Targeted Geoscience Initiative 5: integrated multidisciplinary studies of unconformity-related uranium deposits from the Patterson Lake corridor, northern Saskatchewan
E G Potter, V Tschirhart, J. W. Powell, C J Kelly, M. Rabiei, D Johnstone, J A Craven, W J Davis, S J Pehrsson, Sarah Mount, Guoxiang Chi, K M Bethune
Abstract
Basement-hosted uranium deposits of the Patterson Lake corridor are located on the southwestern margin of the Athabasca Basin in atypical hosts: altered and metamorphosed granite, granodiorite, and ultramafic to mafic rocks. Fluid inclusions record incursion of two fluids, NaCl- and CaCl2-dominant, at temperatures up to 250°C and approximately 1 km into the basement during episodic brittle reactivation of high-strain-ductile to brittle-ductile structures, in particular late west- and north-northwest-striking brittle conjugate faults that crosscut the Athabasca sandstone. Isotopic data from pyrite and tourmaline record basinal fluid-rock interactions under fluctuating pressure and oxidizing to reducing conditions. New 3-D geophysical modelling illustrates linkages between the surface architecture and lower crust to mantle and influence of the Clearwater Domain granitic intrusions on the ore systems. High radiogenic heat production from these intrusions and other ca. 1.8 Ga felsic intrusions contributed to a prolonged, elevated geothermal gradient under the Proterozoic basins that permitted shallow (less than 3 km) depths of mineralization.