Geological and geochemical examination of Ortakoy/Ciftevi (Aksaray) regional metamorphic units and intrusives

The metamorphic rocks consist of the Pre-Cambrian aged Dedetepe Metasedimentary Association and the Paleozoic Navruztepe Metasedimentary Association. The Dedetepe Metasedimentary Association consists of metapelite, calcsilicatic schist/gneisses and marble rocks. Metamorphism has developed in greenschist, amphibolite, upper amphibolite and granulite facies. According to thermo-barometer studies, the regional metamorphism developed in 1.5-3.5kb pressure, 519-832 oC temperature conditions in low pressure/high temperature type. The temperature values of the sharp pressure peaks observed in the temperature pressure diagram, correspond to the temperature values at which the chemical composition change takes place. The Navruztepe Metasedimentary Association was metamorphosed in the Upper Cretaceous and affected by the Alpine deformations. It consists of metapelite, calcsilicatic schist/gneiss and marble rock types. The regional metamorphism developed from greenschist facies to the upper amphibolite facies. The regional metamorphism has developed as in prograde character from the greenschist facies to the upper amphibolite facies. Because of the overlying ophiolites on the CACC metamorphism has been developed due to the crustal thickening in the upper cretaceousIn the peak of metamorphism (84 My) due to melting of metapelite, 83-81 My in aged calcalkaline, peraluminous, crustal-dominated magmas were formed. Felsic peraluminous magmas were formed in the upper continental crust in the same period. The NAG contains magmatic origin andalusite, sillimanite and spessartine type garnet minerals. Primary magmatic andalusite and sillimanite minerals may be formed when the water-saturated peraluminous granite solidus area and alumina silicate stability areas overlap. During the plunge, silicic magmas originating from the metasomatized mantle and formed by melting of the continental crust are placed in the lower crust. Intensive heat transfer into the upper crust of mantle-dominated magmas with mantle contribution result in expansion and partial melting of the upper crust. These fine grained, felsic, peraluminous magmas, cut all older magmatic and metamorphic rocks. Keywords: Dedetepe metasedimentary association, Navruztepe metasedimentary association, CACC, Precambrian.