Clinopyroxene Compositions of the Isotropic Gabbros From the Sarıkaraman Ophiolite: New Evidence on Supra-Subduction Zone Type Magma Genesis in Central Anatolia

Authors: KENAN M. YALINIZ, M. CEMAL GÖNCÜOĞLU

Abstract: The Sarıkaraman Ophiolite is one of the least dismembered ophiolitic units of the allochthonous Central Anatolian Ophiolites, which retains its recognizable pseudostratigraphy. The Sarıkaraman Ophiolite is represented in its lowermost part by isotropic gabbros. Within the isotropic gabbro sequence, clinopyroxenes are observed as small, colorless relicts with a cloudy appearance. In most of the samples, they are completely replaced by a successive generation of green to brown amphiboles. Clinopyroxenes display diopsitic to augitic compositions within the range of En 45 Fs 5 Wo 49 to En 50 Fs 9 Wo 41 . They are Ca-rich and Na-poor (Na 2 O<0.55) and characterized by high-Mg (Mg#= 81.4-91.19) and low-Ti (<0.68 wt %). The occurrence of a high-Mg and low-Ti magma constrain the formation of the Sarıkaraman ophiolitic gabbro in a supra-subduction zone environment. The clinopyroxenes of the Middle Turonian-Lower Campanian Sarıkaraman Ophiolite have similar chemical com- positions to those of the other supra-subduction zone-type Eastern Mediterranean ophiolites (e.g., Troodos, Varinous, Pindos and Oman ophiolites) that show island-arc affinity.

Keywords: Clinopyroxene, Ophiolite, Chemistry, Turkey

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