V Tf CN oo VH I 00 oo V 00 C J "BH g £ S3 00 O T3 T3 X> X> i-H wo cn cn »—< Tf wo »-H l-H ON © © <n CN c- in r- CN CN wo t-H cn" Os' © © vo CN _ cn 00 © CN so m t-H cn r-' © © ' in CN CN CN 00 00 r- t"H Tf © Tf 00 © ' © ' m CN cn _ 00 © CN in © in oo' © ' © ' m CN rt Tf VO Tf in Tf SO t-H »-H Os' © ' © ' m CN 00 cn © Tf Tf t-H CN Os © © ' W0 CN 00 © _ in VI -H t-H OS © © ' m CN OS 00 ON _ 00 00 m t-H t-H Os' © ' © ' m CN r- 00 r~ © Tf OS SO t-H CN Os © © wo CN SO Tf m OS r- CN cn © ' xi m CN ,• OS so sq Os cn TO vl r-' © ' xi in CN x> x> xi T3 T3 xi xi = -q £ x> x> TO T3 xi xi X) X) T3 T3 xi xi T-J TO xi xi r-sq cn ON C N V) ON C N Tf ©' ON OS so l-H ON NO in C N C N cn cn t-H cn ©' oo' Os Tf wo ON wo t~-C N ON Tf Tf © ON Os C N © © cn SO ©' v i ©' t> ON r-t> so o cn C S SO ©' in ©' ON ON v-i r- 00 © cn r~ ©' wo ©' ©' © cn in Os Tf C N VI © cn cn © ON ON cn r- m ON cn C N m © C N ro ©' ON OS NO © © 00 VI C N © © ro cn ©' OS OS cn t> 00 Tf C N cn co ©' Os Os © OS Os ON SO C N oo m C N cn ©' ©' © C N wo Tf ON cn Os Os ©' in © r-' Os 00 cn co ON cn Tf o ©' in ©' © © .T- —« Pi ^ TL 03 W n c cj 00 c o Os 00 C N SO Tf NO SO C N wo © Tf vo © © C N © ' © ' C N 00 _ C N C N C N C N cn V0 t-H © Tf wo © © C N -' © ' © ' Tf SO C N C N Tf NO OS SO © C N © C O sq © © C N © ' © ' cn SO SO OS C N NO C N 00 OS C N © cn W0 © © C N i-H © ' © ' V) 00 SO © Tf wo 00 ON so © i-H © cn NO © © C N —' © ' © ' © 00 Tf Os cn C N OS C N S O i-H © Tf wo © © C N © ' © ' cn C O S O m 00 © so so © C N © Tf wo © © C N — 1 © ' © ' O O O N C N cn Os i-H S O wo r~ © i-H © Tf wo © © cs' — 1 © ' © ' 00 C N C N S O l-H ON wo 00 Os i-H © Tf Tf o © C N —' © ' © ' W O wo C O l> Tf C N O S S O O N C N © C O W O © © C N — 1 © ' © ' Os ro C N S O wo C N S O 00 oo ON l-H © C O V " © © C N * ~ © d C O so C N Tf 00 f-S O © t-H © ro N O © © C N * d © ' S O _ Tf Tf S O N O © so © C N o ro N O O © C N —' © ' © ' wo O N 00 00 W O O N C N S O r- ON C N © ro wo © © C N * — 1 d © ' C N 00 W O Tf Tf 00 00 © © Tf W O © 1 C N * — 1 © ' Os so C N C O V-i C N © oo i—H wo Tf © 1 C N © + 60 oo < Fe 2 © © vo vo © wo 00 SO Tf f - OS »-H Os VO cn © Os © ' © ' © ' Tf © m Os Tf 00 CN Tf OS t- OS t-H 00 W0 m © OS © ' © © ' Tf wo NO CN Tf t-H f-H CN 00 Tf Tf t—t OS NO cn © OS © © ' © Tf ON 00 OS SO cn SO r~-t-H NO r-H Os SO cn © Os © ' © ' © Tf vo vo © CN H Tf SO vo cn t-H Os SO m © OS © © ' © Tf vo vo SO r-CN Tf vo WO SO © t-H OS wo Tf © OS © ' © ' © ' Tf r- 00 r- © Tf © r- Tf cn vo i-H © wo Tf © © © ' © ' © ' vo' OS Tf r-CN CO r~ SO CN vo i— i OS wo Tf © OS © © ' © Tf SO r - wo Tf OS CN VO t-H vo i-H Os vo Tf © OS © © ' © ' Tf* t-H ON 00 SO CN CO SO Tf wo i-H © SO cn © © © ' © ' © ' v i CN wo CN 00 vo © cn t-H CN wo t—H Os so CO © OS © © ' © Tf SO Tf r- cn CN 00 Tf so Tf cn F-H Os SO cn © Os © ' © © ' Tf 00 vo 00 SO H^ CN cn 00 Tf Tf t-H OS SO CO © Os © ' © ' © ' Tf © 1—1 00 OS SO © Tf vo CN vo t-H OS SO cn © Os © ' © ' © Tf Os so © © 00 00 cn 00 l-H vo CN ON VO Tf © ON © ' © ' d Tf © Tf NO r~ t-H Co CN oo © SO CN 00 VI Tf © ON © ' © ' © ' Tf £ 03 03 if"! o CO r~- © r- © SO WO © - H Tf VO CO © CN vo wo oo' OS wo ro SO —i oo © cn Tf t—i so co Os r - f -CN —i SO ^ H ' SO' so ro Os 00 r- oo Tf CN —i so cn © Tf r-oo oo vo V0 Tf vo Os so O-CN Tf" —<" Vl Tf so C O © CN Tf r-CN vo I - H V l Tf © OS WO I - H ro O C N wo —' wo Tf 00 wo SO C N Tf ro ro' Tf t—I so co CO Tf CN sq - H ro CN WO t-H* so ro so ro r -© r- Tf Tf ro —-so ro ro so r-00 © ro ro' Tf - H ' so ro Tf Os ON r-~ © Tf CN wo' f—H NO cn WO CN Tf NO wo ON t— ON CN © wo NO CN Tf N? X? v© ON C> \ C X) T-< < O 213 SO cn oo ©V in Ov cn vd CN ©' ©' VO Tt CN cn m OV © CN Ul OS CN © © VO 00 m 00 VO OV 00 © m' V, vd CN ©' ©' t> © Tt © l—c Tt m t-' CN © CN o 00 OV m 00 © r-H CN in r> CN ©' ©' OV vo © cn cn r-H Tt' V) f-' CN rH ©' in o Ov 00 VD cn r—c CN in Ov CN ©' ©' •n VO OS CN VO Tt ©' m © cn o' ©' 00 cn © VO CN r—l •—< m ©' cn ©' ©' Ov fN m © CN Tt H m ©' cn ©' ©' 52.68 m m 00 CN 00 CN ©' •d rO © Ov Tt r» © cn VO © cn •n oo' CN ©' ©' vo © CN r-cn CN •n ©' cn ©' ©' cn Tt cn © m vo CN V, ©' cn ©' ©' 00 00 © cn VO Tt cn i-H m ©' cn ©' ©' CO OS oo Ov Tt I-H CN in Ov CN ©' ©' O bo co o < cn o CM CJ He o 60 cn cn r-CN t-Tt © m ©' I-H m' ©' 00 Ov cn © CN Tt cn CN cn CN Tt ©' Ov ov m r- cn in 00 m CN VO ©v m © Ov OV CN m Os © © m CN Tt ©' in ©' Ov Ov Appendix G . 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U 00 (J I o 6 oo C M C £ '53 rt ,t! oo O f l f i r> vo f i vo o CN d d © ui c-i 00 00 Ov p fN © f i Ov d © ' CN Tt vO VO r t p vo CN CN f-H d CN f i Ul ,—1 f - H f l m r-00 vo m v_J vd vd d -6 Ul CN r~ r t vo r--f-^  Ul m © t> vd d © ' u-i CN r- O Ov © r- r t r-f i 00 d © ' u-i CN f l 00 r- VO t- CN f - H CN fN 1--' CN f - H Ul fN O fN CN rt t~-© ' f i d X> VO CN VO u-i cn r- Ov 00 - - H f i r-' d d Ul fN r> VD f i r t Ul 00 f^ f i oo' d d u-i CN O Ov u-i r t 00 © f i 00 d © ' Ul CN CI CN © vq r t 00 c i oo' d © ' u-i CN f i u-i ©v © f-^ f l f -H © d d © in f l r t CN f> © © f l - H d d © in f i o Ul f i VO © VD © fN Ov d © Ul CN O r» VD 00 OV m © fN od d © ' in CN x> x> .d x> T3 TJ x> -d •a -d x T3 X> -D X -a -a -a -a -d xi •a JD nd rn vo vq CN f i c i ©' Ov f l oo f l f i CN rt ©' CN f l Ov vq rt f i ,—1 Ov CN vo Ov VO OV u-i ©' rt © 00 © f i V0 OV vd ©' VO r-© VO f l »—i rt ©' r t f l 00 f l f l f-H rt ©' Ov OV CN OV CN u-i r> r—< r-co Ov 00 rt f-H rt ©' © Ov CI m r t f l rt ©' u-i oo_ Ul vq f i f l f-H rt © r t VO VO f l rt ©' f l © Ul rt © CN rt f i © Ul 00 VO in CN CN f i f i © Ov © Ul f l f l CN rt ©' P~ rt CN f i CN rt ©' Appendix G . Electron microprobe analyses of plagioclase o 3 00 < ° -9 , % Q o Q CJ fj-rt xl rt 03 oo O o s CJ or II oo c o •a CJ CN .2 f ) CJ ci .2 Ov 0C .3594 ,6178 ,0228 0038 CN © © .4033 .5628 .0267 0900 CN © © .5568 6296 4620 2420 CN © © © ,5595 .4145 0192-• CN © .5692 ,4058 .0190 0047 CN © © .4418 ,5198 0272 0068 CN © © .4159 .4732 .0748 ,0860 CN •J—H; © © .7167 ,2575 ,0242 i CN — , © 4543 ,5041 0286 0074 CN © © .4321 ,5312 ,0283 0073 CN -* © o ,4352 ,5239 ,0297 0063 CN © © .4391 .5231 .0296 .0071 CN — ' © © .3118 ,6494 0275 0072 CN © © .3321 .6325 .0251 ,0071 CN o © .4043 ,5650 ,0218 0051 CN o © .4123 .5602 ,0194 0051 CN © o bo < + m CJ P H Mg CN CN f l f l 00 f-H in 00 rt CN f-H 00 VO f l © OV © ' © ' © ' r t f-H r-H r- r-f-H u-i r- CN © 00 f-H © VO f l © © © ' © ' © u-i CN Ov r t — f l CN f—i f l © VO 00 © © r> f i —i © ' © ' © ' © f l VO Ov © 00 © Tt Tt CN f l Ov Tt u-i © OV © ' © ' © ' Tt f l 00 f l CN in Ov VO © f i CN f i © r t u-i © © © © ' © ' m' f-H u-i 00 CN f i © f-H r- CN © i n Tt © © © © ' © ' v i 00 CN rt vo OV 00 rt i n 00 f-H f-H u-i f l © © © © © ' u-i Ov CN CN Tt m r t f l 00 f i Ov CN VO © Ov © ' © ' © ' r t _ r~ © CN VO CN Tt m cn CN © m Tt © © © ' © ' © ' V i CN U-1 VO © OV Ov 00 00 Ov f-H Ov u-i f l © Ov © ' © ' d Tt ov r~ © r- © cv H — m r t © © ' © © ' f l in VO CN CN VD © 00 r> © CN OV in Tt O OV © ' © © ' r t r t 00 Cv © f l 00 r—l © Ov © VO f l © © © © ' © u-i OV rt , , u-i f l f i i—H f-H © VO f l © © © ' © d u-i 00 00 CN CN VO oo Ov OV Ov f-H f-H in f l © © © ' © ' © u-i OV OO CN VO 00 rt OV Ov © in f l © p © ' © ' © u-i pa co u CO •z, 00 in Ov Tt Ul u-i u-i VD CN f l CN u-i f l f-H m OV u-i od f i ' — ' - u-i i n OV <n u-i CN vd VO VO VD CO 00 r t r t r t f—H m f i f~ CN vo vq vq f i r t CN m f i r-r t CN CO r t © vd m ©' Tt CN © m © i n f i m r-' f i ^ CN vo en Ov vo r t od CN f i VD r-' m f-H rt m cn rt Ul CN rt CN rt VD CO VO Ul Ov r-' m Ov f l —* © © m r-00 m © Tt vo 00 OV f l m © vd in © Tt CN © Ov Tt CN i-H r> VO ©' f l OV 00 CN Ov CN VD VO f l m © r-H Ov OO od u-i Ov f i '-™, f l ul - VD OO CO in Ov f l An% X < o 216 S3 00 a a a OQ a. c £ 'S3 CS r« Tt CN o cn Tt XI so' t> © ' xi vo CN Vl 00 u-i 00 00 SO © ' © ' © ' © ' Vi cn SO cn © CN r- SO l - H CN os' © © ' vo CN Tt Tt Tt _ vo SO Ui » - H CN OS © ' © ' Vl CN SO © © © CN © Vi T - H CN © ' © ' © VO cn NO CN © SO CN - H u-i © SO r-' © ' © ' CN © CN Vl CN Cs u-1 XI SO SO © ' X) Ul CN r~ CN © OS CN Tt © © CN as 1 — i © ' U-1 CN Vl CN SO © • — ' 00 © co Os © ' © ' u-i CN O SO SO CS r—l CO OS © ' © ' u-i CN Tt Cs cn OO Tt Tt CS o CN OS © ' © ' u-i CN C\ CO 00 SO Tt cn 00 © CN Cs © ' © ' u-i CN Cs Ul V 00 © SO Cs o CN CS © ' d u-i CN SO Cs Os oo Tt r> © ro oo' r—1 © ' Ul CN Cs CN Ui i - H ro SO 00 '—< ro 00 © ' © ' u-i CN oo , ( © Cs CN 00 © m co © © ' u i CN Appendix G . Electron microprobe analyses of plagioclase T3 x> XI X) X> X> X> X> XI T3 x i x i XJ XI xi xi X) XI xi xi XI XI Xi Xi XI x i XJ x i XI X) x i X) XI XJ Xi Xi XI XI x i x i 00 00 so u-i Ui OS u-i ©' OS cn 00 cn Os i-H Tt i-H cn ©' SO Os 00 OS SO CN CN l-H cn ©' cn c- © Ul CN CN Tt" ©' CN © © © CN cn Tt ©' cn u-i © sO SO Cs u-i ©' O u-i SO SO OS u-i Os' u-i © Tt Ul u-i cn CN Tt ©' Tt CN SO cn © cn CN Tt ©' t-_ u-i CN cn CN 1-H Tt ©' Tt 00 CS © so CN CN Tt ©' SO SO © CN © cn CN Tt ©' © © r-CN m Tt ©' XI XI x i x i XI XI Xi Xi so cn CN 00 ui m XI x i O < o o o PH 9 m oo u uo Tt CO CO OS U0 CO p-i-H Tt © ' Cs 1-H Cs UO Cs cn SO OS Tt cn sq Tt © ' CS Cs o O fN o S CO rst o U 2 H a CJ 6£, Si 00 a o XI CJ vi n x> cj Vl cd .5292 .4533 .0143 1 i .4775 4865 0329 9937 CN ~* © © © © Tt .3116 .6509 .0233 .0100 i • 7008 2977 0108 0051 CN © © © © © uo .3758 .5956 .0206 .0084 i 6325 3512 0149 0666 CN —1 © © © © © Tt .3878 .5876 .0185 .0074 i • 6197 3613 0146 9970 CN © © © © © Tt .3722 .6049 .0170 .0065 i • 6333 3523 0124 9987 CN © © © © o Tt .5405 .4431 .0169 .0041 i .4610 4901 0350 9908 CN — o © o © © Tt .5436 .4360 .0187 • i .4608 4969 0341 9901 CN "* © © © o Tt .3831 .5811 .0342 .0064 .6123 .3666 0182 0020 CN © o © © © UO .4080 .5607 .0281 .0042 i • .5958 3844 0175 9986 CN — © © © o © Tt .3920 .5713 .0324 .0073 i 6134 3621 0181 9965 CN — © © © © © Tt .3828 .5793 .0317 .0053 i .6251 3601 0152 9666 CN © © © o © Tt .3879 .5755 .0302 .0040 i 6173 3708 0173 0031 CN — © © © © © UO .3705 .5902 .0327 .0055 t • 6346 3540 0156 0030 CN — © © © o © UO .4222 .5371 .0404 .0056 i .5755 3979 0187 9974 CN © © © © © Tt .4278 .5338 .0290 .0076 i • .5822 3999 0191 9995 CN © © © © © Tt .4256 .5404 .0273 .0062 i i 5829 3966 0192 9982 CN © © © © © Tt OO < + m CJ P H 2 Ba »~ oo Ca Na Sum © OS 00 © m (v Tt oo' Tt m UO c~ CN so © 00 so OS CN 00 (V 00 00 Tt CN SO Tt cn *—1 00 p-CN © SO Tt SO SO cn ' ' Tt © © Tt CN CO SO uo m — uo uo Os Tt Tt UO SO Tt Os' Tt co" SO Tt © Tt Tt SO Tt ©' UO cn © CO UO CN oq SO so' CO 1 1 r-Tt t> CO Tt Osuo CO CO —' oo CN r— CO so sd CO so © oo UO CN SO uo cn uo Tt CN r~ so sd CO uo oo SO © Tt UO CN SO u-i CO Os SO oo oo 00 oo r-' uo Cs CO —^  Tt SO © Cs r~' uo Cs ro © so Tt Cs 00 uo Cs ro An% N? X) < o 217 _* <u <u k. U u cs E o H •a OJ 3 _C e o U d x •5 e u . 