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Pegmatite- and leucogranite-hosted uranium and thorium mineralization in northern Saskatchewan: Fraser Lakes Zones A and B...
Outline <ul><li>Regional Geological Setting </li></ul><ul><li>Fraser Lakes Uranium and Thorium Mineralization </li></ul><u...
Location <ul><li>The Fraser Lakes mineralized zones are located on JNR Resource’s  Way Lake Property </li></ul><ul><li>Out...
Regional Geology <ul><li>The Way Lake Project is within the  Eastern Wollaston Domain </li></ul><ul><li>The Wollaston Doma...
Fraser Lakes Geology and Geophysics <ul><li>Divided into the  Zone A and Zone B mineralized zones </li></ul><ul><li>Zone A...
Fraser Lakes Radiometrics <ul><li>Fraser Lakes Zone B shows up as  clearly visible radiometric highs  (bright orange to re...
Fraser Lakes Topography and Aerial Photograph <ul><li>The surface expression of the  EM conductor  adjacent to  Fraser Lak...
Cross-Section 1: WYL-09-39, -30, and WYL-08-524, -525 <ul><li>Mineralization consists of  uranium- and thorium-bearing gra...
Cross-Section 2: WYL-09-41, -42, -49, -49a, and -50 Fault/Shear zone? <ul><li>The Wollaston Group – Archean contact is hig...
Granitic pegmatite mineralogy and textures  <ul><li>Granitic pegmatites  with  variable  amounts of  quartz ,  feldspar , ...
Pegmatites – Partial melts at depth and in situ <ul><li>Migmatites   associated with the granitic pegmatites and leucogran...
Mineralogy  <ul><li>Uranium and Thorium Minerals </li></ul><ul><li>Zircon  (Zrn) </li></ul><ul><li>Monazite  (Mz) </li></u...
Alteration of granitic pegmatites <ul><li>Retrograde Alteration </li></ul><ul><li>Chlorite  (Chl) </li></ul><ul><li>Epidot...
Fraser Lakes Geochemistry <ul><li>Significant Anomalies </li></ul><ul><li>Up to  0.453% U3O8 in outcrop  grab samples </li...
Similarities to Athabasca U deposits and other U deposits <ul><li>Similar granitic pegmatites  are found throughout the  W...
Conclusions <ul><li>Structurally controlled, basement-hosted U and Th mineralization (+/- REE mineralization) </li></ul><u...
Future Work <ul><li>Petrography </li></ul><ul><li>Microprobe  work to constrain mineralogy and mineral chemistry </li></ul...
Acknowledgements
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WIUGC 2010 - Pegmatite and Leucogranite-Hosted U-Th Mineralization In northern Saskatchewan: Fraser Lakes Zones A and B

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Talk presented at WIUGC 2010 in Saskatoon, SK on my research about the Fraser Lakes pegmatite-hosted U-Th-REE mineralization

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Transcript of "WIUGC 2010 - Pegmatite and Leucogranite-Hosted U-Th Mineralization In northern Saskatchewan: Fraser Lakes Zones A and B"

  1. 1. Pegmatite- and leucogranite-hosted uranium and thorium mineralization in northern Saskatchewan: Fraser Lakes Zones A and B Christine Austman, Kevin Ansdell, and Irvine Annesley
  2. 2. Outline <ul><li>Regional Geological Setting </li></ul><ul><li>Fraser Lakes Uranium and Thorium Mineralization </li></ul><ul><li>Fraser Lakes Geological Cross-Sections </li></ul><ul><li>Granitic Pegmatite Mineralogy, Textures and Alteration </li></ul><ul><li>Geochemistry </li></ul><ul><li>Similarities to other deposits </li></ul><ul><li>Conclusions </li></ul><ul><li>Future Work </li></ul>“ The aim of this project is to determine whether these [granitic pegmatites and leucogranites] represent a distinct target for uranium exploration in Saskatchewan or if the mineralization is related somehow to unconformity-type uranium deposits. “
  3. 3. Location <ul><li>The Fraser Lakes mineralized zones are located on JNR Resource’s Way Lake Property </li></ul><ul><li>Outside of the Athabasca Basin (~25 km from SE edge) </li></ul><ul><li>~ 55 km from Key Lake U mine </li></ul>Way Lake Property Fraser Lakes Zones A & B Key Lake U mine
