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Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
Ronald Ng M.Sc. thesis presentation (Oct 2012)
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Ronald Ng M.Sc. thesis presentation (Oct 2012)

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  • Focus of research is the Athabasca Basin in Northern Saskatchewan, CanadaPaleo-Mesoproterozoicclastic sedimentary basin (fluvial sandstones)Unconformity-related U deposits – between Athabasca Group and Paleoproterozoic basement
  • Sandstone-hosted U deposits, what they are, how they form, clay alterationStudy #1: Mineralogy and geochemistry of McArthur River Zone 4, what the implications of the overlying silicified zoneStudy #2: Oxidation state of Fe in alteration minerals, are there differences between systems that are mineralized and those which are barren.What can it tell us about how these systems form?How can it be used in exploration?U hosted entirely sandstones or in both sandstones and basement rocksIllite and chlorite alteration zonesFluid-mixing and redox-controlled depositionBarren and mineralizedSilicified barriers
  • Do introduction on all sandstone hosted systems in study here to save timeMineralizedMcArthur River Zone 4 2) Maurice Bay Apparently-barren3) Wheeler River Zone K(Cloutier et al., 2010)4) Spring Point(Alexandre et al., 2009)(Alexandre et al., 2009)Distal to mineralization5) Centennial(Alexandre et al., 2012)
  • Four main alteration stages: 1. early pre-ore, 2. late pre-ore, 3. ore stage, 4. post-oreSilicified zone formedduring early stages of diagenesisAlteration minerals record increasing formation temperaturesUraninite is coeval with hematite and formed shortly after and coevally with chlorite
  • What I did: We measured the hydrogen and oxygen isotopic composition of alteration minerals in sandstone and basement, using their temperatures of formation which we calculated from their chemistry or inferrence, we calculated the isotopic composition of the corresponding fluidWhat this figure shows: Aside from post-ore kaolinites which formed from a fluid with an isotopic composition similar to relatively recent meteoric waters of the athabasca basin, basin and basement alteration minerals have similar isotopic compositionWhy is it important: This tells us that a single likely, likely basinal fluid, was responsible for causing alteration in both the basement and basin.
  • What I did: I combined all relative and absolute timing of alteration and U minerals and their spatial distributions, I came up with a genetic model for McArthur River Zone 4: Early pre-ore alteration caused silicification of the lower Manitou Falls Formation with flow of oxidizing basinal fluids leaching U from detrital minerals; Late pre-ore alteration resulted in formation of alteration zones in both the sandstones and basement rocks. During the late stages of pre-ore alteration, basinal fluids that interacted with basement rocks circulated out of the fault and producing sudoite alteration near the faulted unconformity, mixing of oxidizing basinal fluids circulating down fractures that breached siicified zone or along porosity along the unconformity with reducing fluid generated by fluid-rock interaction triggered U deposition.Why is it important: Emphasize the Zone 4 has a fluid-evolution history similar to basement-hosted unconformity-related U deposit, involved interaction between basinal fluids with basement rocks
  • What I did: Distribution of clay alteration around Zone 4 determined from XRD and PIMA analysis of clay separates from drill coreWhat the result say: Chlorite alteration forms a narrow halo surrounding the P2 fault and the size is confined by the overlying silicified zone, illite alteration forms a more spatially-extensive outer zone of alteration that can reach 200-250m above unconformity.Why its important: This allows us to map the distribution of the iron oxidation state ratios around the deposit
  • What I did: using WAL technique and measurement by HR-ICP-MS, we measured the leachable Pb isotope ratios from drill cores.What results show: 238U decays to 206Pb, and 235U decays to 207Pb, near ore body, get radiogenic Pb isotope ratios (defined as 7/6 ratios less than 0.7) and this can be used to indicate potential buried mineralizationWhat is it important? At Zone 4, the occurrence of a silicified zone (200 m-thick) blocks radiogenic Pb from reaching above the silicified zone; no surficial geochemical expression; silicified zone effective at concealing the deposit.
