Seismic images of crustal variations beneath the East Anatolian Plateau (Turkey) from teleseismic receiver functions
Published:January 01, 2010
A. Arda Özacar, George Zandt, Hersh Gilbert, Susan L. Beck, 2010. "Seismic images of crustal variations beneath the East Anatolian Plateau (Turkey) from teleseismic receiver functions", Sedimentary Basin Tectonics from the Black Sea and Caucasus to the Arabian Platform, M. Sosson, N. Kaymakci, R. A. Stephenson, F. Bergerat, V. Starostenko
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We used teleseismic P-wave receiver functions recorded by the Eastern Turkey Seismic Experiment to determine the crustal structure across an active continent–continent collision zone. Moho depth and Vp/Vs variations in the region are mapped by incorporating crustal multiples and later two-dimsional (2-D) seismic profiles are produced using a common conversion point technique with our crustal Vp/Vs estimates. Moho depths do not correlate with surface topography and reveal a relatively thin crust consistent with the high plateau being supported by hot asthenosphere near the base of the crust. Under the Arabian plate, the crust is thinnest (c. 35 km) and exhibits high Vp/Vs (≥1.8) associated with mafic compositions. In the east, the crust gradually becomes thicker towards the north and exceeds 45 km in the northeastern side whereas in the west, the crust thickens sharply near the Bitlis suture and displays pronounced Moho topography within the Anatolian plate that suggests the presence of multiple fragments. Vp/Vs variations show an anomalously high Vp/Vs corridor (≥1.85) along the North Anatolian Fault and near the youngest volcanic units (c. 3 Ma) and support the presence of partial melt. This corridor is spatially limited from both north and south by low Vp/Vs regions implying a change in crustal composition. Near the Bitlis suture, a layered Vp/Vs model points to the source of low Vp/Vs in the lower crust that may be rich in quartz. Furthermore, the seismic profiles indicate a prominent low velocity zone in the lower crust across a large area beneath the plateau that may act as a decoupling zone between the crust and upper mantle.
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Sedimentary Basin Tectonics from the Black Sea and Caucasus to the Arabian Platform
This wide area of the Alpine–Himalayan belt evolved through a series of tectonic events related to the opening and closure of the Tethys Ocean. In doing so it produced the largest mountain belt of the world, which extends from the Atlantic to the Pacific oceans. The basins associated with this belt contain invaluable information related to mountain building processes and are the locus of rich hydrocarbon accumulations. However, knowledge about the geological evolution of the region is limited compared to what they offer. This has been mainly due to the difficulty and inaccessibility of cross-country studies. This Special Publication is dedicated to the part of the Alpine–Himalayan belt running from Bulgaria to Armenia, and from Ukraine to the Arabian Platform. It includes twenty multidisciplinary studies covering topics in structural geology/tectonics; geophysics; geochemistry; palaeontology; petrography; sedimentology; stratigraphy; and subsidence and lithospheric modelling. This volume reports results obtained during the MEBE (Middle East Basin Evolution) Programme and related projects in the circum Black Sea and peri-Arabian regions.