"Science, Faculty of"@en . "Earth and Ocean Sciences, Department of"@en . "DSpace"@en . "UBCV"@en . "Cross, Jodi. 2009. The Diamond Potential of the Tuwawi Kimberlite (Baffin Island, Nunavut). Undergraduate Honours Thesis. Department of Earth and Ocean Sciences. University of British Columbia."@en . "Cross, Jodi"@en . "Cross, Jodi"@en . "2009-04-22T21:08:01Z"@en . "2009-04-22"@en . "Ten samples of kimberlite and associated mantle xenoliths were studied to constrain the diamond potential of the Tuwawi kimberlite of Baffin Island, Nunavut. The Tuwawi kimberlite, one in a cluster of 3 kimberlites, is located at the northwestern end of Baffin Island on the Brodeur Peninsula. Baffin Island is underlain by Archean crust of the Rae craton with Paleoproterozoic reworking, and is known to contain several kimberlites, possibly, one at least, of Cretaceous age. These include the Freightrain and Cargo kimberlites.\n\nPetrographic analyses established that both hypabyssal and volcaniclastic kimberlitic types are present among the four kimberlite samples. Hypabyssal kimberlite is the predominant type in Tuwawi, consisting of olivine macrocrysts set in a carbonate-serpentine groundmass with olivine microphenocrysts, phlogopite and spinel. Volcaniclastic kimberlite is characterized by the presence of 1) irregularly-shaped juvenile lapilli; 2) two semi-intermixed dark cryptocrystalline matrix materials; 3) olivine grains with a restricted size distribution and angular shapes. These features suggest mild sorting of the kimberlite, a possible incorporation of mud to the matrix, an epiclastic origin and formation in the crater facies.\n\nPetrographic analyses established that the six mantle xenolith samples include two garnet lherzolites, a spinel and a garnet-spinel harzburgites, a dunite, and a clinopyroxenite. Both coarse and deformed (porphyroclastic and mosaic-porphyroclastic) textures are present within the peridotite xenoliths. Garnet is present in all but one sample, whereas spinel occurs only in coarse peridotites. Electron microprobe geochemical analyses of the mantle xenoliths provided important information regarding the equilibrium compositions of the major minerals present: olivine, orthopyroxene, clinopyroxene, garnet, and spinel. All minerals, except spinel, show chemical homogeneity between and within grains. Cr-diopside from deformed xenoliths shows higher TiO2 (0.16 wt%) content than in coarse peridotites. All garnets present are pyropes (Mg81-84), and spinels are magnesiochromites showing strong chemical heterogeneity. This is controlled by random intra-grain compositional changes in FeO (from 12 to 16 wt%), MgO, Al2O3 and Cr2O3 (from 43 to 57 wt% ). Olivine andorthopyroxene in all xenoliths are very magnesian (Fo91-92 and En92-93), slightly more so in coarse peridotites.\n\nPressures and temperatures of mineral equilibria for the mantle xenoliths were estimated using various two-pyroxenes, garnet-pyroxene, olivine-garnet, and olivine-spinel geothermobarometers. Deformed garnet lherzolite and garnet clinopyroxenite were formed at 1103-1209oC and 53.8\u00E2\u0080\u009360 kb. Deformed peridotites are equilibrated at higher temperatures and pressures than coarse peridotites. Garnet peridotites and pyroxenites show higher temperatures than spinel peridotites. These patterns match the commonly observed mantle lithological columns below cratons. In comparison to temperature and pressure data from kimberlites of Somerset Island, xenoliths from Tuwawi plot farther into the diamond stability field and at a lower geothermal gradient (~42 mW/m2). The majority of mantle xenoliths from Cretaceous Somerset Island kimberlites plot in the graphite stability field along a geotherm of ~44 mW/m2.\n\nSeveral factors were identified that give a positive outlook on the diamond potential of the Tuwawi kimberlite. These factors include 1) a preservation of the crater facies kimberlite, and 2) kimberlite sampling of the deep diamondiferous mantle. The diamond potential is reduced by the estimated 42 mW/m2 geothermal gradient that is hotter than the desired low geotherm for Archean cratons. In addition, a relatively narrow \u00E2\u0080\u009Cdiamond window\u00E2\u0080\u009D (i.e. the range of temperatures where diamond is stable in the asthenosphere), 1050-1100 \u00C2\u00B0C, lowers the diamond potential of the Tuwawi kimberlite."@en . "https://circle.library.ubc.ca/rest/handle/2429/7475?expand=metadata"@en . "1095530 bytes"@en . "application/pdf"@en . "THE DIAMOND POTENTIAL OF THE TUWAWI KIMBERLITE (BAFFIN ISLAND, NUNAVUT). by JODI CROSS A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BACHELOR OF SCIENCE (HONOURS) in THE FACULTY OF SCIENCE (Geological Sciences) This thesis conforms to the required standard \u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6 Supervisor THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) MARCH 2009 \u00C2\u00A9 Jodi Cross, 2009 ABSTRACT Ten samples of kimberlite and associated mantle xenoliths were studied to constrain the diamond potential of the Tuwawi kimberlite of Baffin Island, Nunavut. The Tuwawi kimberlite, one in a cluster of 3 kimberlites, is located at the northwestern end of Baffin Island on the Brodeur Peninsula. Baffin Island is underlain by Archean crust of the Rae craton with Paleoproterozoic reworking, and is known to contain several kimberlites, possibly, one at least, of Cretaceous age. These include the Freightrain and Cargo kimberlites. Petrographic analyses established that both hypabyssal and volcaniclastic kimberlitic types are present among the four kimberlite samples. Hypabyssal kimberlite is the predominant type in Tuwawi, consisting of olivine macrocrysts set in a carbonate-serpentine groundmass with olivine microphenocrysts, phlogopite and spinel. Volcaniclastic kimberlite is characterized by the presence of 1) irregularly-shaped juvenile lapilli; 2) two semi- intermixed dark cryptocrystalline matrix materials; 3) olivine grains with a restricted size distribution and angular shapes. These features suggest mild sorting of the kimberlite, a possible incorporation of mud to the matrix, an epiclastic origin and formation in the crater facies. Petrographic analyses established that the six mantle xenolith samples include two garnet lherzolites, a spinel and a garnet-spinel harzburgites, a dunite, and a clinopyroxenite. Both coarse and deformed (porphyroclastic and mosaic-porphyroclastic) textures are present within the peridotite xenoliths. Garnet is present in all but one sample, whereas spinel occurs only in coarse peridotites. Electron microprobe geochemical analyses of the mantle xenoliths provided important information regarding the equilibrium compositions of the major minerals present: olivine, orthopyroxene, clinopyroxene, garnet, and spinel. All minerals, except spinel, show chemical homogeneity between and within grains. Cr-diopside from deformed xenoliths shows higher TiO2 (0.16 wt%) content than in coarse peridotites. All ii garnets present are pyropes (Mg81-84), and spinels are magnesiochromites showing strong chemical heterogeneity. This is controlled by random intra-grain compositional changes in FeO (from 12 to 16 wt%), MgO, Al2O3 and Cr2O3 (from 43 to 57 wt% ). Olivine and orthopyroxene in all xenoliths are very magnesian (Fo 91-92 and En92-93), slightly more so in coarse peridotites. Pressures and temperatures of mineral equilibria for the mantle xenoliths were estimated using various two-pyroxenes, garnet-pyroxene, olivine-garnet, and olivine-spinel geothermobarometers. Deformed garnet lherzolite and garnet clinopyroxenite were formed at 1103-1209oC and 53.8\u00E2\u0080\u009360 kb. Deformed peridotites are equilibrated at higher temperatures and pressures than coarse peridotites. Garnet peridotites and pyroxenites show higher temperatures than spinel peridotites. These patterns match the commonly observed mantle lithological columns below cratons. In comparison to temperature and pressure data from kimberlites of Somerset Island, xenoliths from Tuwawi plot farther into the diamond stability field and at a lower geothermal gradient (~42 mW/m2). The majority of mantle xenoliths from Cretaceous Somerset Island kimberlites plot in the graphite stability field along a geotherm of ~44 mW/m2. Several factors were identified that give a positive outlook on the diamond potential of the Tuwawi kimberlite. These factors include 1) a preservation of the crater facies kimberlite, and 2) kimberlite sampling of the deep diamondiferous mantle. The diamond potential is reduced by the estimated 42 mW/m2 geothermal gradient that is hotter than the desired low geotherm for Archean cratons. In addition, a relatively narrow \u00E2\u0080\u009Cdiamond window\u00E2\u0080\u009D (i.e. the range of temperatures where diamond is stable in the asthenosphere), 1050- 1100 \u00C2\u00B0C, lowers the diamond potential of the Tuwawi kimberlite. iii TABLE OF CONTENTS Title Page\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6i Abstract\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..ii Table of Contents\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6iv List of Figures\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.......vi List of Tables\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...vii List of Appendices\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6.vi Acknowledgements\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6ix 1) Introduction 1.1. Purpose..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6\u00E2\u0080\u00A61 1.2. Location\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A61 1.3. Previous Work\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6..4 2) Geology 2.1. Tectonic Setting\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6\u00E2\u0080\u00A65 2.2. Geological Setting 2.2.1. Regional Geology\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6.\u00E2\u0080\u00A6.7 2.2.2. Local Geology\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6....8 3) Petrography of the Tuwawi Kimberlite 3.1. Introduction...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6...\u00E2\u0080\u00A6.9 3.2. Hypabyssal kimberlite..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A69 3.3. Volcaniclastic kimberlite\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6......10 4) Petrography of the Tuwawi Mantle Xenoliths 4.1. Introduction\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6.12 4.2. Coarse Peridotite\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6.13 4.3. Deformed Peridotite 4.3.1. Porphyroclastic Samples..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.....\u00E2\u0080\u00A6.13 4.3.2. Mosaic-Porphyroclastic Sample..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.....\u00E2\u0080\u00A6.14 4.4. Clinopyroxenite Sample..