  • What Mossbauer is: A technique which allows the oxidation state if Fe and its coordination (octahedral/tetrahedral sites) in phyllosilicate minerals to be determined. This is determined based on the isomer shift and the quadrupole splitting parameters.What results show: Fe3+ in hematite appears as 6 line pattern, octahedral Fe3+ in illite appears as doublet with isomer shift near 0mm/sOctahedral Fe2+ in sudoite has higher isomer shift and quadrupole splitting than octahedral Fe3+ ; both appear as doublet.
  • C1 chlorite is early depositional diagenetic; not from wolverine
  • Emphasize C1 is early not related to chlorite halo; simplify; remove average; just explain use medians
  • Remove o2 as oxidant; just oxidizing basinal fluid; Fe is one of the reductants in system; other ones tooOxidation of Fe2+ in reducing basement fluids by O2 and U6+ in basinal fluidIncorporation of Fe2+ and Fe3+ into chlorite and Fe3+ into hematite
  • 1. The silicified zone functioned as a physical barrier to fluid flow, creating favourable conditions for uranium mineralization by focusing uranium-bearing basinal fluids into the site of deposition, localizing reducing fluids which enabled focused uranium deposition, and enhancing the preservation of the ore body (Fig. 1). These factors collectively contribute to the occurrence of high-grade mineralization at Zone 4;2. The oxidation state of iron in chlorite provides an indirect monitor of fluid-mixing at the redox front. Fe3+/ΣFe ratios of chlorite enable a method for evaluating newly-discovered alteration systems for their potential to host economic U mineralization.3. Presence of structural Fe2+ in late pre- to syn-ore chlorite chlorite indicates that reducing fluids transporting mobile Fe2+ were available to reduce U6+ in basinal fluids. The Fe3+/ΣFe ratios of chlorite in barren and mineralized systems support Fe2+ as a reductant of U6+  pelitic basement rocks and not graphitic pelites are required geochemically for U formationFe3+/total Fe in chlorites indicate thatMobile Fe2+ Fluid mixingProximity to reducing fluids4. spatial distribution of Fe3+/ΣFe ratios in chlorite are spatially related to the source of reducing fluid. When trends of decreasing Fe3+/ΣFe ratios are correlated with decreasing 207Pb/206Pb ratios represent prospective vectors to ore;
  • Focus of research is the Athabasca Basin in Northern Saskatchewan, CanadaPaleo-Mesoproterozoicclastic sedimentary basin (fluvial sandstones)Unconformity-related U deposits – between Athabasca Group and Paleoproterozoic basement
  • Add halo illite and chlorite – still contemplating
  • Ages of U highly affected by meteoric waters
  • For example in glasses and amphiboles, Fe3+/ƩFeratio is related to the position of the FeLα peak or the ratio of the FeLα/FeLβ peak intensities
  • Transcript

    • 1. Geochemical and mineralogical evolution of the McArthur River Zone 4 unconformity-related uranium ore body and application of iron oxidation state in clay alteration as indicator of uranium mineralization Master of Science Ronald Ng Queen’s University with the assistance of Kurt Kyser1, Paul Alexandre1, Dan Jiricka2, Donald Wright3, Gary Witt2, Don Chipley1, Jonathan Cloutier5, Yassir A. Abdu4, Frank C. Hawthorne4, April Vuletich1, Steve Beyer1, 1Queen’s Facility for Isotope Research, 2Cameco Corp., 3Peridot Geoscience Ltd., of Manitoba, 5CSIRO Earth Science & Resource Engineering 4University 1 October 2012
    • 2. Outline of presentation Modified after Jefferson et al. (2007) and references therein Study #1: McArthur River Zone 4 and silicified zone Study #2: Oxidation state of Fe in clay alteration from sandstone-hosted alteration systems 2
