Petrological and source region characteristics of ophiolitic hornblende gabbros from the Aksaray and Kayseri regions,central Anatolian crystalline complex,Turkey |
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| Institution: | 1. ?stanbul Teknik Üniversitesi, Avrasya Yer Bilimleri Enstitüsü, TR-34469 Ayaza?a, ?stanbul, Turkey;2. Institut für Geowissenschaften, Universität Heidelberg, Im Neuenheimer Feld 234-236, 69120 Heidelberg, Germany;3. Dokuz Eylül Üniversitesi, Jeoloji Mühendisli?i Bölümü, T?naztepe Yerle?kesi, Buca, ?zmir, Turkey;4. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;5. Maden Tetkik ve Arama Genel Müdürlü?ü, Jeoloji Etütleri Dairesi, 06800, Çankaya, Ankara, Turkey;6. Department of Earth Sciences, University of Gothenburg, 40530 Gothenburg, Sweden;7. Institut für Geo- und Umweltnaturwissenschaften, Universität Freiburg im Breisgau, Albertstr. 23b, 79104 Freiburg, Germany;8. Institut für Geowissenschaften (Geochemie), Universität Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany |
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| Abstract: | Many Neo-Tethyan ophiolitic bodies are well exposed as thrust-slices in Central Anatolia and are predominantly represented by massive hornblende gabbros, most of which are cut by Supra Subduction Zone (SSZ) plagiogranites. The allochthonous gabbros are distinct from their autochthonous counterparts, with their mineralogy including both igneous hornblende, relict diopside rimmed by replacement hornblende and their chemical composition corresponding mostly to gabbro rather than diorite.The results of major and trace element analyses of forty-two samples, and REE analyses of nine samples, indicate that the hornblende gabbros are SSZ-type and formed from a wet magma by high-degree partial melting of peridotite possibly coupled with contamination by predominantly neighbouring-slab derived fluids within an intra-oceanic back-arc basin. The mafic magmas then underwent high-level fractional crystallization involving titaniferous magnetite, diopside, tschermakite and possibly olivine. Emplacement was followed by extensive ocean–floor metamorphism, which has induced crystallization (or recrystallization) of chlorite, biotite, amphiboles and mobilisation of most of the major elements such as alkali and alkali earth elements, and some LREE. |
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