BASEMENT HEAT-FLOW IN THE WESTERN CANADA SEDIMENTARY BASIN

The effective thermal conductivity of the entire sedimentary succession is calculated at 487 locations in the Western Canada Sedimentary Basin, based on net-rock analyses and thermal conductivity values corrected for temperature and porosity effects. An easterly trend of increasing values is caused by shallower burial depth and by a reduced proportion of low conductivity shales. Geothermal gradients, calculated previously and corrected for Pleistocene glaciations, are used in estimating the basement heat flow after subtracting the heat generated by radioactive decay in the sedimentary strata. The distribution of basement heat flow, with values between 30 and 80 mW/m2, is linked with the complex structure of the basement, which is comprised of Archean blocks, accreted terranes, orogenic belts and magmatic arcs. Heat flow-heat generation relations in Alberta show that the reduced heat flow and the characteristic length scale for the uppercrust thermal layer are of the order of 35 mW/m2 and 6 km, respectively.