    • 3. Introduction to research: Sandstone-hosted alteration systems Fe3+/ΣFe? Fe3+/ΣFe? Fe3+/ΣFe? Data from Percival and Kodama (1989), Percival (1993), Cloutier et al. (2010), Alexandre et al. (2009, 2012)  Major goal of thesis: Are there differences in the oxidation state of Fe in clay alteration between mineralized and barren systems?  Scientific and exploration implications? 3
    • 4. Introduction to research: Sandstone-hosted alteration systems Data from Percival and Kodama (1989), Percival (1993), Cloutier et al. (2010), Alexandre et al. (2009, 2012)  Test site for Fe oxidation state study: McArthur River Zone 4  Mineralogy, geochemistry, and evolution?  Implications of overlying silicified zone? 4
    • 5. Research objectives and rationale Study #1: McArthur River Zone 4 evolution and silicified zone      Mineralogical and geochemical evolution Spatial and temporal Role of silicified zone Sandstone-hosted ore bodies at McArthur River are not well understood Implications of the overlying silicified zone is unclear Study #2: Oxidation state of Fe in phyllosilicates from sandstone-hosted alteration systems      Spatial distribution of Fe oxidation state in alteration minerals Mineralized vs. barren systems Temporal evolution of Fe oxidation state in sandstone-hosted systems Fe oxidation state vs. geochemical pathfinders for U Can Fe oxidation state be used as an exploration tool? 5
    • 6. Mineralogical and geochemical evolution of the unconformity-related McArthur River Zone 4 ore body in the Athabasca Basin, Canada: Implications of a silicified zone Submitted to Economic Geology Ronald Ng1, Paul Alexandre1, & Kurt Kyser1 Queen’s University 1Queen’s Facility for Isotope Research 6 October 2012
    • 7. McArthur River U deposit Modified after Hoffmann (1989) and Ramaekers et al. (2007) 7
    • 8. McArthur River Zone 4  332.6 Mlbs U3O8, 20.7% U3O8 (avg. grade)  Basement-hosted and sandstone-hosted ore bodies 8
    • 9. McArthur River Zone 4  Zone 4: U hosted in Manitou Falls Formation sandstones and hanging wall basement (Wollaston Group)  200 m-thick silicified zone  Age of initial mineralization: ca. 1.6 Ga  Resetting ages: ca. 1268 Ma and 838 Ma 9
    • 10. Evolution I: Mineral paragenesis 10
    • 11. Evolution II: Origin of alteration fluids Post-ore kaolinite: recent meteoric waters A single fluid produced alteration in basement and sandstones: Basinal fluids 11
    • 12. Genetic evolution of McArthur River Zone 4 12
    • 13. Silicified zone I: Alteration pattern  Spatial extent of late pre- to syn-ore chlorite alteration limited by silicified zone 13
    • 14. Silicified zone II: Dispersion of radiogenic Pb  Contours of 207Pb/206Pb isotope ratios  Silicified zone restricts dispersion of radiogenic Pb and U pathfinder elements  Silicified zone conceals surficial geochemical expression of the Zone 4 ore body 14
    • 15. Key Findings Genetic evolution of McArthur River Zone 4  Silicified zone formed during early stages of diagenesis  Basinal fluids responsible for alteration in basin and basement – no significant contribution of a distinct basement-derived fluid  Reducing fluids generated when basinal fluids interacted with basement rocks  Affinity to genesis of basementhosted deposits Scientific and exploration implications of silicified zone  Focus U-bearing basinal fluids into fault zone  Enhance ore preservation  Limit spatial extent of chlorite alteration  Restrict dispersion of reducing fluids (e.g. Fe2+)  Limit dispersion of radiogenic Pb and U pathfinder elements 15
    • 16. Oxidation state of iron in alteration minerals associated with sandstone-hosted unconformityrelated uranium deposits and apparently barren alteration systems in the Athabasca Basin, Canada: Implications for exploration Submitted to Journal of Geochemical Exploration Ronald Ng1, Paul Alexandre1, Kurt Kyser1, Jonathan Cloutier2, Yassir A. Abdu3, and Frank C. Hawthorne3 Queen’s University 1Queen’s Facility for Isotope Research, 2CSIRO Earth Science & Resource Engineering, 3University of Manitoba 16 October 2012
