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$Fayek & Kyser 2000 uraninite fractionations.pdf - Queen's University$

Tectonic Event Formation temperature Pre-ore Stage Diagenesis Ore Stage Post-ore stage Nimbuwah event Late stage Nimbuwah event Post stage Nimbuwah event Various tectonic events 160 o to 300 o C - 250 o C ca. 100 o C δ 18 O fluid (‰) 5.1 to10.7 - 2.8 to 4.8 - δ 2 H fluid (‰) -81 to -52 - -75 to -57 - Complexing agent F - , PO 3 -4 , Cl - Fluid source low grade greenschist metamorphic Basinal Basinal Meteoric Table 4.7. Summary of the major results presented in this chapter showing the paragenetic mineral assemblages and timing of the U mineralization, major thermotectonic events, formation temperatures, isotopic compositions of fluids, source of fluid events recorded in U deposits in the SAVMF area. (Ap=apatite, Cal=calcite, Chl=chlorite, Hem=hematite, Qtz=quartz, Src=sericite, U=uraninite). 4.6.1. Basement metamorphism and basin diagenesis The pre-ore alteration assemblage Src 1 -Qtz 1 -Chl 1 -Cal 1 (Figs. 4.5 and 4.9) at the Coronation Hill and El Sherana deposits is similar to alteration patterns described by Warren and Kamprad (1990) and Wyborn et al. (1991), which they interpreted as related to early metamorphism and metasomatism of the basement rocks during D 2 deformation associated with the 1860-1840 Ma Nimbuwah tectonic event. This event predates deposition of the ca. 1830 Ma El Sherana Group. δ 18 O and δ 2 H isotopic compositions of the pre-ore Src 1 sericite indicate that the pre-ore alteration fluids at the Coronation Hill and El Sherana deposits are metamorphic in origin (Fig. 4.11) and therefore associated with deformation and regional metamorphism during the Nimbuwah event (Fig. 4.15 A). The high δ 18 O value of pre-ore Src 1 sericite at the El Sherana deposit is indicative of extensive water/rock interaction. The fluid formed at ca. 300 o C at the El Sherana deposit and ca. 175
160 o C at Coronation Hill. The temperature of ca. 300 o C at the El Sherana deposit is consistent with fluids derived from low grade greenschist metamorphic processes (Wyborn et al., 1991). Extensive hematite inclusions in pre-ore Qtz 2 quartz veins (Fig. 4.5D) at the Coronation Hill deposit suggest that pre-ore metamorphic fluids were highly oxidized (e.g. Mernagh et al., 1994). A Sensitive High Resolution Ion Microprobe (SHRIMP) U-Pb age of 1827±3 Ma for the Pul Pul Rhyolite (Jagodzinski, 1998) near the top of the El Sherana Group indicates that sediments of the El Sherana Basin could have begun to accumulate well before ca. 1830 Ma during deformation associated with the Nimbuwah event (Fig. 4.15B). Ahmad et al. (2006) suggested that the initial deposition of El Sherana Group sediments occurred at around ca. 1865 Ma associated with graben formation centred on the South Alligator River valley. Therefore deposition of the El Sherana Basin sediments took place rapidly in a tectonically active environment associated with the Nimbuwah Orogen (Friedmann and Grotzinger, 1994). The prevailing geothermal gradient must have been higher compared to the younger and larger Kombolgie Basin. Petrographic analysis of the Coronation sandstone at the El Sherana deposit indicate features typical for diagenetic alteration processes (Fig. 4.10), including well developed Qtz 2 quartz overgrowths outlining detrital Qtz 0 quartz grains accompanied by partial to complete resorption and pressure solution features that occurred during compaction at deep burial levels. Extensive Kln 1 kaolinite alteration that is associated with development of secondary porosity indicates that there were diagenetic aquifers in the El Sherana Basin sandstone, which could have conducted U-bearing basinal brines (Fig. 4.15B). This 176
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FLUID EVOLUTION AND STRUCTURAL CONT
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Abstract Uranium deposits associate
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Co-Authorship This thesis and the m
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Sarah Rice and Jonathan Cloutier, a
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TABLE OF CONTENTS Abstract………
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2.5.2. Temporal relationships of fa
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4.5.3. Isotopic compositions of min
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List of Figures Figure 1.1. General
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Figure 4.16. Distribution of 207 Pb
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Table 4.4. Isotopic data of the U-P
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processes by which these deposits f
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Figure 1.1. Generalized geological
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which is the equivalent of the Mill
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dolostone and carbonaceous shale (L
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Mineral Field (Figure 1.2). Many de
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2005). U mineralization is controll
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Figure 1.4. Schematic representatio
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In particular, the key issues to be
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genetic model for the U mineralizat
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fourth and most significant uranium
