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C. P. Orth and V. S. Solomatov
Department of Earth and Planetary Sciences
Washington University in Saint Louis
Advisor: V. S. Solomatov
Abstract
The isostatic stagnant lid (ISL) approximation assumes that the stagnant lid (including both the lithosphere and the crust embedded in the upper part of the lithosphere) overlying a convective mantle is in isostatic equilibrium and ignores any contribution of dynamic, elastic, and transient effects on the topography. Two-dimensional numerical calculations show that in the stagnant lid regime of temperature-dependent viscosity convection the dynamic support associated with convective motions is small and that the topography and geoid anomalies are largely caused by density variations in the upper viscous layer (i.e. the stagnant lid). For a given rheology, the results obtained in the ISL approximation can be very close to those obtained by the exact numerical models. Application of the ISL approximation to Venus suggests that the global lithospheric thickness is ~ 200 km and that crustal thickening is required only in a few regions to satisfy the long-wavelength gravity and topography data.
Luke Nowicki Orth is a doctoral candidate in the Department of Earth and Planetary Sciences at Washington University in St. Louis.
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