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A614 iv 5) Mineral Chemistry of the Tuwawi Mantle Xenoliths 5.1. Analytical Methods\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A616 5.2. Olivine\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6.17 5.3. Orthopyroxene\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.17 5.4. Clinopyroxene\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A618 5.5. Garnet\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6.18 5.6. Spinel\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6.19 6) Geothermobarometry of Tuwawi Mantle Xenoliths. 6.1. Geothermobarometers Used\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A626 6.2. Methodology of P-T Estimates\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A627 6.3. Results and Comparison with Literature Data\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A630 7) Diamond Potential of the Tuwawi Kimberlite\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6..34 References\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6.37 Appendix I A. Mantle Xenoliths...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..41 B. Kimberlites...\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6...49 Appendix II\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6...58 v LIST OF FIGURES Figure 1 \u00E2\u0080\u0093 Map showing the locations of kimberlites discussed in this paper on Baffin and Somerset Islands, Nunavut\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.2 Figure 2 \u00E2\u0080\u0093 Map of Palaeozoic geology of Brodeur Peninsula, also showing Brodeur Property claims and location of Tuwawi kimberlite\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.3 Figure 3 \u00E2\u0080\u0093 Map of tectonic setting of Baffin Island\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.6 Figure 4a \u00E2\u0080\u0093 Photo of hypabyssal texture\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6....11 Figure 4b \u00E2\u0080\u0093 Photo of contact between different matrices in volcaniclastic kimberlite sample\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6....11 Figure 4c \u00E2\u0080\u0093 Photo of light matrix in volcaniclastic kimberlite sample\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..11 Figure 4d \u00E2\u0080\u0093 Photo of lapillus in dark matrix in volcaniclastic kimberlite sample\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6.\u00E2\u0080\u00A611 Figure 5a \u00E2\u0080\u0093 Photo of coarse peridotite texture\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..15 Figure 5b \u00E2\u0080\u0093 Photo of porphyroclastic peridotite texture\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A615 Figure 5c \u00E2\u0080\u0093 Photo of mosaic-porphyroclastic peridotite texture\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..15 Figure 5d \u00E2\u0080\u0093 Photo of clinopyroxenite sample\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6..15 Figure 6 \u00E2\u0080\u0093 Plot of P-T values calculated using all geothermobarometers\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6.29 Figure 7 \u00E2\u0080\u0093 Plot of P-T values calculated using the FB thermometer \u00E2\u0080\u0093 MG barometer\u00E2\u0080\u00A6\u00E2\u0080\u00A6...31 Figure 8 \u00E2\u0080\u0093 Plot of P-T values calculated using the BK thermometer \u00E2\u0080\u0093 MG barometer\u00E2\u0080\u00A6\u00E2\u0080\u00A6...32 Figure 9 \u00E2\u0080\u0093 Plot of P-T values calculated using the OW thermometer \u00E2\u0080\u0093 MG barometer..........32 vi LIST OF TABLES Table 1 \u00E2\u0080\u0093 Minimum detection limits of electron microprobe analyses\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6.16 Table 2 \u00E2\u0080\u0093 Average composition of olivine from Tuwawi mantle xenoliths\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6..20 Table 3 \u00E2\u0080\u0093 Average composition of orthopyroxene from Tuwawi mantle xenoliths\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6..21 Table 4 \u00E2\u0080\u0093 Average composition of clinopyroxene from Tuwawi mantle xenoliths\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6....22 Table 5 \u00E2\u0080\u0093 Average composition of garnet from Tuwawi mantle xenoliths\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.23 Table 6 \u00E2\u0080\u0093 Average composition of spinel from Tuwawi mantle xenoliths \u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.....24 Table 6 \u00E2\u0080\u0093 Continued\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.....25 Table 7 \u00E2\u0080\u0093 Equilibrium pressure and temperature estimates for the Tuwawi mantle xenoliths\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6.29 vii LIST OF APPENDICES Appendix I \u00E2\u0080\u0093 Thin section descriptions\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6..\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A641 Appendix II \u00E2\u0080\u0093 Electron microprobe analysis of mantle xenolith samples\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6\u00E2\u0080\u00A6.\u00E2\u0080\u00A6...\u00E2\u0080\u00A6..58 viii ACKNOWLEDGMENTS First I\u00E2\u0080\u0099d like to thank Maya Kopylova, my supervisor, for her endless patience and help. Many thanks to David Ritcey and the rest of Diamondex Resources for letting me study their samples, without which this project would never have happened. Thanks to Mary Lou Bevier for providing so many resources, and Mati Raudsepp and Edith Czech for their help on the microprobe. Thank you to the Department of Earth and Ocean Sciences at UBC for helping with funding this project. Thank you also to my fellow honours students; this has been quite an experience that I\u00E2\u0080\u0099m glad to have shared with you. Lastly, I\u00E2\u0080\u0099d like to thank my parents for all the love and support. ix CHAPTER 1 INTRODUCTION 1.1 INTRODUCTION It is important to recognize at an early stage in exploration whether a diamond deposit has the potential of being economic or not (Griffin and Ryan, 1995). The diamond potential of a kimberlite pipe is determined through detailed petrographic and chemical analyses, and the calculation of equilibrium pressures and temperatures to determine the depths of the mantle sampled by the kimberlite. These depths provide information about the probability of the kimberlite magma sampling diamonds; the thermal properties of the mantle below the surrounding area are also crucial. The textural classification of a kimberlite is another important process in determining its diamond potential. This paper presents the petrography, geochemistry, and geothermobarometry of the Tuwawi kimberlite and associated mantle xenoliths for the discussion and determination of the pipe\u00E2\u0080\u0099s diamond potential. 1.2 LOCATION The Tuwawi kimberlite is one of three kimberlite occurrences found on the Brodeur Property of Baffin Island, Nunavut. This is the second kimberlite cluster found on the Brodeur Peninsula of Baffin Island, the first being the Freightrain (previously known as Zulu), discovered in 1975 by Cominco Ltd. (now owned by Atlanta Gold Corp.; Ritcey, unpublished, 2008). The Brodeur property is located approximately 100 km northwest of the Arctic Bay community (Fig. 1), and is claimed by Diamondex Resources Ltd. The property claims extend from 73.12\u00C2\u00B0 to 73.71\u00C2\u00B0 N latitude and 85.96 \u00C2\u00B0to 88.36\u00C2\u00B0 W longitude (Fig.2), and are situated directly northeast of the Freightrain and Cargo kimberlites (Ritcey, unpublished, 2008). 1 Figure 1. Map of Somerset Island and the Brodeur Peninsula of Baffin Island, Nunavut. Locations of kimberlite occurrences are shown. The community of Arctic Bay is also shown for reference. 2 Figure 2. Palaeozoic geology of the area around the Brodeur Property. Modified from Ritcey, 2007. 3 1.3 PREVIOUS WORK Jago et al. (2002) studied the Freightrain kimberlite; a pipe exposed in the crater facies with the presence of pyroclastics kimberlite indicating it is near the transition into diatreme facies. The kimberlite contains xenoliths of garnet and chromite harzburgite, garnet lherzolite, garnet spinel lherzolite and rare eclogite. An approximate geotherm of 42 mW/m2 was calculated using the geothermobarometry method of Nimis and Taylor (2000) for single clinopyroxene grains, and the majority of samples analyzed were found to originate in the diamond stability field. In comparison, kimberlites from Somerset Island are reported to have a hotter geotherm of approximately 44 mW/m2 and originate in the graphite stability field (Schmidberger and Francis, 1998; Jago and Mitchell, 1987; Kjarsgaard and Peterson, 1992). Among these kimberlites are the Ham, Nikos, and Batty Bay Complex, all located on the western edge of Somerset Island, and thought to of been emplaced during the Cretaceous (Heaman, 1989). Predating the study by Jago et al. (2002) was another done by Zhao et al. (1997) in which the Freightrain kimberlite (still called Zulu then) was dated and found to be of Cretaceous age. No previous work has been conducted on the Tuwuwi kimberlite, or the other kimberlites on the Brodeur Property (Nanuk and Kuuriaq). 4 CHAPTER 2 GEOLOGICAL SETTING 2.1 TECTONIC SETTING Baffin Island can be divided into two separate tectonic sections (Fig. 3). The Northern half of the island is composed of the Archean Committee Belt, a section of the Rae Domain (part of the Western Churchill Province). The rest of the Western Churchill Province is designated as the Hearne Domain and lies to the southwest of Baffin Island. To the northwest of the Rae Domain lies the Slave Craton, separated by the Thelon Tectonic Zone (Berman et al., 2005). The southern portion of Baffin Island is composed of the Paleoproterozoic Baffin Orogen which is a part of the Trans-Hudson Orogen. The Baffin Orogen is composed of a multitude of tectonic belts thrust upon one another. These include the Foxe Fold Belt, the Dorset Fold Belt and the Nagssugtoqidian Mobile Belt (Fig. 3). 5 Figure 3. Tectonic setting of Baffin Island. Modified from Jackson and Berman (2000). 