1°-a a a v co CO r- 00 Tt •-^ o CN CN rs OV rH d m fN VO VD 00 t- CN os Ov © ' d SO CN CN in Tt cn •n WO CN OV * — i d d d WO <n CN fN Tt >n fN CN rH d d d VI cn in o Tt CN m d d d i n cn ov Tt Ov r- r—< CN vj vo" r-' d x" m CN o vo o vq o cn vd C-' d X) m CN o r-r- Tt 00 © ' d d d i n cn fN Tt in Ov VO rH d d d d m cn m m CN vq 00 cn 73 co oo' d X •n CN r~ 00 VD vq cn O Tt oo' d d i n CN _ o VD wo CN r-H •—i d d d m cn fN CN Tt VO ov m r-H d d d d m cn Ov cn m co 00 m rH fN OV d d •n CN o Ov o o m Tt m r-H vd tS d d m CN Ov Tt cn vo i—< CN in o vd r-»' d d wo CN C M C E 'jo rt rfe c o O 73 13 X X5 73 -a 73 ; x xi x x 73 73 x xi 73 73 xi X 73 X 73 73 X X> 73 73 Xi X 73 X 73 73 X X) 73 73 X) X) 73 73 x xi 73 73 X> xi © OV Tt in CN 00 Ov CN r-H Tt d Ov Ov VO o CN i n 00 CN cn 00 Tt cn d 00* Os r-Tt Ov r-l-H CN cn cn cn cn d d o r> t> ov sq VO i-H m OV cn rH cn d v"OV OV cn cn r- cn CN © O en cn d d © r-H m cn i-H r~ vo VO Ov ov m' d ©V Ov m CN 00 00 Tt vq cn r-OS m d ©v Ov Os © oo cn o CN in r-Tt cn d Ov ©v >n cn Ov r-H VO CN 00 Tt cn d ©V* ©v o VD o VO i n Tt Tt r-Ht-H Tt d OS OS 00 CN m 00 cn m 00 00 i-H Tt d OS Os o vq en r- o CN CN cn rH cn d '©' © cn cn r-cn VO -Tt cn d d o 00 Os 00 ov Tt CN oo © CN cn d ©' o Tt Ov VO m Tt Tt cn m Ov m' d © © cn 00 CN in wo in cn Ov OV m' d Ov Appendix G . Electron microprobe analyses of plagioclase o 2 iv3 < Q. o O o 9 0 CJ P H _ rt co eq co o Z c CJ M, |1 00 c o 73 CJ trt CO X .3787 ,5627 ,0425 ,0140 CN © © .4130 .1350 .2497 .2103 CN — © © 3418 6198 0319 0100 CN © © .3367 6248 .0255 0102 CN — o © .3543 .6194 ,0194 .0094 CN © © .5530 4380 ,0100 i CN — © .5512 .4378 ,0101 • CN © .3202 .6401 .0279 .0113 CN —• © © 3047 6999 0211 6600 <N —• © © .4399 5462 0110 CN — © .4517 .5311 ,0129 .0039 CN — © © .3444 .6207 ,0240 0108 CN — © © .3077 6611 0196 9600 CN — © © 3784 5950 0182 0102 CN — © © .5301 .4509 ,0168 6900 CN — © © .5331 .4470 .0180 ,0038 CN © © bo < + CJ P H Mg CN Ov 00 © m Tt 00 m vo rH © so cn © © © © d i n CN m Ov r--VO Tt SO i n r-H CN rH VO r- cn © © © ' © ' © ' •n* 00 © CN Tt m Tt CN m i n cn 1-H © so cn © © © ' © ' © m' cn 00 © cn cn VO OV so CN © © VO cn © ©_ © ' © ' © ' i n Ov Ov CN VO CN 00 cn r-in CN rH ov vo cn © OV © ' © ' © " Tt VO r- cn m © i> oo r-i n ©v cn oo Tt Tt © ©V © ' © © ' Tt" r~ ©v t> cn VO cn SD vo Tt r-H cn OV Tt m © ©v © ' © ' © ' Tt" © r~ in l> r-H ©v rH rH Ov ©v rH © SO CN © © © © ' d m t - _ i n © CN cn Ov 00 © oo © OV r- CN © ©v d © ' © Tt" cn Tt © 00 m m VO cn VO © CN Ov m Tt © OV © ' © ' © ' Tt Ov VO Ov •n © cn Tt CN cn © m Tt © © © ' © ' © ' i n r-H CN m 00 cn Ov rH cn vo CN rH © so cn © © © © ' © ' i n ov CN CN cn Ov 00 Ov m OV Ov © © VD CN © o © ' © © ' i n cn in Ov Tt r-H © cn cn m rH Ov vo cn © Ov © ' © ' © ' Tt rH vo CN m r~ CN m ©v 00 CN 00 Tt Tt © ©v © ' © ' © Tt © VO OV fN >n CN rH rH r> 00 cn OV Tt Tt © Ov © ' © ' d Tt E CO CO -4 3 U "Z OO Ov Tt © Tt Tt r-H VO in cn 00 Tt Ov i n Tt cn vd •n m fN rH 00 © © © CN Tt vo cn cn m © vo © Ov 00 vd VO CN cn ©' © © Tt r-fN CO m' so CN cn t> vq Tt Tt Os oo m' Tt ©' m cn OV r-cn m 00 vq Tt" Tt i n m' 00 m cn oo" SO Ov CN © OV r~ Tt ©V Ov VO 00 CN d CN r~ r~ VO vq SO m © Tt CN cn cn m fN Tt © Tt" •n CN Tt cn m cn m Tt Tt m" VO CN m CN OO cn cn Ov 00 vo Ov CN d VD r~ Tt OO oo CO CN vo Tt m ~ rH r-H VD SO Tt m OO Tt od Tt CN CN 00_ OV in CN t-' Tt od Tt CO An% X < o 218 Appendix G . Electron microprobe analyses of plagioclase it u -t cs C -c '5 P H CS cn s cn ti 00 t-l a u u CS £ o H T3 g •g O U d X •5 c a a a a a a, a £ 'cs cs "s GO O 00 CO CN CN Tf vo CS WO ©' CO ©' ©' o CO © © Tf © CN WO ©' CO ©' ©' OV CN CN 00 00 Tf 00 © Tf' wo oo' CN ©' ©' 00 os CN © 00 Tf 00 © co' wo OV CN ©' ©' © © CN VO Tf r -© t-H vd wo r - ' CN ©' ©' 00 CN r -wo CN r -t-H CO WO Ov CN ©' ©' Ov Cv 00 r -CO Tf CN CN wo Ov CN ©' ©' o\ CO Tf VO Tf O CN wo ©' CO ©' ©' CO oq Tf © wo Ov © CO wo oo' CN ©' ©' wo VD VO CO OV CO 00 © CO wo 00 CN ©' ©' VO CO © CO CN © VO wo ©' CO r—< ©' oo © CO oq wo 00 VO t-H CN WO Ov CN ©' ©' WO Tf CN Tf Ov vo t-H wo ©' CO © ' © ' CN CN Tf CN ro Ov 00 f—< WO ©' CO © ' © ' wo Tf wo OV Tf CO CO CN CN wo 00 CN ©' CN VO wo ro © wo f-H ©' wo ©' ro — 1 ©' X> X> TO T3 •a T3 x> xi T3 T3 xi xi -a -a xi xi x> x> T3 T3 xi xi T3 T3 xi xi T3 T3 xi xi •a xi TO T-J xi xi ^ T3 T3 xi xi T3 TO xi xi TO T3 xi xi X> X) GO < O O o T N 6TI V CJ PH CO 00 r-_ Tf CN © wo CO co' ©' ©' © VO Ov WO Ov CO CN VO Ov CN co' ©' Ov Ov VO Tf VO t-00 CN t~-"""j Tf © ' ©' © Tf Tf wo r -CO CO 00 © t-H p—< Tf © ©' © Tf CN 00 CN wo 00 Tf ©' W0 ©' ©'© i> wo r - r -CN 00 vq CN Tf ©' ©' © CN VO VO CN CO CN CO Tf CN Tf ©' ©'© Ov OV © © CN CN © CO CN Tf ©' ©' © CN © OV © CO Tf CN Tf ©' Ov Ov Tf CN vo l> CO CO CN 00 Tf ©' od Ov wo Ov Tf WO 00 t-H wo co' f-H CO ©' ©' © © © wo © CN CN © CN CO Tf ©' ©' © VD W0 oo r~ 00 O CN ro ro ©' ©' O © vq rv Ov VO o ro ro ©' o ' © r ~ vq CN VO CN CN Tf ©' ©' © CS 00 Tf 00 Ov Tf ro ©' © o CaO o CN CS Z o fN o H CJ o 00 a o T3 CJ t/l CS X> o o "Sol CS .3680 6609 .0217 .0077 1 6359 3313 0137 9881 cs -1 © © © © © Tf .3758 .6059 .0142 .0071 1 t ,6307 .3482 .0135 ,9954 CN © © © © © Tf .4502 .5329 .0162 .0057 ' 1 1 ,5541 4168 0162 9920 CN l-H © © © © © Tf ,4400 .5458 ,0163 .0054 ( I 5541 4163 0188 9967 CS T-H © © © © © Tf ,5136 .4610 .0250 ,0064 1 1 4926 4597 0290 9873 cs — © © © © © Tf .4018 .5707 .0244 ,0075 1 I 6070 3641 0153 9907 CN © © © © © Tf .3939 ,5857 ,0145 ,0079 1 I 6110 3729 0135 9994 CN — 1 © © © © © Tf .3725 .6088 .0156 .0067 1 1 ,6301 ,3514 ,0125 9975 CN © © © © © Tf ,4535 ,5263 .0171 0900 1 I .5473 ,4327 0174 0002 CS © © © © © wo ,4541 .5289 .0136 ,0055 1 ( 5511 4223 0195 9951 CN "-' © © © © © Tf ,3321 ,6216 .0347 ,0109 1 I 6788 3119 0104 0004 CN -* © © © © © WO ,3658 ,5970 ,0292 ,0111 1 I ,6329 3568 0129 0057 cs '-' © © © © © wo ,3418 .6155 ,0323 ,0108 1 I ,6614 3336 0106 0060 cs © © © © © WO ,3345 6244 ,0317 0119 I 6641 3282 0111 0900 cs — © © © © © wo ,3871 .5528 ,0459 .0156 1 I ,6180 .3713 0152 0059 CS © © © © © wo ,3103 ,6411 ,0354 ,0104 1 .6950 ,3077 0104 0103 CN l-H © © © © © wo 00 < + t-i CJ U H oo 2 Ba Sr Ca Na Sum CN ro WO 00 ro Tf VO CO ro ' Tf oo wo CO ro VO Tf ro CN 00 00 OS CO vq wo' WO Tf "~l r- wo oq Os oq WO WO Tf r-. 00 Tf WO Tf Ov Ov Tf vd Tf CN © Tf vo Tf WO VO vd CO * - * 00 (V Ov © Tf CO ©' vo r-' ro t> Ov - Tf CN CN VO wo' ro Tf WO ro ro Tf wo ro Tf Ov Ov CN VD Ov wo wo CN Tf oo © CN OO ro © VO ©' CO CO Tf © CN cs CN VO wo ro —-00 © CN OO Tf © WO VO CN ro © Tf CN ro © wo vo CN ro 00 WO Ov CO OV Tf © VD vd ro © Ov vo © CN © r-' vo ©' ro An% X> < v° ON o 219 u< 1 SO r-00 CO Tt l - H Old CN Vl Os CN ©' d U. 1 00 Vl - CO Tt l - H T - H Old fN Vl ©' CO d d V OS co Os CN Tt CN T - H Old co V, OS CN d d V l ~ -VI Vl CO 00 Tt l - H © CU ro' VI OS CN d d T H SO l> Os Os Vl CO M5- CN V) Os CN d d Ut SO fN o VI CN t>-M5- CN Vl Os CN d d Ut O CS OS r~ CO SO CO r—1 s T—C VI OS CN d d Ut CN SO Tt VI o SO CN M5- CN VI Os CN d d V CN Os Tt Tt © uo cn' VI Os CN d d V Tf VI r~ 00 VI CN l - H uo en VI oo' CN d © V CO VI CN SO VI Tt OS © S fN Vl OS CN d ©' l> sq Tt CO 00 SO CN M5. CO VI Os CN d ©' so CN Vl SO CN CO VI Cs CN d ©' Ui rv SO VI VI o VI Tt V, CN VI OS CN d ©' c-co ro 00 CN Tt © i n CN VI Os' CN d © U CO 00 t> ro o © T - H M3- CO VI 00 CN d © Grain CN o 'do o < el o tN CU U H o oo CN C- CN CN so CN Tf' ©' ©' © T-H © 00 CN CN CN SO ro CN Tf d ©' © OS 00 Tf r-CN 00 r~-- Tf d Os' OS CO Os r~ Tf so CN SO T-H - Tf d d © © CO 00 © CN Tf © © © Os Tt Tf T-H CN Os Tf CN Tf © Os Os v, Tf OS CO CN SO l> CO CO © Cs Cs Tt Tt CO CN V CN © oq CN Tf © Cs Cs ro ro r-~ CO ro CN Tf CN Tf ©' ©' © Os CO VI SO CN Tf l> Tf ©' OS Cs CN so ro CN SO SO CN Tf ©' OS Os CO 00 ro CO Tf SO CN Tf' d d o o OS OS CO CN SO - Tf ©' © © © sq Vl CN CO oo CN Tf' ©' Os Os ro Tt CN ro CN O VI CN Tf' ©' Cs Cs Tt Tf r- Cs ro Tf VI - Tf d Os Cs CaO O CN Z o tN "ca o H Appendix G . Electron microprobe analyses of plagioclase H u s i C/j T3 CJ S3 _C '•in (3 o O d T-•3 a | l cj "5, £ cs T3 T3 T O xi •O T3 X) X> X> T3 XS xi xi •O T3 xi xi T3 T3 X i X i TO -o X i X> T3 T3 X) X> e cj W . |1 00 CS o T3 CJ V) CS CS cl| <*H o c o Tf Tf Os T-H Tf r-00 Os T-H © CO uo © © CN T-H © © CO OS SO CO 00 Tf Tt r- © T-H © ro SO © © CN - H ' © ' © r- _H CO Os CN T-H Tf CN SO © Tf uo © © CN - H ' ©' ©' CN CO uo uo T-H CO SO CN SO T-H © Tf VI © © CN i-H © © CO rt 00 Tt o © 00 OS r- CN © CO uo © © CN l-H © © ' 00 Tf 00 CO VI r- Tt r-00 00 CN © CO U0 © © CN T-H © ' © ' OS SO OS SO l-H T-H 00 SO © CN © CO so © © CN © ' © ' Os Os SO © CN CN © oo CS 00 CN © .CO uo © © CN — 1 © ' © ' V Cs Cs oo oo CN ro SO © i> T-H © Tf uo © © CN i-H © ' © ' © 00 VI CN l-H Tf 00 CO Tf T-H © Tf UO © © CN ^ © ' © ' ro 00 VI T-H T-H 00 uo SO OS 00 T-H © ro uo © © CN © © rv Tf CN ,_ i> CO 00 T-H uo CN o Tf uo © © fN —1 © ' © ' rv Tf CN Tt ro SO CN 00 CN VI CN © Tf uo © © CN —1 © © ' OO r- ro 00 ro CN r- Os Os 00 i-H o CO uo © © CN ^ © ' © ' CO tv ro © SO l-H Tf rv 00 © T-H © ro sq © © CN —' © ' © ' OS ,_ o 00 1—H Tf l> Tf CN CN o Tf UO © © CN d © ' + < cn 00 OO Fe T - H 00 CO 00 t> T - H CN CO T - H SO l - H OS sq ro © OS © © © ' Tf Tf © Os CO © T - H CN Os CN SO i - H OS SO ro © OS © ' © ' © Tf' CN Tf CN Os Tf Vl uo t~- OS T - H OS VI CO © Os © ' © © ' Tf SO 00 SO t> T - H Tf CN r- OS T - H Os VI ro © OS © © ' © ' Tt Os _ H OS r- l - H r- SO T—C so T - H Os SO ro © Os © ' © ' © ' Tf 00 l> 00 UO © SO Vl 00 i - H SO T - H OS SO ro © Os © ' © ' © ' Tf CO Tf SO OS CN oo CO CN Tf Tf T - H © SO CO © © © ' © ' © v i ro CN Tt CN SO ro Tf OO © l> T - H Os SO ro © OS © © © ' Tf © uo Tf 00 ro CO r-Cs 00 l - H OS uo ro © Os_ © ' © ' © ' Tf' ro 00 Os UO Cs 00 Tf Tf r- Os T - H Os uo ro © Os © ' © ' © ' Tf' uo Tf U0 CN uo Tf CN Tf T - H SO i - H Cs sq ro © CS d © ' © ' Tf SO Tt 00 CN U0 CN r- CN 00 00 »—i OS VI CO © OS d © ' © Tf uo SO oo UO so Tf uo r-l> 00 T - H 00 uo CO © Os © ' © © ' Tf oo _ CN r-ro SO CN uo T - H so T - H Cs SO CO © OS © ' © © Tf OS Os so 00 SO CO CO CO © SO i - H Os SO CO © Os © ' © © ' Tf U0 _ Tt _ r- uo CN so uo l - H CN Os uo Tf © Cs © © © ' Tf CS £ cs CJ z OO © oq CO CN CO CN so SO CO Tf OS uo © 00 CN SO so CO 00 © so UO uo oo' U0 Os' CO U0 CN © uo OS Tf oo' uo Cs' CO T - H uo Tf oo OS © SO v i CO Tf © uo SO 00 V) SO SO CO —~* OS CO Os CO Tf CO CO SO Tf CO CN uo Tf uo CN Tf © ' t— , — i SO CO Cs 00 Tf SO CN ro Cs' od ,—c U0 ro SO ro Os 00 oo Tf r-' Cs , — i U0 ro uo © UO sq uo CN T - H SO T-H* SO CO CN r- Os Cs Tf Cv 00 od . — ' UO CO , , Tt © U0 © SO od Os T - H uo CO so Tt CN CN U0 CN . — i SO , — ' SO CO CN CN ro , — ' SO , — i so ro Tf rN Tf SO Tf CN v i T - H CN* VI Tf N? os-CS N? OS x> < < o 220 VO ON en rH rt r t cs m ©' c i d d oo r t 00 r t o CN WO OS CS d d o © f l f ) r t vo cn vo Os CN d d Appendix G . Electron microprobe analyses of plagioclase .a CS 13 e i<3 IU i . IW s-OJ eS c "S I C/0 c vU u o o, a E '55 t>o O cs u-i rH r t © © CS OS f i rt © ' Os Os 73 73 X i X r-.r~.r-! 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Electron microprobe analyses of plagioclase u .a "o cs io B O c c i U GO ci O 03 00 "H. c 00 o 0 00 VO Cl-u-i VO 0 c i 10 od fN © d fN in Ov Tt CN Tt 0 Tt v i 00 fN © d r t 00 c i 00 0 u-i 0 c i m od fN d d u-i Tt r> 0 CN t-H c i Ul 00 CN d 00 VO fN fN CN VO CN i-H u-i © m d d c i 00 Tt r-Cl VO 0 fN Ul OV fN d d Ul OV u-i 0 VO Ov 0 c i Ul 00 fN d d u-i c i 0 CN r-' Ul u-i fN d d VO Ov r~ u-i 00 0 00 Ul u-i CN d d c i O fN Cl 00 0 OV v i v i fN d d Tt O Tt fN CN CN Tt c i U i OV fN d vo r- 00 Tt CN Tt Ul 00 fN d d VO r> cn Os 0 Tt c i u-i 00 CN d d Ov <n cn 00 Cl rH i-H c i u-i Os CN d d OV CN 00 00 vo Cl fN Ul 00 CN d d OV O p u-i Tt fN i-H fN ui 0 ' cn d d 73 73 xi X 73 73 X X> _• X X 73 73 X xi 73 73 X) X 73 73 xi xi 73 73 xi xi _• 73 X 73 xi Tt Cl Cl r-CN Cl T-H Cl »-H Tt d Ov Os Tt Cl vo p Cl SO O - u-i d d 0 VO u-i Cl 00 00 CN u-i Os *~l Tt d OS OS 00 0 0 u-i Cl Cl CN O CN Tt d d 0 I-H fN Cl 0 Ov 0 CN u-i 0 c i c i d d 0 vo Tt Tt Cl CN 0 Tt fN i-H Tt d d 0 r- Tt r-u-i CN u-i u-i - Tt d OV OV Tt O Tt t> u-i Ul r-00 od VD d 00 OV 00 vo Os Tt Ul Ov O t-~' vd d d 0 VO u-i 0 VO CN t-i r> d d 0 Os cn ui cn 0 Cl 00 VO CN Tt d d 0 I-H ui r-i> 0 Cl u-i 0 Tt d d 0 Os 00 O Tt CN Tt O - Tt d d 0 VO 0 VD u-i CN 0 CN i-H Tt d d 0 O T-H VO u-i 0 Cl VO Ul CN Tt d Os Os u-i p Cl OS O c i i-H Tt d d 0 Q 0 % o £ 0 9. o CJ fie ca t co ca oa 00 cj z c u I t 00 e o 73 cj VO CN Tt Ov T—H Cl CN VD Ul CN CN O Tt u-i O O CN -H' d d Tt Tt Tt OV vo 00 Tt V0 u-i rH l-H 0 Tt u-i O 0 CN ~* d d 0 rH 00 OS OV r> VO cn Cl T-H 0 Tt u-i 0 0 CN d d _ Tt _ u-i Ov t- 00 T-H Cl C l 0 Tt u-i 0 0 fN rt d d rH Cl cn 0 t-H 0 I-H 00 u-i CN CN 0 Cl VO O 0 CN rH d d Cl Cl Tt VO Os u-i rH VO 00 00 CN 0 Cl Ul O 0 CN d d 0 u-i Tt VO Cl 0 