  4. 4. Regional Geology <ul><li>The Way Lake Project is within the Eastern Wollaston Domain </li></ul><ul><li>The Wollaston Domain consists of </li></ul><ul><ul><li>Archean orthogneisses (predominantly granitic gneisses) </li></ul></ul><ul><ul><li>Paleoproterozoic Wollaston Group metasedimentary rocks </li></ul></ul><ul><ul><li>Hudsonian granites, amphibolites, leucogranites , migmatites , and granitic pegmatites </li></ul></ul><ul><li>The domain was metamorphosed and complexly deformed during the Trans-Hudson Orogeny (approximately 1.8 Ga) </li></ul><ul><li>Regional metamorphic grade is upper amphibolite to lower granulite facies in this part of the Wollaston Domain </li></ul>
  5. 5. Fraser Lakes Geology and Geophysics <ul><li>Divided into the Zone A and Zone B mineralized zones </li></ul><ul><li>Zone A is in a NE-plunging synformal and Zone B is in an antiformal fold nose </li></ul><ul><li>5 km section of a complexly folded electromagnetic (EM) conductor (i.e. graphitic pelitic gneisses) is adjacent to Zones A and B </li></ul><ul><li>Zone B is cross-cut by several ductile-brittle and brittle structures (black lines) </li></ul>Total field aeromagnetic image and trace of the EM conductor with location of drill hole collars
  6. 6. Fraser Lakes Radiometrics <ul><li>Fraser Lakes Zone B shows up as clearly visible radiometric highs (bright orange to red spots) on GSC regional radiometric survey maps of U and Th </li></ul>
  7. 7. Fraser Lakes Topography and Aerial Photograph <ul><li>The surface expression of the EM conductor adjacent to Fraser Lakes Zone B is a swampy, low-lying area </li></ul><ul><li>Zone B mineralization outcrops at surface on the eastern edge of the swamp </li></ul><ul><li>Fold nose is visible from the air </li></ul>Section 1 Section 2
  8. 8. Cross-Section 1: WYL-09-39, -30, and WYL-08-524, -525 <ul><li>Mineralization consists of uranium- and thorium-bearing granitic pegmatites and leucogranites </li></ul><ul><li>They intrude the contact between basal Wollaston Group and underlying Archean orthogneisses </li></ul>
  9. 9. Cross-Section 2: WYL-09-41, -42, -49, -49a, and -50 Fault/Shear zone? <ul><li>The Wollaston Group – Archean contact is highly deformed , locally becoming protomylonitic to mylonitic </li></ul><ul><li>Fracture and fault zones can be seen locally in core </li></ul><ul><li>Cross-sections show offsets thought to be related to faulting/shearing </li></ul>
  10. 10. Granitic pegmatite mineralogy and textures <ul><li>Granitic pegmatites with variable amounts of quartz , feldspar , biotite , and other minerals </li></ul><ul><li>Overall coarse grained to pegmatitic </li></ul><ul><li>Variable size (cm to several m scale) </li></ul><ul><li>Commonly zoned (igneous AFC processes) </li></ul><ul><li>Multiple generations of granitic pegmatites, with mineralized pegmatites usually older ( syn-tectonic ) and non-mineralized younger (post-deformation) </li></ul><ul><li>Late Hudsonian (limited age data) </li></ul>
  11. 11. Pegmatites – Partial melts at depth and in situ <ul><li>Migmatites associated with the granitic pegmatites and leucogranites in basal Wollaston Group metasediments </li></ul><ul><li>Upper amphibolite to lower granulite facies metamorphism (~18 – 20 km depth) </li></ul><ul><li>Formed by igneous processes (partial melting and fractionation) </li></ul>
  12. 12. Mineralogy <ul><li>Uranium and Thorium Minerals </li></ul><ul><li>Zircon (Zrn) </li></ul><ul><li>Monazite (Mz) </li></ul><ul><li>Allanite (Aln) </li></ul><ul><li>Uraninite - Uranothorite - Thorite (Urn) </li></ul>Highly Variable!
