Abstract

The Sverdrup Basin, which underlies much of the northern Canadian Arctic Archipelago, forms a northeasterly elongate pericratonic depression, approximately 1300 km by 400 km, containing at least 13000m of hydrocarbon-bearing Carboniferous to Tertiary strata. Geological and geophysical evidence suggests that initial subsidence of the Sverdrup Basin was accompanied by crustal attenuation and development of a complex continental rift system, followed by post-Early Permian thermo-isostatic subsidence.

In order to examine these events quantitatively, a rigorous thermo-mechanical model has been adopted, which incorporates a rheologically layered lithosphere and takes into account the combined effects on subsidence of temperature anomalies, latent heat at the phase change boundary, and sediment loading. The temperature anomalies contribute to deformation of the basin not only by setting up body forces, but also by creating thermal in-plane forces and bending moments. In general, conventional local isostatic and simple elastic plate models of sedimentary loading on a thermally perturbed lithosphere are inadequate due to neglect of these important interactions of thermal and mechanical forces. The relative influence of radiogenic heat sources in the lithosphere is also investigated in the model.

The model explains the subsidence of the Sverdrup Basin as determined by seismic and well data and geological mapping of deformed and exposed stratigraphic sections, and allows constraints to be placed on the required stretching resulting from Carboniferous rifting and the subsequent evolution of the thermal regimes of the rifted lithosphere and overlying sedimentary basin.