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TitleGeoscience and exploration tools for multiple discoveries within the extraordinary range of IOCG (U) polymetallic mineral deposits
AuthorCorriveau, L; Mumin, H
Source35th Annual Yellowknife Geoscience Forum, abstracts of talks and posters; by Cairns, S; Falck, H; Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume vol. 2007, 2007 p. 10 (Open Access)
Alt SeriesEarth Sciences Sector, Contribution Series 20090363
MeetingYellowknife Geoscience Forum; Yellowknife; CA; November 20-22, 2007
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
Subjectseconomic geology; mineral deposits; mineral occurrences; mineralization; iron oxides; copper; gold; alteration; hydrothermal alteration; hydrothermal deposits; mineral exploration; Great Bear Magmatic Zone
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
ProgramSecure Canadian Energy Supply
AbstractWith 7,738 Mt total mineral resources and ore reserves of 399 Mt @ 1.87 % Cu, 0.58 kg/t U3O8, 0.68 g/t Au, 4.0 g/t Ag, the Olympic Dam deposit in Australia underscores the exciting exploration potential of IOCG (U) polymetallic deposits. Canada has no such mine yet, but in the Great Bear Magmatic Zone (NWT) it has stunningly exposed IOCG deposits under development (NICO) or advanced exploration. Moreover, Canada's ancestral active continental margins, now frontier felsic-to-intermediate volcano-plutonic terranes and their metamorphic derivatives, represent prime geological targets. IOCG ore zones are 'non-traditional' and can be difficult to identify in that they are oxide-rich rather than sulphide-rich and may be cryptically disseminated over kilometres within barren iron oxide and alkali-altered host rocks. Fortunately, their large alteration footprint allows effective regional scoping of prospective territories for IOCG type signatures and, within such systems, the alteration effects may constitute excellent vectors toward mineralization.
In this talk, we use the stunning exposures of the Port Radium ' Echo Bay district (past production of 15,000,000 lbs U3O8 and ~32,000,000 Oz Ag), and the NICO (total mineral reserve: 21.8 Mt@ 1.08 g/t Au, 0.16 %Bi, 0.13 % Co) and Sue Dianne deposits to illustrate some of the variations in IOCG mineralization and the tools we need to find them. We also illustrate that key alteration zones, overprinting relationships, breccias and stage of mineralization are important geological criteria for locating IOCG settings. At the same time, they can pose significant challenges when cryptic or misinterpreted. Detailed field work is the key to overcoming these difficulties, including the use of field and airborne spectrometers to measure U, Th and K. Follow-up mineralogical and geochemical studies are an integral part of effective field mapping, allowing for the proper interpretation of field observations through correct identification and classification of hydrothermal zonations and vectors. Finally, because IOCG is a relatively new deposit type and encompasses a great variety of large deposits that may have associated peripheral to distal-type high-grade copper, uranium, silver, and other metal rich veins, the host rocks of some past-producing vein-type mines are now being recognized as part of large IOCG systems. This association has positive implications for both exploration and environmental baseline studies, as the extent over which areas can be naturally enriched in metals is large ' 10's of square km. Moreover, old mine tailings may now be ore and mining them may be the best remediation approach. Though much work is needed before we can assess the full mineral resource endowment of the Great Bear Magmatic Zone, current knowledge provides informed decisions at our doorstep.