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The Beaverlodge area is part of the
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1998; Hartlaub and Ashton, 1998). R
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(D 1 ) produced a regional migmatit
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These previous age models do not ta
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the age when the concentrations of
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Figure 2.3. A: Detailed geologic ma
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hornblende-feldspar gneiss showing
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east-west striking en-échelon quar
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and broken Kfs 1 and Qtz 1 embedded
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A Meters LEGEND B Figure 2.6. A: De
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Figure 2.7. Microphotograph of vari
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eplaces Kfs 1 feldspars (Fig. 2.7A)
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the Qtz 1 quartz dissolution result
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Figure 2.9. Microphotograph of typi
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uraninite (Fig. 2.10). The errors o
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Figure 2.10. Backscattered Electron
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post-mineralization alteration duri
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Post-mineralization alteration even
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Volcanic-type ±U 5 (Sample 6139, G
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6134 pt8a 2 Gunnar 82.92 2.92 5.30
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Regression to zero content of the s
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faults (Fig. 2.13C). The breccias w
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Figure 2.13. Schematic cross-sectio
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Mylonites were then reactivated at
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and thrusting during the 1.94-1.92
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Beaverlodge area (Morelli et al., 2
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dikes (Ernst and Buchan, 2001b) and
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Figure 2.15: Distribution of 207 Pb
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CHAPTER 3 GENESIS OF MULTIFARIOUS U
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eccia-type. The other styles of min
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The basement consist of Neoarchean
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of essentially unmetamorphosed arko
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WDX X-ray spectrometers at Carleton
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3.4. Results 3.4.1. Paragenesis of
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are derived from their chlorite cry
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Figure 3.4. Photomicrographs of typ
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3.4J). Py 6 Pyrite and Cpy 5 chalco
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mineralization varies from 25.70 to
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6137APt71 60.67 13.73 4.59 6.48 0.0
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Fig. 3.6A). The Ca may result from
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Sample ID 1 ± 2 ± 3.a ± 4 ± 5.a
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Stable isotopic O and C composition
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Sample ID Deposit Mineral Mineral v
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equilibrium with a fluid having δ
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Syn-ore Chl 8 chlorite sampled from
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Figure 3.9. Binary diagrams showing
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Figure 3.10. Chondrite-normalized R
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Retrograde metamorphism Early vein
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contents in syn-ore Chl 4 chlorite
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decompression and hydration reactio
Page 143 and 144: mineralizations, which upgraded the
Page 145 and 146: metamorphic origin of the main U 4
Page 147 and 148: y the abundance of Ap 1 apatite and
Page 149 and 150: of late fluid events that have affe
Page 151 and 152: CHAPTER 4 FLUID EVOLUTION AND GENES
Page 153 and 154: 1990, 1991; Wyborn et al., 1990). H
Page 155 and 156: stable isotope geochemistry, U-Pb g
Page 157 and 158: coincident with the initiation of s
Page 159 and 160: plasma mass spectrometry (LA-HR-ICP
Page 161 and 162: The Coronation Hill deposit occupie
Page 163 and 164: arsenides, nickel selenide and copp
Page 165 and 166: No corrections were made to the 238
Page 167 and 168: which was interpreted as being asso
Page 169 and 170: porphyry and coated by Chl 1 formin
Page 171 and 172: Mineralized breccias showing quartz
Page 173 and 174: SOUTH ALLIGATOR RIVER GROUP EL SHER
Page 175 and 176: A Carbonaceous Shale B Src 1 Qtz 1
Page 177 and 178: A Granite Qtz 0 fragments Qtz 0 B M
Page 179 and 180: chemical composition as a result of
Page 181 and 182: Sample I.D SiO 2 CaO FeO ThO 2 MnO
Page 183 and 184: site occupancy (Cathelineau, 1988).
