STRUCTURAL AND METAMORPHIC EVOLUTION OF THE ERICEK AREA (SE TURKEY) NEAR THE SÜRGÜ FAULT, NORTH OF BERIT MOUNTAIN, IN CONTEXT OF EURASIA-AFRICA COLLISION

Abstract

In the current setting of SE-Anatolian escape tectonics, the Ericek area, N of Berit mountain, is integrated by tectonic stacking of units near a palaeo-suture zone. These units record a history of oceanic closure, back-arc rifting and plate collision. Late Cretaceous to Eocene magmatism and intermediate-to-high temperature metamorphism is found to intrude into the complex nappe-stacking system found at Berit Mountain.In addition, Plio-Quaternary Sürgü Fault Zone (SFZ) is a localized strike-slip system that cuts the study area as a small branch of larger-scale escape tectonics. Both the study of intrusions and their relationship to metapelitic and calcitic host rocks and the study of units affected by later faulting can give insight into the tectono-metamorphic evolution of the study area. The following study employs petrological and microstructural tools, such as light microscopy and SEM, to explore the aforementioned two issues. Metapelites are confirmed to be affected by a contact metamorphic aureole of the intrusive batholiths, showing biotite, cordierite (syn-foliation) and andalusite (post-foliation) as index minerals. The timing of events and metamorphic growth correlate to late-to-post orogenic intrusive activity. No clear isograds have been traced, but changes in mineral composition within the contact aureole are attributed to thermal metamorphism and chemical availability. In addition, granitic samples from the Berit group some km apart on either side of the study area have different characteristics, both in nature of the granitic batholith and of the surrounding country rock. This could be attributed to different timing of intrusion. On the other hand,studied fault rocks confirm the action of the more modern strike-slip Sürgü Fault Zone (SFZ) on Jurassic, Eocene and Miocene lithologies, indicating its later occurrence. Pseudotachylite veins have been searched for in fault rocks, but grain-size reduction has proven to be the main mechanism of deformation in place of frictional melting. However, available microstructural evidence is still insufficient for confirmation.