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TitleSulfur isotope geochemistry and 187Re-187Os temporal constraints on the formation of polymetallic iron-oxide-dominated deposits in the Great Bear magmatic zone, NWT, Canada
AuthorAcosta-Góngora, P; Gleeson, S A; Creaser, R; Taylor, B EORCID logo; Samson, I M; Ootes, L; Corriveau, LORCID logo
SourceProceedings of the 12th Biennial SGA Meeting, volume 3; 2013 p. 1366-1369
Alt SeriesEarth Sciences Sector, Contribution Series 20130028
PublisherSociety for Geology Applied to Ore Deposits
MeetingSGA2013 - The 12th Biennial SGA Meeting of The Society for Geology Applied to Ore Deposits; Upsala; SE; August 12-15, 2013
File formatpdf
ProvinceNorthwest Territories
AreaGreat Bear Lake; Lou Lake; Cole Lake; Fab Lake
Lat/Long WENS-117.0000 -116.5000 63.7500 63.5000
Subjectseconomic geology; geochemistry; isotopes; isotope ratios; sulphur isotope ratios; trace element geochemistry; trace element analyses; magnetite; mineral occurrences; mineral deposits; iron oxides; copper; gold; uranium; Great Bear Magmatic Zone; NICO Deposit; Sue-Diane Deposit
ProgramGEM: Geo-mapping for Energy and Minerals Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)
AbstractThe Great Bear magmatic zone (GBmz) contains several examples of iron oxide copper-gold (IOCG) mineralization including the Sue-Dianne and NICO deposits and other prospects like DAMP. The d34S values in pyrite, arsenopyrite and chalcopyrite from NICO range from 2.5permil to 6.7permil; pyrite from DAMP varies from - 0.1permil to 5permil. Conversely, chalcopyrite from Sue Dianne d34S has a dominantly negative signature ranging from - 7.7permil to 1permil. The preliminary d34S data have values close to 0permil suggesting an important magmatic contribution to the formation of IOCGs in the GBmz. However, some of the relatively 34S-enriched (> 5permil) and -depleted (<-5permil) signatures could also indicate that some of the sulphur found in these systems is derived from non-magmatic sources. In addition, 187Re-187Os dating of two molybdenite samples was carried out on NICO deposit. One sample represents a late stage of mineralization (NM3) within the main ore zone and has an age of ca.1865 .The second sample formed ca.1877 and was collected from a U±Cu- Mo- rich zone within the Southern Breccia. The 187Re- 187Os molybenite ages from NICO deposit also suggest a magmatic origin as they are correlative (within error) with plutonic events emplaced between 1866 Ma and 1875 Ma in this area.
Summary(Plain Language Summary, not published)
An ancient volcanic belt in the Great Bear Lake region (Northwest Territories) hosts two multiple metals, iron oxide copper-gold deposits (Sue-Dianne and NICO). Research was undertaken to study the origin and age of mineralization. The chemistry of sulphide minerals (pyrite, arsenopyrite and chalcopyrite) from the studied deposits and affiliated prospects indicate that magmas that have led to the volcanic belt were key sulphur carriers for the mineralization though non-magmatic sources were also involved. The sulphides minerals rich in rhenium and osmium were dated at the University of Alberta. Age of mineralization is of about 1877 million years and are coeval (within error) with plutonic events dated at NRCan between 1866 Ma and 1875 Ma in this area. The work was undertaken as a PhD study at the University of Alberta with NRCan funding from the Research Affiliate Associate and Geomapping for Energy and Minerals programs within the IOCG-Great Bear project.

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