EXTENSIONAL STRUCTURES OF THE MENDERES CORE COMPLEX, WESTERN TURKEY

The Cenozoic extension has produced a number of metamorphic core complexes in the Aegean extended terrain. One of these complexes is Menderes core complex (MCC) located on the eastern side of Aegean region. The most fundamental structural features in the MCC are Cenozoic extensional shear zones and detachment faults. Rock of these zones show well-developed mylonitic foliation, lineation, boudinage and foldings. Mylonitic foliation is commonly defined by recrystallized quartz and micas. Linear structures are characterized by stretching lineations, mineral lineations and fold hinge lineations. Simav and Alasehir shear zones are deformed brittely at depth first and the brittle deformation was overprinted over the ductile deformation as the massif was exhumed. Our field-oriented studies, microstructural analysis and available isotopic age determinations suggest that extensional tectonics within the MCC cover a wide time span (Oligocene to Recent) and that display long- and multi-stage exhumation. The transport direction for earlier stage exhumation event, occurred along the north-dipping main breakaway fault in Gökova basin, and Kayabükü and Simav shear zones, is the-top-the-N-NE sense of shear. This exhumation event was followed by later exhumation event accommodated by Büyük Menderes and Alasehir detachments without significant hiatus. In this stage of exhumation, the-top-to-the-N-NE extensional fabric was overprinted by top-to-the-S-SW extensional deformation structures in the southern half of the central MCC. The most common kinematic indicators, the meso- and micro scale ductile and brittle structures, are asymmetric porphyroclasts, S-C and –C’ fabric, mica fish, oblique foliation and systematic fractures.