Supra-Subduction Zone Ophiolites of Central Anatolia: Geochemical Evidence from the Sarikaraman Ophiolite, Aksaray, Turkey

M. K. Yaliniz, P. A. Floyd and M. C. Göncüoğlu
Dept. of Geological Engineering, Middle East Technical University, Ankara, Turkey
Department of Earth Sciences, University of Keele, Staffordshire, ST5 5BG, U.K.
Department of Geological Engineering, Middle East Technical University, Ankara, Turkey

Abstract: The Central Anatolian Crystalline Complex (CACC), situated between the northern and southern oceanic strands of Neotethys, contain a number of little-studied ophiolitic bodies of late Cretaceous age that have a bearing on the Mesozoic development of this region. The pillow lavas and sheeted dykes of the Sarikaraman Ophiolite were originally a comagmatic differentiated series of vesicular, aphyric and olivine-poor, plagioclase—clinopyroxene phyric tholeiites, but now exhibit greenschist facies assemblages. A set of late dolerite dykes cross-cutting the whole volcanic sequence are more chemically evolved and were probably derived from a different source. Relative to N-MORB the lavas and dykes are enriched in some LIL elements (K, Rb, Cs, U, Th and Sr) and depleted in HFS elements (Nb, Ta, Hf, Zr, Ti and Y) and light REE. In terms of immobile elements the ophiolitic basalts have the broad chemical characteristics of island are tholeiites that were formed in a supra-subduction zone setting, whereas the late dykes are more akin to N-MORB. In this respect the Sarikaraman Ophiolite is similar to other ophiolites found in the eastern Mediterranean region and emphasizes the preservation of this particular environment in the CACC. If all the Central Anatolian Ophiolites (of which the Sarikaraman Ophiolite is one example) were derived via southward thrusting from the Vardar-Izmir-Ankara-Erzincan Ocean branch to the north, age relationships suggest that this segment of ocean crust was relatively short-lived before obduction onto the CACC.

Keywords: ophiolites • supra-subduction zone • geochemical evidence • Central Anatolia • Turkey

Mineralogical Magazine; October 1996 v. 60; no. 402; p. 697-710; DOI: 10.1180/minmag.1996.060.402.01
© 1996, The Mineralogical Society
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