Numerical Model of The Lithospheric Deformation At The Dead Sea Transform
Abstract
The 1000 km long Dead Sea Transform (DST) forms the boundary between Arabian and Sinai plates and it has taken some 105 km of left lateral motion during the last 15-20 my. Surface topography and uppermost crust structure along DST is strongly asymmetric. The relatively low western side of the narrow (10-30 km wide) rift valley is flexed downward while the higher eastern side is flexed upward. Similar flexure at the Moho, superimposed on the regional thinning of the crust eastwards towards the Mediterranean is recently detected by the DESERT 2000 wide-angle and near vertical seismic experiments. We address the problem of the deformation at the DST by the thermo -mechanical numerical modelling constrained by seismic data. We study a dynamic response of the rheologically stratified and heterogeneous lithosphere (with the crust gradually thinning to the West) to kinematic boundary conditions combining large transform displacement and small transform- perpendicular extension. Model includes also possibility for a pull-apart motion (transform-parallel extension). We show that the shear deformation localizes in the mantle lithosphere in a 20-40 km wide zone crossing the entire mantle lithosphere almost vertically. Zone of the localized deformation in the crust appears to be shifted by 10-20 km relative to the mantle deformation to the East, toward the thicker crust. This shift produces asymmetry in the deformation pattern and topography when transform-perpendicular (TPE) o transform-parallel (TPA) extension is applied. Our model suggests that deformation at the Dead Sea itself was controlled by the TPA extension with minor (0-2 km) TPE component. The opposite, (almost no TPA and 4-6 km TPE extension) is likely true for the region to the South of the Dead Sea where the DESERT 2000 transect was located. The modelling results reproduce very well surface topography, seismically imaged lithospheric structure and geological evolution of the DST, suggesting that it is the transtensional feature cutting through the entire lithosphere.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.6895S