6 2.2 REGIONAL GEOLOGY The Committee Belt (ca. 3.0\u00E2\u0080\u00932.5 Ga) is characterized by episodic felsic plutonism and greenschist to upper amphibolite facies supracrustal belts. Three Archean crustal- building events characterize the Committee Belt. The oldest event (ca. 3.0 \u00E2\u0080\u0093 2.8 Ga), is represented by a ca. 2.85 Ga felsic pluton on northwestern Baffin Island and ca. 2.9 Ga felsic volcanic rocks to the southwest (Frisch, 1982). Widespread felsic plutonism and metavolcanic and paragneiss sequences (Jackson and Berman, 2000) characterize the second event, and the final event is represented by younger (ca. 2.6 \u00E2\u0080\u0093 2.5 Ga) granitic plutons and orthogneisses found in the southwestern section of the belt, as well as on islands to the north and northeast of Baffin Island. Subsequently a ca. 2.55\u00E2\u0080\u00932.50 Ga tectonothermal event affected much of the Committee belt (Jackson and Berman, 2000), but did not contribute to it volumetrically. Four major rock assemblages have been identified within the Committee Belt on northern Baffin Island (Jackson and Berman, 2000). Mesoarchean (< 2.9\u00E2\u0080\u00932.8 Ga) rocks consist of felsic orthogneisses and foliated, strongly deformed felsic plutonic rocks. The Neoarchean assemblage (2.76\u00E2\u0080\u00932.71 Ga) is represented by the supracrustal, syn- to late- tectonic felsic intrusions (Jackson and Berman 2000) of the Mary River group. Two Archean and/or Paleoproterozoic units consist of layered gneissic migmatite, and granite \u00E2\u0080\u0093 charnockite; these are of uncertain age due to deformation, metamorphism, and plutonism in the Paleoproterozoic, making dating difficult (Jackson and Berman 2000). Thin sequences of Paleoproterozoic shelf quartzites and marble overlain by turbidites and wackes compose the Piling Group, which was deposited on exhumed Archean crust. Next, the Mesoproterozoic Bylot Supergroup was deposited in the Borden Rift Basin after uplift following Paleoproterozoic orogenesis (Jackson and Berman, 2000). Thick sequences of Palaeozoic shallow marine platform and minor non-marine platform carbonate and clastic sedimentary rocks, as well as some deep water units (Trettin, 1969 and 1991) unconformably overly Archean and Proterozoic units in the area, and are in 7 turn unconformably overlain by unconsolidated Quaternary sedimentary deposits (Trettin, 1969, Ritcey, (unpublished) 2008). 2.3 LOCAL GEOLOGY Brodeur Peninsula is composed of Palaeozoic marine and non-marine platform sedimentary rocks (Fig. 2) underlain by Archean rocks of the Committee Belt. These Palaeozoic sedimentary rocks consist, in stratigraphic sequence, of the Admiralty Group of Cambrian and/or Early Ordovician age, the Early to Middle Ordovician Ship Point Formation, and the Brodeur Group of Ordovician and Silurian age (Trettin, 1969). The Admiralty Group is composed of two formations, the Gallery Formation, composed of quartzose and minor dolomitic sandstone, and the Turner Cliffs Formation, composed of a quartzose and dolomitic sandstone, and dolomitic, fine clastic sandstone. The Ship Point Formation is represented predominantly by pure dolomite (Trettin, 1969). The Brodeur Group is composed of the Baillarge and Cape Crauford Formations, a succession of Ordovician and Silurian self carbonates. The Cape Crauford Formation is unconformably overlain by unconsolidated Quaternary sediments (Trettin, 1969) consisting of a glacial till veneer and blanket, colluvial rubble from carbonates and consolidated clastics, and minor areas of glacio-marine and marine sediments. Units of the Baillarge and Cape Crauford formations underlie the mineral claims of the Brodeur property (Ritcey, (unpublished) 2008). 8 CHAPTER 3 PETROGRAPHY OF THE TUWAWI KIMBERLITE 3.1 INTRODUCTION This section will describe the petrography of samples from the Tuwawi kimberlite. There are four samples (89486, 89488, 89495, and 89496). Two thin sections were made for each sample except sample 89488, for which only one thin section was made due to the low cohesiveness of the sample. The majority of the samples are hypabyssal textured, except 89488, which is of volcaniclastic texture. Hypabyssal kimberlite is characterised as non- fluidized intrusive rock formed from the slow crystallization of kimberlite magma (Scott Smith, 1996). Hypabyssal kimberlites are macroscopically uniform in most cases (Field and Scott Smith, 1999). The classification of volcaniclastic kimberlite is given to extrusively formed fragmental kimberlite deposits for which the process of deposition is unknown (Field and Scott Smith, 1999). Detailed thin section descriptions are in Appendix I. 3.2 HYPABYSSAL KIMBERLITE The hypabyssal kimberlites consist of olivine macrocrysts (>0.5mm; Scott Smith, 1996) and microphenocrysts (<0.5mm) in a fine grained serpentine-calcite matrix (Fig.4a). All hypabyssal samples show olivine macrocrysts in similar abundance (13-14%). A few macrocrysts of spinel are also present, and sample 89495 has a small percentage of garnet grains with opaque kelyphitic rims; one as an inclusion in an olivine macrocryst. Olivine macrocrysts are present in subhedral rounded shapes and are fractured; some grains also show undulose extinction and dynamic recrystallization. This indicates a xenocrystal origin of olivine. Secondary serpentine, and minor calcite and chlorite, are present along fractures of the olivine macrocrysts. Surrounding the macrocrysts is a microcrystalline groundmass. Microphenocrysts of olivine are present in the groundmass, showing subhedral to euhedral grains with equant and elongate shapes. Also in the groundmass are serpentine, calcite, 9 spinel, perovskite, opaque minerals and some phlogopite. Calcite occurs as anhedral fine grained aggregates, as well as fibrous groundmass crystals. Serpentine also occurs as fine grained aggregates. Both minerals show a patchy distribution in sample 89486. Spinel is present in both bead and atoll form. Bead spinel refers to the small spinel grains that form around the grain boundaries of other minerals, mostly olivine microphenocrysts. Atoll spinel refers to spinel grains showing a cubic shape and having a cubic halo around the grain. Perovskite is also present, although not in as much abundance as spinel. Perovskite occurs as small, euhedral, equant grains (40 \u00CE\u00BCm to 0.16 mm). In sample 89495, there is a large anhedral perovskite grain (0.32x0.2 mm). The abundant tiny opaque grains most likely represent the finer grain fraction of spinel. Phlogopite is also present in the groundmass as euhedral laths ranging in size from 30x5 \u00CE\u00BCm to 0.6x0.08 mm. 3.3 VOLCANICLASTIC KIMBERLITE The volcaniclastic sample is composed of two irregularly intermixed matrices both containing discrete olivine macrocrysts and microphenocrysts, as well as lapilli. Only one area in the thin-section shows a clear contact between the two materials (Fig. 4.3b). The lighter matrix is composed of very fine grained, almost cryptocrystalline, carbonate and serpentine with minor spinel, phlogopite and opaque minerals (Fig. 4c). Lapilli are present in irregular shapes, and some are cored by olivine, or orthopyroxene, with thin selvages. The dark matrix material is also composed of cryptocrystalline carbonate and serpentine, except with a larger amount of spinel and opaque minerals (or ash) giving it a darker appearance (Fig. 4d). The majority of lapilli can be classified as juvenile rather than pelletal lapilli; as their olivine cores are surrounded by selvages of varying thickness and shape (Scott Smith, 1996). Few are olivine cored, and most form erratic shapes pertaining to the olivine grains within them. The selvages seem to be composed of the lighter matrix material. Olivine macrocrysts and microphenocrysts within the sample show a restricted size distribution in comparison to those in hypabyssal kimberlite. The smaller grains have a very uniform size of ~160 \u00C2\u00B5m. This is one line of evidence supporting a volcaniclastic texture for this sample. Other evidence includes the angular shapes of the olivines, the presence of lapilli and the unusually dark and cryptocrystalline nature of the matrices. 10 Figure 4. Microscope photos of kimberlite textures. a) Hypabyssal kimberlite; b) Contact between light and dark matrix of volcaniclastic kimberlite; c) Light matrix of volcaniclastic kimberlite; d) Juvenile lapillus in the dark matrix of volcaniclastic kimberlite. L.Matrix=light matrix, D.Matrix=dark matrix, Ol=olivine, Spl=spinel, Phl=phlogopite. 11 CHAPTER 4 PETROGRAPHY OF THE TUWAWI MANTLE XENOLITHS 4.1 INTRODUCTION This section will describe the petrography of the mantle xenoliths found in samples from the Tuwawi kimberlite. There are five samples (89481, 89487, 89490, 89494, and 89497) with six xenoliths. A thin section was made for each sample except sample 89490 for which two thin sections were made, due to the presence of two different xenoliths (89490B xenolith A and B). The samples are all of peridotitic composition, except 89481, which is clinopyroxenite. Detailed thin section descriptions are in Appendix I. After petrographic analysis of the six thin sections, a range of textures and mineralogy has been identified. The samples, excluding the clinopyroxenite, have been divided into three textural groups (Figures 5a-c) after Harte (1977): porphyroclastic (89490B xenolith B, 89494), mosaic-porphyroclastic (89490A and 89490B xenolith A), and coarse (89487, 89497). An increase in the evidence of recrystallization corresponds to an increase in deformation to the sample. Mosaic-porphyroclastic samples are more deformed than porphyroclastic, and coarse samples have experienced very minimal deformation, or none at all (Nixon et al., 1981). Porphyroclastic textures are characterized by the presence of porphyroclasts (large strained grains completely surrounded by smaller grains) of which there is a proportion greater than 10% to that of the finer grained matrix (Harte, 1977). The smaller grains making up the matrix and surrounding the porphyroclasts are called \u00E2\u0080\u009Cneoblasts\u00E2\u0080\u009D (Nicholas et al., 1971). These grains are generally polygonal or tabular showing little strain and are believed to occur from recrystallization. Mosaic-porphyroclastic texture is characterized by the presence of porphyroclasts and a proportion of greater than 90% neoblasts to porphyroclasts (Harte, 1977). Neoblast grains occur in equant hexagonal shapes producing a mosaic look to the matrix. Coarse textures lack porphyroclasts, and the majority of mineral grains are on the order of 2 mm or greater in diameter showing straight, smoothly 12 curved or less regular grain boundaries (Harte, 1977). The clinopyroxenite xenolith is too altered for a representative texture to be identified (Fig. 5d). The mosaic-porphyroclastic xenoliths found in thin sections 89490A and 89490B (xenolith A) are determined to be from the same xenolith sample and thus from now on will only be referred to as sample 89490. The other xenolith in thin section 89490B (xenolith B) will be referred to as 89490B. 4.2 COARSE PERIDOTITE The coarse peridotites are composed of olivine (82-84%), orthopyroxene (10-12%), clinopyroxene (1-3%) and spinel (1-3%) with varied amounts of garnet (0-5%) (Fig. 5a). Rock types include garnet-spinel harzburgite and spinel harzburgite, according to the IUGS classification triangle for ultramafic rocks consisting essentially of olivine, orthopyroxene and clinopyroxene. Grains of olivine and pyroxene are anhedral, mostly equant with some elongate shapes. Olivine and orthopyroxene grains are highly fractured showing undulose extinction, and some of the larger orthopyroxenes have deformational twinning present. Spinels are anhedral and form interstitially in sample 89497. The clinopyroxene present in sample 89487 almost exclusively occurs in association with spinel grains, where as in sample 89497 it occurs in association with orthopyroxene, sometimes even in solid solution equilibrium. Garnet, only present in sample 89497, is mostly all completely recrystallized to kelyphite; a microcrystalline aggregate of spinel, phlogopite, chlorite, amphibole, and (?)plagioclase that develops at the garnet\u00E2\u0080\u0099s expense (Dawson and Stephens, 1975). 4.3 DEFORMED PERIDOTITE 4.3.1 Porphyroclastic Samples The porphyroclastic xenoliths are composed of olivine (85-97%), orthopyroxene (3-8%), clinopyroxene (0-5%), and garnet (0-2%) (Fig. 5b). Rock types include garnet lherzolite and dunite. The porphyroclastic texture is due to dynamic recrystallization of olivine grains forming subhedral to anhedral olivine porphyroclasts and anhedral neoblasts. Olivine porphyroclasts show deformation 13 structures such as undulose extinction, and fluidal inclusions following fracture patterns. Anhedral orthopyroxene and euhedral to subhedral clinopyroxene grains show evidence of deformation such as undulose extinction. Inclusions are also present around grain boundaries, indicative of partial melting. Garnet is only present in sample 89494, and has been almost completely recrystallized to kelyphite. The dunite xenolith is only represented by a very small section present in sample 89490B, and so this petrographic/mineralogical classification must be considered only tentative as a larger sample could prove to show a different composition than seen here. 4.3.2 Mosaic-Porphyroclastic Sample The mosaic-porphyroclastic xenolith is composed of olivine (70%), orthopyroxene (15-20%), clinopyroxene (10%), and garnet (5%) (Fig. 5c). The rock type is garnet lherzolite. Anhedral olivine porphyroclasts commonly show undulose extinction, and neoblasts are present in anhedral equant hexagonal shapes giving the rock the characteristic \u00E2\u0080\u009Cmosaic\u00E2\u0080\u009D texture. Orthopyroxene and clinopyroxene also show porphyroclasts and neoblasts, as well as evidence for partial melting, such as inclusions along grain margins. All garnet grains are surrounded by a kelyphitic rim, although these are the thinnest of all the peridotite samples analyzed. 4.4 CLINOPYROXENITE SAMPLE The clinopyroxenite xenolith consists of garnet (20%), clinopyroxene (10%) and minor orthopyroxene (1%), spinel (0.5%) and olivine (0.5%) (Fig.5d). The sample is highly altered (70%) by a cryptocrystalline material likely to be serpentine and chlorite, making it difficult to determine a texture to the rock. Garnet grains have recrystallized kelyphitic rims. Clinopyroxenes show high birefringence and fracturing. 14 Figure 5. Microscope photos of textures and rocks described above. a) Coarse texture (sample 89487); b) Porphyroclastic texture (sample 89494); c) Mosaic-porphyroclastic texture (sample 89490); d) Clinopyroxenite (sample 89481). Ol=olivine, Opx=orthopyroxene, Cpx=clinopyroxene, Gar=garnet, Spl=spinel. 15 CHAPTER 5 MINERAL CHEMISTRY OF THE TUWAWI MANTLE XENOLITHS 5.1 ANALYTICAL METHODS Electron Microprobe analysis was conducted all six mantle xenolith samples at the University of British Columbia, Earth and Ocean Science Department using a fully- automated Cameca SX-50 Scanning Electron Microprobe, operating on wavelength dispersion mode (WDS). Olivine, pyroxene, garnet and spinel were analyzed at an excitation voltage of 15 kV and a beam current of 20 nA. For all elements peak count times were 20 s, with the exception of K in pyroxene and Na in garnet which were 40 s and 60 s respectively. Background count times were 10 s for all elements, except K in pyroxene and Na in garnet which were 20 s and 30 s. For all elements analyzed the spot diameter was 5 \u00EF\u0081\u00ADm. Data reduction was done using the 'PAP' \u00EF\u0081\u00A6(\u00EF\u0081\u00B2Z) method (Pouchou & Pichoir, 1985). The above analytical conditions and counting times resulted in the following minimum detection limits: Table 1 Minimum Dection Limits for Electron Microprobe Analyses Oxides MDL (wt %) SiO2 0.07 TiO2 0.05 Al2O3 0.09 Cr2O3 0.16 FeO 0.08 MnO 0.08 MgO 0.04 CaO 0.04 Na2O 0.09 K2O 0.09 NiO 0.09 16 5.2 OLIVINE Olivines in all xenoliths are forsterite-rich, with Mg# of 0.91 and 0.92 (Mg# = Mg/(Mg+Fe); Table 2). There is no obvious chemical distinction between neoblasts and porphyroclasts in deformed xenoliths. Deformed peridotites have olivines with slightly lower MgO and higher FeO (49.72-49.57wt% MgO, 8.97-8.93 wt% FeO) than those in coarse samples (50.81-50.71 wt% MgO, 7.37-7.53 wt% FeO). The porphyroclastic xenolith in sample 89490B has olivines with MgO and FeO values between those in the other deformed xenoliths and the coarse xenoliths (50.53 wt% MgO, 8.04 wt% FeO). Xenoliths containing spinel also show the trend of having olivine grains with higher MgO and lower FeO than those in xenoliths without spinel. Nickel content is basically homogeneous in all olivines (0.37-0.39 wt% NiO), except sample 89497 in which grains have a NiO content of 0.34 wt% NiO. All olivines are Al, Cr, Ti and Na-poor with Al2O3, Cr2O3, TiO2 and Na2O all below minimum detection limits (MDL). 2 5.3 ORTHOPYROXENE Orthopyroxenes are all enstatite rich with Mg# of 0.92-0.93 (Table 3), and have similar FeO content (5.06-5.62 wt% FeO). The exception is sample 89497, in which orthopyroxenes have a lower FeO value of 4.63 wt% FeO. Coarse peridotites and clinopyroxenite show grains slightly more Mg-rich (34.74-36.23 wt% MgO) than those in deformed peridotites (33.99-34.67 wt% MgO). Chemical compositions, with regards to Al2O3 content, show orthopyroxenes in deformed xenoliths with higher Al2O3 (0.76-0.68 wt% Al2O3) than those in the clinopyroxenite (0.56 wt% Al2O3) and one of the coarse xenoliths (89497) (0.63 wt% Al2O3). The other coarse sample (89487) has very Al-rich (1.71 wt% Al2O3) orthopyroxenes. Chromium content is homogeneous across all orthopyroxene (0.21-0.23 wt% Cr2O3) except sample 84987, in which the Cr2O3 content of orthopyroxene is approximately double (0.41 wt% Cr2O3). Orthopyroxenes in coarse samples show TiO levels below MDL; all other orthopyroxenes are Ti-poor (0.11-0.22 wt% TiO2). 17 5.4 CLINOPYROXENE Clinopyroxenes are Ti-poor (4.2x3.8 mm to 2.3x2.5 mm. Inclusions of clinopyroxene and talc (?) are present. 10% Clinopyroxene \u00E2\u0080\u0093 Grains occur as euhedral to subhedral, tabular and equant crystals. Only longitudinal sections are present with one cleavage. Grain size ranges up to 1.8x0.56mm, and grains show sub-grains and undulose extinction. 1% Orthopyroxene \u00E2\u0080\u0093 Grains occur as fractured, anhedral crystals showing low interference colours and parallel to sub-parallel extinction. Longitudinal sections are present with one cleavage. Size is 0.24x0.32 mm. 0.5% Olivine (?) \u00E2\u0080\u0093 Grains occur as highly fractured, anhedral, equant crystals ranging in size from 0.76x1 mm to 0.32x0.4 mm, and showing higher relief than clinopyroxene. Secondary Minerals: 70% Cryptocrystalline, yellowy-brown alteration entirely replacing clinopyroxene and groundmass minerals, likely serpentine and chlorite. There is also a dark rusty brown coloured mineral throughout the groundmass alteration, likely spinel. - Kelyphite \u00E2\u0080\u0093 brown, cryptocrystalline, with a radiating fibrous texture although texture is not as distinct as in previous samples. - Calcite veining and alteration throughout sample. - Talc around garnets and in fractures. 48 B. KIMBERLITE: Sample: 89496 Thin Section: 89496A and B Name: Phlogopite kimberlite Texture: Macrocrystal Primary Minerals: 15% Macrocrysts (>0.5 mm): 13% Olivine - Grains occur as subhedral, rounded, equant to elongate crystals ranging in size from 1.9x5 mm to 0.32x0.16 mm. Grains are quite fractured and some show undulose extinction. Birefringence colours are present up to second order yellow. Dynamic recrystallization has occurred in some grains. 1% Spinel \u00E2\u0080\u0093 subhedral to euhedral grain, 0.24x0.32 mm in size. 1% Opaque mineral - subhedral to euhedral grain, 0.88x0.48 mm in size. Likely spinel. 85% Groundmass: 20% Microphenocrysts of olivine \u00E2\u0080\u0093 grains occur as subhedral to euhedral, equant to elongate crystals ranging in size from 0.5 mm to 0.02 mm. Birefringence colours up to second order yellow are present. Some grains have been almost completely altered to serpentine, leaving a euhedral halo around a remnant grain. This is possibly monticellite (?). 15% Phlogopite \u00E2\u0080\u0093 grains occur as euhedral, elongate crystals showing parallel extinction and birefringence colours up to first order grey. Grains range in size from 0.6x0.08 mm to 0.1x0.05 mm. 15% Serpentine \u00E2\u0080\u0093 occurs as a fine grained aggregate between macrocrysts and microphenocrysts of olivine, showing grey/yellow birefringence colours. 15% Calcite \u00E2\u0080\u0093 occurs as a fine grained aggregate between macrocrysts and microphenocrysts of olivine, showing high pastel birefringence colours. 49 13% Spinel \u00E2\u0080\u0093 grains occur as subhedral to euhedral crystals ranging in size up to 0.8x0.4 mm. A dark reddy-brown colour and isotropism can be seen in the larger grains, but the smaller ones are opaque. These small opaque grains are identifiable as bead spinel from their nucleation on microphenocrysts. Atoll spinel is also present, making up approximately half of the spinel percentage. These grains are euhedral to subhedral cubic crystals, showing light brown colour in plain polar light and isotropism. Grains are surrounded by opaque rims/halos. Sizes range from 0.4x0.12 mm to 0.24x0.28 mm. There are also some anhedral grains present as inclusions in olivine macrocrysts. 5% Opaques \u00E2\u0080\u0093 grains occur as subhedral to euhedral, equant crystals, ranging in size up to 0.28x0.2 mm. Most likely spinel. ~2% Perovskite - euhedral, equant, blackish-brown grains, showing high second order birefringence that is muted by dark colour. Grains range in size up to 40 \u00C2\u00B5m in diameter. Secondary Minerals: - Serpentine replacing approximately 80% of the olivine macrocrysts on the outer margins. Some microphenocrysts also have replacement by serpentine. - Calcite veins are present in two forms. The larger vein is 1.44 mm wide, and consists of medium grained equant crystals. The calcite overprints and surrounds the kimberlite material. The smaller vein crosscuts grains and is composed of elongate crystals. Sample: 89495 Thin Section: 89495A and B Name: Carbonate, serpentine kimberlite Texture: Macrocrystal Primary Minerals: 15% Macrocrysts: 50 14% Olivine \u00E2\u0080\u0093 grains occur as subhedral, rounded, equant to elongate crystals. Sizes range from 3.2x2.4 mm to 0.5 mm. Grains are highly fractured and altered to serpentine and carbonate. Some show undulose extinction. 1% Spinel \u00E2\u0080\u0093 subhedral to euhedral, dark red, isotropic grains. Sizes range from 0.56x0.32 mm in size to 1.12x0.88 mm. The larger grain has a small olivine inclusion. Grains have opaque rims/halos, like atoll spinel. 