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TitleGeochemical signatures of IOCG mineralization and alteration in till
AuthorNormandeau, P X; McMartin, I; Paquette, J; Corriveau, L; Montreuil, J -F
SourceGoldschmidt 2012, abstracts; 2012 p. 1
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20120005
MeetingGoldschmidt 2012; Montreal; CA; June 24-29, 2012
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS85N; 86C; 86D; 86E; 86F; 86K; 86L
AreaGreat Bear Lake; Lac la Martre; Hottah Lake
Lat/Long WENS-119.0000 -116.0000 67.0000 63.0000
Subjectsgeochemistry; surficial geology/geomorphology; economic geology; till geochemistry; tills; glacial deposits; copper; gold; mineralization; lithogeochemistry; indicator elements; Great Bear Magmatic Zone; NICO Deposit; Cenozoic; Quaternary
ProgramGEM: Geo-mapping for Energy and Minerals, Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)
As part of Canada's Geomapping for Energy and Minerals (GEM) Program, an applied Quaternary research activity under the IOCG-Great Bear Project was undertaken in the Great Bear magmatic zone (Northwest Territories, Canada) to provide a practical guide for geochemical and indicator mineral exploration targeting iron oxide copper-gold (IOCG) and affiliated deposits in glaciated terrain. Detailed till sampling (n=111) was completed in the vicinity of the NICO Au- Co-Bi-Cu magnetite-group IOCG deposit as well as the Sue-Dianne Cu-Ag-Au magnetite- to hematite-group IOCG deposit, and near showings hosted within other IOCG-type alteration systems in the GBmz. Samples were collected up-ice, proximal to, and down-ice from mineralization, hydrothermally-altered host rocks and least-altered bedrock. Extensive lihogeochemical data set (n=1243) was available within the IOCG-Great Bear Project.
Results and conclusion
Lithogeochemical signatures of mineralization and/or alteration are reflected in the till matrix (K, Na, Ca, Mg, Ti, Cu, Ba, Cr, Co, Th, Bi, Mo, U, As) despite variable degrees of post-glacial weathering and textural differences. Possible IOCG deposit pathfinder elements in till (<2 and/or <63 ?m fraction) include Cu, Mo, Bi and Co (enrichments), as well as Ti (depletion). However, given the high variability of IOCG and affiliated mineralization, a multivariate statistical approach was also applied to see if their associated, and more characteristic, alteration types left a clear signal. A principal component analysis (PCA) was performed on combined data sets of till geochemistry and lithogeochemistry. This innovative approach helps to isolate the role of hydrothermal processes from surface processes such as glacial communition and post glacial weathering in the internal variability of the till geochemistry. Results so far show: 1) grouping of till samples by the first 3 principal components, based on their related IOCG showings; 2) discrimination between anomalous till samples based on multi- enrichments of alteration related elements (K, Ca, Na), and 3) potential to identify the type of bedrock IOCG alteration in overlying till samples.