CORE COMPLEX DEVELOPMENT IN CENTRAL ANATOLIA, TURKEY

Tectonic models for the central Anatolian segment of the Alpine-Himala yan orogen have not considered this region as part of the Aegean exten sional province, We have found evidence, however, for Oligocene-Miocen e extension and exhumation of midcrustal rocks in a metamorphic dome ( Nigde massif) that is structurally and petrologically similar to Mioce ne core complexes >500 km to the west, Strong correspondence in the ti ming and kinematic development of the Menderes (western Turkey) and Ni gde core complexes suggests that extensional tectonics and exhumation of mid-to lower crustal rocks affected much of the eastern Mediterrane an region, In the Nigde massif, supracrustal rocks were buried to dept hs of 16-20 km at high temperatures (>700 degrees C) during contractio n associated with closure of Neo-Tethyan seaways in late Mesozoic-earl y Cenozoic time. Following cooling and decompression to <600 degrees C and <10 km, metasedimentary rocks underwent a second heating event at low pressures during Miocene magmatism that postdated much of the unr oofing of the massif. Development of the Nigde core complex was relate d to exhumation of thickened and thermally weakened continental crust in the upper plate of a north-dipping subduction zone. The partial sub duction of the Tauride carbonate platform in the Eocene resulted in ch oking of the subduction zone, followed by isostatic rebound and exhuma tion of the buoyant platform. This in turn caused a rapid emergence of the upper plate, resulting in erosion of upper-crustal rocks and exhu mation of midcrustal rocks along the northern edge of the Inner Taurid e suture zone, Although northern regions of central Anatolia contain t he same protoliths as the Nigde massif and underwent extensive Tertiar y magmatism, they did not undergo similar extension, suggesting that c ore complex development in south-central Turkey was controlled by the location of thickened and thermally weakened crust adjacent to a sutur e zone.