Crustal nature along the African - Anatolian collision Zone

The African and Anatolian collision zone belt in southwestern Turkey consists of subducting African oceanic crust beneath Anatolian plate. Within the convergent plate margin there are two principle arcs: the Hellenic and Cyprean arcs. The region between the intersection of the Hellenic and Cyprean arcs is named the Isparta Angle(IA). In order to image the crustal variation, we applied joint inversion of receiver functions & surface wave group velocities and h-k stacks to the receiver functions which were obtained from teleseismic events recorded by forty three broad band stations which are combination of nineteen temporary and B.U. KOERI’s permanent stations deployed in the region. Receiver functions are sensitive to compressional and shear wave velocity contrast and vertical travel times while surface wave dispersion curves are sensitive to shear wave velocity averages. Combining these different properties allow us to constrain the lithospheric shear wave velocities. H-K staking leads us to calculate Moho variation along the collision zone. We found that average mid crustal shear velocity is 3.49 km/s however the mid crustal velocities directly above IA is ranging between 3.47 km/s and 3.53 km/s. The average upper mantle P velocity is 7.53 km/s which is a little higher comparing to stations above IA which are varying between 7.08 km/s to 7.30 km/s. Both of the upper mantle P velocities are very low which are comparible with the Pn velocity tomography studies in southwestern Turkey. Moho variations beneath southwestern Turkey indicate a crustal thickness anomaly between the IA and the surrounding regions. The southwestern end of the region has a thinner crust (26 - 28 km) compared to southeastern end of region (30 - 34 km). We have observed that west of the IA has a 38 km thick crust but east of the IA has a crustal thickness of 32 km. In addition to this, south of the IA has 43 km Moho depth thereby suggesting the crust thickens towards the plate boundary (i.e. southward). This research is supported by Bogazici University Research Fund under contract number 07T203.