85% Groundmass: 25% Serpentine \u00E2\u0080\u0093 occurs as interstitial anhedral fibrous crystals showing pale yellow/white colour and grey birefringence. 15% Calcite \u00E2\u0080\u0093 occurs as anhedral, fibrous crystals with ragged edges. Grains show low relief and high pastel birefringence. 18% Microphenocrysts of olivine \u00E2\u0080\u0093 grains occur as subhedral to euhedral equant and elongate crystals ranging in size up to 0.5 mm. Grains are altered to serpentine, carbonate and phlogopite (?). 10% Phlogopite \u00E2\u0080\u0093 subhedral to euhedral laths about 30x5 \u00CE\u00BCm in size. 10% Spinel \u00E2\u0080\u0093 occurs as bead spinel (small subhedral grains which nucleate around olivine microphenocrysts) and atoll spinel (euhedral cubic grains with halos and smaller opaque and non-opaque crystals between the core and halo). There is also a larger anhedral grain approximately 0.56x0.32 mm in size. 5% Opaque minerals \u00E2\u0080\u0093 occurs as subhedral grains, ranging in size up to 0.06x0.06 mm. 1% Perovskite \u00E2\u0080\u0093 occurs as subhedral to anhedral isotropic crystals, showing orangy- brown colour in plain polar light. ~1% Garnet \u00E2\u0080\u0093 very small (0.24x0.16 mm) isotropic grains with opaque rims. Grains have high relief and are colourless in plain polar. One euhedral, equant inclusion approximately 0.36x0.22 mm in size is present inside an olivine macrocryst. Secondary Minerals: - Calcite replacing olivine forms as large euhedral crystals. - Serpentine replacing olivine along fractures and around grain boundaries. - Chlorite (?) replacing garnet. 51 Sample: 89486 Thin Section: 89486A and B Name: Phlogopite kimberlite Texture: Macrocrystal Primary Minerals: 10% Megacryst \u00E2\u0080\u0093 irregular shaped grain 1.12x0.92 cm in size containing chlorite, carbonate, phlogopite laths, opaque minerals, possibly olivine, a dark brown epiclastic material, and a salmon coloured fibrous mineral that is possibly a mica. 15% Macrocrysts: 14% Olivine \u00E2\u0080\u0093 grains occur as subhedral, rounded, equant and elongate highly fractured crystals. Grains range in size from 2x2.1 mm to 0.5 mm. Some show undulose extinction and have serpentine, carbonate and phlogopite (?) alteration. 1% Xenoliths \u00E2\u0080\u0093 carbonate, highly altered to chlorite (?) 75% Groundmass: 20% Microphenocrysts of olivine \u00E2\u0080\u0093 occur as subhedral crystals with ragged edges ranging in size up to 0.5 mm. 15% Calcite\u00E2\u0080\u0093 occurs as anhedral patchy crystals with birefringence colours up to third order. 15% Serpentine \u00E2\u0080\u0093 occurs as anhedral patchy crystals with first order grey birefringence. 15% Spinel - occurs as bead spinel (small subhedral grains which nucleate around olivine microphenocrysts) and atoll spinel (euhedral cubic crystals with halos). Most grains show some brown colour and isotropism. Grains range in size up to 0.28x0.24 mm. 5% Opaque minerals \u00E2\u0080\u0093 subhedral to anhedral equant grains ranging in size up to 0.15 mm. These are possibly the finer grain fraction of spinel and perovskite. 0.5% Perovskite - euhedral, light brown, isotropic cubic grains with opaque rims. Grains are around 0.16 mm in size 52 Secondary Minerals: - Serpentine replacing olivine macrocrysts. - Calcite replacing olivine macrocrysts. Sample: 89488 Thin Section: 89488 Classification: Volcaniclastic kimberlite. The sample is composed of two parts that will be described separately below. Classification of this sample as a whole is very difficult. The two materials described below are hard to distinguish between as there is only one area where a clear contact exists. At this contact there is a distinct difference in colour, sorting, and abundance of phenocrysts. A high concentration of small microphenocrysts of olivine (?) exists along the contact in the matrix of the darker material. Larger olivine microphenocrysts, present along the contact and slightly into the darker material, are surrounded by selvages of the lighter matrix. Throughout the rest of the sample the two materials have diffuse margins making them look intermixed, like two immiscible fluids. Description One: Rock Name: Volcaniclastic Kimberlite The sample is composed of the following: 55% Discrete Macrocrysts - Olivine macrocrysts and microphenocrysts completely replaced by serpentine and carbonate. Grains are anhedral, mostly elongate, with some equant shapes. Sizes range up to 2.2 mm. Both the macrocrysts and microphenocrysts show rounded grain boundaries and a few of the larger macrocrysts have been fractured (or broken). 35% Light brown matrix, composed of: 57% Carbonate \u00E2\u0080\u0093 very fine grained, almost cryptocrystalline. 53 35% Serpentine (?) \u00E2\u0080\u0093 very fine grained, almost cryptocrystalline, showing low grey/blue birefringence. 3% Sedimentary (?) material \u00E2\u0080\u0093 dark brown, non isotropic patches (possibly clasts) scattered throughout matrix. Some have small opaque grains within, and/or carbonate grains in and around them. Material looks similar to darker matrix described below. 2% Opaque minerals are subhedral to anhedral, and sometimes equant. 2% Spinel \u00E2\u0080\u0093 Grains are subhedral, showing a dark brown colour and isotropism. 1% Phlogopite (?) laths are euhedral and range in size up to 40x230 \u00C2\u00B5m. Grains show birefringence colours up to second order yellow. 12% Lapilli (?) \u00E2\u0080\u0093 Irregular shaped, with a higher concentration of phenocrysts, in a dark brown matrix. None are vesicular. Some are olivine cored, and most have very thin selvages. There are a couple cored by orthopyroxene grains, 100x30 \u00C2\u00B5m and 50x35 \u00C2\u00B5m in size. One large, sub-rounded, elongate xenolith, approximately 7.6x2.2 mm in size, is also present with a thin selvage surrounding it. The xenolith is composed of fine grained carbonate, with a coarse grained carbonate vein. Some olivine microphenocrysts have atoll spinel clustered around them. Secondary Minerals: - Carbonate replacing olivine forms as large anhedral crystals showing a mosaic texture usually in the centers of the grains. - Serpentine is present replacing olivine. Grains are colourless and show blue birefringence. - Opaque minerals are euhedral to anhedral, and occurring in four different forms. Large anhedral patches are present, as well as euhedral crystals, and euhedral needle- like grains. There are also small burr-like grains, possibly consisting of small opaque crystals with microfractures extending radially from them. All forms are present overprinting the serpentine/carbonate after olivine grains. 54 Comments: Whether the fine grained material in the matrix mentioned above is actually of sedimentary composition or represents clasts of the other matrix material, cannot be determined by basic petrographic analysis. The designation of lapilli to the irregular shaped clasts of the darker matrix is tentative, as these \u00E2\u0080\u009Cclasts\u00E2\u0080\u009D could merely be part of the patchy mixing distribution of the two different matrices. Description Two: Rock Name: Volcaniclastic kimberlite The sample is composed of the following: 55% Discrete Macrocrysts - Olivine macrocrysts and microphenocrysts completely replaced by serpentine and carbonate. Grains are anhedral, rounded, mostly elongate, with some equant. Sizes range up to 2 mm. The macrocrysts and larger microphenocrysts show rounded grain boundaries and a few of the larger macrocrysts have been fractured (or broken). The smaller microphenocrysts show angular shapes; wedges are most common. 20% Lapilli - The majority of olivine grains have selvages of varying thickness and shape around them (composed of the lighter matrix material) forming juvenile lapilli. These juvenile lapilli form in erratic shapes pertaining to the olivine grains within them. Few are olivine cored. 25% Matrix - Dark brown matrix 35% Carbonate - cryptocrystalline, with high pastel birefringence. 35% Serpentine (?) \u00E2\u0080\u0093 cryptocrystalline, yellow colour with low grey birefringence. 10% Spinel (?) \u00E2\u0080\u0093 dark, fine grained, cryptocrystalline 20% Opaque minerals or ash - euhedral grains of about 5 \u00C2\u00B5m in size. 3% Phlogopite (?) laths are euhedral and range in size up to 40x230 \u00C2\u00B5m. 55 Secondary Minerals: - Carbonate replacing olivine forms as large anhedral crystals showing a mosaic texture usually in the centers of the grains. There is also carbonate occurring as crystals with a fibrous colloform texture around the grain edges of some olivines. - Serpentine is present replacing olivine. Grains are yellow or colourless, and show yellow/blue birefringence. - Chlorite (?) \u00E2\u0080\u0093 subhedral, 35x15 \u00C2\u00B5m in size, slight green pleochroism and anomalous blue birefringence. - Opaque minerals are euhedral to anhedral, and occurring in four different forms. Large anhedral patches are present, as well as euhedral crystals, and euhedral needle- like grains. There are also small burr-like grains, possibly consisting of small opaque crystals with microfractures extending radially from them. All forms are present overprinting the serpentine/carbonate replaced olivine grains. - Pectolite (?) / Apatite (?) \u00E2\u0080\u0093 bright, reddy-orange, euhedral (?) aggregates of grains overprinting replaced olivine macrocrysts. Individual grains are microns in size and resemble fish roe. Comments: The source of the dark colour of the matrix is unknown. Possible sources include a high concentration of cryptocrystalline spinel, the presence of mud making the material epiclastic, or high concentrations of ash. The thin section is too thick for successful focusing of the matrix grains, and thus identification of the materials is limited to the outer edges of the sample. Discussion: The sample is thought to be volcaniclastic due to the restricted size distribution of olivine microphenocrysts and macrocrysts when compared to the more even distribution seen in the hypabyssal kimberlite samples. In the sample, smaller olivines have very uniform 160 \u00C2\u00B5m and appear sorted. Other evidence for a volcaniclastic origin is the angular shapes of the olivines, the presence of lapilli, and the unusually dark and cryptocrystalline nature of the matrices. The irregular shapes and greater selvage thicknesses of the lapilli classify them as 56 juvenile lapilli, which are present in volcaniclastic non-tuffisitic kimberlite. A faint sorting and the possibility of the darker matrix consisting of sedimentary material point to a re- sedimented volcaniclastic (epiclastic) kimberlite classification. Although, the dark nature of the matrix could also be due to the presence of ash, or cryptocrystalline spinel, as has been mentioned above. Since none of these hypotheses can be proved by petrographic analysis, and further analytical techniques are beyond the scope of this description, the sample will be classified as a volcaniclastic kimberlite. 