Results of geophysical studies across the Dead Sea Transform: The Arava/Araba valley and the Dead Sea basin

Michael Weber, Zusanna Alasonati-Tašárová, Khalil Abu-Ayyash, Zvi Ben-Avraham, Sungchan Choi, Jaser Darwish, Radwan El-Kelani, Zvi Garfunkel, H. J. Götze, Gottfried Grünthal, Abraham Hofstetter, Dagmar Kesten, James Mechie, Uwe Meyer, Ayman Mohsen, Marco Paschke, Alexei Petrunin, Trond Ryberg, Stefan V. Sobolev, Manfred Stiller

Research output: Contribution to journalArticlepeer-review

Abstract

The Dead Sea Transform (DST) in the Middle East is a fault zone of about 1000 km length, with a total of ca. 107 km of left-lateral transform motion since early Miocene (∼20 My). It shows uplifted flanks and several deep pull-apart basins, most prominently the Dead Sea Basin (DSB). This study focuses on the DSB and the southern part of the DST, the Arava/Araba Valley with its dominant fault, the Arava/Araba Fault (AF), using a multi-disciplinary approach combining seismics, seismology, gravity, and modelling. Central questions addressed are: (1) What is the crustal structure of the DSB and the Arava/Araba Valley? (2) Is it possible to reconstruct the crustal structure prior to the formation of the DST? (3) What is the interplay between structure and kinematics?Main results of this study are that several faults, manifested in strong lateral velocity gradients, exist in the upper crust in a 40-km-wide zone centered on the AF. The crustal thickness under the southern part of the DST increases smoothly from west to east from 26 to 39 km, with only a small asymmetric topography of the Mohorovičić Discontinuity (Moho) beneath the DST. The massive reworking of the upper crust in the DSB is manifested in deep sedimentary basins interspersed with slivers of high velocity material, most likely associated with the boundary faults. The DSB has a sedimentary fill of more than 8 km and contains three large salt diapirs, under the northern basin, the Lisan peninsula, and Mount Sedom, respectively. In contrast to the shallow structure, the interfaces below about 20 km depth show less than 3 km variation under the DSB.By removing the ca. 107 km of strike-slip motion along the DST and the subsidence associated with the various basins along the structure, a composite section of the crustal structure 20 My ago can be constructed. At deeper level there is strong evidence that the DST formed at the point where the crust starts to thin toward the Mediterranean Sea, with perhaps a pre-existent small depression in the Moho along the western flank of the DST.Thermo-mechanical modelling corroborates most of these findings. Shear deformation in the upper crust is localized along one or two major faults. For the DSB, it is found that N-S extension is the main cause for the thinning of the upper crust, and E-W extension is only a very minor component. The Dead Sea pull-apart basin is most likely an upper crustal feature, with the boundary between the upper and lower crust at about 20 km depth most probably acting as a decoupling zone.

Original languageEnglish
Pages (from-to)147-161
Number of pages15
JournalIsrael Journal of Earth Sciences
Volume58
Issue number3-4
DOIs
StatePublished - 1 Dec 2009

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