[Show abstract][Hide abstract] ABSTRACT:
The Dead Sea Rift / Dead Sea Transform acts as a hinge between the Alpine-Himalayan-Mountain Belt, stretching East-West from the Mediterranean to Indonesia, and the largest active continental rift system, the Afro-Arabian Rift System, which runs South-North from East Africa to the Dead Sea. Except for a mild compressional deformation starting about 180 Ma ago, the Dead Sea region has remained a stable platform almost since its formation in the late Proterozoic. This tectonic stability was only recently (ca. 18 Ma ago) interrupted by the formation of a transform with a left-lateral motion of about 105 km as of today. The simplicity of this system, especially in the Arava Valley, the valley between the Dead Sea and the Red Sea, puts it in strong contrast to other large transform systems like the North Anatolian Fault System, which is in the middle of an orogenic belt, and the San Andreas Fault System, which suffered repeated accretional episodes and the interaction with a triple junction. The simplicity of the Dead Sea Rift / the nearly linear Dead Sea Transform provides a natural laboratory to study and understand transfrom faults, one of the key elements of plate tectonics together with subduction and rifting. Despite the central role of this world geological site, up to now no geophysical profile has crossed the Dead Sea Rift / the Dead Sea Transfrom (DST).
The DEad SEa Rift Transect (DESERT) is a multinational and interdisciplinary study of the Dead Sea Rift, and the main goal of the DESERT project is to help address a fundamental question of plate tectonics: How do shear zones work and what controls them, on different scales?
The project began with field work in February 2000, and first experiments were completed by the DESERT Team in May 2000. The seismic, seismological, and magnetotelluric experiments presented here, along with the future electromagnetic, gravity, magnetic, petrological, geothermal, geodynamic, and geological studies, will provide the geophysical and geodynamic frame for further geoscientific research.
Within the DESERT project, scientists from Germany, Israel, Jordan, and the Palestine Territories joined together for the first time to study the crust and upper mantle, the main shear zones, and the geodynamics of the DST. Over 30 scientists of the GFZ, the universities of Potsdam, Kiel, Köln, and Göttingen; the universities of Tel-Aviv and Jerusalem, the national Ministry of Infrastructure and the Geophysical Institute of Israel; the Natural Resources Authority, Jordan; and the An-Najah University in Nablus and the Palestine Water Authority, Palestine Territories; work together in this project. The 260 km long transect across the DST traverses Israel, Jordan, and the Palestine Territories.
First results of the geophysical experiments show – contrary to the expectations – basically no up-doming of the Moho under the rift, suggesting that the mantle has played a rather insignificant role in the extension process associated with the Dead Sea Rift. The role of an 8 km thick structure, imaged as a band of strong reflectors in the lower crust under the elevated rift shoulder in Jordan, the dynamics of the rift / transform requires additional geophysical studies planned for the next year. On the kilometer scale, a 3-D tomographic image of the fault regions shows significant changes in seismic P-velocities across the fault, and the analysis of fault guided waves indicates a low-velocity zone with a velocity reduction of 15 to 25% and a thickness of only 10 to 20 meters at the surface location of the Arava Fault. This fault is also the location where a roughly 1.5 km thick body with very good conductivity in 2 km depth stops abruptly, possibly indicating the contact of sediments with saline brines to the west of the fault with a high velocity body with bad conductivity to the east.
[Show abstract][Hide abstract] ABSTRACT:
The Dead Sea Rift Transect (DESERT 2000) is a multinational and interdisciplinary study of the Dead Sea Rift. The project began field work in February 2000 and the first experiments were successfully completed in May. The seismic, seismological, and magnetotelluric experiments presented here, along with the future electromagnetic, gravity, magnetic, geodynamic, and geological studies, will provide the basic geophysical frame for further geoscientific research. DESERT 2000 should also help to address a fundamental question of plate tectonics: How do shear zones work and what controls them?
Eos Transactions American Geophysical Union 12/2000; 81(50):609. DOI:10.1029/EO081i050p00609-01