57 Appendix II Electron Microprobe Analysis of Mantle Xenolith Samples Table 1 Composition of minerals in sample 89490B Xenolith B Mineral Olivine Label 90B-13 90B-14 90B-15 90B-16 90B-17 90B-18 90B-19 90B-20 90B-21 90B-22 90B-23 Avg Circle 9 9 10 10 10 10 10 11 11 11 11 SiO2 40.66 40.86 40.32 40.96 40.08 40.96 40.44 41.31 40.77 41.03 40.58 40.72 TiO2 -- -- -- -- -- -- -- -- -- -- -- -- Al2O3 -- -- -- -- -- -- -- -- -- -- -- -- Cr2O3 -- -- -- -- -- -- -- -- -- -- -- -- FeO 8.07 8.00 7.83 8.03 8.04 7.93 8.29 8.05 8.02 8.11 8.03 8.04 MnO 0.12 0.15 0.17 0.13 0.08 0.09 0.10 0.14 0.13 0.11 0.11 0.12 MgO 50.55 50.53 50.50 50.56 50.76 50.48 50.24 50.56 50.58 50.63 50.41 50.53 CaO 0.05 0.09 0.08 0.06 0.05 0.10 0.08 0.08 0.09 0.08 0.05 0.07 Na2O -- -- -- -- -- -- -- -- -- -- -- -- K2O n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a NiO 0.37 0.39 0.42 0.40 0.32 0.38 0.45 0.37 0.37 0.34 0.37 0.38 Total 99.91 100.15 99.34 100.20 99.49 100.08 99.73 100.67 100.06 100.48 99.70 99.98 Oxygens 4 4 4 4 4 4 4 4 4 4 4 4 Si4+ 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 Ti4+ -- -- -- -- -- -- -- -- -- -- -- -- Al3+ -- -- -- -- -- -- -- -- -- -- -- -- Cr3+ -- -- -- -- -- -- -- -- -- -- -- -- Fe2+ 0.166 0.164 0.162 0.164 0.168 0.162 0.172 0.163 0.165 0.165 0.166 0.165 Mn2+ 0.003 0.003 0.004 0.003 0.002 0.002 0.002 0.003 0.003 0.002 0.002 0.003 Mg2+ 1.853 1.843 1.867 1.840 1.887 1.837 1.852 1.825 1.849 1.839 1.852 1.849 Ca2+ 0.001 0.002 0.002 0.002 0.001 0.003 0.002 0.002 0.002 0.002 0.001 0.002 Na+ -- -- -- -- -- -- -- -- -- -- -- -- K+ n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a Ni2+ 0.007 0.008 0.008 0.008 0.006 0.007 0.009 0.007 0.007 0.007 0.007 0.008 Total 3.032 3.024 3.044 3.017 3.068 3.014 3.040 3.005 3.029 3.021 3.032 3.030 Mg# 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 0.92 Here and Further: -- = below MDL n/a = not analysed 58 ATa bl e 2 C om po si tio n of m in er al s in s am pl e 89 49 0A a nd 8 94 90 B x en ol ith A M in er al O liv in e La be l 90 A- 3 90 A- 4 90 A- 5 90 A- 6 90 A- 7 90 A- 8 90 A- 9 90 A- 10 90 A- 11 90 B -1 90 B -4 90 B -8 90 B -9 90 B -1 1 vg C irc le 7 7 7 7 7 8 8 8 8 3 3 6 6 7 Si O 2 40 .9 6 40 .1 8 40 .6 9 39 .6 4 40 .7 3 40 .3 7 40 .8 4 40 .1 9 41 .2 6 40 .2 9 40 .6 3 40 .9 3 40 .6 3 40 .4 2 40 .5 5 Ti O 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Al 2O 3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- C r 2 O 3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Fe O 8. 98 8. 78 8. 87 8. 99 8. 88 9. 10 8. 89 8. 94 9. 03 8. 97 9. 12 8. 96 9. 09 8. 93 8. 97 M nO 0. 14 0. 14 0. 11 0. 11 0. 12 0. 08 0. 12 0. 06 0. 11 0. 11 0. 16 0. 11 0. 10 0. 09 0. 11 M gO 49 .7 1 49 .8 3 49 .7 0 49 .9 2 49 .5 9 49 .6 2 49 .6 9 49 .5 0 49 .6 4 49 .6 9 49 .6 0 49 .9 5 49 .9 7 49 .6 1 49 .7 2 C aO 0. 06 0. 06 0. 09 0. 08 0. 05 0. 07 0. 07 0. 08 0. 06 0. 04 0. 07 0. 07 0. 09 0. 07 0. 07 N a 2 O -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- K 2O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a N iO 0. 41 0. 36 0. 38 0. 41 0. 33 0. 38 0. 33 0. 33 0. 38 0. 39 0. 45 0. 36 0. 33 0. 33 0. 37 To ta l 10 0. 34 99 .4 2 99 .9 4 99 .1 8 99 .8 3 99 .7 1 10 0. 04 99 .1 5 10 0. 55 99 .5 5 10 0. 11 10 0. 45 10 0. 32 99 .5 0 99 .8 6 O xy ge ns 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Si 4+ 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 Ti 4+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Al 3+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- C r3 + -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Fe 2+ 0. 18 3 0. 18 3 0. 18 2 0. 19 0 0. 18 2 0. 18 9 0. 18 2 0. 18 6 0. 18 3 0. 18 6 0. 18 8 0. 18 3 0. 18 7 0. 18 5 0. 18 5 M n2 + 0. 00 3 0. 00 3 0. 00 2 0. 00 2 0. 00 3 0. 00 2 0. 00 2 0. 00 1 0. 00 2 0. 00 2 0. 00 3 0. 00 2 0. 00 2 0. 00 2 0. 00 2 M g2 + 1. 80 9 1. 84 8 1. 82 0 1. 87 7 1. 81 5 1. 83 2 1. 81 4 1. 83 6 1. 79 3 1. 83 8 1. 81 9 1. 81 9 1. 83 3 1. 82 9 1. 82 7 C a2 + 0. 00 1 0. 00 2 0. 00 2 0. 00 2 0. 00 1 0. 00 2 0. 00 2 0. 00 2 0. 00 1 0. 00 1 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 2 N a+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- K + n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a N i2+ 0. 00 8 0. 00 7 0. 00 7 0. 00 8 0. 00 7 0. 00 8 0. 00 6 0. 00 7 0. 00 7 0. 00 8 0. 00 9 0. 00 7 0. 00 7 0. 00 7 0. 00 7 To ta l 3. 00 7 3. 04 5 3. 01 8 3. 08 0 3. 01 1 3. 03 5 3. 00 9 3. 03 4 2. 98 9 3. 03 8 3. 02 3 3. 01 5 3. 03 5 3. 02 6 3. 02 6 M g# 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 59 Ta bl e 2 c on tin ue d M in er al O rth op yr ox en e Cl in op yr ox en e G ar ne t La be l 90 B- 2 90 B- 8 90 A- 13 Av g 90 B- 12 90 A- 1 90 A- 2 90 A- 3 90 A- 4 90 A- 5 90 A- 6 90 A- 8 90 A- 10 90 A- 9 90 B- 1 90 B- 2 Av g Ci rc le 1 1 4 5 8 1 1 1 2 2 4 5 6 5 1 1 Si O 2 57 .3 5 57 .3 1 57 .2 4 57 .3 0 54 .3 2 41 .9 7 41 .7 9 41 .6 3 41 .8 6 41 .6 9 41 .7 5 41 .6 8 41 .7 6 41 .3 7 41 .7 6 41 .7 2 41 .7 3 Ti O 2 0. 11 0. 13 0. 11 0. 12 0. 16 0. 47 0. 42 0. 43 0. 48 0. 50 0. 47 0. 49 0. 44 0. 46 0. 46 0. 45 0. 46 Al 2O 3 0. 77 0. 73 0. 76 0. 75 0. 65 21 .0 1 21 .1 4 21 .0 3 21 .0 3 20 .9 9 20 .8 9 20 .9 0 20 .9 2 20 .8 7 21 .0 3 20 .9 8 20 .9 8 Cr 2O 3 0. 26 0. 26 0. 22 0. 24 0. 96 3. 11 3. 08 3. 02 3. 08 3. 01 3. 10 3. 14 3. 05 3. 03 3. 00 3. 15 3. 07 Fe O 5. 52 5. 64 5. 62 5. 59 2. 94 7. 47 7. 53 7. 76 7. 57 7. 73 7. 69 7. 68 7. 76 7. 82 7. 98 7. 58 7. 69 M nO 0. 14 0. 15 0. 13 0. 14 0. 11 0. 25 0. 31 0. 26 0. 29 0. 33 0. 32 0. 28 0. 35 0. 27 0. 33 0. 34 0. 30 M gO 33 .8 2 34 .0 3 33 .9 9 33 .9 5 18 .9 0 20 .8 4 20 .7 7 20 .8 2 20 .6 2 20 .8 2 20 .7 5 20 .6 6 20 .7 7 20 .6 4 20 .8 7 20 .9 6 20 .7 7 Ca O 0. 89 0. 88 0. 87 0. 88 19 .9 9 4. 62 4. 56 4. 60 4. 52 4. 58 4. 47 4. 55 4. 53 4. 54 4. 53 4. 56 4. 55 Na 2O 0. 16 0. 19 0. 15 0. 17 0. 79 -- -- -- -- -- -- -- -- -- -- -- -- K 2 O -- -- -- -- -- n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a Ni O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 99 .0 2 99 .3 3 99 .1 0 99 .1 5 98 .8 2 99 .8 0 99 .6 5 99 .5 9 99 .4 8 99 .6 9 99 .4 9 99 .4 3 99 .6 2 99 .0 4 10 0. 04 99 .7 9 99 .6 0 O xy ge ns 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 Si 4+ 1. 99 2 1. 98 6 1. 98 7 1. 98 8 1. 98 6 2. 99 8 2. 99 0 2. 98 4 3. 00 0 2. 98 6 2. 99 5 2. 99 2 2. 99 4 2. 98 4 2. 98 4 2. 98 5 2. 99 0 Ti 4+ 0. 00 3 0. 00 3 0. 00 3 0. 00 3 0. 00 4 0. 02 6 0. 02 3 0. 02 3 0. 02 6 0. 02 7 0. 02 5 0. 02 7 0. 02 4 0. 02 5 0. 02 5 0. 02 4 0. 02 5 Al 3+ 0. 03 2 0. 03 0 0. 03 1 0. 03 1 0. 02 8 1. 76 9 1. 78 3 1. 77 7 1. 77 6 1. 77 2 1. 76 6 1. 76 8 1. 76 7 1. 77 4 1. 77 1 1. 76 9 1. 77 2 Cr 3+ 0. 00 7 0. 00 7 0. 00 6 0. 00 7 0. 02 8 0. 17 6 0. 17 4 0. 17 1 0. 17 4 0. 17 0 0. 17 6 0. 17 8 0. 17 3 0. 17 3 0. 17 0 0. 17 8 0. 17 4 Fe 2+ 0. 16 0 0. 16 4 0. 16 3 0. 16 2 0. 09 0 0. 44 7 0. 45 1 0. 46 5 0. 45 3 0. 46 3 0. 46 1 0. 46 1 0. 46 5 0. 47 2 0. 47 7 0. 45 4 0. 46 1 M n2 + 0. 00 4 0. 00 4 0. 00 4 0. 00 4 0. 00 3 0. 01 5 0. 01 9 0. 01 6 0. 01 7 0. 02 0 0. 02 0 0. 01 7 0. 02 1 0. 01 7 0. 02 0 0. 02 1 0. 01 8 M g2 + 1. 75 1 1. 75 8 1. 75 9 1. 75 6 1. 03 0 2. 21 9 2. 21 5 2. 22 5 2. 20 3 2. 22 3 2. 21 8 2. 21 0 2. 21 9 2. 21 9 2. 22 3 2. 23 5 2. 21 9 Ca 2+ 0. 03 3 0. 03 3 0. 03 2 0. 03 3 0. 78 3 0. 35 4 0. 35 0 0. 35 3 0. 34 7 0. 35 2 0. 34 4 0. 35 0 0. 34 8 0. 35 1 0. 34 7 0. 34 9 0. 34 9 Na + 0. 01 1 0. 01 3 0. 01 0 0. 01 1 0. 05 6 -- -- -- -- -- -- -- -- -- -- -- -- K+ -- -- -- -- -- n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a Ni 2+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 3. 99 2 3. 99 9 3. 99 6 3. 99 6 4. 01 0 8. 00 8 8. 01 2 8. 02 2 8. 00 3 8. 01 9 8. 01 3 8. 01 1 8. 01 7 8. 02 1 8. 02 5 8. 02 2 8. 01 6 M g# 0. 92 0. 91 0. 92 0. 92 0. 92 0. 83 0. 83 0. 83 0. 83 0. 83 0. 83 0. 83 0. 83 0. 82 0. 82 0. 83 0. 83 60 Ta bl e 3 C om po si tio n of m in er al s in s am pl e 89 49 4 M in er al Ol iv in e La be l 94 -1 94 -2 94 -3 94 -4 94 -5 94 -6 94 -7 94 -8 94 -9 94 -1 0 94 -1 1 94 -1 2 94 -1 3 94 -1 4 94 -1 5 94 -1 6 94 -1 7 94 -1 8 94 -1 9 Av g Ci rc le 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 Si O 2 40 .5 9 41 .0 8 40 .7 2 41 .2 0 40 .7 0 40 .9 5 40 .4 9 40 .8 9 40 .8 3 40 .8 7 40 .4 8 40 .8 3 40 .6 0 40 .7 7 40 .5 5 41 .0 5 40 .5 8 40 .6 2 40 .6 9 40 .7 6 Ti O 2 -- -- -- -- 0. 06 -- 0. 05 0. 06 -- 0. 05 -- -- -- -- -- 0. 06 -- 0. 06 -- 0. 04 Al 2O 3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Cr 2O 3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Fe O 8. 73 8. 81 8. 83 8. 84 9. 03 9. 17 8. 85 9. 00 8. 94 8. 91 9. 17 8. 90 8. 92 8. 93 8. 88 9. 01 8. 84 8. 97 8. 88 8. 93 M nO 0. 06 0. 10 0. 08 0. 13 0. 10 0. 05 0. 10 0. 10 0. 13 0. 11 0. 11 -- 0. 14 0. 08 0. 16 0. 10 0. 10 0. 10 0. 12 0. 10 M gO 49 .4 2 49 .7 2 49 .7 7 49 .5 0 49 .4 5 49 .7 8 49 .4 2 49 .7 2 49 .5 0 49 .7 2 49 .4 5 49 .6 5 49 .6 8 49 .7 1 49 .5 7 49 .5 6 49 .3 6 49 .5 8 49 .3 5 49 .5 7 Ca O 0. 07 0. 07 0. 07 0. 08 0. 05 0. 06 0. 08 0. 05 0. 05 0. 07 0. 04 0. 04 0. 07 0. 05 0. 06 0. 05 0. 08 0. 05 0. 07 0. 06 Na 2O -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- K 2 O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a Ni O 0. 37 0. 43 0. 33 0. 40 0. 37 0. 40 0. 46 0. 38 0. 42 0. 36 0. 37 0. 48 0. 38 0. 36 0. 38 0. 37 0. 36 0. 39 0. 39 0. 39 To ta l 99 .3 4 10 0. 28 99 .9 2 10 0. 29 99 .7 9 10 0. 49 99 .4 8 10 0. 24 99 .9 3 10 0. 14 99 .6 9 10 0. 06 99 .9 3 99 .9 8 99 .7 1 10 0. 26 99 .4 1 99 .7 7 99 .5 7 99 .9 1 Ox yg en s 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Si 4+ 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 Ti 4+ -- -- -- -- 0. 00 1 -- 0. 00 1 0. 00 1 -- 0. 00 1 -- -- -- -- -- 0. 00 1 -- 0. 00 1 -- 0. 00 1 Al 3+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Cr 3+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Fe 2+ 0. 18 0 0. 17 9 0. 18 1 0. 17 9 0. 18 6 0. 18 7 0. 18 3 0. 18 4 0. 18 3 0. 18 2 0. 18 9 0. 18 2 0. 18 4 0. 18 3 0. 18 3 0. 18 3 0. 18 2 0. 18 5 0. 18 3 0. 18 3 M n2 + 0. 00 1 0. 00 2 0. 00 2 0. 00 3 0. 00 2 0. 00 1 0. 00 2 0. 00 2 0. 00 3 0. 00 2 0. 00 2 -- 0. 00 3 0. 00 2 0. 00 3 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 2 M g2 + 1. 81 5 1. 80 4 1. 82 2 1. 79 1 1. 81 1 1. 81 2 1. 81 9 1. 81 2 1. 80 7 1. 81 4 1. 82 1 1. 81 2 1. 82 4 1. 81 7 1. 82 2 1. 79 9 1. 81 3 1. 81 9 1. 80 8 1. 81 3 Ca 2+ 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 1 0. 00 1 0. 00 2 0. 00 1 0. 00 1 0. 00 2 0. 00 1 0. 00 1 0. 00 2 0. 00 1 0. 00 2 0. 00 1 0. 00 2 0. 00 1 0. 00 2 0. 00 2 Na + -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- K+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a Ni 2+ 0. 00 7 0. 00 9 0. 00 6 0. 00 8 0. 00 7 0. 00 8 0. 00 9 0. 00 7 0. 00 8 0. 00 7 0. 00 7 0. 00 9 0. 00 8 0. 00 7 0. 00 8 0. 00 7 0. 00 7 0. 00 8 0. 00 8 0. 00 8 To ta l 3. 00 8 2. 99 7 3. 01 6 2. 98 6 3. 01 0 3. 01 2 3. 01 7 3. 01 0 3. 00 4 3. 00 9 3. 02 3 3. 00 9 3. 02 4 3. 01 3 3. 02 1 2. 99 6 3. 00 9 3. 01 6 3. 00 5 3. 01 0 M g# 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 0. 