HR: 0800h
AN: T31B-0475    [Abstracts]
TI: Descending Lithosphere Beneath the SE-Carpathians: An Insight From the Past
AU: * Ismail-Zadeh, A
EM: Alik.Ismail-Zadeh@gpi.uka.de
AF: Geophysical Institute, Karlsruhe University, Hertzstr. 16, Karlsruhe, 76187, Germany
AU: Schubert, G
EM: schubert@ucla.edu
AF: Department of Earth and Space Sciences & Institute of Geophysics and Planetary Physics, UCLA, 3806 Geology Building, 595 Charles Young Drive East, Los Angeles, CA 90095-1, United States
AU: Tsepelev, I
EM: tsepelev@imm.uran.ru
AF: Institute of Mathematics and Mechanics, Russian Academy of Sciences, S. Kovalevskoy ul. 16, Yekaterinburg, 620219, Russian Federation
AU: Korotkii, A
EM: korotkii@imm.uran.ru
AF: Institute of Mathematics and Mechanics, Russian Academy of Sciences, S. Kovalevskoy ul. 16, Yekaterinburg, 620219, Russian Federation
AB: Early Miocene subduction beneath the Carpathian arc and the subsequent gentle continental collision transported cold and dense lithospheric material into the hotter mantle. Mantle heterogeneities imaged by seismic tomography in the SE-Carpathians contain information on the present thermal state of the mantle. We develop a model of the present crustal and mantle temperature beneath the region based on P-wave seismic velocity anomalies and constrained by heat flow data. The present model temperatures are assimilated into the geological past using the information on the history of the regional movement in the Early and Middle Miocene. Prominent thermal states of the lithospheric slab descending in the region are restored from its diffuse present state. In Miocene times the slab geometry clearly shows two portions of the sinking body. The northwest- southeast oriented portion of the body is located in the vicinity of the boundary between the East European and Scythian platforms, and this portion of the sinking body may be a relic of cold lithosphere that has traveled eastward. Another portion has a northeast-southwest orientation and is related to the present descending slab. Above a depth of 60 km the slab had a concave thermal shape, confirming the curvature of the Carpathian arc, and a convex surface below that depth. The slab maintained its convex shape until it split into two parts at a depth of about 220 km. We propose that this change in the slab geometry, which is likely to be preserved until the present, can cause stress localization due to the slab bending and subsequent stress release resulting in large mantle earthquakes in the region.
DE: 3260 Inverse theory
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting