Frederick William Beinecke Professor of Geophysics
Spring '13 Earth Science Thursday Speaker Series - "Generation of Plate Tectonics on Earth and Other Planets"
Thursday, February 14, 2013
to 5:00 PM
100 Keith-Wiess Geological Laboratories
6100 Main St
Houston, Texas, USA
The plate-tectonic mode of mantle convection on Earth is thought to provide the fundamental conditions for habitability, from stabilizing the carbon cycle and climate, to supplying energy for early chemosynthetic life. The emergence of plate tectonics versus stagnant-lid behavior, as on the other terrestrial planets of our solar system, relies on mechanisms for shear localization in the lithosphere to create plate boundaries where tectonic activity is concentrated. I first present a new "grain-damage and pinning" model for lithospheric shear-localization. This model allows focussed plate boundaries to develop rapidly, and accounts for long lived dormant boundaries, which are an important feature of the tectonic system. The damage model is then used in simulations of mantle convection to infer conditions at which super-Earths would have plate tectonics. We propose a ``planetary plate-tectonic phase diagram" which delineates the transition from stagnant to mobile surface tectonics in "planet size-surface temperature" space. Both size and surface conditions are found to be important, with plate tectonics being favored for larger, cooler planets. This gives a natural explanation for Earth, Venus, and Mars, and implies that plate tectonics on exoplanets should correlate with size, incident solar radiation, and atmospheric composition.
Biography of David Bercovici: http://people.earth.yale.edu/profile/david-bercovici/about