BASEMENT HEAT-FLOW IN THE WESTERN CANADA SEDIMENTARY BASIN

The effective thermal conductivity of the entire sedimentary successio n is calculated at 487 locations in the Western Canada Sedimentary Bas in, based on net-rock analyses and thermal conductivity values correct ed for temperature and porosity effects. An easterly trend of increasi ng values is caused by shallower burial depth and by a reduced proport ion of low conductivity shales. Geothermal gradients, calculated previ ously and corrected for Pleistocene glaciations, are used in estimatin g the basement heat flow after subtracting the heat generated by radio active decay in the sedimentary strata. The distribution of basement h eat flow, with values between 30 and 80 mW/m2, is linked with the comp lex structure of the basement, which is comprised of Archean blocks, a ccreted terranes, orogenic belts and magmatic arcs. Heat flow-heat gen eration relations in Alberta show that the reduced heat flow and the c haracteristic length scale for the uppercrust thermal layer are of the order of 35 mW/m2 and 6 km, respectively.