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TitleNew developments in the hunt for unconformity-related uranium deposits
AuthorPotter, EORCID logo; Wright, D
SourcePDAC 2016; 2016 p. 1
LinksPDAC 2016 Program (pdf, 5.84 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20170372
MeetingPDAC 2016; Toronto, ON; CA; March 6-9, 2016
Documentunpublished manuscript
File formatpdf
ProvinceSaskatchewan; Alberta; Nunavut
NTS64E; 64L; 64M; 66A; 66B; 74E; 74F; 74G; 74H; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P
AreaMcArthur River; Sissons Lake
Lat/Long WENS-112.0000 -102.0000 60.0000 57.0000
Lat/Long WENS -99.0000 -97.0000 64.7500 64.2500
Subjectseconomic geology; geochemistry; structural geology; soils science; hydrogeology; mineral deposits; mineral exploration; exploration methods; exploration guidelines; unconformity-type deposit; uranium; ore mineral genesis; ore controls; structural controls; remobilization; modelling; fluid dynamics; fluid flow; hydrothermal systems; alteration; bedrock geology; structural features; faults; fault zones; shear zones; structural trends; lithology; sedimentary rocks; sandstones; isotopic studies; uranium thorium ratios; geochemical dispersion; geochemical analyses; metals; iron geochemistry; magnesium geochemistry; soils; soil geochemistry; soil gas geochemistry; soil horizons; humus geochemistry; groundwater geochemistry; radon; helium; argon; Athabasca Basin; Athabasca Group; McArthur River Deposit; Thelon Basin; Bong Deposit
ProgramTargeted Geoscience Initiative (TGI-5) Uranium systems
ProgramTargeted Geoscience Initiative (TGI-4)
Released2016 01 01
AbstractUnconformity-related U remains a prime exploration target in Canada given the potential for large tonnage, high-grade ore deposits. As more diverse geological settings for these deposits are discovered and exploration shifts to greater depths, new exploration methods are required to allow for efficient target generation and discovery of these buried ore deposits.
Recent studies under the Geological Survey of Canada's Targeted Geoscience Initiative Program (TGI-4) clearly illustrate that the ore-forming processes and remobilization of key ore elements produce diagnostic mineralogical, geochemical and isotopic signatures that can be identified and modelled over the entire fluid pathway through fertile fault systems, including post-mineralization dispersal of metals and gases into subsurface sandstones, soils and groundwater. In the eastern Athabasca Basin, basin-scale numerical modelling suggests that the hydrothermal cells extended only a few kilometres laterally from the faults. However, the morphologies of the ore zones and the extent of geochemical and mineralogical expressions of hydrothermal alteration for several kilometres along fault zones support long distance focussing of hydrothermal fluids. In the Athabasca Group sandstones, ore-related signatures (elevated U2/Th and Y2/Th values, etc.) are located directly above deposits and surface projections of fault zones while hydrothermal alteration signatures (e.g. elevated Mg/Li, Cu/Co, Ni, As, etc.) extend along NE-trending structures for several kilometres. Geochemical signatures reflecting remobilization (e.g. elevated U2/Th with low Y2/Th values, elevated base metals, etc.) are best expressed along late NW-trending fault zones that intersect the NE-trending fault zones. At the McArthur River deposit, delta-56Fe(IRMM-014) values >0.5 per mille record proximal redox reactions, whereas at the basement-hosted Bong deposit in the Thelon Basin, high delta-56FeIRMM-014 and delta-26Mg(DSM-3) values that delineate fertile structural zones and alteration assemblages suggest proximal fO2-pH changes. Such new data types indicate the fertility of an alteration system, and can track changes in the alteration along ore-hosting faults.
Metals such as U, Pb, ± Cu, Mo, Ag, Co, Ni and W are concentrated in humus and B-horizon soils directly above deeply-buried ore deposits and the surface projection of ore-hosting shear zones. Elevated Rn concentrations in groundwater support recent dispersal of metals from shallow alteration whereas increasing He/Ar values at depth suggest vertical and lateral dispersion of He from the deposits. In surficial media, the geochemical expressions of deeply buried ore are strongly influenced by the local glacio-fluvial history, soil development and hydrological conditions. Such constraints are critical when considering the potential extents of the ore deposit footprints in exploration.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) was a collaborative federal geoscience program that provided industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This conference abstract and presentation outlines key regional-scale geochemical and isotopic signatures related to unconformity-related uranium deposits recognized during the TGI-4 project. Through linking the signatures to updated ore-forming models and subsequent remobilization of key elements, the methods outlined provide a means of ranking targets and vectoring along prospective fault structures during exploration.

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