HR: 1340h
AN: MR23B-0061    [Abstracts]
TI: Mantle Dynamics of Super-Earth Extrasolar Planet under Extreme Temperature and Pressure Conditions Extreme Temperature and Pressure conditions
AU: Van den Berg, A P
EM: berg@geo.uu.nl
AF: Utrecht University, Institute of Earth Sciences, Utrecht, TA-3508 Netherlands
AU: Beebe, G
EM: bee0020right@gmail.com
AF: University of Minnesota, 310 Pillsbury Dr. Dept. of Geology and Geophysics, Minneapolis, MN 55455-0219 United States
AU: * Yuen, D A
EM: davey@krissy.geo.umn.edu
AF: University of Minnesota, 310 Pillsbury Dr. Dept. of Geology and Geophysics, Minneapolis, MN 55455-0219 United States
AB: The recent discovery of an extrasolar planet with a mass 7.5 times that of the Earth has opened up new possibilities for planetary modelling because of the higher temperature T ( up to around 10,000 K ) and greater pressures P( up to 1,000 MPa ) involved. We have modelled the dynamics of this planet under these extreme conditions with an extended Boussinesq approximation , using a cartesian 2-D model. Rayleigh numbers of the order of 10**7 have been considered.Both the spinel to perovskite and perovskite to post-perovskite phase transitions have been accounted for, as well as temperature-dependent thermal conductivity, where the phonon, photon and electron thermal conductivities have been included because of the high T and P conditions. A strongly decreasing thermal expansivity for post-perovskite phase , varying by a factor of 20 across the super-earth mantle, has been included. These results reveal a tremendous difference in the style of mantle convection between constant and thermal conductivity models, all other parameters being kept the same. Temperature-dependent thermal conductivity, especially that of electron carriers, helps to develop obese plumes, even in the presence of a small value of thermal expansivity in the deep mantle, whereas weak convection is developed at the base of the mantle with constant thermal conductivity.
DE: 1729 Planetology
DE: 1744 Tectonophysics
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005