MINERALOGICAL CHARACTERISTICS OF THE AMPHIBOLES FROM CRETACEOUS HORNBLENDE GABBRO OF CENTRAL ANATOLIAN OPHIOLITES, DEVEDAMI/AKSARAY AREA, CENTRAL TURKEY

Abstract

In Devedamı area, Central Anatolian Ophiolites (CAO) are represented by Late Cretaceous massive hornblende gabbroic rocks, which contain hornblende, plagioclase and clinopyroxene in a holocrystalline granular and rarely holocrystalline porphyric texture. Mineralogical analyses show that the brown-green amphiboles are magnesiohornblende in composition. Geothermobarometer calculation suggests that the amphibole was possibly crystallized from a water-rich magma (H2O melt: ~5.41 wt.%), with ∆NNO 1.57-2.34 and logfO2 (-13.59 -13) in ~2.5 km oceanic depth .