Page 185 and 186: Mineral values Temperature Fluid va
Page 187 and 188: Corrected ratios Apparent ages ( ±
Page 189 and 190: G H Figure 4.12. U-Pb concordia dia
Page 191 and 192: Figure 4.13. Pb-Pb isochron diagram
Page 193: and 4.12B), and to 207 Pb/ 206 Pb a
Page 197 and 198: Figure 4.15. Conceptual genetic mod
Page 199 and 200: of the Koolpin Formation, while dep
Page 201 and 202: at ca. 1820 Ma, approximately 40 My
Page 203 and 204: culminating with the formation of R
Page 205 and 206: deposits is related to fluids deriv
Page 207 and 208: CHAPTER 5 GENERAL DISCUSSION 5.1. I
Page 209 and 210: ed-bed strata and associated volcan
Page 211 and 212: character of the fluid that formed
Page 213 and 214: 5.2.1.2. Metamorphic-related uraniu
Page 215 and 216: during brecciation or reduction as
Page 217 and 218: ca. 1820 Ma that triggered reactiva
Page 219 and 220: Plutons Event at 1.4 Ga (Barinek et
Page 221 and 222: Kolari-Kittila Province Kuusamo Pro
Page 223 and 224: The uranium deposits in various pro
Page 225 and 226: Fig. 5.6. Distribution of the Rorai
Page 227 and 228: Roraima Basin, similar to what is o
Page 229 and 230: etween ca. 2.3 Ga and 1.9 Ga. Later
Page 231 and 232: REFERENCES Adams, J., 1989. Postgla
Page 233 and 234: Ashton, K.E., 2010. The Gunnar Mine
Page 235 and 236: Bowles, J.F.W., 1990. Age dating of
Page 237 and 238: Cuney, M.L., 2005. World-class unco
Page 239 and 240: deposits in the Athabasca Basin, Sa
Page 241 and 242: Hartlaub, R.P., Heaman, L.M., Chack
Page 243 and 244: Saskatchewan Geological Survey, Sas
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Kyser, K., and Cuney, M., 2008. Geo
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two-sided oblique-slip collisional
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Creek Geosyncline: in ‘The minera
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Piper, J.D.A., 2004. Discussion on
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99.Sheppard SMF and Gilg HA 1996. S
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Proceedings Darwin Conference 1984
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Wingate, M.T.D, Pisarevsky SA, Evan
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Sample Deposit 207 Pb/ 206 Pb ±2σ
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Page 263 and 264:
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APPENDIX B REE contents of various
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Sample Y Zr Cs Ba Th La Ce Pr Nd Sm
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Sample ΣREE TLREE THREE LREE/HREE
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SAMPLE ID. SiO 2 TiO 2 AL 2O 3 CR 2
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SAMPLE ID. SiO 2 TiO 2 AL 2O 3 CR 2
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APPENDIX E Electron microprobe data
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SAMPLE Si 4+ AL 4+ Total AL 6+ Ti 4
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SAMPLE Si 4+ AL 4+ Total AL 6+ Ti 4
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Sample ID. Deposit UO 2 SiO 2 CaO F
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Sample ID. Deposit UO 2 SiO 2 CaO F
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Corrected ratios Apparent ages ( ±
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Corrected ratios Apparent ages ( ±
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Sample ID. Al 2O 3 CaO FeO K2O MgO
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Sample ID. Al 2O 3 CaO FeO K2O MgO
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250 85 330 40 145 70 25 65 30 30 27
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Mineralized veins Quartz veins 276
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