HR: 1340h
AN: P33A-0234    [Abstracts]
TI: A Potential Strong Connection Between Climate Change and the Solid Body Dynamics of Terrestrial Planets
AU: * Lenardic, A
EM: adrian@esci.rice.edu
AF: Rice University, Department of Earth Science, MS 126, P.O. Box 1892, Houston, TX 77251 United States
AU: Jellinek, A M
EM: mjellinek@eos.ubc.ca
AF: University of British Columbia, Department of Earth and Ocean Sciences, Vancouver, BC V6T1Z4 Canada
AU: Moresi, L
EM: louis.moresi@monash.edu
AF: Monash University, School of Mathematical Sciences, Building 8, Victoria, 3800 Australia
AB: We explore the possibility that a relatively rapid increase in the surface temperature of a terrestrial planet could initiate a transition from an active lid mode of mantle convection (e.g., plate tectonics) to a stagnant lid mode (i.e., single plate planet). A simple theory is developed to estimate the required temperature change as a function of the temperature-dependence of mantle viscosity and the yield stress of the lithosphere. The theory relies on the assumptions that convective stresses scale with mantle viscosity and that a predominantly internally heated planet will adjust to surface temperature changes so as to maintain a heat flow that balances radiogenic heat production (i.e., internal temperature will increase). The theory is tested against a suite of numerical simulations of mantle convection with visco-plastic rheologies. The comparisons are favorable and the combined theory and numerics suggest that parameter regimes exist for which relatively modest temperature changes (50 degrees or less) could potentially shut down an early active lid mode of convection. We extend our ideas to include the time scale over which atmospheric temperatures could change due to variable rates of volcanic outgassing and explore a range of possible models that are appropriate for Venus, Earth and Mars. The potential of variable effective friction coefficients due to increased temperatures leading to dry conditions is also addressed. We combine our preliminary theoretical work and compare initial predictions to observational based inferences regarding the coupled atmosphere-solid planet evolution of Venus.
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8121 Dynamics: convection currents, and mantle plumes
SC: Planetary Sciences [P]
MN: Fall Meeting 2005