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TitleTrace element geochemistry of magnetite and its relationship to mineralization in the Great Bear magmatic zone, NWT, Canada
AuthorAcosta Góngora, P; Gleeson, S A; Samson, I M; Ootes, L; Corriveau, LORCID logo
SourceProceedings of the 12th Biennial SGA Meeting, volume 1; 2013 p. 260-263
Alt SeriesEarth Sciences Sector, Contribution Series 20130030
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
AreaLou Lake; Cole Lake; Fab Lake
Lat/Long WENS-117.0000 -116.5000 63.7500 63.5000
Subjectseconomic geology; geochemistry; trace element geochemistry; trace element analyses; magnetite; mineral occurrences; mineral deposits; iron oxides; copper; gold; uranium; Great Bear Magmatic Zone
ProgramGEM: Geo-mapping for Energy and Minerals Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)
AbstractThe Paleoproterozoic Great Bear magmatic zone (GBmz) is the focus of ongoing exploration for iron oxide copper-gold (IOCG) mineralization and also hosts numerous iron-oxide-apatite±actinolite (IOA) occurrences. Examples include the Sue-Dianne and NICO deposits and other smaller prospects like DAMP, FAB and Nori/Ra. Furthermore, the past-producing Terra mine (Ag-Ni ±Co,Bi) hosts significant IOCG-like alteration in its vicinity. A petrographic analysis identified the presence of multiple generations of magnetite in NICO, FAB and Nori/Ra and, for the most part, a single generation of magnetite at Sue-Dianne, DAMP and Terra. A laser ablation-inductively coupled plasma mass spectrometric study (LA-ICP-MS), demonstrates important geochemical differences in V, Ni, Cr, Co and Ti. Regionally, the Cr/Co metal ratios proved to be higher for barren magnetite and pre-ore magnetite compared to that of magnetite co-precipitated with ore minerals and/or hosted in veins and breccias. Locally, at the Nori/Ra prospect the V/Ni ratio in magnetite successfully differentiates between pre-ore and syn-ore magnetite and at DAMP and Sue-Dianne the Co/Ni ratio is extremely high, and clearly different from the other magnetites in the Great Bear magmatic zone. These results show that the chemistry of magnetite may be an important tool in the exploration of IOCG-IOA systems.
Summary(Plain Language Summary, not published)
An ancient volcanic belt in the Great Bear Lake region (Northwest Territories) is the focus of ongoing exploration for multiple metals deposits (iron oxide copper-gold deposits). Several case examples were studied by a PhD student at University of Alberta with NRCan funding from the Research Affiliate Associate and Geomapping for Energy and Minerals programs. These include two deposits (NICO, Sue-Dianne), some prospects and the past-producing Terra mine (silver). Research focussed on a mineral (magnetite) that may have important use in mineral exploration. Under the microscope, multiple generations of magnetite were identified. A chemical study demonstrates important geochemical differences in vanadium (V), nickel (Ni), chrome (Cr), cobalt (Co) and titanium (Ti) between magnetite in barren rocks and magnetite associated with mineralization. Consequently chemistry of magnetite may become an important tool for glacial till based exploration programs in the Great Bear region and beyond.

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