HR: 12:05h
AN: T42B-08 INVITED    [Abstracts]
TI: The Dead Sea Transform and the Dead Sea Basin – Structure and dynamics
AU: * Weber, M
EM: mhw@gfz-potsdam.de
AF: GFZ Michael Weber, Telegrafenberg E325, Potsdam, 14473, Germany
AU: DESIRE Groups, D a
EM: mhw@gfz-potsdam.de
AF: GFZ Michael Weber, Telegrafenberg E325, Potsdam, 14473, Germany
AB: DESERT and DESIRE, two multi-national, interdisciplinary research efforts by teams from Germany, Israel, Jordan and Palestine focused on the Dead Sea Transform (DST) and the Dead Sea Basin (DSB), respectively. The DST has accommodated left-lateral transform motion of 105 km between the African and Arabian plates since early Miocene (ca. 20 My), creating during this process also the prime example of a pull-apart basin, the DSB. Within DESERT the DST segment between the Dead Sea and the Red Sea called Arava/Araba Fault (AF) was studied with the following results. On plate tectonic scale the AF is a narrow, sub-vertical zone cutting through crust and lithosphere to more than 50 km depth, while the Moho depth increases smoothly from 26 km to 39 km from W to E under the DST. Several faults exist in the upper crust in a ca. 40 km wide zone around the AF, but none has kilometer-size zones of decreased seismic velocities/zones of high electrical conductivities typical for damage zones. Across the sub-vertical AF abrupt changes in lithology can be identified to a depth of 4 kilometers. The AF also acts as a barrier to fluids. The AF is the main active fault of the DST system but it has only accommodated a limited part (up to 60 km) of the overall 105 km of sinistral plate motion. Now inactive fault strands in the vicinity of the present day AF took up lateral motion until about 5 Ma ago, when the main, active fault trace shifted ca. 1 km westward to its present position. In the top few hundred meters of the AF a locally transpressional regime occurs in a 100 to 300 m wide zone of deformed and displaced material, bordered by sub-parallel faults forming positive flower structures. The damage zones of the individual faults are only 5 to 20 m wide. This narrow width is significantly smaller than at other major strike-slip faults of similar magnitude. Most of these findings are corroborated by thermo-mechanical modeling that show shear deformation in the lithosphere under the DST/AF first localizes in a 20 to 40 km wide zone with a mechanically weak decoupling zone extending sub-vertically through the entire lithosphere. As time progressed upper crustal deformation became quickly focused in a few faults. Within DESIRE the DSB, the largest basin along the DST, is studied using again a multi-disciplinary and multi- scale approach. Some of the open questions presently being addressed in the DESIRE project which started in 2006, are: (1) What is the fault pattern of the DSB at depth? and (2) What is the deep structure of the DSB and the depth and configuration of the major crustal interfaces, e.g. the Moho beneath the basin? We will also report results of DESIRE, with an emphasis on the findings from geophysical studies and modeling.
DE: 7205 Continental crust (1219)
DE: 8010 Fractures and faults
DE: 8106 Continental margins: transform
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting