HR: 13:40h
AN: GP13A-01 INVITED     [Abstracts]
TI: Possible Link Between Numerical Modeling of The Lithospheric Deformation and MT Research Fields
AU: * Sobolev, S V
EM: stephan@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg E3, Potsdam, 14473 Germany
AB: There is almost no connection established yet between two rapidly developing fields of the lithospheric research, namely between numerical simulation of the thermo-mechanical processes and MT studies. To compensate for this gap I focus here on the numerical modeling of the strain localization processes at the lithosphere-scale continental transform faults and on prediction of the possible electrical conductivity structures associated with these processes. First, I use a finite-element thermo-mechanical modelling technique in simplified 3D approximation to study effect of lithospheric rheology on localization of the strike slip deformation in continental lithosphere in general case. The numerical model allows for realistic temperature-, stress- and strain- dependant visco-elasto-plastic rheology as well as for the spontaneous self-generation of faults in brittle upper crust and strain localization in the ductile lower crust and upper mantle. The modeling shows that in the case of brittle upper crust and temperature-independent Newtonian rheology of the lower crust and mantle, the strike-slip deformation localizes in the vertical transform fault in the upper crust and within the broad zone (several tens km) in the ductile lower crust and mantle lithosphere, which rapidly widens with depth. No connectivity of the conducting inclusions in the lower crust and upper mantle can be expected in this case. In the case of temperature-dependent viscosity in the lower crust and upper mantle, more strain localization occurs in the ductile part of the lithosphere. If, in addition the viscosity is stress dependent (dislocation creep deformation mechanism), than the strain localization zone in the lower crust and mantle lithosphere becomes relatively narrow (20-30) km with ca. 5 km wide high-strain core in the middle. In this high-strain core the connectivity percolation threshold for the high-conductive inclusions may be achieved. Finely, I discuss the thermo-mechanical models and associated predicted electrical conductivity structures for the two particular continental transform faults, the Dead Sea Transform between the Dead Sea and the Read Sea as well as the San-Andreas Fault system in the San Francisco Bay area.
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 3914 Electrical properties
DE: 3210 Modeling
DE: 3230 Numerical solutions
DE: 1517 Magnetic anomaly modeling
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting