An upper bound on lithosphere thickness from glacio-isostatic adjustment in Fennoscandia

Abstract

The three-layer Maxwell half-space model of the earth and a disk-load approximation of the Weichselian deglaciation history of Fennoscandia are used to calculate glacio-isostatic adjustment for this region. The calculations include the effects of deglaciation-induced geoid perturbations nd eustatic sea-level rise and regard (1) lithosphere thickness, (2) asthenosphere viscosity and (3) ice thickness as the free model parameters. Numerical values of parameters (1}-(3) are estimated by calculating the past land uplift and present land-uplift rate observed in central Sweden (glaciation centre) and the past land uplift and past land tilt observed in southern Finland (glaciation margin). The uniqueness of the estimates and their sensitivity to uncertainties in (4) subasthenosphere viscosity, (5) ice cross-section and (6) deglaciation time are also assessed. The principal result of the investigation is that it suggests an upper bound of 80 km on the thickness of the Fennoscandian lithosphere.