LITHOSPHERIC STRUCTURE OF THE ARABIAN AND EURASIAN COLLISION ZONE IN EASTERN TURKEY FROM S-WAVE RECEIVER FUNCTIONS

Abstract

Crustal and upper-mantle seismic discontinuities beneath eastern Turkey are imaged using teleseismic S-to-P converted phases. Three crustal phases are observed: the Moho with depth ranging between 30 and 55 km, indicating variable tectonic regimes within this continental collision zone; an upper-crustal discontinuity at approximately 10 km depth; and various crustal low-velocity zones, possibly associated with recent Quaternary volcanism. Imaging of the upper mantle is complicated by the 3-D geometry of the region, in particular due to the Bitlis-Zagros suture zone. However, several upper-mantle S-to-P converted phase are identified as being the signature of the lithosphere-asthenosphere boundary (LAB). The inferred LAB for the Eastern Anatolian Accretionary Complex indicates that eastern Turkey has an anomalously thin (between ~60 and 80 km) lithosphere which is consistent with an oceanic slab detachment model. The observed LAB phases for the Arabian shield and Iranian plateau indicate that lithospheric thickness for these stable regions is on the order of 100 to 125 km thick, which is typical of continental margins. © 2006 The Authors Journal compilation © 2006 RAS.