91 61 Ta bl e 3 c on tin ue d M in er al Or th op yr ox en e La be l 94 -1 94 -4 94 -2 49 4- 1 49 4- 2 49 4- 3 49 4- 4 49 4- 5 49 4- 15 49 4- 16 49 4- 18 49 4- 19 49 4- 20 49 4- 22 49 4- 23 49 4- 25 49 4- 28 49 4- 29 Av g Ci rc le 1 1 1 3 3 3 4 4 2 2 1 1 1 6 6 6 7 7 Si O 2 57 .1 1 57 .3 4 57 .8 2 56 .7 0 57 .2 7 56 .9 0 57 .2 6 56 .5 9 56 .8 7 57 .0 9 56 .8 5 56 .6 9 56 .8 1 56 .8 1 56 .6 4 56 .8 1 57 .0 2 56 .5 2 56 .9 5 Ti O 2 0. 23 0. 22 0. 22 0. 23 0. 22 0. 25 0. 19 0. 20 0. 20 0. 21 0. 22 0. 24 0. 24 0. 18 0. 20 0. 20 0. 21 0. 23 0. 22 Al 2O 3 0. 68 0. 69 0. 68 0. 67 0. 70 0. 67 0. 67 0. 71 0. 67 0. 68 0. 69 0. 67 0. 66 0. 70 0. 66 0. 72 0. 68 0. 71 0. 68 Cr 2O 3 0. 25 0. 23 0. 21 0. 24 0. 25 0. 21 0. 25 0. 21 0. 25 0. 17 0. 26 0. 24 0. 17 0. 30 0. 25 0. 23 0. 22 0. 27 0. 23 Fe O 5. 27 5. 38 5. 23 5. 32 5. 30 5. 65 5. 42 5. 62 5. 37 5. 42 5. 37 5. 24 5. 37 5. 43 5. 46 5. 25 5. 31 5. 35 5. 37 M nO 0. 16 0. 12 0. 11 0. 16 0. 14 0. 10 0. 11 0. 13 -- 0. 11 0. 13 0. 14 -- 0. 14 0. 11 -- 0. 15 0. 19 0. 12 M gO 34 .7 1 34 .7 7 34 .5 6 34 .7 2 34 .5 2 34 .5 9 34 .7 7 34 .5 2 34 .6 9 34 .6 5 34 .7 0 34 .8 0 34 .6 6 34 .6 9 34 .7 0 34 .7 0 34 .6 1 34 .6 9 34 .6 7 Ca O 0. 91 0. 93 0. 87 0. 94 0. 92 0. 93 0. 88 0. 96 0. 95 1. 00 0. 91 0. 94 0. 97 0. 99 0. 99 0. 97 0. 95 0. 92 0. 94 Na 2O 0. 15 0. 12 0. 11 0. 16 0. 15 0. 15 0. 11 0. 15 0. 15 0. 11 0. 13 0. 12 0. 14 0. 12 0. 10 0. 10 0. 13 0. 14 0. 13 K 2 O -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Ni O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 99 .4 6 99 .8 0 99 .8 4 99 .1 3 99 .4 8 99 .4 5 99 .6 6 99 .1 0 99 .2 2 99 .4 5 99 .2 6 99 .0 6 99 .0 9 99 .3 5 99 .1 2 99 .0 6 99 .2 8 99 .0 3 99 .3 2 Ox yg en s 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Si 4+ 1. 97 6 1. 98 9 1. 97 7 1. 97 0 1. 98 0 1. 97 2 1. 97 7 1. 96 9 1. 97 3 1. 97 6 1. 97 2 1. 97 0 1. 97 3 1. 97 0 1. 96 9 1. 97 3 1. 97 6 1. 96 7 1. 97 4 Ti 4+ 0. 00 6 0. 00 6 0. 00 6 0. 00 6 0. 00 6 0. 00 7 0. 00 5 0. 00 5 0. 00 5 0. 00 6 0. 00 6 0. 00 6 0. 00 6 0. 00 5 0. 00 5 0. 00 5 0. 00 6 0. 00 6 0. 00 6 Al 3+ 0. 02 8 0. 02 8 0. 02 8 0. 02 8 0. 02 9 0. 02 7 0. 02 7 0. 02 9 0. 02 8 0. 02 8 0. 02 8 0. 02 7 0. 02 7 0. 02 9 0. 02 7 0. 02 9 0. 02 8 0. 02 9 0. 02 8 Cr 3+ 0. 00 7 0. 00 6 0. 00 6 0. 00 7 0. 00 7 0. 00 6 0. 00 7 0. 00 6 0. 00 7 0. 00 5 0. 00 7 0. 00 7 0. 00 5 0. 00 8 0. 00 7 0. 00 6 0. 00 6 0. 00 7 0. 00 6 Fe 2+ 0. 15 2 0. 15 1 0. 15 5 0. 15 4 0. 15 3 0. 16 4 0. 15 6 0. 16 4 0. 15 6 0. 15 7 0. 15 6 0. 15 2 0. 15 6 0. 15 7 0. 15 9 0. 15 2 0. 15 4 0. 15 6 0. 15 6 M n2 + 0. 00 5 0. 00 3 0. 00 3 0. 00 5 0. 00 4 0. 00 3 0. 00 3 0. 00 4 -- 0. 00 3 0. 00 4 0. 00 4 -- 0. 00 4 0. 00 3 0. 00 2 -- 0. 00 6 0. 00 4 M g2 + 1. 78 9 1. 77 2 1. 78 7 1. 79 8 1. 77 9 1. 78 7 1. 78 9 1. 79 0 1. 79 4 1. 78 7 1. 79 4 1. 80 2 1. 79 5 1. 79 3 1. 79 8 1. 79 6 1. 78 8 1. 79 9 1. 79 1 Ca 2+ 0. 03 4 0. 03 2 0. 03 4 0. 03 5 0. 03 4 0. 03 5 0. 03 3 0. 03 6 0. 03 5 0. 03 7 0. 03 4 0. 03 5 0. 03 6 0. 03 7 0. 03 7 0. 03 6 0. 03 5 0. 03 4 0. 03 5 Na + 0. 01 0 0. 00 8 0. 00 8 0. 01 1 0. 01 0 0. 01 0 0. 00 8 0. 01 0 0. 01 0 0. 00 8 0. 00 9 0. 00 8 0. 00 9 0. 00 8 0. 00 7 0. 00 7 0. 00 9 0. 01 0 0. 00 9 K+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Ni 2+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 4. 00 6 3. 99 3 4. 00 5 4. 01 3 4. 00 2 4. 01 0 4. 00 5 4. 01 3 4. 01 0 4. 00 6 4. 00 9 4. 01 1 4. 00 9 4. 01 1 4. 01 2 4. 00 8 4. 00 6 4. 01 4 4. 00 8 M g# 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 62 Table 3 continued Mineral Clinopyroxene Garnet Label 494-8 494-10 494-14 Avg 94-1 94-3 94-4 94-5 94-2 Avg Circle 5 5 3 1 1 1 1 1 SiO2 54.34 54.56 54.08 54.33 42.05 41.91 41.84 41.99 41.47 41.85 TiO2 0.31 0.30 0.33 0.31 0.43 0.31 0.34 0.34 0.33 0.35 Al2O3 1.49 1.50 1.50 1.50 21.64 21.61 21.78 21.57 21.58 21.64 Cr2O3 0.84 0.78 0.79 0.80 2.68 2.75 2.70 2.59 2.76 2.70 FeO 3.25 3.14 3.09 3.16 7.23 7.13 7.16 7.18 7.40 7.22 MnO 0.13 0.12 0.12 0.12 0.27 0.26 0.32 0.31 0.28 0.29 MgO 18.96 18.85 19.02 18.94 21.14 20.99 21.19 21.03 21.21 21.11 CaO 18.59 18.68 18.86 18.71 4.43 4.53 4.53 4.39 4.54 4.48 Na2O 1.08 1.07 1.16 1.10 -- -- -- -- -- -- K2O -- -- -- -- n/a n/a n/a n/a n/a n/a NiO n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a Total 99.06 99.06 99.02 99.04 99.93 99.53 99.90 99.45 99.61 99.68 Oxygens 6 6 6 6 7 7 7 7 7 7 Si4+ 1.978 1.983 1.971 1.977 2.990 2.992 2.978 2.998 2.966 2.985 Ti4+ 0.009 0.008 0.009 0.009 0.023 0.017 0.018 0.018 0.018 0.019 Al3+ 0.064 0.065 0.065 0.064 1.814 1.818 1.826 1.816 1.819 1.818 Cr3+ 0.024 0.022 0.023 0.023 0.151 0.155 0.152 0.146 0.156 0.152 Fe2+ 0.099 0.095 0.094 0.096 0.430 0.425 0.426 0.429 0.443 0.431 Mn2+ 0.004 0.004 0.004 0.004 0.016 0.016 0.020 0.019 0.017 0.017 Mg2+ 1.028 1.021 1.033 1.028 2.241 2.233 2.248 2.238 2.261 2.244 Ca2+ 0.725 0.728 0.736 0.730 0.337 0.346 0.345 0.336 0.348 0.342 Na+ 0.077 0.075 0.082 0.078 -- -- -- -- -- -- K+ -- -- -- -- n/a n/a n/a n/a n/a n/a Ni2+ n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a Total 4.010 4.004 4.020 4.011 8.008 8.007 8.017 8.005 8.032 8.014 Mg# 0.91 0.91 0.92 0.91 0.84 0.84 0.84 0.84 0.84 0.84 63 Ta bl e 4 C om po si tio n of m in er al s in s am pl e 89 48 1 M in er al O rt ho py ro xe ne C lin op yr ox en e G ar ne t La be l 81 -5 81 -6 81 -1 0 81 -1 1 Av g 81 -8 81 -1 81 -2 81 -3 81 -4 81 -5 81 -6 81 -7 81 -8 81 -9 81 -1 0 Av g C irc le 3 3 5 5 4 1 1 2 2 3 3 4 4 5 5 Si O 2 57 .2 5 57 .2 8 57 .3 9 57 .2 6 57 .3 0 54 .8 7 41 .9 3 41 .8 7 41 .6 8 42 .0 3 41 .9 5 41 .6 4 41 .6 4 42 .0 5 41 .5 7 41 .5 3 41 .7 9 Ti O 2 0. 12 0. 16 0. 10 0. 12 0. 13 0. 14 0. 36 0. 38 0. 36 0. 36 0. 35 0. 36 0. 37 0. 37 0. 42 0. 38 0. 37 Al 2O 3 0. 58 0. 57 0. 51 0. 57 0. 56 2. 00 21 .3 0 21 .2 5 21 .2 5 21 .2 3 21 .5 3 21 .1 9 21 .3 4 21 .4 0 21 .1 8 20 .9 7 21 .2 7 C r 2 O 3 0. 24 -- 0. 23 0. 21 0. 21 1. 36 3. 34 3. 35 3. 47 3. 35 3. 43 3. 42 3. 44 3. 39 3. 43 3. 36 3. 40 Fe O 5. 18 5. 12 5. 22 5. 17 5. 17 2. 69 7. 57 7. 37 7. 34 7. 28 7. 45 7. 30 7. 23 7. 32 7. 35 7. 37 7. 36 M nO 0. 12 0. 10 0. 12 0. 14 0. 12 0. 11 0. 29 0. 25 0. 34 0. 34 0. 30 0. 34 0. 33 0. 37 0. 34 0. 34 0. 32 M gO 35 .1 7 35 .3 5 35 .2 0 35 .0 6 35 .1 9 17 .3 8 20 .9 1 20 .6 2 20 .8 3 20 .7 2 20 .8 0 20 .8 4 20 .8 0 20 .8 1 20 .5 6 20 .5 0 20 .7 4 C aO 0. 62 0. 67 0. 56 0. 61 0. 61 19 .0 1 4. 53 4. 55 4. 57 4. 62 4. 57 4. 61 4. 55 4. 59 4. 47 4. 55 4. 56 N a 2 O 0. 11 0. 11 0. 10 0. 12 0. 11 1. 60 -- -- -- -- -- -- -- -- -- -- -- K 2O -- -- -- -- -- -- n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a N iO n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 99 .3 8 99 .5 3 99 .4 6 99 .2 6 99 .4 1 99 .2 1 10 0. 29 99 .6 8 99 .8 9 10 0. 00 10 0. 43 99 .7 6 99 .7 4 10 0. 35 99 .3 7 99 .0 6 99 .8 6 O xy ge ns 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 Si 4+ 1. 97 9 1. 97 7 1. 98 2 1. 98 1 1. 98 0 1. 99 2 2. 98 3 2. 99 3 2. 97 7 2. 99 5 2. 97 9 2. 97 8 2. 97 6 2. 98 7 2. 98 3 2. 99 1 2. 98 4 Ti 4+ 0. 00 3 0. 00 4 0. 00 3 0. 00 3 0. 00 3 0. 00 4 0. 01 9 0. 02 0 0. 02 0 0. 02 0 0. 01 9 0. 02 0 0. 02 0 0. 02 0 0. 02 3 0. 02 0 0. 02 0 Al 3+ 0. 02 4 0. 02 3 0. 02 1 0. 02 3 0. 02 3 0. 08 6 1. 78 6 1. 79 1 1. 78 9 1. 78 3 1. 80 2 1. 78 6 1. 79 8 1. 79 2 1. 79 2 1. 78 0 1. 79 0 C r3 + 0. 00 6 -- 0. 00 6 0. 00 6 0. 00 6 0. 03 9 0. 18 8 0. 18 9 0. 19 6 0. 18 9 0. 19 3 0. 19 3 0. 19 4 0. 19 1 0. 19 5 0. 19 1 0. 19 2 Fe 2+ 0. 15 0 0. 14 8 0. 15 1 0. 15 0 0. 14 9 0. 08 2 0. 45 0 0. 44 0 0. 43 8 0. 43 4 0. 44 2 0. 43 7 0. 43 2 0. 43 5 0. 44 1 0. 44 4 0. 43 9 M n2 + 0. 00 4 0. 00 3 0. 00 4 0. 00 4 0. 00 4 0. 00 3 0. 01 8 0. 01 5 0. 02 0 0. 02 0 0. 01 8 0. 02 1 0. 02 0 0. 02 3 0. 02 1 0. 02 1 0. 02 0 M g2 + 1. 81 2 1. 81 8 1. 81 2 1. 80 8 1. 81 2 0. 94 0 2. 21 8 2. 19 7 2. 21 8 2. 20 1 2. 20 1 2. 22 2 2. 21 7 2. 20 3 2. 19 9 2. 20 1 2. 20 8 C a2 + 0. 02 3 0. 02 5 0. 02 1 0. 02 2 0. 02 3 0. 73 9 0. 34 5 0. 34 8 0. 35 0 0. 35 3 0. 34 8 0. 35 3 0. 34 8 0. 34 9 0. 34 4 0. 35 1 0. 34 9 N a+ 0. 00 8 0. 00 7 0. 00 7 0. 00 8 0. 00 7 0. 11 2 -- -- -- -- -- -- -- -- -- -- -- K + -- -- -- -- -- -- n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a N i2+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 4. 00 7 4. 00 9 4. 00 6 4. 00 5 4. 00 7 3. 99 9 8. 01 5 8. 00 1 8. 01 4 8. 00 3 8. 00 9 8. 01 7 8. 01 0 8. 00 6 8. 00 4 8. 00 7 8. 00 8 M g# 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 83 0. 83 0. 83 0. 84 0. 83 0. 84 0. 84 0. 84 0. 83 0. 83 0. 83 64 ATa bl e 5 C om po si tio n of m in er al s in s am pl e 89 49 7 M in er al O liv in e Cl in op yr ox en e G ar ne t La be l 97 -1 97 -3 97 -4 97 -8 97 -9 97 -1 0 97 -1 1 Av g 49 7- 22 49 7- 23 49 7- 24 Av g 97 -1 97 -2 97 -3 97 -4 97 -6 vg Ci rc le 1 3 3 8 8 9 9 1 1 1 4 4 5 6 10 Si O 2 41 .3 4 41 .5 1 40 .8 6 40 .8 6 41 .5 2 40 .8 4 41 .3 2 41 .1 8 53 .8 4 54 .3 5 54 .1 3 54 .1 1 40 .5 3 41 .1 0 41 .0 1 40 .6 4 40 .9 2 40 .8 4 Ti O 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Al 2O 3 -- -- -- -- -- -- -- -- 0. 99 1. 00 0. 96 0. 99 18 .8 7 18 .9 0 19 .1 4 18 .6 9 18 .8 5 18 .8 9 Cr 2O 3 -- -- -- -- -- -- -- -- 0. 90 0. 82 0. 81 0. 85 7. 21 6. 89 7. 22 7. 64 7. 25 7. 24 Fe O 7. 74 7. 58 7. 63 7. 46 7. 45 7. 31 7. 51 7. 53 1. 21 1. 18 1. 19 1. 19 7. 39 7. 46 7. 57 7. 49 7. 71 7. 53 M nO 0. 10 0. 10 0. 10 0. 14 0. 11 0. 09 0. 10 0. 10 0. 12 -- -- -- 0. 48 0. 48 0. 46 0. 51 0. 50 0. 49 M gO 50 .9 0 50 .8 5 50 .6 7 50 .5 9 50 .5 5 50 .7 8 50 .6 2 50 .7 1 17 .5 7 17 .6 1 17 .6 0 17 .6 0 17 .7 2 17 .8 5 17 .9 5 17 .5 3 17 .3 9 17 .6 9 Ca O -- -- 0. 04 -- 0. 05 0. 04 0. 06 0. 04 23 .8 1 23 .4 6 23 .7 6 23 .6 8 7. 07 6. 97 7. 03 7. 27 7. 30 7. 13 Na 2O -- -- -- -- -- -- -- -- 0. 67 0. 64 0. 63 0. 65 -- -- -- -- -- -- K 2 O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a -- -- -- -- n/ a n/ a n/ a n/ a n/ a n/ a Ni O 0. 26 0. 32 0. 41 0. 34 0. 40 0. 34 0. 34 0. 34 n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 10 0. 39 10 0. 40 99 .8 2 99 .4 5 10 0. 13 99 .4 1 10 0. 04 99 .9 5 99 .1 1 99 .1 9 99 .1 0 99 .1 3 99 .2 7 99 .6 7 10 0. 37 99 .7 9 99 .9 5 99 .8 1 O xy ge ns 4 4 4 4 4 4 4 4 6 6 6 6 7 7 7 7 7 7 Si 4+ 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 97 0 1. 98 2 1. 97 8 1. 97 6 2. 97 4 2. 99 8 2. 97 5 2. 97 3 2. 98 7 2. 98 1 Ti 4+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Al 3+ -- -- -- -- -- -- -- -- 0. 04 3 0. 04 3 0. 04 1 0. 04 2 1. 63 2 1. 62 5 1. 63 6 1. 61 2 1. 62 1 1. 62 5 Cr 3+ -- -- -- -- -- -- -- -- 0. 02 6 0. 02 4 0. 02 4 0. 02 4 0. 41 8 0. 39 8 0. 41 4 0. 44 2 0. 41 9 0. 41 8 Fe 2+ 0. 15 7 0. 15 3 0. 15 6 0. 15 3 0. 15 0 0. 15 0 0. 15 2 0. 15 3 0. 03 7 0. 03 6 0. 03 7 0. 03 6 0. 45 4 0. 45 5 0. 45 9 0. 45 8 0. 47 1 0. 45 9 M n2 + 0. 00 2 0. 00 2 0. 00 2 0. 00 3 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 4 -- -- -- 0. 03 0 0. 03 0 0. 02 8 0. 03 2 0. 03 1 0. 03 0 M g2 + 1. 83 5 1. 82 6 1. 84 8 1. 84 5 1. 81 5 1. 85 3 1. 82 6 1. 83 6 0. 95 9 0. 95 7 0. 95 9 0. 95 8 1. 93 8 1. 94 1 1. 94 1 1. 91 2 1. 89 2 1. 92 5 Ca 2+ -- -- 0. 00 1 -- 0. 00 1 0. 00 1 0. 00 2 0. 00 1 0. 93 4 0. 91 7 0. 93 0 0. 92 7 0. 55 6 0. 54 5 0. 54 6 0. 57 0 0. 57 1 0. 55 8 Na + -- -- -- -- -- -- -- -- 0. 04 8 0. 04 6 0. 04 5 0. 04 6 -- -- -- -- -- -- K+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a -- -- -- -- n/ a n/ a n/ a n/ a n/ a n/ a Ni 2+ 0. 00 5 0. 00 6 0. 00 8 0. 00 7 0. 00 8 0. 00 7 0. 00 7 0. 00 7 n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 3. 00 1 2. 98 8 3. 01 8 3. 00 9 2. 97 8 3. 01 3 2. 99 0 2. 99 9 4. 01 9 4. 00 7 4. 01 3 4. 01 3 8. 00 2 7. 99 2 8. 00 1 8. 00 0 7. 99 4 7. 99 7 M g# 0. 92 0. 92 0. 92 0. 92 0. 92 0. 93 0. 92 0. 92 0. 96 0. 96 0. 96 0. 96 0. 81 0. 81 0. 81 0. 81 0. 80 0. 81 65 Ta bl e 5 c on tin ue d M in er al O rt ho py ro xe ne La be l 49 7- 1 49 7- 2 49 7- 3 49 7- 5 49 7- 7 49 7- 8 49 7- 9 49 7- 10 49 7- 11 49 7- 12 49 7- 13 49 7- 14 49 7- 15 49 7- 16 49 7- 20 49 7- 21 49 7- 25 49 7- 26 Av g C irc le 7 7 7 8 6 6 4 4 4 3 3 5 5 5 2 2 1 1 Si O 2 57 .2 2 56 .9 7 57 .3 1 57 .4 0 57 .5 8 57 .0 6 57 .4 3 56 .9 4 57 .5 3 56 .8 2 57 .3 7 57 .3 7 57 .2 1 57 .2 1 57 .0 5 57 .7 1 57 .2 6 57 .5 3 57 .2 8 Ti O 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Al 2O 3 0. 65 0. 63 0. 61 0. 63 0. 65 0. 65 0. 64 0. 63 0. 65 0. 61 0. 64 0. 62 0. 60 0. 64 0. 60 0. 62 0. 64 0. 62 0. 63 C r 2 O 3 0. 20 0. 23 0. 23 0. 18 0. 20 0. 23 0. 18 0. 19 0. 20 0. 28 0. 20 0. 19 0. 24 0. 24 0. 21 0. 25 0. 21 0. 21 0. 22 Fe O 4. 48 4. 69 4. 65 4. 69 4. 44 4. 72 4. 60 4. 65 4. 69 4. 62 4. 64 4. 78 4. 74 4. 63 4. 62 4. 52 4. 77 4. 51 4. 63 M nO 0. 15 0. 13 0. 11 0. 09 0. 10 0. 11 0. 09 0. 20 0. 07 0. 10 0. 12 0. 13 0. 14 0. 17 0. 09 0. 12 0. 13 0. 11 0. 12 M gO 36 .1 9 36 .2 6 36 .4 7 36 .3 0 36 .2 5 36 .0 5 36 .2 0 36 .2 1 36 .1 8 36 .2 2 36 .3 0 36 .2 4 36 .1 3 36 .1 0 36 .2 0 36 .3 7 36 .1 4 36 .3 6 36 .2 3 C aO 0. 24 0. 23 0. 24 0. 24 0. 21 0. 27 0. 21 0. 26 0. 22 0. 26 0. 24 0. 23 0. 23 0. 25 0. 23 0. 23 0. 24 0. 24 0. 24 N a 2 O -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- K 2O -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- N iO n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 99 .1 4 99 .1 7 99 .6 6 99 .5 8 99 .4 5 99 .1 2 99 .3 7 99 .0 9 99 .5 5 98 .9 4 99 .5 5 99 .6 1 99 .3 2 99 .2 5 99 .0 4 99 .8 2 99 .4 0 99 .5 9 99 .3 7 O xy ge ns 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Si 4+ 1. 97 4 1. 96 8 1. 96 9 1. 97 3 1. 97 9 1. 97 2 1. 97 7 1. 96 9 1. 97 7 1. 96 7 1. 97 3 1. 97 3 1. 97 3 1. 97 3 1. 97 2 1. 97 7 1. 97 3 1. 97 6 1. 97 3 Ti 4+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Al 3+ 0. 02 6 0. 02 6 0. 02 5 0. 02 5 0. 02 6 0. 02 7 0. 02 6 0. 02 6 0. 02 6 0. 02 5 0. 02 6 0. 02 5 0. 02 4 0. 02 6 0. 02 5 0. 02 5 0. 02 6 0. 02 5 0. 02 6 C r3 + 0. 00 5 0. 00 6 0. 00 6 0. 00 5 0. 00 5 0. 00 6 0. 00 5 0. 00 5 0. 00 5 0. 00 8 0. 00 5 0. 00 5 0. 00 7 0. 00 7 0. 00 6 0. 00 7 0. 00 6 0. 00 6 0. 00 6 Fe 2+ 0. 12 9 0. 13 6 0. 13 4 0. 13 5 0. 12 8 0. 13 6 0. 13 3 0. 13 4 0. 13 5 0. 13 4 0. 13 4 0. 13 7 0. 13 7 0. 13 4 0. 13 3 0. 12 9 0. 13 7 0. 13 0 0. 13 4 M n2 + 0. 00 4 0. 00 4 0. 00 3 0. 00 3 0. 00 3 0. 00 3 0. 00 3 0. 00 6 0. 00 2 0. 00 3 0. 00 4 0. 00 4 0. 00 4 0. 00 5 0. 00 3 0. 00 3 0. 00 4 0. 00 3 0. 00 3 M g2 + 1. 86 1 1. 86 7 1. 86 8 1. 86 0 1. 85 6 1. 85 7 1. 85 7 1. 86 6 1. 85 3 1. 86 9 1. 86 1 1. 85 7 1. 85 7 1. 85 6 1. 86 5 1. 85 7 1. 85 6 1. 86 1 1. 86 0 C a2 + 0. 00 9 0. 00 9 0. 00 9 0. 00 9 0. 00 8 0. 01 0 0. 00 8 0. 01 0 0. 00 8 0. 01 0 0. 00 9 0. 00 8 0. 00 8 0. 00 9 0. 00 9 0. 00 8 0. 00 9 0. 00 9 0. 00 9 N a+ -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- K + -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- N i2+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a To ta l 4. 01 1 4. 01 6 4. 01 7 4. 01 2 4. 00 7 4. 01 3 4. 00 8 4. 01 6 4. 00 7 4. 01 8 4. 01 2 4. 01 4 4. 01 1 4. 01 0 4. 01 4 4. 00 8 4. 01 2 4. 00 9 4. 01 2 M g# 0. 94 0. 93 0. 93 0. 93 0. 94 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 0. 93 66 A Av g 97 -1 4 97 -1 3 97 -1 1 97 -1 2 Ta bl e 5 c on tin ue d M in er al Sp in el La be l 97 -9 97 -2 97 -4 Av g 97 -8 97 -3 97 -5 97 -7 97 -1 8 vg 97 -1 0 C irc le 3 1 1 3 1 2 2 9 8 8 7 7 7 Si O 2 0. 07 0. 01 0. 04 0. 04 0. 03 0. 04 0. 03 0. 02 0. 03 0. 03 0. 06 0. 08 0. 03 0. 01 0. 02 0. 04 Ti O 2 -- 0. 05 0. 05 -- 0. 10 0. 05 0. 05 -- -- -- 0. 07 1. 05 -- -- -- 0. 64 Al 2O 3 14 .2 5 14 .4 1 14 .4 0 14 .3 5 13 .5 1 14 .5 3 14 .7 0 14 .6 7 14 .3 0 14 .5 6 14 .1 4 11 .6 8 13 .6 4 13 .7 7 13 .7 0 12 .5 5 C r 2 O 3 57 .6 1 57 .6 6 58 .0 1 57 .7 6 56 .8 3 57 .1 9 56 .7 5 57 .0 9 56 .7 3 56 .8 6 57 .4 4 56 .6 4 57 .0 3 56 .8 2 56 .9 2 56 .7 2 Fe O 13 .1 1 12 .8 5 12 .9 6 12 .9 7 14 .3 6 13 .2 4 13 .0 0 13 .3 2 13 .0 9 13 .1 4 13 .2 6 15 .5 2 14 .5 7 14 .8 1 14 .6 9 15 .8 2 M nO 0. 10 0. 09 0. 08 0. 09 -- 0. 09 -- 0. 14 0. 13 0. 10 0. 09 0. 12 0. 11 0. 21 0. 16 0. 18 M gO 14 .6 6 14 .4 4 14 .5 2 14 .5 4 14 .4 8 14 .3 3 14 .4 4 14 .1 2 14 .4 4 14 .3 3 14 .4 1 14 .0 7 13 .6 2 13 .3 5 13 .4 8 13 .5 9 C aO -- -- -- -- 0. 04 -- -- -- 0. 08 0. 04 -- 0. 04 -- -- -- -- N a 2 O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a K 2O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a N iO 0. 11 0. 07 0. 06 0. 08 0. 11 0. 06 0. 02 0. 06 0. 17 0. 08 0. 11 0. 17 0. 10 0. 05 0. 07 0. 10 To ta l 99 .9 4 99 .6 0 10 0. 11 99 .8 8 99 .5 1 99 .5 5 99 .0 1 99 .4 8 99 .0 1 99 .1 7 99 .5 9 99 .3 6 99 .1 2 99 .0 7 99 .1 0 99 .6 7 Po si tio n co re co re co re rim rim co re co re co re co re rim co re co re rim O xy ge ns 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Si 4+ 0. 00 2 0. 00 0 0. 00 1 0. 00 1 0. 00 1 0. 00 1 0. 00 1 0. 00 1 0. 00 1 0. 00 1 0. 00 2 0. 00 3 0. 00 1 0. 00 0 0. 00 1 0. 00 1 Ti 4+ -- 0. 00 1 0. 00 1 -- 0. 00 2 0. 00 1 0. 00 1 -- -- -- 0. 00 2 0. 02 6 -- -- -- 0. 01 6 Al 3+ 0. 53 0 0. 53 8 0. 53 5 0. 53 4 0. 50 8 0. 54 3 0. 55 1 0. 54 8 0. 53 7 0. 54 5 0. 52 9 0. 44 5 0. 51 7 0. 52 2 0. 51 9 0. 47 6 C r3 + 1. 43 8 1. 44 3 1. 44 5 1. 44 2 1. 43 5 1. 43 3 1. 42 6 1. 43 2 1. 43 0 1. 42 9 1. 44 1 1. 44 7 1. 44 9 1. 44 5 1. 44 7 1. 44 4 Fe 2+ 0. 34 6 0. 34 0 0. 34 1 0. 34 3 0. 38 4 0. 35 1 0. 34 5 0. 35 3 0. 34 9 0. 34 9 0. 35 2 0. 41 9 0. 39 2 0. 39 8 0. 39 5 0. 42 6 M n2 + 0. 00 3 0. 00 3 0. 00 2 0. 00 2 -- 0. 00 3 -- 0. 00 4 0. 00 4 0. 00 3 0. 00 3 0. 00 3 0. 00 3 0. 00 6 0. 00 4 0. 00 5 M g2 + 0. 69 0 0. 68 1 0. 68 2 0. 68 4 0. 68 9 0. 67 7 0. 68 4 0. 66 8 0. 68 6 0. 67 9 0. 68 2 0. 67 8 0. 65 2 0. 64 0 0. 64 6 0. 65 2 C a2 + -- -- -- -- 0. 00 2 -- -- -- 0. 00 3 0. 00 1 -- 0. 00 1 -- -- -- -- N a+ n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a K + n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a N i2+ 0. 00 3 0. 00 2 0. 00 2 0. 00 2 0. 00 3 0. 00 1 0. 00 1 0. 00 2 0. 00 4 0. 00 2 0. 00 3 0. 00 4 0. 00 3 0. 00 1 0. 00 2 0. 00 3 To ta l 3. 01 3 3. 00 8 3. 00 8 3. 01 0 3. 02 5 3. 01 0 3. 00 9 3. 00 9 3. 01 5 3. 01 1 3. 01 2 3. 02 6 3. 01 6 3. 01 5 3. 01 6 3. 02 3 M g# 0. 67 0. 67 0. 67 0. 67 0. 64 0. 66 0. 66 0. 65 0. 66 0. 66 0. 66 0. 62 0. 62 0. 62 0. 62 0. 60 67 Ta bl e 6 C om po si tio n of m in er al s in s am pl e 89 48 7 M in er al O liv in e O rt ho py ro xe ne C lin op yr ox en e La be l 87 -1 87 -2 87 -5 87 -1 5 87 -1 1 87 -1 2 87 -1 3 87 -1 4 A vg Av g 87 -5 87 -6 C irc le 1 1 3 7 6 6 6 6 6 3 3 Si O 2 41 .0 7 41 .5 9 41 .0 6 41 .1 9 40 .9 9 41 .4 2 41 .0 7 41 .2 9 41 .1 9 41 .2 2 56 .9 3 53 .8 2 Ti O 2 -- -- -- -- -- -- -- -- -- -- -- -- Al 2O 3 -- -- -- -- -- -- -- -- -- -- 1. 71 1. 89 C r 2 O 3 -- -- -- -- -- -- -- -- -- -- 0. 41 0. 98 Fe O 7. 20 7. 22 7. 29 7. 51 7. 74 7. 64 7. 62 7. 47 7. 62 7. 37 5. 06 1. 54 M nO 0. 06 0. 05 0. 05 0. 15 0. 11 0. 10 0. 09 0. 11 0. 10 0. 08 0. 12 0. 08 M gO 50 .7 3 50 .8 6 50 .9 6 50 .5 7 50 .8 6 51 .0 6 50 .9 5 50 .9 3 50 .9 5 50 .8 1 34 .7 4 17 .3 0 C aO -- -- -- -- -- -- -- -- -- -- 0. 45 22 .8 6 N a 2 O -- -- -- -- -- -- -- -- -- -- -- 0. 58 K 2O n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a -- -- N iO 0. 36 0. 37 0. 36 0. 35 0. 38 0. 35 0. 39 0. 39 0. 38 0. 37 n/ a n/ a To ta l 99 .4 9 10 0. 18 99 .7 7 99 .7 9 10 0. 17 10 0. 62 10 0. 12 10 0. 28 10 0. 30 99 .9 1 99 .4 7 99 .0 5 O xy ge ns 4 4 4 4 4 4 4 4 4 4 6 6 Si 4+ 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 00 0 1. 96 3 1. 96 5 Ti 4+ -- -- -- -- -- -- -- -- -- -- -- -- Al 3+ -- -- -- -- -- -- -- -- -- -- 0. 06 9 0. 08 1 C r3 + -- -- -- -- -- -- -- -- -- -- 0. 01 1 0. 02 8 Fe 2+ 0. 14 7 0. 14 5 0. 14 8 0. 15 2 0. 15 8 0. 15 4 0. 15 5 0. 15 1 0. 15 5 0. 14 9 0. 14 6 0. 04 7 M n2 + 0. 00 1 0. 00 1 0. 00 1 0. 00 3 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 2 0. 00 4 0. 00 2 M g2 + 1. 84 1 1. 82 3 1. 85 0 1. 83 0 1. 84 9 1. 83 8 1. 84 9 1. 83 8 1. 84 4 1. 83 7 1. 78 5 0. 94 1 C a2 + -- -- -- -- -- -- -- -- -- -- 0. 01 7 0. 89 4 N a+ -- -- -- -- -- -- -- -- -- -- -- 0. 04 1 K + n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a n/ a -- -- N i2+ 0. 00 7 0. 00 7 0. 00 7 0. 00 7 0. 00 8 0. 00 7 0. 00 8 0. 00 8 0. 00 7 0. 00 7 n/ a n/ a To ta l 2. 99 8 2. 97 9 3. 00 8 2. 99 3 3. 01 9 3. 00 2 3. 01 4 3. 00 2 3. 00 9 2. 99 7 3. 99 8 4. 00 1 M g# 0. 93 0. 93 0. 93 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 92 0. 95 68 Table 6 continued Mineral Spinel Label 87-2 87-3 87-4 87-5 87-6 87-7 87-11 87-16 87-17 87-18 Circle 1 1 1 2 2 2 4 7a 7a 7b SiO2 -- -- 0.48 -- -- -- 0.43 -- -- -- TiO2 -- -- -- -- -- -- -- -- -- -- Al2O3 25.04 25.43 24.93 24.82 24.45 23.22 22.97 26.74 20.53 24.20 Cr2O3 45.36 44.93 44.76 46.01 45.64 46.43 45.82 43.51 50.73 46.28 FeO 14.47 15.53 13.90 15.53 14.89 15.38 15.45 13.22 13.66 14.53 MnO 0.11 0.12 0.08 0.13 0.15 0.13 0.20 0.10 -- 0.09 MgO 14.28 13.31 14.86 13.64 13.85 13.78 14.00 15.56 14.66 13.90 CaO -- -- -- -- 0.07 0.11 0.11 0.09 0.08 0.11 Na2O n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a K2O n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a NiO -- -- 0.09 -- -- -- 0.13 -- 0.09 -- Total 99.29 99.48 99.15 100.13 99.12 99.07 99.11 99.33 99.84 99.22 Position core core rim rim core rim rim core rim rim Oxygens 4 4 4 4 4 4 4 4 4 4 Si4+ -- -- 0.015 -- -- -- 0.013 -- -- -- Ti4+ -- -- -- -- -- -- -- -- -- -- -- Al3+ 0.897 0.913 0.890 0.887 0.882 0.844 0.833 0.944 0.745 0.872 Cr3+ 1.090 1.081 1.072 1.103 1.104 1.132 1.115 1.031 1.234 1.119 Fe2+ 0.368 0.396 0.352 0.394 0.381 0.397 0.398 0.331 0.352 0.372 Mn2+ 0.003 0.003 0.002 0.003 0.004 0.003 0.005 0.002 -- 0.002 Mg2+ 0.647 0.604 0.671 0.617 0.632 0.633 0.642 0.695 0.672 0.634 Ca2+ -- -- -- -- 0.002 0.004 0.004 0.003 0.003 0.004 Na+ n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a K+ n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a Ni2+ -- -- 0.002 -- -- -- 0.003 -- 0.002 -- Total 3.006 3.001 3.004 3.005 3.006 3.012 3.013 3.010 3.009 3.004 Mg# 0.64 0.60 0.66 0.61 0.62 0.61 0.62 0.68 0.66 0.63 69"@en . "Graduating Project"@en . "10.14288/1.0053586"@en . "eng"@en . "Unreviewed"@en . "Vancouver : University of British Columbia Library"@en . "Attribution-NonCommercial-NoDerivatives 4.0 International"@en . "http://creativecommons.org/licenses/by-nc-nd/4.0/"@en . "Undergraduate"@en . "University of British Columbia. EOSC 449"@en . "The Diamond Potential of the Tuwawi Kimberlite (Baffin Island, Nunavut)."@en . "Text"@en . "http://hdl.handle.net/2429/7475"@en .