  13. 13. Alteration of granitic pegmatites <ul><li>Retrograde Alteration </li></ul><ul><li>Chlorite (Chl) </li></ul><ul><li>Epidote (Ep) </li></ul><ul><li>Sericite (Ser) </li></ul><ul><li>Hematite (Hem) </li></ul><ul><li>Quartz (Qtz) </li></ul><ul><li>Hydrothermal Alteration </li></ul><ul><li>Fluorite (Fl) </li></ul><ul><li>Chlorite (Chl) </li></ul><ul><li>Hematite (Hem) </li></ul><ul><li>Clay minerals </li></ul><ul><li>Sausserite </li></ul><ul><li>Carbonate (Cal) </li></ul><ul><li>Quartz (Qtz) </li></ul>
  14. 14. Fraser Lakes Geochemistry <ul><li>Significant Anomalies </li></ul><ul><li>Up to 0.453% U3O8 in outcrop grab samples </li></ul><ul><li>WYL-09-38 </li></ul><ul><ul><li>0.177 % Cu, 0.056% Ni, 0.044% Zn, and 0.0681% Mo over 6.50 m </li></ul></ul><ul><li>WYL-09-39 </li></ul><ul><ul><li>0.166% U3O8 and 0.113% ThO2 over 0.15 m </li></ul></ul><ul><li>WYL-09-41 </li></ul><ul><ul><li>0.134% U3O8 and 0.077% ThO2 over 1.0 m </li></ul></ul><ul><li>WYL-09-50 </li></ul><ul><ul><li>0.183% U3O8 and 0.062% ThO2 over 1.0 m </li></ul></ul>
  15. 15. Similarities to Athabasca U deposits and other U deposits <ul><li>Similar granitic pegmatites are found throughout the Wollaston Domain , many containing elevated U, Th, REEs and other elements </li></ul><ul><li>Radioactive leucogranites and granitic pegmatites are in the basement rocks under several Athabasca Basin unconformity uranium deposits (ex: McArthur River Zone 2, Millenium, Roughrider, and others) </li></ul><ul><li>Chlorite, clay, and hematite alteration found in Zone B drill core is similar in appearance to that of basement-hosted unconformity uranium deposits </li></ul><ul><li>~ 200 – 250 m of erosion below the Athabasca/ basement unconformity in the area </li></ul><ul><li>Similarities to Grenville Province igneous-related uranium deposits </li></ul>
  16. 16. Conclusions <ul><li>Structurally controlled, basement-hosted U and Th mineralization (+/- REE mineralization) </li></ul><ul><li>Hosted by Hudsonian leucogranites and granitic pegmatites that intruded at the contact between Wollaston Group metasediments and Archean orthogneisses </li></ul><ul><li>Zone B has significant U-Th-REE mineralization in drill core and outcrop </li></ul><ul><li>Granitic pegmatites and leucogranites formed by partial melting </li></ul><ul><li>Granitic pegmatites experienced post-crystallization hydrothermal alteration (and remobilization of U and Th?) </li></ul><ul><li>Potential exists for basement-hosted unconformity uranium deposits in the Fraser Lakes area </li></ul>
  17. 17. Future Work <ul><li>Petrography </li></ul><ul><li>Microprobe work to constrain mineralogy and mineral chemistry </li></ul><ul><li>Whole rock geochemical analysis </li></ul><ul><li>REE and Fl-Cl analysis, and Pb-isotopes for selected samples </li></ul><ul><li>U-Pb chemical age dating </li></ul><ul><li>Determination of local metamorphic conditions </li></ul><ul><li>Development of a metallogenetic model for Fraser Lakes Zones A and B </li></ul>
  18. 18. Acknowledgements
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