ABSTRACT: An integrated study of surficial geology, geochemistry and airborne radiometrics to aid geological investigations, NEA-IAEA study area, Eastern Athabasca Basin, Saskatchewan.

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Abstract

Integration of geological, geochemical, and radiometric data reveals correlations among the radiometric data, surficial geology (provenance, geochemistry, drift thickness), and bedrock geology. From the ternary K-eU-eTh map, sandstone bedrock and sandstone-rich tills overlying the Athabasca Basin are clearly distinguished from crystalline-rich tills by relatively high eTh and an absence of K. Variations in radiometric properties reflect the proportions of sandstone and crystalline debris. Outside the Basin, crystalline-rich till and bedrock is characterized by high eU and K, and the contact between the geological terrains is clearly delineated by the radiometric differences. Factor analysis (GSC) shows that geochemical data characterize sample mineralogy and provenance, broadly distinguishing detritus of intra- and extra-basinal origin, and supporting radiometric interpretations. The integrated approach affirms the linkages between geochemical mapping and gamma ray surveys, and the use of surficial geology and geochemistry to map glacial dispersal patterns and drift provenance. The work further indicates the potential to identify effects of diagenesis, basement structure, and uranium mineralization on both sandstone bedrock and the derived tills. Two enigmatic trends expressed by airborne gamma ray data are under investigation using these methods. A distinct 1-3 km-wide NE-SW, SE-convex curvilinear trend defined by high-K and -eU spans the 45 km diagonal of the NEA-IAEA area. It was previously interpreted as the radiometric expression of a granitic boulder dispersal train formed during an older glacial advance (240 degrees). At least a portion of this trend is associated with increased concentrations of crystalline pebbles in till. The length and orientation of this trend are, however, inconsistent with known surficial geology, glacial history and ice flow dynamics. The regional ternary data outline a diffuse, 30-50 km-wide, NE-SW high-K trend that transects the eastern Athabasca Basin extending onto basement in both directions, and intersecting the NW corner of the NEA-IAEA area. This trend is roughly parallel with the regional ice flow direction. We are testing two non-exclusive hypotheses for the origin of these high K-eU trends, both of which transect mapped sandstone stratigraphy: 1) as-yet undetermined Quaternary features, and/or 2) reactivated regional basement structures that may be targets for uranium exploration.

Bibliography of Canadian Geomorphology