HR: 1340h
AN: T43A-1090    [Abstracts]
TI: Large Alluvial Fans in the Araba Valley (Jordan) as a Record of Tectonic Deformation of the Southern Dead Sea Fault and Regional Paleoclimates
AU: * Le Beon, M
EM: lebeon@ipgp.jussieu.fr
AF: IPGP, Equipe de Tectonique, 4 Place Jussieu Box 89, Paris cedex 05, 75252, France
AU: Klinger, Y
EM: klinger@ipgp.jussieu.fr
AF: IPGP, Equipe de Tectonique, 4 Place Jussieu Box 89, Paris cedex 05, 75252, France
AU: Al-Qaryouti, M
EM: almah2010@yahoo.com
AF: Natural Resources Authority, Seismology Division, PO Box 7, Amman, 11118, Jordan
AU: Meriaux, A
EM: a.s.meriaux@ncl.ac.uk
AF: University of Newcastle, School of Geography, Politics and Sociology, Claremont Road, Newcastle Upon Tyne, NE1 7RU, United Kingdom
AU: Finkel, R C
EM: finkel1@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550-9234, United States
AU: Mayyas, O
EM: mayyasomar@yahoo.com
AF: Natural Resources Authority, Seismology Division, PO Box 7, Amman, 11118, Jordan
AU: Ryerson, F J
EM: ryerson1@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550-9234, United States
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: IPGP, Equipe de Tectonique, 4 Place Jussieu Box 89, Paris cedex 05, 75252, France
AB: The Dead Sea fault is the 1000 km-long strike-slip fault that accommodates northward motion of Arabia relative to Sinai at a rate of about 5 mm/yr. This study focuses on the southern segment of this fault, the Wadi Araba fault. From the Dead Sea basin to the Gulf of Aqaba, the fault runs along an axial valley, about 20 km wide and 150 km long, bounded to the east by the Jordanian Plateau, reaching 1500 m in elevation and to the west by the Negev Plateau, lower in elevation (500-700 m). The Araba valley is floored with Plio-Quaternary deposits and in particular with large alluvial fans that are cut by the fault and offset relative to their feeding channel. We mapped the valley floor in details and dated some of these fans first to assess their lateral offset and further constrain the slip rate on the fault, and secondly to try to correlate alluvial fan aggradation periods in this arid/semi-arid environment to paleoclimatic variations at the regional and global scales. To identify the possible sources of the large alluvial fans, we analyzed the drainage network and the catchment basins on the valley rims based on SRTM3 topography. Previous study suggested that these fans were Pliocene and underwent offsets of 15 to 30 km. Ages as young as 50 to 350 kyr derived from 10Be exposure dating of 33 samples from the surface of some of these fans indicate that such offsets are very unlikely. Actual offsets have to be smaller. Preliminary reconstructions suggest offsets of 700-1300 m and 1600-2000 m for fans dated at 160 +/- 20 kyr and 330 +/- 22 kyr respectively, and offsets of 2.5-3.5 and 4.4-5.4 km for older fans that have not been dated yet. Consistent ages at different sites suggest simultaneous fan emplacement controlled by some external controlling factor such as climate variations. The correlation between these aggradation episodes and paleoclimatic variations would allow us to draw hypotheses on the age of these older surfaces. These preliminary results provide new constraints on the slip rate of the fault of 4-9 mm/yr since the Middle to Late Pleistocene.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4918 Cosmogenic isotopes (1150)
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: 2007 Fall Meeting