VD Cl Cl CN O Tt Ul 0 O CN --• d d c- 00 OV CN u-i u-i Cl O0 T-H Tt CN O VO Cl 0 O CN —' d d 0 Cl CN CN 0 00 Ul Ul Tt CN CN O VD Cl 0 O CN - 1 d d Tt 0 r - CN i-H u-i Tt u-i Tt CN CN O vq Cl O O CN rH d d Ul Cl Tt Tt VD r - rH ©v Ov vy .Tt O Cl ui O O CN -H' d d 00 Ov Tt Ov 00 OS SO t~-Tt CN rH 0 Tt Ul O 0 CN —' d d rH Tt r> u-i Cl Cl Cl l> Cl Tt rH 0 Tt u-i O 0 CN — 1 d d 00 Ov rH CN VO Cl Cl r~ rH VO rH 0 Tt u-i O 0 CN — 1 d d u-i 00 Tt r> u-i 00 Cl 00 i-H Tt CN O Tt u-i 0 O CN — 1 d d 0 vo Tt rn VD Os u-i 00 VO 0 i-H 0 Cl vq O 0 CN d d + < ro 00 GO Fe 2 CO w. u-i CN 00 u-i Cl 00 00 Tt u-i rH rH C7v Ul Tt O OV d d d Tt u-i rn Ov OV Tt 00 r-Tt Tt rH 0 u-i Tt O p d d d v i rH Cl Tt 00 Tt vo C l VO CN T-H 0 Ul Tt 0 0 d d 0 v i OV rn C l r~- VO Ov Cl 00 Ov rH 0 u-i C l O p d d O v i Tt VO 1> Ul Ov Cl rH Ul Tt Tt rH 0 VO Cl O p d d d v i vo OV u-i Vl Cl SO C l VD 0 00 T-H 0 VO Cl 0 0 d d d u-i rH rH 00 VO Tt 00 Tt Cl rH rH 0 u-i Tt O p d O d v i VO OV rn C l rH Cl CN rH OV OV Cl T-H Cl u-i 0 0 d d d v i VO Ov Ov rH 00 Ov 0 00 VO Ov Cl OV Cl u-i 0 Ov d d d Tt u-i Tt Ov 1—H CN Cl Tt r-VO rH Cl 0 Cl VO 0 p d d d v i Ov rn CN 00 Ov rH r - CN OV 00 rH O u-i Cl O O 0 d O v i 00 r- CN 00 l> r- r-~ VI u-i rH rH OV u-i Tt O OV d d d Tt VO Ov rn CN VO CN Tt rH r~ rH I-H O ui Tt O O d O d v i 0 Cl CN CN ui Tt Tt Tt 00 O rH O u-i Tt O O d d d v i Tt Tt VO 00 rH Cl r- 00 OV 0 rH 0 Ul Tt O 0 d d d v i 0 VO 0 r -u-i Cl rH 00 Cl VO rH 0 VO Cl O p d d d v i s ca ca -H CJ Z r_! GO O VI Cl Ov 00 00_ v i U-l Tt '—, u-i OV Ov VI 00 r~ c i VI c i Tt '—' Cl vq r-0 C l vq v i VI CN Tt u-i r- OS OO 00 V l Ov Cl '-H CN Cl OV VO Tt VO c i C l C l r-00 CN Cl C l ©v VI 00 C l VI VO SO CN SO Tt vd Vl Tt r- 0 ©V Cl 00 Cl r-' v i c i ©v SO CN t -00 0 so cn Ov VI Cl r~ SO 00 Cl Tt Tt v i C l © VO c i Tt v i CN 00 r-OV V! r-' C l Tt r-_ Tt CN v i u-i Tt C l 0 Cl 00 0 Tt F-' u-i d Tt 00 00 0 0 O Tt r-' VI 0 Tt ^ CN OV VI CN r> u-i Ov Cl rH 0 Tt C l r> OO O CN VO v i C l An% "N? 0 s-X < N? O 222 V OS P H CN 00 CN 00 uo Tf CN 1—< u-i Os' CN ©' ©' MlO-i uo P CN uo Os © MlO-i ro uo OS CN ©' ©' MlO-i 00 ro Tf o 00 Tf 00 © MlO-i co' uo Os' CN ©' ©' MlO-i OS r- 00 UO Tf 00 © MlO-i ro uo oo' CN ©' ©' Ui ro OS r- 00 Tf 1 00 CU CN uo ©d CN ©' ©' Ui CN © o o CO Tf t 00 P H UO o' CO © ©• UI SO CO CO uo CN 00 Tf P8- CN UO Os'CN ©' ©' Ui © Tf OS CN CO r-CO P8- CN " " 1 Os CN ©' ©' Ui SO Tf SO o © CO T-H P8-UO ©' CO ©' © Tf Tf CN CO Tf uo Tf P8-UO ©' CO ©' ©' CO Tf r-H Tf T-H so CN P8- uo ©' ro ©' ©' — uo CO © o © uo CN P8- CN uo ©' ro ©' ©' P8-c | Os Os rv 00 Tf T-H P8-c | CN UO Os CN ©' ©' Ui o uo r- uo uo CO T-H M6- CN uo Os CN ©' ©' Ui 00 CO Tf uo uo OS -M6- CN uo od CN ©' ©' I o CN SO OS Tf Os © M6 Tf uo od CN ©' © Grain CN o bo m o < o CN CJ U H MgO Appendix G . Electron microprobe analyses of plagioclase s. 'S CS c o sj s sJ T3 xi T3 x> x> -a -a xi J O x> x> T O X> TO T3 xi xi T3 T3 X> jo T3 T3 X ) xi 9 9 uo ro CN CN 00 CN CN UO CN Tf © ' OS Os OS CN 00 U0 Os UO CN SO T - H Tf © ' Os' -H OS Tf 00 T - H © uo r- CO SO T - H Tf © ' OS —' OS SO OS Os sq f~ ro 00 T - H Tf © ' OS Os CO UO r-CO Tf ro S0 CN Tf © ' Os Os © © SO sq 00 CN uo CO ro © ' Os T - H OS a CN , — i CO CN OX) 00 CN CN T - H CN Tf © ' © ' o T - H © 00 c o SO © CO Tf TO UO CN CN UO CJ CN Tf © ' OS C/l 03 — OS X ) CJ Ul SO T - H OS CN 00 CN SO "o ro ro © ' Os o T - H OS '5b CO "a UO 00 oo uo <*H Tf '—1 oo o ro ro © ' Os C — OS O 03 uo O 00 T - H 3 CN Os T - H Os CJ CO ro © ' Os 03 o OS C O © 00 T - H U0 ca - H CN © U CN Tf © ' © ' — H © SO UO Os Tf ro CN *—H CN Tf © ' © ' ~ H © _ uo CN ro 00 ro CN ro CN Tf © ' © ' T - H © — 1 Tf © CO uo • ' so ro p CN Tf © ' OS OS Tf 00 Tf Tf Os CN 00 T-H Tf © ' Os Os o o CN o "re 03 03 n o u z H ro SO © 00 so uo oo SO © T-H © ro sq © © C N * —' © ' © ' Tf C N Tf C N C O SO r~ SO T-H SO T-H © Tf uo © © C N * ~* © ' © ' © Os uo C O U0 so uo C N U0 T-H © Tf uo © © C N —< © ' © ' uo C N uo Tf O O Os uo uo C O C O T-H © Tf Vl © © C N — 1 © ' © ' Tf Os Os U0 C O C N Cs T-H Tf C N © Tf U0 © © C N © ' © ' _H ro C O uo 00 © uo OS C O C N C N © C O so © © C N — 1 © ' © ' r-~ r> © so OS T-H 00 Os r- 00 C N o C O uo © © C N — © ' © ' Os oo © 00 T-H uo uo 00 Os r- C N o C O uo © © C N — 1 © ' © ' 00 C N Os o 00 Tf 00 uo T-H C N © C O sq © © C N — 1 © ' © ' T-H OS C N uo 00 00 Cs Tf C N T-H © ro sq © © C N — © ' © ' -< C N C N ro C O T-H O O Tf C O C N o ro sq © © C N — © ' o' SO uo © Tf uo Tf 00 r- © T-H © co sq © © C N * — © " o' 00 C N ro C N © © so Os Os T-H © C O uo © © C N * ^ © ' © ' T—C Os Cs OS Os Os 00 oo r~ 00 T-H © ro Ul © o C N * — © ' © ' C N ro Cs uo SO uo C N © Tf C O © Tf uo © © C N * © ' © ' rf 00 00 ro 00 00 SO SO Tf C N T-H © Tf U0 o o C N o © ' + 60 O0 < Fe 2 CN © Cs t-H OS uo CN »n CN rv T-H t-H SO ro © © © ' © ' © ' uo' UO ro uo uo Tf oo SO CN 00 OS T-H © uo ro © © © ' © ' © ' uo' Tf © © © CN T-H 00 SO so CN T-H © uo Tf © © © ' © ' © uo' _ CN CN T-H SO T-H 00 Tf SO CN T-H © U0 Tf o © © ' © ' © ' uo CN © 00 SO CN ro t>- SO © Os T-H © SO ro © © © ' © ' © ' uo uo © Tf _ T-H oo T-H Tf ro T-H T-H SO ro © © © ' © ' © ' UO Tf ro ro Tf T-H ro 00 CN t> T-H © SO CO © © © ' © ' © ' u-i CN SO _ Tf Tf —H ro © T-H r~ T-H © SO ro © © © © ' © uo' 00 SO SO oo CN CN uo Tf Tf T-H © SO ro © © © ' © ' © ' UO 00 ro uo SO SO Tf © CO uo ro T-H © SO ro © © © ' © d uo o Cs ro r~ t> Tf © Tf Tf —H © sq ro © © © ' © © U0 CO CO Cs r- r- CN CN T-H NO T-H © sq ro © © © ' © ' © U0 l> © ro Tf Tf CN CN ro © OO T-H o SO CO © © © ' © ' © ' uo CN Cs Cs oo CN —H CN ro CN oo —H T-H SO ro © © © ' © ' © uo Tf U0 CN © r~ CS CS 00 Cs © —H T-H uo Tf © © © o' © UO © U0 _ SO Tt Tf SO Tf uo ro T-H o uo Tf o o © ' © © ' UO E 03 03 -3 u z OO 00 ro 00 uo UO CN so SO ro ' ' ro T-H SO Tf sq 00 uo OS ro r-oq CN 00 00 r-uo uo Tf —-, © © r-sq © oo so' uo Tf —' © Cs Tf Tf Tf r~ 00 uo 00 ro T-HSO © oq uo so CN CO —"' ro UO Tf © CO so so' ro U0 Cs oo oo © CO ©' SO SO ro oo © Tf oq © CN Tf SO ro ro —' r-Os rv © Tf © Tf SO CO ro ro © ro CN © Tf SO Tf ro 00 ro SO uo ro CN SO SO ro —— © SO Os CN CN © SO t>' ro uo so ro CN SO CN © SO r»" CO T-H © oo CN SO SO OO r~' U0 OS ro © oo Cs Cs Cs U0 Tf UO CN Tf —' s° Sj .o tfs r> X c x i T H < < O 223 VI © Ul u-i cn CN CN f - H Tf © Os' OS SO SO CN SO r -cn 00 SO - Tf ©' Os' Os Tf o u-i Os CN SO CN Tf d Os' OS SO oq u-i SO cn cn CN Tf d d © o Ul cn cn cn Os CN Tf d Os' Os Tf Tf CN Os o Tf 00 !> ' Tf d Os' Os Tf CO o 00 o r -Os Os vi ©' d o O cn © Ul cn cn o © CN Tf d d o i> F—( CN u-i CN cn cn Tf CN Tf d Os Os OS o cn CN Tf r~ cn Tf d Os Os r-Tf o Tf VI CN OS O CN Tf d d © I - H © CN Tf SO CN 00 00 CN Tf d Os' Os Tf 00 CN SO Os Ul OS cn CO d OS Os u-i ui u-i CN so CN OO l> CN Tf d OS Os Tf SO o o CN SO SO cn Tf d Os OS 00 © SO CN © cn ft"! Tf d Os OS CaO o CN ca z O CN 2 o Appendix G . Electron microprobe analyses of plagioclase cs cj c © o CJ "H. c E' 'j3 oo O 00 m cn Os 00 00 CN t-H CN u-i 00 CN d d Tf cn OS cn 00 cn cn ui oo' CN d c-OS VI oo Tf CN <o 00 CN d d u-i SO so r -SO 00 cn v-i oo" CN d d © O r-00 00 Os o cn ui oo' CN d d u-i SO SO p VI cn Vl od CN t—< d ui CN Tf oo p CN so' u-i SO CN t-H d SO OS SO OS Tf 00 t-H CN VI oo" CN d d cn VI t-H o VI r-cn t-H CN v> OS-CN d d Os Vl cn OS SO CN V) Os' CN d d t-H r-cn r- SO Tf Os o CN Vl Os' CN d d o t-H Os Tf CN Vl OS o cn ui OS CN d d Tf O O Tf Tf r -VI d cn d d SO CN so u-i o cn CN Vl OS CN d d t—H CN SO © 00 VI ui 1-H Vl d cn d d 00 sq Os Vl Tf CN VI Os' CN d d T3 t-J x i x i XJ XJ X i X) Xi xi XI XI X) X)' XI XI xi xi XI XI xi X) XI XJ XJ Xi XI XS X)' Xi X) X) bo <3 O O o ^ oo Ss CJ T? CO UH 2 CQ 3998 5621 ,0303 .0085 CN -1 © © 4299 ,5243 ,0404 0089 CN -1 © © .4148 .5498 .0255 .0073 CN o © .4286 ,5345 ,0294 .0075 CN © © ,4105 .5479 ,0334 6900 CN © © ,4411 ,5105 ,0366 .0105 CN — 1 © © .5511 ,4039 ,0368 .0078 CN © © ,4073 ,5515 ,0288 0073 CN — 1 © © .4011 ,5629 ,0259 0600 CN o © ,3559 6107 0229 0084 CN — © © 3905 5893 0156 0058 CN — 1 © © ,4084 ,5766 ,0176 .0059 CN — 1 © © ,3293 ,6351 ,0256 ,0078 CN © © ,3812 ,5875 ,0265 ,0087 CN — o © .3430 .6208 .0200 ,0101 CN —' © © .3687 .5984 0161 0082 CN © © ibo < + ci-i U P H 60 2 © © SO 00 © © i—H cn 00 Tf OS © ^H t-H Vl Tf © © © ' © ' © v i cn Os Tf CN Os (v 1-H CN SO © CN © VI Tf © © © © ' © ' V l t-H Vl © 1-H cn rv rv VI Os OS f-H © Vl cn © © © ' © ' © V l _ CN CN Tf Vl 00 OS CN r - © f-H © VI Tf © © © ' © ' © v i cn cn OS CN f- 00 C-OS Os f-H © u-i cn © © © ' © ' © ' v i VI © © CN r- Tf cn cn VI cn CN t-H U-1 Tf © © © ' © ' © ' v i m 00 © cn t-H CN © Vl VI 1-H Tf © Tf ui © o © d © v i © Tf Tf 00 Os SO Os OS Os Os —H © VI cn © © © ' © ' © u-i f-H CN u-i rv SO © 00 cn Os © t-H t-H u-i Tf © © © © © ' v i cn _ CN Tf VI Vl cn t-H Tf u-i t-H t—H SO cn o © © ' © ' © ' v i r- VI cn 00 VI SO Tf rv © 00 —H © sq cn © © © ' d © v i Tf Os © cn oo u-i SO 00 00 1—H Os Vl cn © Os © ' d © Tf Cv _ CN Os SO o t-H VI r - CN t-H © SO cn © © © d © v i 00 Tf CN cn CN Vl VI 1-H c —H © SO cn © © © ' d © u-i CN Os Tf u-i Cv Os ~H CN v-i V —H CN SO cn © © © d © v i 00 © CN CN Os CN u-i Tf SO t-H f-H SO cn © © d © ' © v i e CS ca U z OO OS oo v i SO rv rv' v i Os' cn © Ul Os Tf cn SO v i ©' Tf CN Tf Tf tr- 00 sq 00 Vl Os' cn Tf OS Tf © OS SO Vl ©' Tf —" cn cn m Cv oq 00 VI Os cn f-H © Tf Tf cn Tf CN Tf u-i CN Tf CN cn Vl Os VI Tf Os Tf Tf ©' v i cn © so oo rv © Os od u-i od cn cn CN Os © © oq 00 v i Os' m t-H VI VI rv Os CN cn SO Tf cn —"* cn 00 00 Tf Os V) od cn f-H cn Cv v> t-H CN u-i 00 u-i Os' cn t-H SO VI © SO SO i-H m Vl u-i Os © © VI © SO C^ ' m 1-H 00 CN VI so © cn SO Tf m CN CN m 00 CN SO v i m An% N? OS X> < o 224 Os 00 CO uo OV Ov SO rv' © Os" Ov ts Ov VO o 00 Ov T-H VO SO r-' © Os Ov r-Cv t> Tf © CO cs Tf - Tf ©' © © o cs CS cs uo 00 ts Tf © Ov Ov VO oq uo cs vO uo vo od uo " — l Ov Ov vo o o © Ov U0 Tf © OV vd © " © T-H CS CO cs 00 cs VO VO ro' CO © Ov" Ov vo r- 00 VO cs rv cs cs' Tf © © © o cs 00 r-© cs © ro co' © © © Ov o CO CS VO © CO Tf ©' © © r- Ov Ov Tf cs © Tf ro CO © ©' o vo vq Ov vq Ov Ov © CO CO © © © T-H o vq rv oo T-H CO 00 © Tf. ©' © © © CO cs CO 00 Tf VO © d UO © © © rv Tf uo CO uo Tf Ov CO d uo © © © Ov CO © Tf uo cs OV 00 cs Tf d Ov Ov Appendix G . Electron microprobe analyses of plagioclase UO 00 uo 00 uo 00 CU B o oo "c-H OO w cs eu a 6 "c3 oo O uo r- uo © © cs Ov" uo uo' cs ©' Tf VO Tf 00 00 Ov" uo Tf* CS ©' Ov uo sO 00 00 © CO* uo 00 CS Tf 00 CO uo Tf Tf cs" uo OS* cs ©' uo r- rv r-CN CN Tf uo CO CS UO © © cs 00 Ov Tf rv' uo SO cs ©' CO CO SO Os SO uo ©' CO © Tf oq 00 cs uo fv cs uo OS CS ©' OS so Tf Tf oq uo ©' CO ©' © © © 00 Tf cs' uo ©' CO ©' 00 00 T-H CO UO cs' U0 ©' CO ©' 00 Tf Tf Tf uo T-H uo ©' CO ©' rv OS so t> SO Tf co" uo 00 cs ©' CS rv OS SO rv Tf uo uo rv' cs ©' r-so © © uo Tf uo' uo oo' cs © ' rv oq uo © 00 rv cs uo OS cs ©' T3 XI T3 X> xi X> •a T J T J xi xi xi T - ; © - ° - ° Xt X) xi xi g Xt X) ©' Xi x> X) x» xi xi © CN X) X) xi xi x> x> XI XI xi xi X) x> XI XJ xi xi XJ XJ xi XJ so © XJ XI Xi Xi XI XI xi xi XI xi O0 -3 CJ TH ™ l _ ivi < U H 2 m oo u q ca Os rv l-H OS vO t- T-H © VO CO © 1 CN © ' Ov 00 Ov UO CO uo O T-H © vo CO © 1 CN T-H © ' U0 CO Os rv CN rv SO OS CN CO CO © Tf uo © © CS © ' © ' r- r- CN Os © uo Ov oo T-H © CO uo © © CN T-H © ' © ' c cj o oo c o XI T - H Tf Tf - H CS Ov UO CN CN T - H >—< Tf CO <— uo cs 00 CO © T-H © O © ' © ' © ' ,5623 .4209 0166 0043 CN -1 © © ,3457 6241 0238 0090 CN © © ,3953 ,5644 ,0256 0133 CN -1 © © .3526 ,6164 ,0288 ,0102 CN © © .3637 .6076 .0165 6600 CN — © © .3636 .6109 ,0180 ,0068 CN o © ,3421 .6303 ,0184 ,0091 CN © © .4422 .5336 .0158 ,0065 CN —1 © © ,5111 .4708 ,0159 ,0042 CN —1 © © ,5002 .4823 ,0151 • CN —• © .4048 .5572 .0267 .0097 CN © o c/5 < + m CJ U-i 00 SS tH cs CN CO Tf © 00 Tf © CO T-H