Abstract

The Patterson Lake corridor is situated along the SW margin of the Athabasca Basin and contains several basement-hosted uranium deposits and prospects. Drill core investigations during this study have determined that granite, granodiorite, mafic and alkali intrusive basement rocks are entrained in a deep-seated NE-striking subvertical heterogeneous high-strain zone defined by anastomosing ductile to semi-brittle shears and brittle faults. The earliest phases of ductile deformation (D1/D2), linked with Taltson (1.94–1.92 Ga) orogenesis, involved interference between early fold sets (F1/F2) and development of an associated ductile transposition foliation (S1/S2). During subsequent Snowbird (c. 1.91–1.90 Ga) tectonism, this composite foliation was re-folded (D3) by NE-trending buckle-style folds (F3), including a regional fold centred on the Clearwater aeromagnetic high. In continuum with D3, a network of dextral-reverse chloritic-graphitic shears, with C–S geometry, formed initially (D4a) and progressed to more discrete, spaced semi-brittle structures (D4b; c. 1.900–1.819 Ga). Basin development (D5a; <c. 1.819 Ga) was marked by a set of north-striking normal faults and related east- and NE-striking transfer faults that accommodated subsidence. Primary uranium mineralization (D5b; c. 1.45 Ga) was facilitated by brittle reactivation of NE-striking basement shears in response to WSW–ENE-directed compressional stress (σ1). Uraninite was emplaced along σ1-parallel extension fractures and dilational zones formed at linkages between NE- and ENE-striking dextral strike-slip faults. Uranium remobilization (D5c) occurred after σ1 shifted to WNW–ESE, giving rise to regional east- and SE-striking conjugate faults, along which mafic dykes (1.27 and 1.16 Ga) intruded.

Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways

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