Keban metamorfikleri (Pertek, Tunceli) içerisindeki amfibolitlerin jeokimyasal ve petrolojik özellikleri

The Keban Metamorphics are exposed within the Upper Nappe of the Nappe zone in the Southeast Anatolian Orohenic Belt together with the Malatya and the Binboğa metamorphics. The unit was formed as a result of metamorphism of the sedimantary rocks precipated during Middle Devonian -Creataceous and magmatic rocks formed in various phases during Cretaceous. The exposers of the unit around Pertek (Tunceli) includes amphibolite and amphibole schists of which have a protolith of within plate alkalen basalts features below the recrystallized limestones and marble. The amphibole schists show nematoblastic texture and consist of hornblende+plagioclase+biotite+pyroxene+quartz+sphene +opaque minerals. The amphibolites shows granoblastic texture and includes hornblende+plagioclase+quartz+sphene+opaque minerals. The amphiboles show ferrotschermakite chemical composition in schists, whereas tschermakite chemical composition in amphibolites. The plagioclases are andesine and oligoclase in composition. The amphibolite and amphibole schists of the Keban metamorphics yields in 2-7 kbar pressure and 475-500C temperature. The zircon U-Pb age of 79.94±1.7 Ma from the amphibole schists and 89.83±1.03 Ma from the amphibolites are evaluated as the age of the metamorphism. The age of the granitoids cutting the metamorphic rocks is 78.1±0.9 Ma. These results show that the Keban metamorphics was underwent an amphibole facies metamorphism during the north dipping subduction where the unit was active continental margin during late Cretaceous.