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TitleUranium metallogeny in the Great Bear Magmatic Zone (Wopmay Orogen) and adjacent terranes
AuthorOotes, L; Goff, S; Corriveau, L; Harris, J; Jackson, V
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. 44-45 (Open Access)
LinksOnline - En ligne
Year2007
Alt SeriesEarth Sciences Sector, Contribution Series 20070564
MeetingYellowknife Geoscience Forum; Yellowknife; CA; November 20-22, 2007
Documentserial
Lang.English
Mediapaper; on-line; digital
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; uranium; metallogeny; mineral deposits; mineral occurrences; mineralization; iron oxides; copper; gold; alteration; hydrothermal alteration; hydrothermal deposits; mineral exploration; Great Bear Magmatic Zone
ProgramSecure Canadian Energy Supply
ProgramTargeted Geoscience Initiative (TGI-3), 2005-2010
AbstractU2O3 spot prices, as of October 2007, remain over $70/lbs (USD), having rocketed to just over $130/lbs (USD) in July, 2007. This is part of a hot cycle of increasing value and spot prices since early 2005 after two decades in the $20/lbs range (for historical details and current spot prices visit: http://www.uxc.com/). The ca. 1.87 Ga Great Bear magmatic zone (GBmz) of the Wopmay orogen was a major producing district for uranium with first production at Port Radium on Great Bear Lake in 1931. Port Radium, as with a number of other prospects and past-producers in this area and throughout the GBmz, is polymetallic and now recognized as part of the iron oxide copper-gold/uranium (IOCG/U) clan of deposits. Uranium has also been produced from the Rayrock Mine in the southern GBmz, which is hosted by a giant quartz vein/stockwork possibly representing the late-stage epithermal pulse of the IOCG/U event, or alternatively it may be part of a later unconformity-related style of mineralization.
This presentation will briefly review uranium-bearing mineral prospects/past-producers in the GBmz and their generic mineral deposit type. In parallel, we will illustrate how high background uranium values is in host-rocks from a case study in the central Wopmay Orogen, using geochemical data and regional airborne derived radiometric data. The uranium in IOCG/U deposits is directly related to the uranium in the host-rocks and our data (when coupled with regional alteration studies) highlight lithologic units that are most prospective for new discoveries of uranium-bearing IOCG prospects.
The relatively high number of known uranium occurrences and the regionally elevated uranium in some igneous rocks of the GBmz has implications for another style of mineralization. Unconformably overlying the Wopmay orogen is the Paleo to Mesoproterozoic Hornby Bay and Dismal Lakes groups of the Coppermine Homocline and equivalent rocks in the Leith Peninsula area south of Great Bear Lake, parts of which are considered equivalent to the uranium-rich Athabasca and Thelon basins. Indeed, the Coppermine Homocline and Leith Peninsula areas have known unconformity-related uranium prospects. The uranium-enriched GBmz basement could have provided a uranium source to circulating hydrothermal fluids, or could have provided detritus that formed the basin(s); therefore, enriching the host-sandstones in uranium-rich minerals to be leached during basinal fluid mobilization. The Wopmay orogen is also unconformably overlain by Palaeozoic Platformal rocks to the west; significantly, it is likely that these Palaeozoic rocks may locally unconformably overly Hornby Bay and/or Dismal Lake group equivalents, such as the proposed "Dessert Lake" basin to the south and other sub-basins previously documented at the contact between the Wopmay-Palaeozoic unconformity. This possible unconformity and the regional metallogenic character encourages the speculation that there may be 'blind' unconformity-related uranium deposits hiding under the Palaeozoic cover.
With the currently strong uranium market, the GBmz of the Wopmay orogen provides a regional exploration target for uranium-enriched IOCG (i.e. IOCG/U). Similarly, the known and Paleo to Mesoproterozoic rocks unoconformably overlying the GBmz (but underneath the Palaeozoic cover) may turn out to be a new, exciting target for 'blind' uranium deposits.
GEOSCAN ID224830