HR: 0800h
AN: T21C-0512    [Abstracts]
TI: Predictions from the Geodynamic Model of a Pull-Apart Basin
AU: Petrunin, A
EM: alexei@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, D-14473 Germany
AU: * Sobolev, S V
EM: stephan@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, D-14473 Germany
AB: Pull-apart basins belong to a special type of sedimentary basins associated with continental transform faults. They are depressions that are formed as a result of crustal extension in domains where the sense of fault overstepping or bending coincides with the fault motion sense. The outstanding classic example of a pull-apart basin is the 150 km long Dead Sea basin which is located at the Dead Sea Transform and where more than 8 km of sedimentary cover has accumulated since 15-17 Ma. It remains unclear what determines the length of a pull-apart basin and the thickness of its sediments and how the associated extension strain is distributed at depth beneath the basin. We present a simplified 3-D thermomechanical model of a pull-apart basin formed at an overstepping of an active continental transform fault. The modelling shows that, in addition to the magnitude of strike-slip displacement, the major parameters, which control basin length, thickness of sediments and deformation pattern beneath the basin are thickness of the brittle layer and friction strength at major faults. The unusually large length and sediment thickness of the Dead Sea basin can be explained by 100 km of the strike-slip motion, thick (up to 27 km) brittle part of the cold lithosphere beneath the basin and friction coefficient of less than 0.15 at major faults. The much thinner sedimentary cover in the Gulf of Aqaba basin, located at the southernmost part of the Dead Sea Transform, close to the Red Sea Rift, is likely due to a thinner brittle part (12-15 km) of the warmer lithosphere. Based on our model and observed distribution of seismicity in the deepest part of the Dead Sea basin, we predict relation between depth of the basin and friction coefficient at major faults. Moreover, we also predict that uplift of the Moho beneath the basin is less than 3 km. We also infer that the values of surface heat flow of 40 mW/m2, reported for the Dead Sea, are probably much too low (by 15-20 mW/m2), because, otherwise, either the depth of the Dead Sea pull-apart basin would be more than 16 km or no pull-apart deformation would occur in such cold lithosphere. All these predictions can be tested in a multidisciplinary project including seismic, geothermic and stress-field observations.
DE: 0545 Modeling (4255)
DE: 0560 Numerical solutions (4255)
DE: 8004 Dynamics and mechanics of faulting (8118)
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: Fall Meeting 2005