uo © CO SO © © © ' © ' © ' uo VO OS Os CN CO uo oo CO T-H UO Os CO SO © OS © ' © ' © ' Tf" uo 00 CN OS Os T-H rv Tf rv Os i-H Ov uo CO © OS © © ' © ' Tf" VO © SO Ov 00 © CN CO © fv T-H Ov VO co © OV © ' © ' © ' Tf" uo OS Os SO rv 00 rv 00 co SO SO © Tf Tf © © © ' © ' © ' uo" Tf CN T-H 00 vO CO Tf rv CO cs CO Ov Tf uo © OS © ' © ' © " Tf" © rv CO rv CN 00 CN uo UO CO T-H © VO CO © © © ' © ' © ' uo' o rv OS cs © rv Tf T-H CN so © VO CO © © © © © vo rv OS C-- Tf CO CO T-H rv Tf CO T—H OS VO CO © OS © ' © © Tf* uo „ CO UO CN CO CO so Tf UO T-H © VO CO © © © ' © ' © ' UO* CO SO oo © Ov © CO CO CO uo i-H © vq CO © © © ' © © ' vo' VD 00 00 UO uo © CN VO CN © vq CO © o © © ' © ' uo UO _ Os CN rv 00 UO VO CN T-H © uo Tf © © © ' © ' © vo' uo CN 00 VO |v uo CN Ov SO CN OS Tf Tf © OS © ' © ' © ' Tf OS Ov <v CO uo uo CO © VO cs Ov uo Tf © Ov © © ' © ' Tf © OS uo rv Tf rv Tf Tf © oo T-H © VO CO © © © © ' © ' VO E C3 03 •o o oo CO Ov uo vq Tf CN CO vo VO 00 Tf CN rv uo CO CO VO uo' VO © uo CN CN rv 00* VO Os* CO rv Os SO © SO CN ©' SO rv' CO CO CN CO ro r-CO* Tf SO Tf so CO rv CO Tf Tf CO* Tf CS uo co' CO Tf rv Tf CN Tf* SO CO CO CO © OS rv Tf vo SO CO © Tf o Tf OO Tf* SO CO ro SO © SO SO CO CO SO Tf ro SO CN © rv SO CO CO sO Tf ro CN oo cs rv © vo SO cs ro SO Tf l Ov rv vo' vo cs Tf T-H © rv rv © 00 © VO vd Tf cs CN SO © oc Os UO ©' UO vd Tf CN uo Tf oo CN Tf Ov uo oc ro N? a < X) < 6 225 Appendix G . Electron microprobe analyses of plagioclase .S> 'u 03 o 4) C o u 73 CJ 3 C C o U d >< •5 c 8. < a CJ "a, c S '53 rt rb co O Tt u-1 00 cn Tt 00 Tt 73 73 Tt u-i oo CN 00 CN O © CN «/-> ON CN d d x i x i CN Tt d d o CO m r -NO u-i •q' Cl r -t -u-i Cl Cl <n d Cl d d x i X ) ci ci d d o ON 00 CN CN Cl •q ON u-i 00 NO CN Ul Tt Wt d Cl d d x> x i ci en" d d o F-H r -o T t T t r -Tt 73 Cl 00 © u-i CN NO •n ON CN d d X X CN F-H Tt d ON ON cn en u-i Ul Cl NO u-i o •q CN Cl u-i NO NO Ul ©' >n d Cl d d d X Tt ci d ON ON 00 ON 00 00 u-i u-i 73 73 r - CN 00 00 F-H ON NO <n ON CN d d x i x i ci ci d ON' ON ON NO ON NO r -T t ON O 73 00 NO Tt CN Ul CN CN CN m ON CN d d x i x i CN Tt d d o NO ON Cl o NO Tt T t rH 73 73 © F-H Cl o CN Tt ON rH Ul d Cl d d x i X ci F-H Tt d ON ON o ON NO o Tt T t T t 73 73 Tt CN ON ON f-H ON r-~ U-I d Cl d d X x i ci ci d ON ON © © u-i u-i ON Cl 73 73 NO Tt 00 00 CN CN O u-i ON CN d d X X ci rH ci d ON ON Tt r> NO Cl NO Tt 73 73 u-i o Tt Tt u-i ON Tt ©' Ul d Cl d d x ' x ' Tt Cl d ON ON r -u-i Tt U-l Cl 73 73 Cl u-i CN Cl Cl CN CN ON CN Ui ON CN d d x ' X CN Tt d ON ON r - NO Cl o u-i CN 73 73 Tt Cl CN ON 00 u-i CN u-i d Cl d d x " x i ci ci d d © r -ON u-i Tt 00 u-i - 73 73 ON 00 o NO NO f-H NO r> © ' Ul d Cl d d x i x i Cl Cl d ©N ON o r> Tt o Cl Ul oo o 73 73 u-i 00 u-i NO 00 CN Tt cn u-i ON CN d d x ' x ' - Tt d d o NO U-l CN r—t 00 ON o 73 73 ON ON NO ON NO Cl Tt 00 Tt u-i 00 CN d d X x i d Tt d ON ON o bo m q 3 Cl O (N CJ PH O 00 O rt m 9 oo O CS U O (N CS rZ O 2 O H o CO c o 73 CJ c/1 CS X CJ l / l CS 8 s CS GJ MH o c o © Ul ON Cl ON Tt 00 ON CO l > CN © Cl u-i O © CN f-H d © ' NO Ul Cl ON o rH T t ON Cl Tt CN © Cl N0 © © CN © © ' o f - NO CN Tt T t 00 u-i rH CN © Cl NO © © CN rt © © ' _H CN Tt T t Cl O u-i ON r - ON CN © Cl u-i © © CN rH © ' © ' Cl o r~- Tt O CN t-H © f-H Ul CN rH Cl NO © © CN rt © ' © ' CN CN u-i rH ON u-i © NO O t-H Cl NO © © CN —1 © © r - OO CN CN ON NO NO NO oo OO t-H © Cl u-i © © CN - 1 d © Cl Cl 00 00 Tt o ui ON NO t-H f-H © Cl NO © © CN © ' © ' rH Tt ON r> Tt Cl Tt ON NO t-H rH © CO NO © © CN © ' © ' NO u-i rn r ~ ON Tt r - CO Tt © CN © Cl NO © © CN " © ' © ' r - ON ON m t-H r- rH ON rH ui CN © Cl NO © © CN rt © ' © ' r> CN u-i ON o NO U-l CO ON !> CN © Cl u-i © © CN — 1 d •©' NO u-i r n © CO O r - oo u-i H t-H © Cl NO © © CN —1 © © Tt _ rH i n ON O © CN Tt CN © Cl NO © © CN — 1 © © ' CN o CN r n ON oo oo m CN Tt rH © Tt u-i © © CN —< © © rH OO i n © rH o NO NO r> © CN © Tt u-i © © CN —~* © ' © + CJ PH 00 00 < © © ON t-H r - NO Ul rH r - © NO cn © © © ' © ' © ' u-i © © ON CN 00 Tt ON 00 NO rH © ON NO Cl © ON © ' © © ' T t rH NO CN c n © Cl CN i n ND CN r H ON NO Cl © ON © © ' © ' T t ON u-i 00 Ul © Tt T t 00 rn NO t-H © NO Cl © p © © ' d u-i NO ON r n T t Tt Cl ON Tt ON t-H © ND Cl © © © ' © ' © ' u-i rH CN NO © m r - © cn Tt cn ON NO cn © ON © ' © ' © ' T t cn u-i r - T t NO CN Tt CN t-H r - r H © NO cn © p © ' © © ' u-i 00 Cl © oo u-i CN cn u-i rH © NO cn © © © © © ' u-i rn cn r n 00 t-H NO r H © Tt T t T—H © ND cn © © © © © u-i Tt © NO r H Tt CN Tt NO Tt r H l-H ND m © © © © © u-i ND NO u-i u-i © u-i 00 Ul ON © o o ND rn © © © © © ' vi rn oo cn 00 © © cn Ui rH 00 F-H © ND m © © © © ' © ' u-i Cl u-i 00 r -NO cn ON © Tt Tt © © NO m © © © ' © ' © ' u-i ON ON cn r n ON 00 ON u-i IT- rH o © NO Cl © © © ' © ' © ' u-i Tt _ Cl i n Tt 00 NO ON r - © t-H ON u-i Tt © ON d © ' © ' Tt rH ND u-i NO rn i n © Cl rn rn CN ONui Tt © ON © © © ' Tt CS s CS U 0O ON CN © CN ON i n © ' NO r - ' cn r n 00 NO T t cn ON ON SO NO cn © ' r -CN CN CN u-i NO CN cn I H r -00 u-i r -u-i Tt NO u-i cn Ul T t 00 T t 00 00 l > NO ©' Cl ©' T t CN 00 NO NO © Tt NO ci m Tt © © ON NO Tt NO ND* cn *"* Tt 00 ON ON CN CN NO Tt* cn rH © NO T t cn © Cl NO T t cn Tt Cl NO CN CN Tt' NO ci cn "~1 Tt Tt 00 00 NO ©' cn © ' Cl CN 00 u-i cn NO c-' Cl Tt ON © ON Tt NO T t Cl © i n ON © Tt ON NO NO cn © ' CN u-i NO Cl NO r~' i n ©' Tt I-H NO i n r -r ~ NO © ci i n Cl Tt CN NT N? vO CN ON >N = X X-< < O 226 Appendix G . Electron microprobe analyses of plagioclase .a 93 5 a © CJ CJ oo O 00 VO CS ool a a a a a oj "a- G E 'S3 oo O Tt © 00 Tt vo © Cn" v i Ov CS t-H ©' VO VI © Tt 00 VO © cn V, Ov" CS ©' ©' r ~ CS Tt © cn © VO © CO Vl OV CS ©' cn © VO r-© r-© v i Ov cs ©' O ov Tt CS cn ov © Vl Ov cs ©' ©' VI cn Tt © r--© cs Vl OV CS ©' ©' o v i Vl r-t— 00 © cn Vl Ov cs ©' ©' cs vo VD OV VI VI © v i VI r-' cs ©' ©' CS vq Tt Tt VO Tt r -© cn V) oo' cs ©' ©' c-© T—1 Ov vo © cn VI Ov" CS ©' ©' T3 T3 X> X> •a XI xi xi XI TO Xi Xi XI XI XI X) Xi Xi T3 TO xi xi T3 X) xi xi © 00 cn t-cn Tf CS cs' Tt ©' ©' © cn Ov cn Vl r-cn cn cn Tt ©' ©' o © CS cn cs Tt Tt CS Tt ©' ©' © t-H I-H 00 oo t-H cn r-cn t-H cn ©' Ov Ov cn vq cn © CS cn CS cs' t-H Tt ©' Ov Ov CS Tt cn cs cn CS CS cs' Tt ©' Ov Ov XI xi t-H vo cn 00 © Ov cn t-H cn vd t-H © VI cs Tt oo cs Tt vO Ov oo '—1 t-H Ov o o VI CS Vl t-» Tt CS 00 VI t-H CS VI Ov cs ©' ©' VI r-cs Tt oo VI ©' cn ©' ©' oo r- cn Tt o OV cs cs VI Ov CS © ©' © VI © Ov Ov v i VI r-' cs ©' ©' T3 XI xi xi XI xi XJ XI xi xi XI XI xi xi XI xi X> X3 XI XI X) Xi o 2 oo < o o o VD _H t-H r -© Tt cn CS CS Tt © ' © ' i-H © VO CS _ Ov V) cs Tt cn © ' vi © ' © ' r—H © V) © 00 _ cs Ov cn t-H f—* Tt © ' OV t-H ov Tt 00 cn t-H t—' Tt cs 00 cs' Tt © ' Ov Ov cs Tt Tt 00 Ov Tt VI © ' Tt © ' c-° t-H Ov VI Ov © cn m e'- CS Ov cn en © ' Ov OV Tt 00 r- Tt Tt cs cs Ov CS Tt © ' Ov '"H Ov VO V © Ov Tt oq cs cs cn cn © ' © ' t-H © *~1 r- OV oo VD Tt Tt CS Tt CS Tt © ' © ' t-H © Ov VI 00 Ov Ov vq Tt Ov Ov vi © ' Ov OV o q o CO o u z H c "J I $ 00 G o cs x> cj E/l •Eb| SS "E ,4045 .5590 .0390 .0039 CS -1 © © 4218 5480 .0285 0039 cs ~* © © .4148 ,5515 .0352 .0041 CS © © .3521 .6049 .0371 ,0050 cs © © .3822 5818 ,0319 ,0047 CS © © .3967 ,5725 ,0242 ,0051 cs © © .4194 ,5533 .0261 ,0051 cs © © .4994 ,4810 .0185 ,0044 CS © © ,4487 5307 0158 0046 cs © © 4119 5592 .0235 6900 cs — © © 4649 ,4778 .0465 0124 CS — 1 o © ,3535 6103 0281 0097 cs © © ,3980 5668 .0278 0100 cs — • © © ,3433 .6209 .0286 .0078 CS © © ,3899 .5706 .0308 .0078 cs © © .5175 .4409 .0336 .0074 cs © © O0 < + el CJ U H Mg cn VO r- OS VO Tt t-H 00 00 00 CS Os v i cn © Os © ' © ' © ' Tt Ov © VO 00 r- r- t-H 00 r> Cv cs Ov Vl cn © OS © ' © © ' Tt cn © cs © cn © Tt en 00 00 cs OS VI en © Os © ' © ' © ' Tt _ H Ov cn cn VD VI 00 OS Tt Tt i-H © vq en © © © ' © ' © ' vi cn © r> SO t-H Ov 00 OS cs VI i-H Os VO en © OS © ' © ' © ' Tt cs VD t-H Tt Ov VI 00 © r - t-H © vq en © © © ' © ' © ' vi _ l> OO VO Tt vo t> cs OO oo t-H Ov VI en © OS © ' © © ' Tt Tt ov r - en 00 Tt cn © © VI cs Os VI Tt © OS © ' © ' © ' Tt Tt VI _ Ov © cn cs VI v i cn cs © VI Tt © © © ' © ' © ' vi OV Tt _ Os © Tt cn Os Ov Ov t-H OS v i m © OS © ' © ' © Tt VI , | Tt Tt VI vO cn Tt CS © Vl Tt © © © ' © ' © ' vi Ov © Tt © t-H v i t-H © VI cn f-H © VO cn © p © © ' © vi oo cs cn VI r~ V ^ H © r-~ t-H © VO en © © © ' © ' © vi V) oo v i Tt VI 00 —H SO v i m wH © VO cn © © © ' © © vi © © © cs V) Tt VO Tt © Ov f-H l-H vo en © © © ' © ' © vi Ov VI OV l> cn v i vo 00 Ov cs o Tt Tt © © © ' © ' © ' Vl E CS CO CJ Z 00 Tt 00 © VO r--00 VI oo' cn cs r~ r- 00 VO VO r-' VI OS en CS cs oq cs en Tf Tf 00 VI oo' en CS cn vq © © oq en SO Tf cn © Ov r-r~ VO oq VO v i cn Tt Tt cs OS r— ©' VO tS en 00 r-_ t-H Os ov 00 v i oo' cn 00 cs oo 00 Ov en VI v i Tf cs' VO Tf Ov 00 Ov Tf Vl cs Tf cs' 00 r-Tf CS en 00 V Ov cn *—^  VD Tf vo r- VO VI cs VI en Tf cs t> vq Tf cs en Tf vO en cn VI © © Tf so V) ©' VO l> cn *-' tv >o en Tf en Tf SO cn cn VI cs VI VD v i Ov VI OO cn Ov vq en oo VI i> Tf oo' Tt cs' An% x= CA XI < s$ o 227 Tt o CN c i OS Tt r»' so © J O Ui fN 00 Cl r-00 00 Tt so SO © ' -ci u-i fN 00 IT- CN <r-i CS Ul C l r-' N O * © ' -ci Ul fN O N C l CN N O Tt Cl *o 1> SO © ' xi u-i fN r- C l Os © CN r_' 00 Ul fN Tt _ 00 r- t-H CN u-i r-' x i u-i fN c i NO 00 00 NO v i NO _' X u-i fN Ul fN u-i r> CN Cl © Cl' ON r—i © ' u-i CN Cl Cl © rt—t Cl oo CN c i oo _' x i u-i CN -Cl © Tt *T—{ Tt 00 ND Tt od © X u-i CN Os u i © © CN u-i © Tt ON © ' © ' u-i CN Cl u-i © © © Tt Tt I—' ' c! ON © © Ul CN r- 00 © 00 Tt Tt Ul © fN ON © © ' u-i CN r—l Tt O i> NO 00 © t-H ON © © Ul fN Tt ON Tt ON Cl Cl © CN ON © © ' u-i CN o 00 ON 00 ON r- ND_ © c i 00 © © ' Vl CN cn cn CN o o o o rs 60 bo Al Fe 2 u-i r~ Cl r-H O N C— CN Cl od N O ©' ©' © r-H O N r—l © O O r-O N 00 G O N O * ©' O N ON tr-Tt © © 00 CN r-od N O ©' O N O N u-i N O 00 r-ON 00 N O ' ©' ON ON Appendix G . Electron microprobe analyses of plagioclase a 'is » B S o 8 U OH a .13 o e o I H N O N O DH CN K C O rH N O OH CJ a c c i U co Cl CJ CO cj a, c 6 3 « rb co O T3 T3 x i Xi T3 -o X X •a -cs xi xi -a -a x x T 3 T 3 xi X T3 X X> •a xi © ON Cl NO ON Cl CN - Tt ©' od ON r> NO Cl u-i CN Tt © ON u-i ©' ©' © O u-i CN r-© Ul © Tt ON u-i ©' ON ON NO © CN t—i 00 Cl U-I Tt CN Tt ©' ©' © ON fN u-i Cl u-i Tt ©' ©' © CN Tt ON r-ON Cl 00 Tt Tt ©' ©' © © oo NO Cl .NO - Tt ©' ©' © Cl CN NO Cl ON CN NO 00 CN Tt ©' ON ON oo Tt u-i CN O CN Cl u-i CN* Tt ©' ON ON Cl © Cl ON ON CN NO Tf Cl Cl © ON ON NO 00 NO Cl ON Cl 00 -~' Tt ©' ON ON r-Ui 00 NO ON Cl © Tt ©' ©' © O o ° c« T; co CQ co CJ O tN CO c 60 o 00 c o •a CJ c/l CO X cj t/i rS o '601 <*H o c o .5685 .4201 .0141 I 1 • .4201 .5322 .0450 ,0001 42.12 53.36 4.51 CN © © © © u-i 53.36 .5613 .4239 .0160 1 1 .4299 .5248 .0450 .0010 43.00 52.49 4.51 CN © © © © u-i 52.49 .5796 .4100 .0108 1 1 .4204 .5272 .0460 .9940 42.31 53.06 4.63 CN © © © © Tt 53.06 .5901 .3985 .0107 I 1 .4124 .5363 .0463 .9942 41.45 53.90 4.65 CN © © © © Tt 41.45 53.90 .4090 .5352 .0428 I 1 i .5918 .4165 .0230 .01841 57.381 40.39 2.23 CN — 1 © © © © u-i 57.381 .5181 .4432 .0435 I I i .4678 .4841 .0416 .9983 47.09 48.72 4.19 CN —• © © © © Tt .5342 .4262 .0404 I 1 .4619 .5038 .0287 ,9952 46.45 50.66 2.88 CN © © © © Tt 50.66 .4053 .5587 .0461 .0045 .0019 • .5845 .3619 .0218 ,9847 59.97 37.13 2.24 CN © o o © © © Tt 59.97 37.13 .4182 .5407 .0409 i • ,5787 ,3974 .0215 ,9973 58.01 39.84 2.15 CN © © © © Tt 58.01 39.84 .4504 .5283 .0218 i i .5510 .4178 .0223 .9916 55.60 42.15 2.25 CN © © © © Tt 55.60 .4329 .5505 .0168 .0044 i • .5685 .4022 .0178 ,9931 57.25 40.50 1.80 CN © © © © © Tt 57.25 .4073 .5755 .0135 .0067 • • ,5948 ,3839 ,0170 ,9988 59.34 38.30 1.69 CN © © © © © Tt 59.34 38.30 .3933 .5847 .0170 .0053 .6098 .3757 .0158 .0017 60.58 37.32 1.57 CN © © © © © u i 60.58 37.32 .3665 .5990 .0276 .0048 • • .6388 .3483 .0167 .0018 63.34 34.53 1.66 CN — 1 © © © © © Ui 63.34 34.53 ,3953 .5853 .0256 0900 i .5817 ,3870 .0228 ,0037 58.31 38.80 2.28 CN © © © © © u-i 58.31 38.80 4395 .5352 .0235 .0055 i .5611 4110 .0225 9982 56.11 41.10 2.25 CN © © © © o Tt 56.11 GO < + "CJ U H Mg Ba M CO Ca Na Sum An% Ab% 0r% 228 Appendix G . Electron microprobe analyses of plagioclase ' 3 B Tt Ol OH c CJ o OH CJ a, g rt r"S oo O VO in o cn OV cn VD m l> CN d Tt 00 Tt m cn vd m r-' CN © VO Tt Tt vo cn vd in r»" CN d e'-en Ov cn 00 cn VD r-' CN d cn O m o m m r-' •n r~ CN d o 00 CN cn t> m vd CN d r-00 VO 00 VO cn vd m vd CN d Tt m O CN VO Tt vd in r-' CN d CN Tt VO o cn cn vd m r> CN d m o OV 00 Tt cn r-' m vd CN d r> OV CN t— o m vd in vd CN d r-r> in cn CN r~" m vd CN d o Tt CN Tt Tt cn m vd CN d VO Tt 00 m CN Tt r-' m vd CN d CN CN CN VO Tt r-' •n VD CN d vo CN r-cn cn r-~' m vd CN d o bo ci o <N < m O CJ U H •a xt " O "O TJ Tj "d TJ nd x i x> *o TJ *d 4 3 4 3 4 3 13 13 13 43 43 43 13 13 13 43 43 43 n—J T3 n—J 4 3 43 4 3 43 43 4 3 13 13 13 43 43 43 1 3 1 3 -a 4 3 43 4 3 1 3 XI 4 3 43 13 Xt 13 43 43 43 •a TJ TJ 4 3 43 4 3 13 XI 13 43 43 4 3 1 3 1 3 4 3 43 § 3 9 2 PH 00 CN Tt m r- cn vo OV in d cn CN O OV VO vo OV in d cn Tt cn r- OV VO OV m' d Ov Tt r-r- r-VO Ov m d 00 00 o Ov m' d 00 00 Ov VO 00 m' d m OV 00 00 Tt r-00 m' d Tt 00 o Ov in d cn CN r-OV VD Ov m' d Ov 00 Ov Ov o 00 00 m d r-00 o VO oo 00 vd d cn cn cn VD 00 00 vd d Tt m cn Tt 00 00 vd d cn m Tt Tt OO 00 vd d t> OV O Ov 00 vd d o r- m CN 00 00 vd d CaO O CB 2 O CN NH c CJ M , |1 00 e o | <*H o c o U 5421 ,4461 ,0132 0039 1 • 4538 ,5015 .0362 .9968 CN o o © © © Tt 5521 4365 0119 1 • 4440 ,5135 .0379 0966 CN -1 o © © © Tt .5385 ,4526 ,0120 1 ,4544 ,4993 0393 9961 CN "-• o © © © Tt 5353 4519 0127 I ,4575 ,5032 .0384 9990 CN r—1 o © © © Tt 5595 ,4306 0118 • 1 i ,4412 ,5058 .0402 9892 CN — © © © © Tt .5695 ,4220 ,0109 • 1 i ,4247 ,5215 ,0439 .9925 CN © © © © Tt .5630 ,4268 ,0121 i .0019 i ,4324 .5138 ,0424 9924 CN © o © © © Tt 5427 ,4414 ,0154 • • ,4536 ,5043 ,0399 ,9973 CN © © © © Tt .5517 .4423 TITO • • • ,4424 .5011 ,0399 ,9885 CN —• © © © © Tt 5647 .4249 ,0115 i i ,4282 ,5220 .0456 ,9970 CN © © © © Tt .5653 .4177 6910 i • • .4278 ,5247 .0496 .0021 CN — 1 © © © © m .5975 .3962 ,0093 i • .4012 .5343 .0495 .9879 CN © © © © Tt .5857 4028 0114 • .4120 ,5357 ,0484 9959 CN o © © © Tt 5866 3994 0143 • i .4113 ,5355 ,0481 ,9953 CN © © © © Tt 5743 4113 0139 • ,4225 ,5310 .0452 ,9982 CN '-' © © © © Tt .5830 ,4019 ,0105 • i .4204 .5381 .0471 6000 CN © © © © >n bo < + CJ U H Mg Ba V H 00 Ca Na N H Sum Ov m 00 cn Tt vq in Tt © m en © vo OV <n 00 Tt Tt •n en VO 00 CN VD OV m Tt ©' m en OV f- r~-en m 00_ m' Tt ©' m cn OV VD Tt CN © Tt Tt T-H m Tt OV 00 r--vq Tt Tt CN Tt CN m Tt in vq 00 oo 00 CN en Tt t-H in Tt vo Tt in m © © in Tt © •n Tt 00 Ov VO Ov VO © Tt Tt © m Tt © © CN Tt 00 m cn Tt CN m Tt OV VO vo cn m OV CN Tt CN in Tt en Tt CN CN © © Tt Tt •n in VO en oo r~ VO OO Tt cn m Tt Tt en CN 00 Tt OO Tt cn m Tt r-H en t> en m CN Tt en •n Tt 00 m 00 VO Tt cn m Tt N? N? \« c x X C 4 3 T H < < O 229 Ov Tf VO 00 r - VO o vd vd © ' d vo tN vo Ov UO r- t— r- o uo° r-' d d vo CN tN U0 CO Tf OV Ov 00 uo UO CN d vo CN uo CN Ov 00 CO VO uo' r-' d JO uo CN O IT- Ov f-H f-H CN oo' vd d JO u i CN Ov Ov 00 Tf CN T3 r-' vd d u-i CN o uo 00 to Ov CN "O r-' VD d x i uo CN CN CO o to 00 CO *o r-' vd d x i U0 CN Tt Ov CN o uo OV vd r-' d x i uo CN 00 Tf uo r-Ov Ov vo o u-i r-' d d uo CN _ vO 00 f-H oo uo Tt-' vd d x i U0 CN vo f-H r- Tf *o r- vd d x i uo CN r- CN o VO Tf ' o vd t"-' d x i uo CN VO 00 o o r- CO VD r-' d x> U0 CN Tf 00 uo VO o ro uo o vd r-' d d uo CN 00 uo 00 VO f—\ Ov uo p uo r- d d uo tN 00 Ov f-H r-Ov uo' © UO Ov Tf 00 U0 Ov UO © ' O 00 00 vq ro r-oo' uo' © CN r-Tf uo Ov VO Ov U0 © ' Ov CN Tf © Ov so' vd © ' Tf Tf 00 CN CO 00 00 vd © ' CN Ov VO o r-r-oo' vd © ' 00 Tf © CO oo' vd © ' 00 t— UO Tf Tf VD Cv u-i © ' OV O uo CO © VO d uo' © VO oq 00 CN © Ov uo © ' 00 Tf © ' 00 r-00 vo © ' OV Ov vo uo CN VD Ov uo © ' Tf o t-Tf Ov uo d u-i © ' CN r-r-uo vo Ov uo © ' VO Tf CN ro CO uo d uo' d Appendix G . Electron microprobe analyses of plagioclase B 3 O u o •55 o V 00 ©I OH CN -o OJ 3 a c o U d •>< •3 c u . I1 tj "H. 3 E '« c« .t oo O T3 T3 Xi X) X> X> X) T3 xi xi 73 TO Xi X)' T3 XI Xi Xi •a -a x i x i • - H 3 I 00 c o T3 tj c/l ca .o cj tyi ca - H ca .5582 .4202 ,0217 .0042 i l .4426 ,5051 ,0408 .9929 CN © © © © © Tf .5073 .4727 .0253 .0049 .0017 ( ,4794 .4719 .0333 .9965 CN © © © © © © Tf .5304 .3841 ,0724 ,0565 ,0017 l 4265 4981 0424 0120 CN © © © © © © uo .5226 .4544 .0235 .0019 i ,4702 .4853 .0395 9975 CN —' © © © © © Tf .6048 .3830 .0097 l ,3934 .5581 0513 0002 CN ~" © © © © uo ,5940 ,3950 .0097 • • i 4051 5460 0475 9972 CN © © © © Tf .5672 ,4230 .0094 l ,4283 ,5265 0440 9984 CN © © © © Tf ,5735 ,4198 .0100 • i l 4239 5258 0419 9951 CN — 1 © © © © Tf ,5170 ,4603 .0312 • 4707 4744 0365 9902 CN I—< © © © © Tf ,5075 ,4748 .0218 .0044 6100 i ,4844 ,4649 .0346 9943 CN © o o © © © Tf .5081 .4674 .0203 • i i ,4896 .4741 .0417 .0013 CN © © © © uo .5694 .4177 .0139 i i l .4243 .5267 .0446 9965 CN © © © © Tf .5202 .4635 .0137 i i i ,4810 .4845 0357 9986 CN © © © © Tf .5183 .4708 .0103 i i i ,4835 .4761 .0339 9929 CN © © © © Tf .5269 ,4549 .0187 ,0042 i i ,4697 .4873 0351 9967 CN —1 © © © © © Tf .4904 .4870 ,0196 ,0039 .0019 l ,5057 .4657 .0306 0047 CN © © © o © © uo 00 3 + CJ 60 2 Ba Sr Ca Na Sum OV uo 00 oo t-H Tf" Tf ©' uo Tf f-co © VO VO ro oo" Tf r-' Tf co" © vq Ov UO CO f-H Tf od Tf Tf VO 00 VO VO Ov lS Tf od Tf CO CO CN uo vq CN f-H Ov CO uo uo uo' r-UO 00 VD VO r-©' Tf Tf UO Tf oo 00 CN r-© Tf CN Tf CN UO Tf UO r-CN © CO CN CN Tf ro uo Tf UO Ov ro ro 'CN r— r~' Tf 00 Tf co' CN Ov uo Ov Ov Tf od Tf vd Tf ro © tr-vo Tf od Tf r-' Tf Tf CN vq Ov r-Tf CN Tf CN v-i Tf Tf © Ov CO r-UO od Tf 00 Tf ro r-VO CN OV Tf od Tf r-' Tf ro UO Cv CN uo r-' Tf 00 Tf ro oo CN Tf © © uo vd Tf ro s? •*•? An' XI < o 230 00 VO uo Tf ro CN Tf" © ' VO co 00 cn ro ro CN Tf © ' Ov uo fN O 00 ro Tf d Tt vq VO VO O Tf - Tf d vo 00 o r- Tf r~ vd d oo •o ro vo o 00 l> vd d r-co V) Tf vo fN fN Tf d VD fN VD ro OV fN fN Tf d 00 r— fN ro ro vq oo' vd d Tt vq uo ro Ov uo 00 vd d Ov V) Ov (N ro vo 00 vd d Appendix G . Electron microprobe analyses of plagioclase u TJ e CN 00 CN 00 V CN 00 c O a a. c E 'e3 oo O l-H 00 Tf CO ro © CN Ov d © U0 CN Tf Tf f-H VO 00 CN UO Ov CN ©' VO r- r»_ OV VO ro uo 00 CN © © uo r-VO UO uo ro' uo 00 CN ©' vo Tf Ov O Tf CO oo' uo uo' CN ©' Ov uo Tf CO uo CO 00 uo uo' CN ©' 00 oq CN r-l> CN U0 Ov CN ©' Tf © CN © oo ro' uo Ov CN ©' 00 © CN 00 Tf r-' uo vd CN ©' Ov VO 00 Tf UO ro t S UO vd CN © oo l> CN Tf Tf ro r-° uo vd CN ©' TJ TJ xi xi XJ TJ xi X> TJ T j T3 xi xi X) TJ TJ xi xi TJ TS xi xi r-© TJ TJ X)' Xi TJ TJ TJ Xi Xi X) TJ TJ TJ xi xi xi TJ xi TJ TJ TJ X)' Xi Xi Tf Tf UO f-' UO CN Ov VO © Ov TJ 00 Ov Tf ro Ov VO © ©' ©' xi Ov uo' © CN VD O VO CN VO © l> ">' © ' © uo CN TJ TJ X) xi CN Ov Tf vq Ov uo d Ov r- uo i> Ov VD © CN TJ CN Ov uo VO VD uo r-' ©' © ' ©' xi Ov V) ©' r-Tf Tf vo © ro TJ UO ro uo vq CN l> v i vd © ©' © xi Ov v i ©' CN 00 VO © VO 00 © v i vd © ' © uo CN TJ xi Ov CN 00 uo uo Tf vq CN Ov v i © oo' Ov r-O ° O ON O OO cj U H CQ oo U Z e u , OO si 00 c o TJ CU Vi 03 XI <U t/l es ,3867 .5799 .0255 .0051 1 I 6199 .3668 .0200 ,0039 CN © © © © © uo ,3956 .5669 .0297 ,0038 1 ( 6051 .3882 0192 9800 CN © © © © © UO .4371 .5372 .0235 1 .5631 .4145 .0222 ,9975 CN —1 © © © © Tf ,4365 .5391 0610 • 1 0025 5678 4113 0235 9998 CN — © © © © © Tf ,6220 .3635 .0114 1 .0038 .3777 .5828 0425 0037 CN © © © © © uo ,6407 .3460 ,0118 1 .0025 .3661 5789 0463 9923 CN © © © © © Tf .4041 .5602 .0263 ,0051 1 .6024 .3925 .0152 ,0058. CN —1 © o © © © uo .4095 .5604 ,0274 i 1 i .5958 3832 0167 9930 CN © © © © Tf .5773 3982 ,0163 • 1 i .4250 .5533 0363 0063 CN — © © © © uo .5861 .3990 .0120 1 ( .4148 .5521 .0340 9979 CN ~" © © © © Tf 5902 3960 .0116 1 1 4127 ,5463 0359 9927 CN © © © © Tf ,5084 .4653 .0270 .0042 .0033 .4837 .4680 .0398 ,9998 CN —• © © © © © © Tf ,5391 .4465 .0233 .0037 I .4481 4896 .0402 9904 CN — © © o © o Tf .5082 .4610 .0329 .0041 .0021 1 .4780 .4798 .0380 .0042 CN © © o © © © uo .5449 .4251 .0254 .0038 .0024 1 .4577 .5000 .0417 .0010 CN © o © o © © UO .5268 .4441 .0279 .0042 1 .4718 ,4827 0397 9971 CN © o © o © Tf OO < + m <D U H 00 2 Ba oo Ca Na i4 Sum CN vo CN OO Ov VO vd CO Tf UO © CN Ov oq Ov uo 00 CO CN CO VO Tf CN CN vd uo Tf CN Ov Tf CN Ov Tf CO vd uo © ' Tf CN VI Ov 00 CN CN CO UO Tf Tf 00 vo CN VO VO vd ro 00 uo Tf Tf ro VO VO © UO Ov' VI 00 ro Tf 00 Ov Tf vq Ov UO od ro Ov OO ro uo 00 uo Tf Tf UO ro Tf Tf vo Ov ro Tf v i uo ro OO Tf Ov VD Tf Tf UO ro CN Tf uo 00 oo Ov 00 Tf VD Tf ro UO VO 00 00 Ov © v i Tf Ov Tf Tf © 00 00 Ov t> r-' Tf r-' Tf ro V CN r~_ uo v i Tf Ov Tf Tf VO CN UO ro r~ Ov r~' Tf od Tf ro An% N? ov X> < N? w o 231 Tf Tf 00 cs ON CN CN* Tf d t-- CO 00 00 © NO NO 00 ON c s t-H c s uo 00° NO d CO c s ON Tf f-H 00 NO d 00 00 UO 00 00 00 NO * d d o o o uo r -uo © ' uo' d Tf 00 oo NO NO Ul ON UO d o CN ro CN ro ro CN Tf d Tf Tf Tf r -00 ro Tf d ON CN o oq o Tf Tf d Tf NO uo ON ro - Tf d UO CO ro ON CN O Tf' NO CO O © CN uo 00 ro CN* Tf d r> CO ro NO ON NO r - ' d Tf >n t-NO ro r - ' NO d o UO Tf ro NO 00 NO d Appendix G . 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CN 00 ON uo 00 NO ND XI CO l> d x i U0 CN CN r - o o c - uo Tf r-" d x i U0 CN 00 uo CO oo CO ON uo © CO f-° d © ' uo CN r - O CO CN r—i uo XI CN CN d x i NO CN Tf CO NO Tf 00 © CO oo' d © uo CN CO 00 Tf x i d Tf X> x i ND CN CN ON o oq Tf CO """""I 00 UO d XI uo CN r - Tf ) ( t> ON Tf XI tS uo d x i uo CN XI XI x i x i X) xi XI XI x i x i XI XI X i X i X) XI x i x i XI XI X i X i 2 T J © ^ XI XI x i x i XI XI x i x i XI XI x i x i XI XI x i x i C J CN CN O0 < P H O Q 00 CQ oo U q CO 2 03 o c °->, 00 M o oo 3 o XI CJ t/l 03 x> CJ CN © ON NO uo NO Tf UO ON r - CN © CO uo © © CN © ' © ' Tf 00 UO Tf CO © CO Tf CN ON © © 1 CN © ' t - © 00 uo 00 CN NO I-H p-H UO Tf © 1 CN © ' NO U0 ON NO p-H © r - I-H NO ro © 1 CN © ' Tf © 00 00 Tf © 00 t—H ON ON © © NO CN © © CN © ' © ' Tf 00 00 © NO CN CN NO I-H uo CN © U0 Tf © © CN © ' © ' CN U0 Tf © p-H u-i r - U0 CN Tf CN © UO Tf © © CN © © ' NO U0 ON UO CN ro CN Tf O r - CN © Tf uo © © CN —' © ' © ' i-H NO © r - Tf UO NO ON CN Tf Tf © 1 CN —1 © ' r - Tf © I-H r - ON r - ON p-H Tf Tf © 1 CN —' © ' U0 ND CN CO CN ro O U0 U0 I-H CN © Tf UO © © CN —1 © ' © _ _H ON Tf ro ON © r - t-H 00 -H © 1 cs —1 © © NO CN CN NO CN Tf Tf CN Tf CN o Tf uo © © CN —' © © ' ro cs t> Tf ON ON NO CN 1 1 CN — I-H U0 CS CN ON © Tf Tf t-H NO ro © 1 CN — © U0 Tf © I-H NO Tf © r - t-H NO ro © 1 CS © + 00 < O0 Fe 2 © © uo © uo r-uo NO © © r - t-H © NO ro © © © ' © ' © ' uo' 00 P - H CN CN NO © F - H © UO © UO t -H © NO CO © © © ' © ' uo i - H CN © 00 U0 NO © r -CO CO CO ON Tf UO © ON © ' © ' © ' Tf" NO NO 00 © NO UO © ON ON NO Tf ON CO UO © ON © ' © © ' Tf ro CN 00 Tf ro p-H © CN ro © uo 00 ro NO © ON © ' © ' © ' Tf uo CO ON r-r - uo cs co oo 00 CO © Tf Tf © © © ' © ' © ' U0 Tf ON uo © r - 00 c s 00 ON CO © Tf Tf © © © © © uo' CN ro _ rt 00 U0 ON ND ON l> I - H ON uo ro © ON © ' © ' © ' Tf t -H ro © t-H t -H CN r-H NO CN CN ON UO Tf © ON © ' © ' © ' Tf NO ON ro ON CO U0 ro © uo CN CN ON U0 Tf © ON © ' © ' © ' Tf ON r - Tf CO NO CN Tf r - O CN ON uo Tf © ON © ' © ' © ' Tf _ © CO ON © UO CO o i - H © r - 00 CN NO P-H ON © ' © ' © ' Tf NO CN © 00 CO 00 CN © oo ON CN o uo ro © © d d © uo' © © ON Tf NO NO Tf 00 o ro uo 00 CO NO © ON © ' © © ' Tf 00 CN © 00 CN t—H CN r -NO 00 Tf 00 CO uo © ON © ' © ' © ' Tf © NO CN 00 © ON NO r -t-H UO ro ON Tf uo © ON © ' © ' © Tf E 03 03 -3 o O0 CN CN UO uo NO © ' NO r--' ro NO ro ro CN r -uo' ON uo Tf ro U0 Tf U0 U0 © © CO Tf ro' uo ro' Tf UO ON ro © ON CO NO uo Tf © 00 r -Tf ro' ro ©' NO uo' ON P-H r -ON UO CN oo' Tf r - ' Tf CO ON © CN CN r - ' Tf ON Tf CO ON ON Tf ND CN ON ON UO o ' CO r ~ oq Tf ON ON uo U0 Tf CN © CN Tf ro ro uo uo CN Tf CN uo oo r -ro U0 CN NO uo © ' Tf CN © CN NO © ON Tf CN ND r - ' © ON © UO ON r - ' uo ON ro CN* ON NO © 00 © UO ©' ro ro NO uo* ON l> uo ON NO CN NO CO 00 uo Tf r -l> Tf NO © NO © ' Tf U0 U0 ro An% N? ov X) < o 232 Appendix G . 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VH GO Ca Na Sum An% Ab% 0r% 233 Appendix G . 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X < o 234 A p p e n d i x G . E l e c t r o n m i c r o p r o b e a n a l y s e s o f p l a g i o c l a s e it I-2 X) OJ I c o o d C ex v v V s rH I o 00 © 00 I o 00 V o 00 CJ 00 00 u 00 00 CJ 00 00 CJ 00 & c E 'fS w r*K oo O oq Tt Tt © Tt W0 Ov CS d d VO r-Ul Ov VO Tt cs eo uo 00 cs d d Ov CN u-i Tf Tt CN vo Ov CS d d TI-CS Tt cs CO Tt © cs vo Ov cs d d Tf Tt cs t> 00 CO CN vo 00 cs d d co 00 o cs VO VO © ' V0 d cn d d Tt o ir-es VO VO 00 o r-' V0 vd cs d d o u-i vq cs UO VD o vd vo vd cs d d 55.48 CO VO vd cs OV uo d x i X) 00 co 00 CO 00 uo vo Ov CS d d OV u-i Tt 00 VO VO uo d Ul d CO d d VO cs CO 00 r-UO VO d u-i d CO d d CO Ov Ov o uo Ov o u-i u-i vd cs d d Tt cn Tt uo VO uo VO © vo u-i vd cs d d u-i 00 Tt Ov CO VO VO p u-i UO vd cs d d Tt cs o VO Ov CS cn UO Ov cs d d ,• X> X) XJ X) x i x i x> x> X! X) x i x i x ! d XJ x i XI XI x i x i XJ XJ x i x i XJ XJ Xi X) vo ir-o o VO cs U0 00 es' f-H Tf d 00 Ov UO oq r-Tt i-H CO cs Ov —* Tf d Ov Ov Tf CS ir-es VO CS f-H Tf d Ov' OV cs CO 00 Tf CO uo oo cs' i—H Tf d oo' OV CS CO c-CS ir-es r-©v cs Tf d 00 Ov cs Ov o Tf Ov Ov TT CO CO d 00 Ov r-Ov oo CO oo r-Ov 00 U0 d Ov Ov Ov CO vO vq vo vo r-o Ov U0 d OV Ov O uo CO vq CO VO r-Tt Ov u-i d 00 Ov CO cs Ov CO cs O © CO CO d Ov OV VO oq Ov CS r-U0 CO CO d Ov Ov Ov CO 00 Tf Tf uo Tf' CO d Ov Ov r-vq Tf vq r-Tf cs Ov u-i d Cv Cv Ov Ul cs vq cs VO CO CO Ov u-i d 00 Ov r-Tf 00 U0 00 uo CN Ov U0 d Cv Cv CS CO CO cs VO cs CO cs Tf d d o 2 O0 < Q . q o o o o CJ Q CJ 9 . -Q oo o z I oo c o XI CJ t/l ca X) cj ui ca oo £2 *o-C*H o c o CJ 00 00 r-CN Tf ro r-00 CV f-H o CO UO o o CN —' d d CO r- CO UO uo UO 00 CO Tf f-H o Tf uo o o CN —1 d d 00 Tf o VO cs 00 Tf CV 00 f-H © CO UO o o cs' —' d d cs Cv 00 r-00 f-H Tf VO Cv 00 f-H o CO U0 © o cs —' d d Cv tr- 00 vO eo o Ov O uo CN o Tf uo O o cs' -- d d CO CO uo 00 CN CN i-H o CN Tf CN f-H CO vq O o CN —1 d d r - I/O VO vo f-H CN UO oo o CN o U0 Tf O o CN —1 d d VO _ o Ov CO Cv 00 CO Tf CN i-H o uo Tf o o cs —' d d u-i CN CN 00 VO O CO eo CS uo Tf o • CN —1 d Tt U0 Ov CN Tf CO r- o VO Cv CN H^ CO U0 © o CN — d d CN CO r- CO ui ro CN o — t vo CN f-H CO vq © p CN — d d Cv Cv VO _H CO Ul OV f-H o vo f-H i-H CO vq © o CN — d d CO © o ro 00 Cv r- VO CO ro •—H O ui Tf o O CN — d d r- uo Tf CN r- Tf Cv Tf ro ro i-H o uo Tf © o CN —' d d 00 uo Tf CN r- CN r-H Tf eo Tf CN o uo Tf © o CN — d d Cv OO vo Tf CN cv CN 00 r—« Tf CO o Tf UO o o CN d d + ro 60 OO < Fe 2 o o o Tt © Ov 00 vo uo (— CN uo f-H Ov VO CO © OV d © ' © ' Tf o 00 r- Ov U0 CN r- Ov r- Ov 1—H 00 uo CO © Ov d © " © ' Tf VO 00 Ov _ 00 eo U0 f-H © r- f-H © vo cn © © d © © ' uo' Ov © © uo uo CN © Ov © r- CN OV VO ro © Ov © ' © ' © ' Tf" © vo Ov rt VO Ov UO Ov © r- l-H Ov VO co © Ov © © ' © ' Tf Cv Tf © CN © UO Tf Cv © f-H © vq CO o © © ' © ' © ' uo _^ r-uo CN U0 co ro r- Tf VO Tf Tf © Ov © ' © ' © ' Tt VO uo VD eo r- Ov OO r-UO OV CO Ov Tt Tt © Ov © ' © ' © ' Tf 00 r- VO Ov uo Ov VO VO VO Ov eo Ov Tf Tf © Cv © ' © © ' Tf' Tf UO 00 r-r- Ov eo VD Tf Tf t-H © VO CO © o © ' © ' © uo r- CN r- © Ov CS Ov ro r- Ov © Cv VO CN © Ov © © ' © Tf Cv © uo Ov VO ro oo 00 o 00 © Ov r- CN © Ov © ' © ' © ' Tf _ © eo © © VO r- Tf r- Ov cs Ov Tf Tf © Cv © ' © ' © ' Tf _H OO CO © f-H Ov VO ro r- Ov eo © Tf Tt © © © ' © ' © ' u-i CN r> r- VO i-H H^ CO CN VO Ov CO Cv Tf Tf © Cv © © ' © ' Tf _ Ov oo uo 00 i-H Tf 00 Cv r- 00 UO eo © Cv © ' © ' © ' Tf E ca ca -J CJ Z i4 oo U0 ro Ov ro Ov Tf CN vo uo' ro '—, vo oo cs uo 00 r-r-' uo Ov ro © uo VO 00 U0 d VO r-' eo —H CO eo © OV ©v © VO r-' eo l-H VO OV VO uo 00 uo OV uo r-' eo '"•1 vo 00 OV Ov oo © r-vo OV cs CN Tf OV CN f-H p-uo' Tt Ov Tt Tt Ov vq VD 00 uo oo uo Tf Cv Tf CO Ov Tt VO 00 uo vq vd Tf Ov Tf ro Tf eo CN uo ro ro VO Tf CO ro uo VO Tf oo Cv od VO Ov CN ©' ro © eo © Tf 00 © ' r- od CN ©' ro © CN vq ro r-r-' Tf OV Tf CN 00 U0 CN Tf Ov uo vd Tf Ov Tf CO uo uo eo vo © Tf vd Tf Ov Tt eo* cs cs uo Tt Ov Tf © ' VO r-' CO An% N? tjv X) < N? o 235 Appendix G . Electron microprobe analyses of plagioclase e i -TS B O , S _-CJ cj u. U tsx| B Tj CD I C o O O * -3 c I I c 1) MP2-i c i IT) 00 Tt © vo MP2-i ©' Ul © Cl ©' ©' MP2-i cn Ui r f r- r> VD MP2-i ©' Ul © C l ©' ©' i O 53.17 28.04 1.05 0.14 u-i vq 00 CN OV © Cl I o ci u-i od CN ©' CN 00 r-© VO 00 Ul 1 o © u-i OV CN ©' ©' CN © oo r- OV rt 1 o CN u-i oo' CN ©' ©' VO OS Tt © Cl 1 a ci u-i oo' CN ©' u-i r» VO CN VO VO rt i o ©' u-i ©' Cl ©' ©' 00 Cl Cl vq r~ VO VO • a Ul OV CN ©' ©' V-x 1 o o o Ov u-i vo Cl r—l cu u-i ©' Cl ©' ©' I Cl 00 © Cl u-i ui PH Ui ©' Cl ©' ©' l-H 1 o u-i © CN oo Cl -Pll CN u-i Ov CN © ©' CJ oo oo © oo r t © Pll Cl u-i OS CN ©' ©' V rH CN Cl Cl r-r t © EC ci u-i Ov CN ©' ©' Mll-r 51.42 29.90 0.67 0.17 t-t I VO © OS vo u-i Cl Mil © Ui Os CN © ©' Grain o bo m q < o CJ U H MgO TJ TJ X5 X> X X TJ TJ X> X X X TJ TJ x xi X X X X 9 9 03 &o CN rt Cl CN Os SO r t ci ©' OS Os Cl CN rt CN © CN CN 00 rt ci © ' OS OS 00 r-Ul r t cn cn so OS r t © 00 Ov rt Ov u-i u-i Cl Cl 00 - rt" © ' Os Os r t Ul CN © © CN rt © ' 00 Os r-r t CN u-i CN 00 r-CN f-H r t © ' 00 Ov Cl <q r t r t OS CN OS Os CN f-H r t ©' Os Os r- VD Ul 00 SO CN Cl cn ©' Cv Cv rt Os OO OV VD © Cl Cl ©' Ov OV VO CN VO Cl Ov © u-i r t Cl ©' ©' © VD vq vo rt © CN Cl u-i ci Cl ©' ©' © u-i u-i u-i rt CN CN CN rt © Cv Cv rt Cl rt 00 CN © CN rt ©' Cv CV Os OS cn © Cl oo Ov CN rt ©' CV OS 00 rt Cl 00 u-i u-i ci Cl ©' Os Os © CO Cl vo Os rt ci ©' 00 Cv CaO o fN CS z O fN id 73 o H o 00 c o TJ CJ CO CS X CJ Ul JS 73 o '5b| V— O c o 00 r- f-H VO rt Ul r t © f-H r t CN rH Cl vq © © CN -H' © ' © Ul VO Ul OS © SO r t © fH u-i CN rH Cl vq © © CN ~* © ' © ' Cl 00 rH Cl 00 u-i VO Ov Cl f-H C l o r t Ul © © CN —' © ' © ' 00 rt rH OS 00 U-l 00 Cl rH C l © r t Ul © o CN —' © ' © ' r t Cl rn CN Cl Cl © © SO Ov Cl t-H cn Ul © © CN —' © ' © ' © u-i r» r-u-i f-H rH OV Ov VO Cl © Cl u-i © © CN —' © ' © ' OS CN r t VD © u-i 00 f-H Ul Cl © r t u-i © © CN —' © © ' VO 00 © r- CN OV Cl Cl CN © Cl vq © © CN —' © ' © ' Ul u-i C l f-H © rt Cl f-H VO © CN f-H Cl vq © © CN —' © ' © ' CN Cl CN 00 u-i Cl CN 00 rH Ul CN o Cl vo © © CN —' © ' © ' rt VO rH Cl rt VO 00 © rt Cl rH rH Cl vq © © CN — © © ui rn r t CN rt Cl 1— © r> rH © rt u-i o © CN — © ' © ' © CN VD Ov 00 00 VD VO rH Ul f-H © rt u-i © © CN — © ' © ' VO CN © Ul CN r- VD vo f-H vO rH © rt Ul © © CN —1 © ' © ' Cv _ rH VO rH CN Cl rH u-i rH CN rH cn vq © © CN —1 © ' © © © u-i CV rt OV oo Cl CN f-H © Cl vq © o CN © ' © ' + CJ U H OX) bo < 2 u-i 00 CN 00 © SO CN r t © OS rH © t - CN © © © ' © ' © " u-i CN 00 Ov Ul t- VO f-H 00 Ov 00 f-H Ov VO CN © OV © ' © ' © r t © 00 u-i r-Ov u-i OS C l r- Ov f-H OV u-i Cl © OV © ' © ' © ' r t 00 r t Cl 00 rH r t © VO r~ © CN Os u-i r t © Os © ' © ' © ' r t rH VO rn OO Cl Cl Ul 00 Cl r- rH f-H VO Cl © © © ' © ' © ' u-i Cl VO OO u-i Ui u-i r t C l rH r~ f-H © VO Cl © © © ' © ' © u-i CN r- oo Ul © SO oo 00 OV rH Ov u-i Cl o Ov © ' © ' © ' r t VD © t— rH rt © Cl r> rH rH © VD Cl © © © ' © ' © ' u-i VD rt © u i VO VO r—. Cl r t r t r—« © VD Cl © © © ' © ' © ' u-i VO © OO 00 Cl VD © Ov Os Ov rH Ov SO CN © Ov © ' © ' © ' Tt oo Cl r t Ov f-H Cl rH u-i VO © f-H oo VO Cl © Ov © ' © ' © ' Tt CN © © oo u-i oo Tt Tt rH VO rH Ov vo Cl © Ov © ' © ' © Tt Cl VO u-i Cv rH © VO r~ Os Cv rH Cv U-l Cl © Cv © ' © ' © ' Tt CN rt VO CN u-i r~ r-Ov 00 rH OV u-i Cl © CV © ' © ' © ' Tt VO Cv r- Cv © O © © vo Cl rH O SO Cl © © ci © © u-i Cv VO Cl rH H Cv r t Ov © © Ov VO Cl © Os © © © ' r t £ co CS rr U z GO r-VO © Ov oo' VO Os CN Ui CN OV Tt OV Os so 00 CN OS SO r t r t u-i Ov r-' u-i OS cn rH r-00 cn CN CN © vd u-i ©' Tt CN r t C l © CN VO r t VO VD Cl ^ © VO OS OS vo r t ©' VO vd C l u-i Tt CN © r-SO oo' u-i OV Cl VO SO CN Cl u-i vd vo Cl Os sq CN 00 © cn SO Tt Cl cn r- Cl Cl © oo' SO Ov CN VO © Tt r-VD r»' VO ©' Cl Tt CN Tt VO Cv Cl VO vd Cl CN 00 VD 00 Tt vq od u-i od C l - © u-i Tt r-OV u-i od C l VO Tt SO u-i © u-i VO" CN Cl 00 Cl CN oo Tt Ov 00 vo OV CN © ' An% N? X < O 236 r-uo Tt o p o u-i ON CN l-H d NO r-CN CO NO NO CO f—t ©' ui d CO d d uo NO 00 00 CN NO CO ©' u-i d CO d d oo NO Tt Tt uo CN ui d CO d d 00 00 00 ON ON uo CN Ov d CO d d u-i p ON CN o o © u-i d CO d d CI Tf CO CN u-i d CO d d •> 00 NO CN © Ul d CO d d u-i © Tt uo NO CN u-i d CO d d Tf o NO NO NO CN d Ul d CO d d o NO ON O o CO CN Tf d ON r-Tf uo © CN co t-H co' d NO CN r-CO Tf Tf CO d 00 © NO CN CN CO co' d rv Tf ON CN VO Tt CO d ON NO 00 uo o CN co' co" d A p p e n d i x G . E l e c t r o n m i c r o p r o b e a n a l y s e s o f p l a g i o c l a s e a £• u its c © u , *» XJ OJ 1 c o CJ O •3 c d> , C U £ '« XI X) xi xi XI X3 X i X i X) XI X i X i XI XI X i X i X! XI x i x i XI X>' XI X) x i x i CO ON ON CO 00 NO d UO d CO ©' © © CN ON © CN f-H UO © CO © NO Tt NO UO © U0 d uo ©' CO © ©' CO o NO NO UO NO uo f-H d uo ©' CO © ©' 00 Tt NO 00 Tt NO NO d uo © CO ©' d 00 Tt CN r-ON l> CO d uo ©' CO ©' ©' o 00 m q < m o CN CJ [IH o 00 t-H U0 CN vq ro CN U0 ON CO CO © ON ON Tt ON t—H UO vo ON 00 ro' ro ©' ON ON © © ON UO ON U0 Tt ro ©' ©' © ON © Tt Tt ON CN 00 Tt ro ©' ON ON ro 00 NO Tt © CN CO OO ro to d ON ON ON ON Tt uo CN 00 ro CO © ©' © NO ro © to CN CN Tt r~ Tt ro ©' ON ON o uo - ON © CO Tt ro © ON ON ON CN NO tN 00 00 00 Tt ro d ON ON ro cs uo CN ON ON r-Tt ro © ON ON O CO 2 o CO q CO o fN m 00 CJ z c cj 6i | l 00 a o XI CJ in CO x> CJ t/l •2 "o '5o| CO .3871 .5774 ,0342 ,0065 CN © © .3285 .6395 ,0228 .0087 CN © © 3101 6598 ,0212 0088 CN -1 © © .3339 ,6372 0186 0085 CN © © ,2910 .6772 ,0204 ,0085 CN -1 © © ,3360 .6334 ,0240 ,0068 CN -1 © © ,3432 ,6277 ,0245 0084 CN © © ,3154 .6557 ,0235 ,0079 tN © © ,3256 ,6394 ,0228 0081 CN i-H © © .3191 .6482 .0226 ,0079 CN © © ,3271 ,6362 ,0298 0106 CN © © ,3301 ,6230 0375 0081 CN © © ,3111 ,6494 ,0240 ,0101 CN © © ,3017 .6625 ,0227 ,0101 CN —• © © .3067 ,6621 ,0222 ,0110 CN © © .3095 ,6565 ,0271 ,0092 CN © © OO < + CJ PH oo 2 ON CN NO ON CN © r- UO t—4 NO t-H ON NO CO © ON © ' © ' © ' Tt ON ON 00 © r- Tt f-H Tt t-H f-H © NO CO © © © © © uo" ON CO 00 NO r- 00 CN ON ON © © NO CN © © © ' © © UO ON © r-. Tt 00 CN CO r- f-H t-H © vo ro © © © ' © ' © u-i tN ro Tt ON CN ro ON t-H t-H ON O I-H r- CN © © © ' © ' © ' uo' ON r - Tt CN © r-- t-H © f-H t-H © NO CO © © © © ' © ' uo' NO CN Tt © ON © CO uo CN t-H ON NO CO © ON © © ' © ' Tt © © Tt 00 CN t-H ON Tt 00 f-H © © NO CO © © © ' © ' © ' uo' Tt 00 _ ro CO vo t-H oo f-H t-H © NO CO © © © © ' © ' uo' 00 © CO ON Tt CO 00 © t-H © NO CO © © © ' © ' © ' uo © CO NO NO t-H 00 O t-H ON VO CO © ON © ' © ' © ' Tt r- CO Tt ON oo Tt t-H r-- © © NO CO © © © ' © © U0 Tt ON r- NO Tt CN CN Tt © ON f-H © CN © o © ' © © uo' vo NO _< Tt Tt r- t-H © f-H r- t-H o CN © © © ' © ' © uo UO © VO ON ON © f-H ON 00 f-H © NO CN © © © ' © © ' uo' ro © H^ NO r~ oo t-H 00 ON 00 t-H ON NO CN © ON © ' © ' © ' Tt £ CO CO -3 CJ z OO NO Tt CN t-H VO VO NO CO © ON © VO vo' NO CO *—' t -00 UO Tt CN 00 od NO ON CN ©' NO UO NO CO uo CN NO NO CO ' 1 © NO ND NO CN ON ON NO 00 CN ©' Tt NO NO UO CO t-H vd VO CO uo 00 r-ON Tt CO uo' NO CO © uo 00 r~ CO ON r-NO ©' CO ©' Tt © oo © ON © r-' NO CO © © 00 © od NO ©' CO CO CO NO Tt uo l> NO ©' ro f-H Tt CN Tt uo Tt r-' NO ©' ro UO © r- UO CN ON NO od CN UO ON ro © ©' r~ tr-' CN ' 1 UO CN NO uo © ON NO od Tt CO Tt NO © ON NO od CN An% N? ON X) < N? o 237 m © r t r t m' © 00 vo rs VO o r t rH Tt' d r-Ov © 00 vq r-' vd Appendix G . Electron microprobe analyses of plagioclase r t m i X col r-U co c-CJ co o to J a a a a c CJ o Ti, e E '53 rt ."s co O Ov CN r- 00 OV r-i r- o Cl" oo" © ' d <n CN VO VO Ov OV © VO © ci OV O © ' m CN 00 r- o rH* r> r> 00 V_l r> m' © xi m tN o r t CN © rs r t r- rH ci OV d © ' i n CN «i Ov CN H 00 o r- rH rs OV d © ' m CN o cn © OV rs ov r- © r-i oo" d © ' cs m CN r t Ov vo r t O © ts OV , — * d m CN OV CN i CN m r- OO >—i d d d © ' m r-i 00 r- o © < CN p ' — ' r-i oo' r H © ' m tN o r-i _ © p ts Ov rH rs Ov" d © ' i n CN _ Cl Cl r t Cl Ov rH r-H d d © ' m Cl r-i vo o CN 00 i n C l rH CN 00 rH © i n CN OV OV r t Cl CN r t CN * — 1 ci 00 ,—i © ' >n CN r- 00 O rH f - p - Ov rH CN OV d © ' i n CN m r n r t r> 00 Cl Ov CN ci r-' rH © ' m tN 00 r n m © m O CN rH ci OV , — * d i n CN •a xi TJ TJ xi x TJ TJ xi xi r r TJ TJ xi xi TJ TJ xi xi © Cl rt Cl 00 Tt CN r t © ' © ' © rH TJ TJ X> xi TJ TJ xi xi TJ X TJ X TJ xi TJ TJ xi xi TJ TJ xi xi © CN Cl Cl Cl CN VO cs' Tt ©' Ov Ov m 00_ VO vq m Cl 00 r-rH Tt ©' Ov Ov Ov m m CN m Cl O Tt cs Tt © ©' © m cs CN Tt 00 OV 00 rt rH ci © Ov OV CS vq r-r~ © rt m Cl - Tt ©' Ov Ov Tt m m cs © Cl Cl Cl cs rt ©' Ov OV r> vq © CN VO Cl ci ci ©' ©' © Cl Ov r> rt © rt VO rt ©' Ov Ov Ov m Cl m Ov Cl m VO rt ©' Ov Ov vo Ov CN © Cl m Ov CN rt ©' ©' o Ov © m rt Tt r> © m © OV Ov VO Ov rt rt m Cl OV VO rt ©' d © • -,^5 c j « i ! r r t T , r t r t r< C O < r H r H O Q C O U 2 r H CM VH o c o CJ .4522 .5160 .0263 .0053 i .5424 .4413 .0253 ,0089 CN © © © © © m .4341 .5424 ,0226 ,0059 i • 5645 ,4040 ,0227 9963 CN © © © © © Tt .6039 .3687 .0272 i i .3847 5251 0964 0061 CN — 1 © © © © m ,4039 .5676 .0244 9900 i • ,5955 3864 0181 0024 CN © © © © © m ,4079 ,5623 .0248 ,0073 i • 5956 3812 0195 9986 CN © © © © © Tt .4196 .5507 .0238 .0062 i i ,5774 4109 ,0205 0091 CN r—l © © © © © m .3867 .5721 .0354 .0064 i • 6116 3733 0204 0900 CN © © © © © m .3051 .6565 .0281 .0079 i • ,6983 ,3032 ,0106 0097 CN © © © © © i n .4317 .5237 .0345 .0070 i • ,5694 ,4227 ,0235 0124 CN r—< © © © © © m .3826 .5784 .0312 .0070 i 6154 3779 0178 0103 CN © © © © © i n .3360 .6244 .0311 0600' i • .6675 ,3238 ,0114 ,0032 CN © © © © © m .4123 .5372 .0447 .0079 i • .5838 3961 0233 0053 cs © © © © © m .4280 .5300 .0425 ,0087 i i ,5657 3999 0226 9973 CN © o © © © r t .3792 .5823 .0304 0075 i 6262 3602 0175 0032 CN © © © © o m .4561 .4681 .0665 .0185 i .5329 .4434 .0264 ,0119 CN © © © © © m 4168 5421 0423 0070 i 5783 3886 0204 9954 CN © © © o © r t CO < + m CJ U H 2 Ba tH CO Ca Na rH Sum 00 rt m Ov Tt ci m ci Tt CN vo CN m 00 CN vd i n © Tt CN Cl cs Ov 00 m 00 Cl CN i n Ov" VO 00 Cl © OO Ov' >n oo" C l m Cl 00 Ov r t Ov OV m r-~" C l *~* OV 00 00 Tt CN © vd i n ©' r t cs m r t O OV CN © ©' VO vd Cl CN VO r t C l r-r t © oo' VD OV CN 00 vq Tt Cl © C l m'm r t r-i ' Tt r t CN m © VD r~' Cl 00 OV © © Cl m" vo CN Cl Tt r-00 © C l ' i n Ov Cl CN m r-rH r~ CN VD m d r t CN CN Ov VO Cl VO i n Cl —* OO rH CN r t CV m CN m ci r t CN VO rH 00 © i n © 00 m Ov Cl CN An% N? N? ^ r o 238 Appendix G . Electron microprobe analyses of plagioclase u © fcC-CM > 93 l-J (3 a a OJ a< c E 'c3 C rfa O Tt Ov 00 oo c i oo © u-i tN t-H O tn Tt —' ©' u-i C l O O Ov Ov t- O VO O 00 Ov Tt r- ut © —< d d d u-i c i XJ X> X> x i X) X) X i X) XI Xt XI X> fN r- fN 00 _j _j vq c-- © c i . . Ov u-i vd wi X x Tt p-H t— c i OV VO © © u-i tn 00 Tt u i vo c i vo r- © Tt od © © ' Ul fN XI XI X> X> XI XI x> xi CN Cl r~ © oo © Ov c i — i © r- vo •-H © CO Ov Ul CN © © X> X> XI XI X) xi c i cn fN CN OO I— I - H ' © ' © ' u-i tn cn vo 00 Tt © cn oo oo vo © © © oo © — < © ui c i l> r-H oo vq oq rv c i od u i CN XI XI xi xi XI X) x> xi © © OV -H u-i cn ov Ul fN — i Ov © ' XI XI —< © © © Ul CI r t 2 -a x i X i X i Ov © VO oq Cl Ul Ov Ul Ov u-i © 00 Ov 00 Tt © r-Cl CN Ov Ov en i—t c i © Ov OV o u-i 00 Tt CN r-Cl c i p-H c i © © © CN VO Cl Cl Tt © rv Tt c i © Tt Ov © © u-i fN © CN Tt c i © ©' © cn cn 00 00 VO Tt T-H Ul r-H r-H Tt ©' d © t-H CI Tt Cl vq Ov VO © Ov u-i ©' © Ov Cl © Ov Ul © Tf VO © CN r-H Tt © © © CN Ov u-i u-i Ov Tf u-i c i c i © © © Tt 00 Tt vq fN fN Ul c i f-H c i © Ov Ov Cl Tt fN oq 00 CN Cl 00 c i c i © © © Ov vq r~ u-i Ov Cl CN © - Tt © © © VD vo VD u-i Cl Ul CN - Tt © ©' © Cl Tt Tt Ov u-i CN VD u-i c i f-H c i © © © C O < £ 2 P Q C O U Z N H c cj o 00 c o x> CJ Vi JS T> o '5b cd "E. t+H o e o Cl Ul u-i Ul © 00 © u-i u-i f-H Cl © u-i Tf © o CN -' © ' © ' CN 00 _< Ov 00 CN rv u-i Cl Cl CN © Cl vq © © CN © ' © Ul © Ov u-i CN Ov u-i Cl Tf T-H © Cl vq © © CN r-H © ' © Ov VO 00 vO T-H u-i u-i Ov r- CN fN Ov Tf Ov CN Cl fN © ' © ' © _ Tf Tf 00 Cl T-H T-H Tf T-H VO fN © Cl vq © © CN — • d © Ov Cl VO Cl © f-H u-i Tf u-i CN CN © Tf Ul © © CN © ' © ' VO Tt T-H CN Cl Ov u-i © f-H Cl © u-i Tf © © CN — ( ' © © ' Cl Ul CN T-H Cl Tf u-i VO f-H u-i CN © Tf u-i © © CN "-1 © © ' Tf o VO u-i Cl 00 Tt vO CN Tf CN © Cl vq O O CN — • © © _ oo u-i Tf u-i T-H Cl u-i CN Tf fN © Cl vq © © CN —' © ' © © oo tN u-i 00 vo r^ u-i CN Cl Cl © Cl vq © © CN — ' © © CN oo VO oo CN oo vo VO Cl Cl CN © Tf u-i © © CN — 1 © ' © © Cl Tf © cn T-H f-H VD CN u-i Cl © Tf u-i © © CN © ' d Cl Ov Cl r- Ov Tf rv Tf T-H CN © Cl vq © © CN — • ' © ' © bo <; CJ CQ oo U © Cl © CN u-i Ov T - H © Tf T - H Cl © Tf ui © © © ' © © ' u-i C l vo Tt CN 00 VO Cl CN u-i CN t -H © vO Cl © © © © ' © u-i CN u-i |v Ul VO Ul Cl oo u-i Cl T - H © VO Cl © © © ' © ' © ' u-i u-i CN Tf rt Cl Tf rv 00 u-i CN CN CN tv Cl © T - H © ' © ' © ' u-i VO u-i ui Tf CN Ov CN u-i 00 © T - H © VO Cl © © © ' © ' © ' u-i fN rv Tt u-i rv VO VO CN Tf CN CN © u-i Tf © © © ' © © ' u-i _< Tf r- T - H T - H T - H Tf 00 T - H Ul Tf vo u-i u-i © © © © ' © ' u-i _ H VO Ov VO u-i Cl CN © 00 © CN u-i Tf © © © © ' © ' u-i Tf CN CN Cl VO CN r-H CN rv T - H i - H © vo Cl © © © ' © © u-i Cl 00 00 VO 00 CN fN Ov tv CN T—1 © VO Cl © © ' © ' © u-i © 00 T - H u-i VO Ov u-i Cl T - H o VD Cl © © © ' © ' © u-i tv rv VO u-i r- f-H tN VO V0 © tN Ov u-i Tt © Ov © ' © d Tf © 00 Ov u-i Ul Ov rv Tf VO Ov — H OV u-i Cl © Ov © ' © ' © ' Tf" Ov Ov rv © T - H u-i Tf f-H u-i Tt T - H T - H VO Cl © © © ' © © ' u-i 93 E 93 u z tv Ov Ov Tf OO © Tf T - H ' Cl" Tf Ul VO C l C l u-i u-i C l Ul' CN i-H VO Cl O0 00 u-1 oq c i Tt c i p—* VO Cl 00 Tf CN © Ul 00 © ' - H ' Ul fN CN VO C l vO VO CN rv' ©' vo c i rv tv c i Tt Tt vq Tf CN CN Ul Tf CN u-i Ov u-i u-iTf VD Ul Tf Ov © VO Ul u-l VO CN I--' ov CN ui c i T - H Cl CN CN © - H rv' ^ H " VO Cl ui rv u-i vo vo — — i VO Cl -H Tf © vq CN vq Tf ci r-H vo c i Tf CN VO OO CN CN Ul Cl - H - H Tt oq r-' © ' —<" Ul Tf c i c i vo c i N? N? v P tfv OV C X) T -< < O 239 Appendix H . Electron microprobe analyses of glasses S o 00 GO X 00 X 00 X 00 X 00 00 X 00 1-oo I—I t X 00 HI 00 X 00 X 00 X oo •t x 00 X 00 X 00 X oo . rt oo o a CN CN m" vO Tt vq Tt vO 00 VO in VO 00 CN in VO Tt CN r> vo TJ TJ x> TJ X) TJ X o CN TJ oo' X Tt m CO r—t Ov d rt 00 CO m r—t 00 d rH OV r—t •—< d d CN t-co —* © ' d CN O CN TJ _; X CN r- m r—t r—t Ov d t—* TJ TJ X X> i X rt rt TJ x> x> m • r -Tt Tj r-i n x i Ov d VO H >n rt CN CN <n TJ r - CN i n X) 00 d VO r—t o m m 00 TJ rt r—t vd X Ov d VO •n TJ CO VO Ov in -H Tt X oo' d VO rt VO CN Ov VO TJ O *—< vd X Ov © ' VO r—t. TJ TJ X X TJ TJ X X TJ TJ Xi X) TJ TJ X X. TJ TJ X X TJ TJ x xi • 00 00 vq TJ r-m' xi oo' d VO '—1 CO Ov O OV <J r- CN vd X 00 d VO Tt Ov OV vo *o r~ f - H vd X oo' d VO f - H © r—t TJ- Tt Tt TJ m' X d x i VO CN TJ TJ X X> TJ TJ X) x i TJ TJ X X) •n m Ov co m Ov 00 Tt d TJ TJ Tj X X) X o 9. o H < U H o o c oo m Tt m 00_ 00 o d m t--' r - 00 CO o m vd vd oo Tt CO CO d vd r-~' CN Tt o Tt •n Tt vo' vd m Tt o f-H vd vd m O o o CN r> m' CN m CO Ov CN Ov d i n vd 00 VO 00 •n Tt © d vd Tt m Ov r-00 CO d m r-i Tt CN CN CO CO d vo" r-' m i n Tt o r-o d vd r> m Tt VD m CN d vd r> Ov Tt <n CO Ov d vd VD Tt m r-CO Tt d vd r-' Ov Tt o CN Ov d VD VD CO CN VO Ov 00 CN CN vd <n CN f-H in vq m d r-H rH d CO f-H CO in CN d d CaO O a O tN _ M TJ TJ X X TJ TJ xi xi TJ TJ X x> TJ TJ X X TJ TJ X) X> TJ TJ TJ X' X X> X X X TJ TJ TJ X X X TJ TJ TJ X> xi X TJ TJ TJ Xi X) X X X TJ TJ x i X TJ TJ TJ X X X TJ TJ TJ X) X) X TJ TJ TJ x i X> X TJ TJ X) X TJ TJ TJ X x i x i O _ fN rH D H U H U p TJ f a = § < u I X •= TJ I  5H o < 3 ° oo CO oo CO r-H J o oo i o CO S o CO a a a a J o oo a I S oo H TJ xi O CN CO o o 00 f— -; x x 8 3 - a - a x x o r - © oo ov r> vo — — VO VO CO Tt d od d x x Tt VO CO 00 r- co o Tt r-' d ov d VO - H r-' -° vo cS? 22 -q TJ on f-v' Xi' X i Tt _.- r - CN rH TJ rt CN r-' - 0 ov' VO rH TJ TJ X X r-' -° —« m O Tt © d m Ov vd VO ^ 2 v ? TJ TJ X CO 00 oo co •o' X. TJ X Ov 00 O r-rH (— VO —I r> d vo CO o r> CN r- vo - H ' -x> tn' rt o 00 ov r -CN 00 m CN © t CN CO VO 00 VO Tj' CO © m m Tt VD X Ov © ' VD ' O r—t- r~ © TJ rH Tt (-' xi Ov © ' VO © TJ CO Tt TJ r-' xi 00 X VO r—t TJ X d 9, o P < £ OV CO OV r - i vo i n i n . r-' - i o -° r- © VD Ov © Tt -' © X3 TJ x i -  — —. 2 ° ' "° "° © CO m © TJ © ' VO vd xi OV ro r> ro Tt 00 TJ © ' vd in xi P- m 00 Tt t— Ov TJ © vo' <n xi CO r> © Tt r> © TJ © ' vo' vd X rH CO © m 00 CN TJ © ' vd vd xi CO r - VO Tt m CO TJ © ' vd vd xi I Ov © CO vo CN rH © ' vd vd © ' m CO vo 00 CO TJ © ' vd VD xi m rt r~ Ov m vo rH CN d vd vd © ' CO Tt VO m TJ © ' i n VD X m CN © © m OV rH rH © ' Tt VD © 00 VO m vO vo TJ © ' vd VD X) VO OV VO Tt 00 CN TJ © ' Tt vd X 00 00 Tt "rt" m CO CO © ' i n vd xi oo m Tt m Tt CN o © m vd Xi 00 © VO ro m m t> CN © vd VD © © Tt VO ro m © Ov rH © ' vd VD © ' CO rt Ov m Tt CO Ov CN © ' vd vd © ' O O r> S S CJ TJ TJ X> x i TJ TJ xi x ' TJ TJ X> X TJ TJ X x i TJ TJ xi x i TJ TJ Xi XJ TJ TJ X X TJ TJ Xi X TJ TJ X X TJ TJ X X TJ TJ x i x i TJ TJ x i X i TJ TJ xi xi TJ TJ x i X TJ TJ X X TJ Xi o 6 l7 r" r r CU TJ TJ x i X TJ TJ Xi X U H O 240 Appendix H . Electron microprobe analyses of glasses J o 00 00 1 ° 1/1 i-H f-H J o oo S o a. i-H 00 Tf I X 00 t 00 t ac oo Tf I X 00 X CO t X 00 Tt I X oo CO J o oo 3 » OO O 1 ° CO B 00 in © •a 00 CS wo TJ •a" NO xi oo" o" xi X) vo T - H eo _j ts ov wo ^-i vo r--_• x> VO Tt Tt 2 £ * ©' o" •° tN r-Tt ON (S 00 Tt co ro Tt wo O Ov I - H © CN NO vo © VO Tt CS W0 CS WO NO © r-. _ o 00 CS CO cs WO OV oo r— ON CS NO WO W0 l - H CO vo cs vq oo' cs' wo VO CS © r-oo' cs' wo vd -° NO VO © oo XJ Xi Tt CO r-H ON © 00 CS vo >. T7 •a 5 ^ © XI X) cs ~ r-' -° VO § -q r-" -° NO r~- Tt ON Ov ©' —• VO VO - i UN ON ~ r -H r- vo cs ^ I - H x> 0 -00 cs © ON • ° ©• l> o CS CS wo Tt n - 0 -*' °, xi -,' Xi x> •a xi 00 cs ON ©' wo CO © © ' wo 00 ©' cs -a XJ xi xi X) XI xi xi © 00 rv vO wo Tt cs © ' wo' 1--' © ' W0 cs 00 ON wo XI © ' CO wo' xi © vo ,_ TfH Tt © r--"' wo' vd X> wo _ CO Tt oq wo cs T-H CO CO © ' © ' Ov rv OV VO r> ON Tt Tt co' Tt Tt © ' ON 00 VO © © 00 WO Tt Tt co' Tt © ' 00 rv © vO '—1 © T-H cs ro' wo' wo' © ' © © CO NO © rv NO C04 Tt" Tt Tt © ' © ON ^ 00 Tt 00 ON CO Tt Tt CO © ' VO NO CO © 00 CO XJ rt" WO NO xi ro ts Tt Ov ts © XJ © ' wo NO xi © Ov l-H o T-H XI NO vd xi Tt Ov Ov © 00 CO XJ W0 vd X) ON ^ VO Ov Tt Ov 00 CS ro wo' CO © rv CO 00 ON vq ro XI © ' wo NO xi ro Ov oo © wo Ov i-H •—* © ' vd vd © ' rs Ov Tt © rv 00 XI rs rv CO xi rv cs cs OV ts © Ov l-H CS 00 CO © ' O o O O o H < £ 2 2 <3 XJ XJ xi xi XI XI X> Xi XJ XI xi xi X, XI XI xi xi XJ XI xi xi XJ xi XI xi iff O O X) XI Xi Xi XI X) XI xi XI xi XJ x i XJ xi XI xi XI xi XI XI xi xi OH P H O 3 c c o o ac" >< •3 3 °-> I, cs J o CO cs I » CO 00 X m 00 00 . CQ CO 00 CO CO ac 00 © wo I X 00 Tt I ac CO "0, E ca 00 i-H CS CO l-H wo ON © © xi Ov r-r-CS ON Ov r-Tt XJ 00 f-©' xi ©' "-' co' '"' xi cs cs r- vo CO cs r-H XJ © 00 wo cs cs ON xi 00' (v ©' © ' »-H ts xi ©' T—H co' xi 63.75 xi xi 00 ir-es xi xi xi xi X) xi tv t--cs' vO vq wo' CS oq wo xi xi VO CO CO CS © Tt © cs VO Tt cs r- O N cs 00 © NO ON vd Tt NO Tt" CO ©' ~* ©" Tt cs ©' WO oq CO VO Tt r-VO CO xj 00 Tt wo CO vo © Ov wo NO CN wo ©' NO cs CO xi ©' CN Tt" ©' ©' XI vo Tt xi VO WO © ON CO to CO © Ov Ov xi Ov xi © ' cs' Tt W0 XJ Xi 00 NO WO Tt 00 © vq xi WO ON cs cs Tt rv Ov Tf i-H CO vo ©' rv' CO xi ~" cs t wo' ©' © Ov (v CO oq r-WO tv 00 vq © fv CO W0 ON © W0  VO © co' CO ©' rt CO CO CS ©' VO 00 00 00 00 wo NO 00 rv T-H rv vq wo ON CS vq © © ON VO ©' co' CO ©' r-H CO eo* cs' ©' © r> cs oq 00 cs CS CS cs ir-es cs CS cs 00 NO ts WO 1 - 1 NO cs' ©' cs wo Tf' CO ON ON NO rv cs cs WO ts Tt cs eo cs r- ON r-NO ©' W0 NO ts' ©' cs WO Tf CO XI XJ Xi Xi XJ XJ xi xi X) XJ xi xi XI XJ xi xi XJ XJ xi x> XJ XJ X) Xi XJ XJ xi xi XJ xi XJ XI Xi xi X) XJ Xi X>" S -3 —; x> Tf NO © Tf CS cs NO Tf 00 r- NO Tf r-©v W0 eo NO WO wo Tf CO NO* CO* ©' wo 00 CO ©' ts © rv ON vq Tf - H CO WO eo' NO CO Tf • - H •—H 00 ON t- ro wo O N ; • i-H r-H ro O N ro wo XI © ' wo' 00 ro* l-H © ' x> xi wo vq ro ro i - H CO eo Tt 00 cs WO rv eo © Tf CO cs wo WO* Tf ro" NO CO ©' 0 00 eo' rt ©' ON ON cs ro NO cs Tf r- Ov CO Ov Tf Tf ON O N CS 00 wo WO Tf CO vd CO ©' wo' 00 eo' ©' 62.63 xi xi CO ON ©' cs Tf © © xi xi XJ Xi NO WO CN wo r-wo cs oq wo' xi xi NO CO xi © CO CO xi Tf eo vo eo © wo CO © r-' wo XJ r-' cs ©' xi ©' Tf wo Tf ©' O CO n O H m O C N < 0 CJ u_ 0 c 2 3. 