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TitleGeometric and hydrodynamic modelling and fluid-structural relationships in the southeastern Athabasca Basin and significance for uranium mineralization
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AuthorLi, Z; Chi, G; Bethune, K M; Bosman, S A; Card, C D
SourceTargeted Geoscience Initiative 4: unconformity-related uranium systems; by Potter, E G (ed.); Wright, D M (ed.); Geological Survey of Canada, Open File 7791, 2015 p. 103-114, https://doi.org/10.4095/295788 (Open Access)
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Potter, E G; Wright, D M; (2015). Targeted Geoscience Initiative 4: unconformity-related uranium systems, Geological Survey of Canada, Open File 7791
File formatpdf
ProvinceSaskatchewan
NTS74A/13; 74G/01; 74G/08; 74H/03; 74H/04; 74H/05; 74H/06; 74H/07; 74H/10; 74H/11; 74H/12; 74H/13; 74H/14; 74H/15; 74I/03; 74I/04
AreaKey Lake; Millennium; McArthur River
Lat/Long WENS-106.5000 -104.5000 58.2500 56.7500
Subjectseconomic geology; radioactive minerals; unconformity-type deposit; unconformities; uranium deposits; uranium; mineral deposits; mineral occurrences; mineralization; models; modelling; formation fluids; fluid dynamics; fluid flow; Athabasca Basin
Illustrationslocation maps; models; cross-sections
ProgramUranium Ore Systems, Targeted Geoscience Initiative (TGI-4)
Released2015 03 02 (08:30)
AbstractUnconformity-type uranium deposits in the Athabasca Basin are spatially associated with reactivated basement faults intersecting the unconformity surface. However, questions such as what special factors focused fluid flow along and within fault zones, and why some faults are more fertile than others, are still unclear. This study aims to tackle these questions through examination of the southeastern Athabasca Basin. First, a basement structural map was compiled based on basement geophysical signatures, which shows three dominant sets of faults trending NE, NW, and NNW. A 3D model of the sub-Athabasca unconformity was constructed with GoCADR using publicly available geological and drill-hole data, revealing a number of dominantly NE-trending ridges and valleys. These unconformity topographic features are interpreted to be the products of the combined action of three main factors: 1) pre-Athabasca group ductile faulting and alteration; 2) differential weathering and erosion; and 3) post-Athabasca reactivation of pre-existing, graphite-rich ductile shear zones. The basin-scale numerical modelling of hydrodynamics indicates that fluid pressures in the Athabasca Basin were close to hydrostatic throughout its sedimentary history, and that thermal convection cells may have been well developed in the lower part of the basin, particularly below the Wolverine Point Formation aquitard. The modeling results also show that individual convection cells are less than 2 km, implying that individual mineralization centres, if controlled by thermal convection, may be spaced at just a few kilometers. Local-scale numerical modelling of fluid flow indicates that the location and spacing of basement faults influence thermally-driven fluid convection. In a model with an isolated fault, the fault coincides with an upwelling plume. In the case of two faults, the faults may coincide with upwelling flow or alternatively be centrally located below convection cells, depending on fault spacing. In the latter case, fluid may flow into and out of individual fault zones. Modelling of fluid-flow in response to mechanical compression suggests that fluid migrates up the fault during compression, and that the models with the most shallowly dipping fault and those with offset on the fault have slightly greater flow rates than the other models. The various relationships between fluid-flow and faults can explain why some faults are more favourable for fluid flow than others, which may be potentially used to evaluate whether a given structure has the potential to host mineralization.
GEOSCAN ID295788