Dynamics of the Dead Sea Transform from lithospheric-scale thermo-mechanical modelling
Abstract
The Dead Sea transform system (DST) is the boundary between the Arabian and African plates, where left-lateral transform motion has largely accommodated the opening of the Red Sea basin during the last 15-20 My. To study dynamics of the DST during the last 17 Myr, we use the internally consistent finite element thermo-mechanical modelling of the lithospheric deformation constrained by high-resolution geophysical observations and especially by the recent geophysical data of the DESERT Project. Our numerical model operates with realistic visco-elasto-plastic rheology of lithosphere without predefined faults. Faults are generated in a self-consistent way due to the strain localization process associated with the strain softening in plastic deformation mode. Our modelling suggests that the DST lithospheric structure is controlled by the plate-scale transform displacement within a relatively cold lithosphere. In such a lithosphere, shear strain is localized in a narrow (20-40 km wide) vertical decoupling zone (VDZ), which crosses the entire lithosphere. In the upper crust the deformation localizes at one or two major faults located at the top of this zone. The location of the VDZ is controlled by the temperature of the uppermost mantle prior to the transform motion. The lithospheric structure imaged along the DESERT seismic line is consistent with the 105 km transform motion combined with less than 4 km transform-perpendicular extension. Uplift of the Arabian Shield adjacent to the DST can be explained by young (<20 Ma) thinning of the lithosphere at and east of the plate boundary. Such lithospheric thinning is consistent with seismological observations, with the low present-day surface heat flow and with the high temperatures derived from mantle xenoliths brought up by Neogene-Quaternary basalts. The modelling suggests that the lithospheric thinning in the southern part of the DST have enabled transform motion at the DST by lowering the strength of the otherwise to strong Arabian lithosphere.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....7525S