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Petrogenesis of gabbroic rocks from the Malayer plutonic complex (Sanandaj-Sirjan zone, west Iran)

Amir Esna Ashari, Massimo Tiepolo

Abstract


The Sanandaj-Sirjan zone (SSZ), extending from northwest to southeast of Iran, is a continental arc developed during subduction of the Neotethyan oceanic crust below the Central Iran microcontinent. The Malayer plutonic complex (MPC) is located in northern half of the SSZ and is characterized by the occurrence of subduction-related ultramafic to felsic rocks. Calculated composition of the melts in equilibrium with minerals from the gabbroic rocks were compared with the literature whole rock data from the MPC and from other neighboring complexes in the SSZ. The results showed that the parental melts at the origin of the gabbroic rocks is a high Mg andesite (HMA) with a sanukitoid geochemical affinity originated by a melt-rock reaction process between a felsic melt and ultramafic rocks. This study further confirms that although ultramafic rocks are not commonly found associated with subduction-related rocks, their petrogenetic role cannot be underestimated.


Keywords


boninite; sanukitoid; gabbro genesis; melt-rock interaction; Sanandaj-Sirjan zone

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0369-8963 - ISSN ONLINE: 2239-1002