    • 17. 57Fe Mössbauer spectroscopy Oct. Fe3+ phyllosilicate Oct. Fe2+ phyllosilicate Oct. Fe3+ hematite Oct. Fe3+ phyllosilicate McArthur River Zone 4 illite Centennial (Virgin River) sudoite Δ = quadrupole splitting (mm/s) δ = isomer shift (mm/s) 17
    • 18. McArthur River Zone 4 (mineralized)  Fe3+/ΣFe ratios  Outer illite and illite-chlorite mixed layer clay zones are oxidizing  Inner chlorite alteration zone is reducing 18
    • 19. Wheeler River Zone K (apparently barren)  Oxidizing illite alteration  Reducing sudoite and clinochlore alteration 19 Modified after Cloutier et al. (2010)
    • 20. Fe oxidation state vs. Pb isotope ratios Mineralized alteration systems  Decreasing Fe3+/ΣFe ratios in sudoite (more reducing) and 207Pb/206Pb ratios in drill core (more radiogenic) towards U mineralization 20
    • 21. Fe oxidation state vs. Pb isotope ratios Barren alteration systems     Decreasing Fe3+/ΣFe ratios in chlorite at WR Zone K; uniform at Spring Point No trend in 207Pb/206Pb ratios with proximity to fault zone Decrease in Fe3+/ΣFe ratios in both mineralized and barren systems Implication: Fe3+/ΣFe ratios reflects proximity to reducing fluid and not to U 21 mineralization
    • 22. Comparison of Fe3+/ΣFe ratios in chlorite  Mineralized systems: higher Fe3+/ΣFe ratios  Barren systems: lower Fe3+/ΣFe ratios 22
    • 23. How clay alteration acquired their Fe3+/ΣFe ratios? (2) U6+(aq) + Fe2+(aq) + 2H2O = U4+O2(uraninite) + Fe3+(chlorite or hematite) + 4H+(aq) Basin Oxidizing basinal fluids Illite Fe3+ Fe3+ U 4Fe2+(aq) + Basement Fe2+ 4H+(aq) (1) O2(aq) + = 4Fe3+(chlorite or hematite) + 2H2O Chlorite Fe2+ Reducing basement fluids 23
    • 24. Key findings  Critical geochemical factor for U mineralization  U-bearing, oxidizing, basinal fluids must mix with reducing Fe2+-bearing basement fluids: (1) basinal fluids must be available (2) right timing  Implications to U exploration  Fe3+/ΣFe ratios in chlorite reflect fluid-mixing process  Predict whether new alteration systems are potentially mineralized  Spatial distribution of Fe3+/ΣFe ratios vector to reducing fluids  Validate 207Pb/206Pb isotope ratio trends  Structural Fe in chlorites  Oxidizing conditions favour formation of di-trioctahedral chlorites (e.g. sudoite) in Athabasca Basin U deposits Fe2+ + Fe3+ + □ (vacancy) = 3 octahedral Mg2+ (Billault et al., 2002) 24
    • 25. Summary Redox conditions Implications of silicified zone Source of Fe2+ Oxidation of Fe2+ to Fe3+ Evolution of McArthur River Zone 4 Data from Percival and Kodama (1989) , Percival 25 (1993), Cloutier et al. (2010), Alexandre et al. (2009, 2012)
    • 26. Acknowledgements Special thanks to the following individuals: Supervisors: Kurt Kyser, Paul Alexandre QFIR staff: April Vuletich, Don Chipley, Evelyne Leduc, Kristen Feige Former QFIR staff: Kerry Klassen, Allison Laidlow, Bill McFarlane QFIR pdfs and students: Steve Beyer, Jonathan Cloutier, Yulia Uvarova, Majdi Geagea, Sandeep Banerjee, Urmidola Raye, Serigne Dieng, Vivian Wasiuta, Paul Stewart, Phillip Adene, Claudio Munoz, Alexi Li, Valeria Li, Sara Rice, John Burns, and the many undergraduate students over these years Queen’s Geology: Brian Joy, Alan Grant University of Manitoba: Yassir A. Abdu, Frank C. Hawthorne Cameco Corporation: Gary Witt, Dan Juricka, Donald Wright Office mates: Ehsan Ghazvinian, Matt Perras Others: Eric Hiatt, Mostafa Fayek, James Brenan, Ed Spooner Thank you for your attention. 26

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