Glacially Induced Stress Across the Arctic From the Eemian Interglacial to the Present—Implications for Faulting and Methane Seepage

Abstract

Strong compressive and shear stresses generated by glacial loading and unloading have a direct impact on near-surface geological processes. Glacial stresses are constantly evolving, creating stress perturbations in the lithosphere that extend significant distances away from the ice. In the Arctic, periodic methane seepage and faulting have been recurrently associated with glacial cycles. However, the evolution of the Arctic glacial stress field and its impact on the upper lithosphere have not been investigated. Here, we compute the evolution in space and time of the glacial stresses induced in the Arctic lithosphere by the North American, Eurasian and Greenland ice sheets during the latest glaciation. We use glacial isostatic adjustment (GIA) methodology to investigate the response of spherical, viscoelastic Earth models with varying lithospheric thickness to the ice loads. We find that the GIA-induced maximum horizontal stress (σH) is compressive in regions characterized by thick ice cover, with magnitudes of 20–25 MPa in Fennoscandia and 35–40 MPa in Greenland at the last glacial maximum. Simultaneously, a tensile regime with σH magnitude down to −16 MPa dominates across the forebulges with a mean of −4 MPa in the Fram Strait. At present time, σH in the Fram Strait remains tensile with an East-West orientation. The evolution of GIA-induced stresses from the last glaciation to present could destabilize faults along tensile forebulges, for example, the west-coast of Svalbard. A more tensile stress regime as during the Last Glacial Maximum would have more impact on pre-existing faults that favor gas seepage from gas reservoirs.