Thermal History of Planetary Objects: From Asteroids to super-Earths, from plate-tectonics to life


Friday, August 16 2013 - 12:00 pm, PDT
Tilman Spohn
Director of the Institute for Planetary Research at DLR, Berlin

super earthConvection in the interiors of planetesimals (asteroids), planets, and satellites is driving the thermal and chemical evolution of these bodies including the generation of possible magnetic fields.  The wide size range induces a wide range of time scales from hundreds of thousands of years for small planetesimals to a few tens of Gigayears for massive super-Earths.

Spohn presented a model that includes mantle convection, mantle water vapor degassing at mid-oceanic ridges and regassing through subduction zones, continental crust formation and erosion and water storage and transport in a porous oceanic crust that includes hydrous mineral phases.

Dr. Spohn will show how an abiotic world is predicted to have a much drier mantle than the present Earth but may have a similar surface coverage by continents. The reduced rate of continental crust production on the abiotic world would be balanced by a reduced rate of continent erosion. He will suggest that through the effect of water on the mantle rheology, the biotic world would tend to be tectonically more active and have a more rapid long-term carbon-silicate cycle.

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