2 O ca O O CN CO 0 C N q eu XJ xi TJ XJ Xi Xi XJ XJ X) XJ XJ XJ Xi Xi PH U 241 Appendix I. Estimates of accuracy and precision Appendix I. Estimates of accuracy and precision on whole rock analyses. Whole rock analyses were made in two different laboratories (GSC and McGill) and the precision of analyses of major and trace elements were tested through blind replicate analyses. Five samples of ICG-9, a basalt from Cone Glacier, were analyzed by the GSC and three samples of SH9360, a basalt from Lava Fork, were analyzed by McGill (Table LI). Figures L I and 2 compare results from replicate samples from one laboratory to a single analyses of the same sample by the other laboratory. Error bars shown are for Is error for the replicate samples and for the single analysis Is error was calculated from % error of replicates of a different sample analyzed by the same laboratory. Figure 1.3 shows a comparison of results for all samples analyzed by both laboratories (Appendices C l and C.2). The error bars show Is error estimates based on replicate analyses of samples ICG-9 and SH9360 (Table 1.1). Both laboratories analyzed1 several standards and results were compared to accepted values of in-house standards (Tables 1.2a and b). The GSC laboratory analyzed standards All-pit , MM-88-7, SE-24 and HW-1868-3 and the McGill laboratory analyzed HW-1950-3, HW-1852-1 and BAR-5. Figures 1.4 and 1.5 show the results of analytical accuracy for the both laboratories. Error bars show Is error recalculated from % error for replicate analyses. The results from McGill laboratory shows better accuracy for most major elements analyses than the GSC laboratory; they show a better fit to accepted values of in-house 242 Appendix I. Estimates of accuracy and precision standards. Comparison of the two laboratories (Figures 1.1 and 1.2) show that analyses of the same sample are different for most major elements, exceeding Is analytical error. The chemical analyses from McGill laboratory were favored for the work done in the thesis. Replicate analyses from McGill also gave a better estimate of the precision of major and trace element analyses. Analytical precision of analyses of H20, C02 and FeO measurements made at the University of British Columbia was tested through duplicate analyses (Table 1.3). Figure 1.6 shows comparison of FeO concentration analyzed at University of British Columbia and GSC (Table 1.4). Error bars represent Is. 243 Appendix I. Estimates of accuracy and precision © © CN r- CS CS © © C l cs C l CS © Ov © © VO u-i ©' © ©' ©' © © © f-H © © ci © © c i © c i © © © CS © cs © VO © © © © f-H cs © © ©' ©' © © © ©' ©' © © Tf Tf 00 Tf ©v Tf r-00 « / T vr 00 00 00 vq © u-i Tf CS 00 VO Tf CN vo" i—* ci ©' VD 00° ci f-H ©' © © f-H f-H Cl 00 cs © UTi UTi C l f—I Ov vd r-' oo' cs" r-cs cs Tf CS VO Ov 00 r- cs ci vo U T Tf Tf Tf ©' Tf —< ci r> © ci © ci vq © ci © vo" <-" cs' oo' oo' CS UT U-l Tf UT CS Cl Tf Tf 00 VO Ov r-00 f-H C l UT 00 Cl r-Ov © UT Tf OV Cl Tf UT Tf r- vo Tf Tf CS VO VD Tf cs vd ci ©' vd oo' C]° l-H ©' ©' © CS UT Tf 00 Ov r~ r- 00 UT UT © Ov 00 vq f-H UT Tf © OS UT cs Tf UT Ov UT Cl OV UT vd Tf CS' vd ci ©' vd 00 ci © ©' © CS 00 Tf Cl 00 VO Ov C l 00 f-H VO UT VO 00 CS vq © f-H UT Tf r-r- - H 00 cs vq Tf © UT VO Cl UT vd Tf cs vd ci ©' vd 00 ci ©' ©' © cs VO © 00 C- 00 f-H r-i—i Tf ci CN C l OV Cl Ov Cl Ov cs 00 f-H* Tf" r-' CN CS C l C l © C l C l C l © Cl r-' ci r-' vd VO Cl CS © CS f-H cs 00 Ov C l CN © CN VO Ov UT 00 UT Cl CN © CN Tf © UT Cl UT Cl C l © CN © Tf VO 00 VO Tf © © © © CN VO Tf CN © © 00 © © r-Tf ©' ©' ©' ©' ©' ©' ©' © ' ©' ©' Tf Ov f-H © Tf © © © © © Tf © CN © © © f-H © © © Tf Tf ©' ©' ©' ©' ©' ©' ©' ©' ©' © ©' ©' Tf Tf Tf i-H Tf oo CN Ov © r- Cl Tf 00 Cl © Tf Ov 00 Cl r~ oo' Tf CN vd ci r-' ©' vd Ov ci ©' ©' Ov" Ov © © © © © © © © Ov Ov 00 © © i— © Tf © o © 00 r- © © 00 Tf © © £> l-H 00 Ov l-H Cl Cl Tf OV Cl C N r-H ses 00 C N . vd Cl" © ' V©' Ov ci © ' © ' Os © ' © ' ses Tf i-H Ov _>-. an © Cl © © © l> C N Ov © C N 00 t-H © © an UT 00 © f-H Tf Cl Tf Ov Cl 00 r-H •—1 CM oo' C N vd Tf" r-' © ' vd OS ci © ' © ' Ov © ' © O g asa Tf OS CL) x> .C G-9 © Cl © © © r~- Ov t- © f-H 00 UT © o G-9 C J VO f-H Ov Ov r-H Tf Cl Tf Ov Cl Ov CL) G-9 o 00 C N vd ci r-' © ' vd Ov Cl © © ' Ov © ' "ca o :Gla Tf t-H OV . Replic :Gla © V . Replic one © VO © © © t - Cl r-H © r-H 00 VO © © . Replic one UT f-H © Ov r^  Tf Tf Tf Ov Cl ©v r-H -H . Replic o oo' C N IT-' ci r-' © ' vd Ov ci © ' © ' Ov" © ' © Tf © V f-H CJ "cl © UT © © © r> Tf UT © f-H 00 © o o UT f—' Ov »—* Tf Cl Tf OS Cl VO <—1 r-H H oo' C S vd ci © ' vd Ov ci © ' © ' Ov © ' © ' Tf f-H Ov f-H -3 c — CJ O. fN O d fl o tN) ro o rN CJ fc O O 00 o O CN O d CN "a Q H O C N rs o < oo < % 2 o H X u © © Tf VD Cl © 00 C N Cl © © ' V o Tf C N Cl © d V © 00 C N Cl © © ' V © C N Cl © © ' V © UT C N Cl © © V UT 00 © Cl t— © Ov © ' © 00 © © • — 1 C N © ' o © © © SO © © tv' © ' C N r-H Tf VO Ov 00 © r-H r-H Tf V0 C N UT © C S r-H Tf VO 00 © © r-H C N Tf VO ©V ©V © i-H r-H Tf vO C N VO © C N t-H Tf o q ca ca cj o d rZ w in > N N Cl O C N C J - J H c/l ca 1) E C J rC o 4-t CJ >> X) cn C o ca C3 244 Appendix I. Estimates of accuracy and precision Appendix I. Table I.2a. Reproducibility on major elements by the GSC laboratory of in-house standards A l l - D i t 1 MM-88-7 1 SE-24 HW-1868-3 2 Oxide Accepted values GSC Accepted G S C Accepted G S C Accepted G S C Si0 2 42.84 43.51 40.80 68.33 68.50 71.66 71.70 51.24 51.30 Ti0 2 1.89 1.92 2.09 0.47 0.45 0.21 0.20 2.13 2.02 AI2O3 5.79 5.70 6.00 16.45 15.60 16.77 15.50 13.96 13.10 Fe 20 3 T 19.48 19.00 21.20 3.24 3.20 2.00 1.60 12.20 12.30 MnO 0.43 0.43 0.46 0.07 0.07 0.07 0.05 0.17 0.16 MgO 8.11 8.22 7.81 1.46 1.35 0.60 0.37 7.72 8.56 CaO 19.16 19.35 18.30 3.33 3.17 2.53 2.54 9.99 10.20 Na 20 1.43 1.45 1.40 5.48 4.60 5.07 4.90 2.21 2.10 K 2 0 1.13 1.16 1.02 2.44 2.52 2.04 2.13 0.44 0.40 P2O5 1.17 1.18 1.12 0.15 0.15 0.07 0.08 0.22 0.24 Total 101.43 101.92 100.20 101.42 99.61 101.02 99.07 100.28 100.38 1 analyses by X R F 2 analyses by wet chemical methods Appendix I. Table I.2b. Reproducibility on major elements by the McGill laboratory of in-house standards. HW-1950-3 2 HW-1852-1 2 B A R - 5 1 Accepted McGill Accepted McGill Accepted McGill Si0 2 51.12 51.19 48.92 49.05 52.37 51.45 Ti0 2 1.94 1.97 1.69 1.72 0.62 0.64 A1203 14.01 13.26 12.12 11.01 14.94 14.93 Fe 20 3 T 12.03 12.24 12.06 12.33 10.56 10.82 MnO 0.17 0.18 0.12 0.17 0.17 0.17 MgO 7.23 8.89 15.00 15.48 8.37 8.16 CaO 10.13 10.16 8.23 8.47 10.74 10.56 Na 20 2.11 2.60 1.80 2.21 2.13 2.02 K 2 0 0.32 0.38 0.37 0.36 0.97 0.93 P2O5 0.20 0.22 0.23 0.21 0.05 0.05 Total 99.26 101.09 100.54 101.01 100.92 99.73 1 analyses by X R F 2 analyses by wet chemical methods 245 Appendix I. Estimates of accuracy and precision 2.5 h 2.5 6.5 4 h 0.5 h 2 0 0.5 Weight % (McGill) Figure 1.1. Mean of replicate analyses of sample ICG-9 by GSC compared to a single analyses of sample ICG-9 by McGil l . Error bars represent Is error. 246 Appendix I. Estimates of accuracy and precision 46 47 48 49 2 2.5 3 0 1 2 0 0.5 1 Weight % (McGill) Figure 1.2. Mean of replicate analyses of sample SH9360 by McGill compared to a single analyses of sample SH9360 by G S C . Error bars represent Is error. 247 Appendix I. Estimates of accuracy and precision 248 Appendix I. Estimates of accuracy and precision 80 60 h 40 0 s 20 10.0 c cs u +j S3 «*> a © £ 8.0 o o 6.0 4.0 2.0 0.0 All-pit : S102, Fe203T and CaO MM-88-7 and SE-24: Si02 and A1203 HW-1868-3: S102, A1203, Fe203 and CaO 20 40 All samples: Ti02, MgO, Na20, K20, MnO and P205 All-pit : AL203 MM-88-7 and SE-24: Fe203 and CaO • All -pi t (a) • All-pi t (b) A MM-88-7 • SE-24 X HW-1868-3 60 X 2 4 6 8 Measured concentration (wt%) 80 10 Figure 1.4. Accepted concentration vs measured concentration for major element determination on in-house standards A l l - p i t (a and b), MM-88-7, SE-24 and HW-1868-3 by the GSC laboratory. Error bars are Is. 249 Appendix I. Estimates of accuracy and precision 60 40 20 a © ' i SI02, A1203, Fe203T and CaO. MgO for HW-1852-1 only. 1 • H W - l 950-3 • HW-1852-1 / ' 1 A i BAR-5 20 40 60 2 4 6 8 Measured concentration (wt%) 10 Figure 1.5. Accepted concentration vs measured concentration for major element determination on in-house standards HW-1950-3, HW-1852-1 and BAR-5 by the McGill laboratory. Error bars are Is. 250 Appendix I. Estimates of accuracy and precision oo CN i fc fc CN CN m cn Tt-CN i fc d C l 00 Wi 00 ca x fc m ov CN CN CN m VO a u cj > •c c 9 fc CS c cs ts CJ f 1 CS -O o CS CJ N? Tf m oo f-H VO r-' VD 00 oo VO © Cl r-od r-ov Cl m Tt-ci Tt-o s 00 00 m p od 8 5 CS Cl X CS H •a e . a. vo VO r-av Tt oo vo o O CJ fc a CJ o CJ > •c 1-C P O ( N X <4-t I o c CS cj §.1 Q X Cl fc O CN i £ CN CN CN 7s © c/l cs Xl in fc 00 J CN © o CJ Tf Ov o u T3 C •3 c D I O u o >> 7s c cs CJ a. a TJ C CJ C H < m © d cs i/i cs X m fc p d 251 Appendix I. Estimates of accuracy and precision Appendix I. Table 1.4. Wet chemical analyses on FeO, H 2 0 and C0 2at UBC on samples from the Iskut-Unuk rivers centres Sample FeO H 2 0 co2 IIC-2 8.1146 0.26 b.d. IIC-3 7.7350 0.30 0.02 IIC-4 9.4717 0.38 0.02 IIC-5 9.3084 0.33 0.08 IIC-6 9.0113 0.34 0.02 IIC-7 8.7096 0.25 0.03 IIC-8 9.3727 0.25 0.04 ICG-9 7.8718 0.26 0.04 ICG-10 9.4284 0.24 0.02 ICG-11 7.6970 0.17 b.d. ICG-12 7.5766 0.22 0.04 ICG-13 9.2649 0.34 0.04 ICG-14 7.4733 0.40 0.04 ICG-15 7.5692 0.25" 0.08 ICG-18 9.4886 0.56 0.12 ICM-19 8.3412 0.45 0.02 ICM-20 8.1452 2.01 0.03 ICM-21 9.1169 0.90 0.04 IKC-22 8.5019 0.52 0.04 ISC-23 8.2752 0.62 0.04 ILF-24 7.9050 0.20 0.04 ILF-28 0.3729 0.35 0.05 ILF-30 9.1635 0.23 0.03 ILF-31 9.9131 0.25 0.05 ILF-32 9.8550 0.18 0.03 252 Appendix I. Estimates of accuracy and precision 2 4 6 8 10 12 Concentration FeO GSC (wt%) Figure 1.6. Comparison of FeO concentration analyzed by GSC and at U B C . Error bars represent Is analytical error. 253 

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