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TitleThe paragenesis and chemistry of alteration minerals within the basement rocks associated with the P2 fault and the McArthur River Uranium Deposit, Athabasca Basin
AuthorAdlakha, E E; Hattori, K; Potter, E GORCID logo
SourceMineral deposit research for a high-tech world, proceedings of the 12th Biennial SGA Meeting; vol. 4, 2013 p. 1567-1570
Alt SeriesEarth Sciences Sector, Contribution Series 20130170
PublisherSociety for Geology Applied to Mineral Deposits (SGA)
Meeting12th Biennial SGA Meeting; Uppsala; SE; August 12-15, 2013
File formatpdf
AreaMcArthur River
Lat/Long WENS-105.0000 -104.5000 58.0000 57.7500
Subjectseconomic geology; geochemistry; structural geology; paragenesis; structural features; faults; basement geology; metamorphism; mineral occurrences; uranium; mineralization; alteration; Athabasca Basin; McArthur River Uranium Deposit
Illustrationslocation maps; tables; photomicrographs
ProgramTargeted Geoscience Initiative (TGI-4) Uranium Ore Systems
AbstractThe main ore body (Zone 2) of the McArthur River deposit, Athabasca Basin, is almost completely hosted in the basement rocks immediately below the Athabasca sandstones, and is spatially associated with the P2 reverse fault. The Paleoproterozoic basement
rocks have undergone upper-amphibolite facies metamorphism, retrograde metamorphism, paleoweathering, diagenetic effects from the overlying sandstones and multiple episodes of hydrothermal alteration. Peak metamorphism produced garnet-biotitecordierite
assemblages in paragneiss and metapelite, plus quartzite. Three distinct horizons occur below the unconformity: i) a lowermost Green Zone formed through retrogression then paleo-weathering and is characterized by the chloritization of ferromagnesian minerals and
illitization of K-feldspar, ii) an overlying Red Zone of pervasive hematite and kaolinite alteration due to paleoweathering, and iii) a Bleached Zone that formed along the unconformity from K-bearing, diagenetic, basinal fluids that crystallized coarse-grain illite and altered kaolinite to dickite. Multiple stages of hydrothermal activity overprinted earlier alteration minerals, particularly along the P2 Fault and proximal to the ore body. Two generations of tourmaline occur along the P2 Fault Zone: an earlier, coarse-grained dravite, and later, fine-grained magnesiofoitite. A second chlorite-forming event, a third illite-forming event, and a second hematitizationrutilization event have also occurred along the P2 fault within the basement.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. The McArthur River and nearby Millennium deposits within the Athabasca basin are spatially associated with a regional fault system termed the P2 structure the local VQ fault system, implying that the structures played a role in focusing ore-forming fluids during creation of the deposit. This publication highlights mineralogical changes along the fault systems and within the basement rocks associated with economic mineralization. Textural relationships and mineral assemblages clearly illustrate that alteration previously interpreted unrelated to ore-forming processes may reflect pre- to syn-ore hydrothermal alteration.

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