Some Thoughts on Lithospheric Overturn on Venus

Scott D King, Virginia Tech, Blacksburg, VA, United States and Aaron C Prunty, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States

Contact First Author: Scott D King; sdk@vt.edu

Previously Published Material: Some of this was shown at the Fall Meeting.

Abstract ID#: 33980

 

English Abstract:
Impact crater distribution on Venus indicates that the present surface is on average 750 Myr old. There has been considerable debate regarding the nature of the resurfacing, with progressive volcanism or catastrophic overturn endmember models. We present a series of 3D spherical convection simulations with a reasonable yield stress rheology and show that even with an initial degree-1 mantle structure, a lithospheric overturn event is characterized by a number of small downwelling instabilities. We constrain our simulations using the observed geoid, topography, heat flow, and melt production. Very large yield stresses result in a degree-1 type overturn; however the resulting geoid and topography are too large by at least an order of magnitude. We compare the distribution of downwelling instabilities with the global distribition of subduction sites proposed by Schubert and Sandwell (Icarus, 117, 173-196, 1995).
Back to: Surface Expressions of Volcanism and Associated Tectonism on Venus and Implications for Interior Dynamics