HR: 0800h
AN: T11D-0409    [Abstracts]
TI: The Messinian Evaporites in the Levantine Basin
AU: Netzeband, G L
EM: netzeband@dkrz.de
AF: Institute of Geophysics, University of Hamburg, Bundesstr. 55, Hamburg, 20146 Germany
AU: * Huebscher, C P
EM: huebscher@dkrz.de
AF: Institute of Geophysics, University of Hamburg, Bundesstr. 55, Hamburg, 20146 Germany
AU: Gajewski, D
EM: gajewski@dkrz.de
AF: Institute of Geophysics, University of Hamburg, Bundesstr. 55, Hamburg, 20146 Germany
AB: The Levantine Basin in the Southeastern Mediterranean Sea is a world class site for studying the initial stages of salt tectonics. The deposition of the evaporites took place during the Messinian salinity crisis 5.9 - 5.3 Ma ago. About 2 km of halite, gypsum and anhydrite were deposited in the basin. The evaporite body is not uniformly transparent, but marked by several internal reflections. Between these reflections, the evaporites appear transparent. This leads to the conclusion that they represent different cycles of evaporite deposition, each with a succession of upper and lower evaporites. All of these internal reflections are differently folded and distorted, proving that the deformation was syn-depositional. Thrust angles of up to 14 degrees are observed. The sediment cover on top mainly originates from Nile sediments. Hence, the sediment thickness varies between about 400 m in the northern part of the basin over 1000 m near the shelf off Israel and Lebanon to almost 3000 m near the Nile Delta. A simple 1-D backstripping analysis reveals that this immense difference in sediment load is the driving force for salt migration. Hence, the main direction of salt movement is SSW-NNE, there has been no movement in E-W direction. The superposition of 'thin-skinned' tectonics and 'thick-skinned' tectonics is clearly visible in the Levantine Basin: At the Cyprus Arc, the convergence zone of Africa and Eurasia, deep-rooted compression heavily deformed the base of the salt, whereas at the Eratosthenes Seamount mainly superficial compression affecting the Post-Messinian sediments and the top of the evaporites is observed. Shear zones and fault lines, which have been postulated in the Levantine Basin, follow two trends: SSW-NNE and NW-SE. They add a component of 'thick-skinned' transpression to the generally 'thin-skinned' compressional regime in the basin. These deep-rooted fault lines represent zones of weakness, above which salt-related pop-up structures and thrust faults develop.
DE: 8104 Continental margins: convergent
DE: 8108 Continental tectonics: compressional
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8169 Sedimentary basin processes
SC: Tectonophysics [T]
MN: Fall Meeting 2005