MEG Lunch Talk Wednesday May 18, 2016
Location: Kerby Centre, 1133 – 7 Ave SW, Calgary, AB. This month’s talk will be held in the Lounge. Please ask for directions at the Reception Desk. If you are using the Kerby Centre parking lot, you can validate your parking at the same time
Unconformity-related uranium deposits in the Athabasca Basin (northern SK/AB): Glimpses of their origin, age, evolution, and discovery
Dr. Kevin Ansdell
The Athabasca Basin hosts the highest grade uranium deposits in the world, exemplified by the McArthur River and Cigar Lake deposits, which are, at present, the two operating mines. The deposits are spatially associated with structures that cross-cut the unconformity between the sedimentary rocks of the Athabasca Group and the underlying metamorphosed Archean-Paleoproterozoic basement rocks, but can be hosted in the basement, at the unconformity, and less commonly, in the sandstones. Uranium is transported by oxidized high-salinity brines, and is deposited when these brines interact with a reductant; it is not known whether this is a reduced fluid, graphite or its breakdown products in the basement, or sulphides or ferrous iron-bearing minerals, or some combination thereof. The depositional process is also associated with the development of alteration zones comprising clay minerals, chlorite, hematite and tourmaline, indicative of chemical disequilibrium between the fluids and the host rocks, although the deposits have a complex paragenetic history. The timing of primary mineralization is now considered to be ca. 1.6 Ga, and related to the collision of proto-Australia with Laurentia during the Racklan/Forward Orogen, which may have driven fluids through the sedimentary rocks that covered northwestern Laurentia at that time. However, uranium-bearing minerals, which are very prone to resetting by fluids, also record much younger ages, some of which may be related to far-field stresses imposed by other orogenic episodes around the margins of Laurentia. One geological event that certainly affected the Athabasca Basin was the intrusion of the Mackenzie Dykes at 1.27 Ga, and well-constrained paragenesis at the Centennial deposit allows the examination of the thermal and fluid history imposed by this event and which may have also affected the deposits in the eastern Athabasca Basin. Fluids have been present in the Athabasca Basin throughout its history, and secondary redistribution of elements and isotopes associated with uranium mineralization towards the surface represent one method of identifying potential mineralization at depth. The discovery of deposits has involved the combination of geophysical and geochemical techniques in order to identify the location of structures and alteration, but integrating the many types of data available is a challenge. This is the focus of the ongoing NSERC-Canadian Mining Innovation Council Footprints project, which attempts to better constrain the “footprint” of a uranium ore system to improve exploration at depth. However, new recent discoveries in the southwestern Athabasca Basin (Patterson Lake South, and Rook properties) emphasize that there is still potential for near surface high-grade uranium deposits. Overall, the presentation will highlight the history of exploration and mining in the Athabasca Basin, and provide examples of the issues associated with our understanding of the deposits, namely their complex paragenesis, age, and post-formation history. In addition, a brief overview of the “Footprints” project, and the geological relationships in the emerging uranium camp in the southwestern Athabasca Basin will be provided.
Kevin grew up in Sheffield, England, and obtained his Bachelor’s degree in Geology from Oxford University in 1982, Master of Science from University of Alberta in 1984, and Ph.D. from University of Saskatchewan in 1992. He has been a faculty member of the Department of Geological Sciences at the University of Saskatchewan since completing a post-doctoral fellowship with the Geological Survey of Canada in 1993, and has been actively involved in the teaching and supervision of undergraduate and graduate students in the areas of mineral deposits, tectonics, Precambrian Geology, petrology, tectonics, and isotope geology.
He has a varied background in Mineral Deposits. He worked for Anglo-American as a Mine Geologist in the Witwatersrand Gold Fields, and Western Mining Corporation as an Exploration Geologist in northern Australia prior to his PhD. Kevin has been involved in research projects that have examined the geology, geochronology, geochemistry, petrology, paragenesis, and fluid evolution of orogenic gold, sediment-hosted and volcanic-hosted base metal, unconformity uranium, and rare earth element mineralization and the rocks with which they are associated, especially in the Precambrian Shield of Canada.
Kevin is a PGeol with Permission to Consult in Saskatchewan, a Fellow of Geoscientists Canada, the Saskatchewan representative of the Canadian Geoscience Standards Board, a Director of the Canadian Geological Foundation, and a member of numerous academic societies.
The Calgary Mineral Exploration Group Society offers monthly lunchtime seminars relating to geology and mining in the province of Alberta, across Canada and around the world.
$20.00 for members
$10.00 for students (with student ID)
$25.00 for non-members
Lounge, Kerby Centre, 1133 – 7th Ave SW, Calgary, AB
Doors Open at 11:30am Talk Commences at 12:00 noon
Please confirm your intention to attend by email to firstname.lastname@example.org so that the appropriate number of meals can be ordered.
If you would like to present a lunch time talk to a keen audience of 40 or 50 professionals, please contact Glen Jones at: email@example.com or telephone 403-651-3086 to submit your topic and abstract for review. If you or your company would like to sponsor a meeting please contact Glen Jones for further information.