HR: 1340h
AN: V13C-0567    [Abstracts]
TI: Early degassing of the mantle: what is the role of convection?
AU: * Coltice, N
EM: coltice@univ-lyon1.fr
AF: Laboratoire Sciences de la Terre, ENS Lyon, 46 allee d'Italie, Lyon Cedex 07, 69364 France
AU: Schmalzl, J
EM: jpergs@earth.uni-muenster.de
AF: Institute for Geophysics, Munster university, corrensstrasse 24, Muenster, 48149 Germany
AU: Ricard, Y
EM: ricard@ens-lyon.fr
AF: Laboratoire Sciences de la Terre, ENS Lyon, 46 allee d'Italie, Lyon Cedex 07, 69364 France
AB: The Earth's mantle experienced an extensive degassing very early in its history. Various phenomena can be invoked and two end-members are (a) a large-scale catastrophic melting and degassing and (b) a continuous degassing of an extremely vigorous solid-state convective mantle. We study the physics of model (b) through 2D and 3D convection simulations with passive tracers and show that mantle temperature and heating mode have a drastic influence on mixing and degassing. In a mantle 300~K hotter than today, convection is able to remove more than 90% of its initial noble gas content in less than 100~Myrs, especially if internal heating is dominant.
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1025 Composition of the mantle
DE: 1038 Mantle processes (3621)
DE: 8121 Dynamics: convection currents, and mantle plumes
DE: 8125 Evolution of the Earth (0325)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005