HR: 0800h
AN: U41A-0721    [Abstracts]
TI: Temporal Variations in the Convective Style of Planetary Mantles
AU: * Loddoch, A
EM: loddoch@earth.uni-muenster.de
AF: Institute of Geophysics, University of Muenster, Corrensstr. 24, Muenster, 48149 Germany
AU: Stein, C
EM: stein@earth.uni-muenster.de
AF: Institute of Geophysics, University of Muenster, Corrensstr. 24, Muenster, 48149 Germany
AU: Hansen, U
EM: hansen@earth.uni-muenster.de
AF: Institute of Geophysics, University of Muenster, Corrensstr. 24, Muenster, 48149 Germany
AB: Investigations of mantle convection with temperature- and stress-dependent viscosity have revealed the existence of fundamentally different convective styles: By varying e.g. the Rayleigh number, the viscosity contrast or the stress dependency of viscosity, the planform of convection in the asymptotic stationary state changes from the so-called stagnant lid regime to an episodic behaviour and further to a state characterized by a mobile surface. Our studies suggest that this transition may not only be induced by a change of parameters but also occurs temporally, i.e. a system that initially shows an episodic behaviour falls into the stagnant lid mode of convection as time proceeds. Such a temporal variation can probably describe the evolution of terrestrial planets like Mars, which is assumed to have undergone a change of convective style in its early history. In this contribution we present a 3D fluiddynamical model that exhibits a change of the convective style for temporally constant parameters. We also describe the methods developed to characterize different regimes and to identify the transitions observed.
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8147 Planetary interiors (5430, 5724)
DE: 8149 Planetary tectonics (5475)
DE: 3230 Numerical solutions
SC: Union [U]
MN: 2004 AGU Fall Meeting