HR: 0800h
AN: S51E-1050    [Abstracts]
TI: Crustal and Upper--Mantle Structure of Eastern Turkey From S--Wave Receiver Functions
AU: * Angus, D A
EM: angus@nmsu.edu
AF: Department of Physics, New Mexico State University, Las Cruces, NM 88003-8001 United States
AU: Wilson, D
EM: davew@speer.geo.utexas.edu
AF: Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712-0254 United States
AU: Sandvol, E
EM: sandvole@missouri.edu
AF: Department of Geological Sciences, University of Missouri, Columbia, MO 65211-1380 United States
AU: Ni, J F
EM: jni@nmsu.edu
AF: Department of Physics, New Mexico State University, Las Cruces, NM 88003-8001 United States
AB: Eastern Turkey is a region dominated by the early stages of continent--continent collision. The high topography (~ 2 km) of this young plateau has resulted from the convergence of the Arabian, Anatolian and Eurasian plates since the Middle Miocene, where the supporting mechanism of the plateau has been the focus of debate. Evidence suggests that a northward subducted oceanic lithosphere steepened and detached from the continental lithosphere of the Bitlis--Poturge Massif, which brought the asthenosphere in contact with the crust or a thinned lithosphere of the Eastern Anatolian accretionary complex (EAAC). The upwelling of hot asthenosphere has resulted in low upper--mantle velocities, a high free--air gravity anomaly and basaltic volcanism. We present S--wave receiver function profiles of the crust and upper mantle seismic structure of Eastern Turkey as well as portions of the Arabian Shield and the Iranian Plateau. The lithospheric thickness for the Arabian Shield and the Iranian Plateau is observed to be on the order of 100 and 125 km, respectively. Our results also indicate the lithosphere below the EAAC (where new continent is being created) is between ~ 60 and 70 km thick, while the crust is ~ 45 km thick. Hence, the 2 km high topography is partially supported by the hot and buoyant asthenospheric mantle. The Moho depth ranges between 30 and 45 km for Eastern Turkey, where it is observed to deepen from south to north and west to east within the Anatolian Plateau, and lie relatively flat within the EAAC. The Moho characteristic from dipping to sub--horizontal is delineated by the NAFZ and EAFZ. This transition possibly reflects the differing deformation styles within these units; from extrusion and little internal deformation in the west (Anatolian Plateau) to translational movement and transcompressional deformation in the east (EAAC). We also observe an upper--crustal discontinuity at approximately 10 km depth and isolated regions of crustal low--velocity zones (CLVZ) at approximately 20 km depth and lateral extent of about 100 km. The CLVZs are most probably related to Quaternary volcanism.
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere (1236)
DE: 8100 TECTONOPHYSICS
DE: 8110 Continental tectonics: general (0905)
SC: Seismology [S]
MN: Fall Meeting 2005