Mineral chemistry of isotropic gabbro and plagiogranite from the Central Anatolian Ophiolites in the Derinkuyu (Nevşehir, Central Anatolia) region

Authors : Ayşe Orhan, Musa Avni Akçe

Pages : 1505-1517

Doi:10.65206/pajes.63504

View : 121 | Download : 150

Publication Date : 2025-12-17

Article Type : Research Paper

Abstract :The isotropic gabbro and plagiogranite belonging to the Central Anatolian Ophiolites, are exposed as stocks around Derinkuyu (Nevşehir). Plagiogranite, which cuts the isotropic gabbro, contains mafic microgranular enclaves (MME) belonging to these rocks. Gabbro and MME contain plagioclase, clinopyroxene and hornblende minerals. The isotropic gabbros are in hornblende-pyroxene and pyroxene-hornblende/hornblende gabbro compositions. Plagiogranite is composed of quartz, plagioclase and hornblende, and exhibits a tonalite composition. Mineral chemistry analysis results indicate that plagioclases in the gabbro, plagiogranite, and MME have compositions of andesine–bytownite (An47–85), andesine (An38–48), and labradorite–bytownite (An65–75), respectively. Clinopyroxenes (Mg#=0.73–0.84) and hornblendes (Mg#=0.57–0.79) are characterized by their high-Mg contents. Clinopyroxenes, diopside–augite (En37–43Fs12–15Wo42–47), and the hornblendes exhibit compositions of tschermakite–magnesio-hornblende. Clinopyroxene and hornblende data on the discrimination diagrams indicate the presence of an island arc for the source magma. Pyroxene and amphibole thermobarometry suggest that P–T crystallization conditions for clinopyroxene and hornblende 2.60–1.37 kbar 1199–1186°C and 1.95–1.09 kbar; 864–790°C, respectively. These data manifest that the magma of supra-subduction type ophiolite rise towards shallow lithospheric levels (9.2–3.9 km).
Keywords : İzotropik gabro, Plajiyogranit, Mineral kimyası, Dalma-batma zonu üstü, Orta Anadolu

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