Mantle Viscosity Stratification and Flow Geometry: Implications for Surface Motions on Earth and Venus

Walter S. Kiefer (Geodynamics Branch, Goddard Space Flight Center)

Geophysical Research Letters, 20, 265-268, 1993.

Abstract: For a fixed heat flow, the surface flow velocity of a convecting layer is not strongly sensitive to the variation of viscosity as a function of depth. Thus, the inferred absence of a low viscosity asthenosphere on Venus can not account for the limited surface motions there. The surface velocity is dependent on the convective geometry. Cartesian geometry convection can produce large surface velocities if the high viscosity surface layer is broken in places by weak zones. On the other hand, a high viscosity surface layer may inhibit the development of large surface velocities in axisymmetric convection.

Text of article (on AGU website)