Petrology, geochemistry and geodynamic importance of volcanic units in the Robat ophiolites, Shahr-e-Babak (Kerman province)

The Robat ophiolite complex is located along the Nain- Baft fault and at the western margin of the Lut block. The volcanic rocks in the Robat ophiolites consisting of pillow lavas, lava flows and massive units that are classified as andesi-basalts, andesites, trachy-andesites, dacites and rhyolites. Geochemical results show that these rocks have tholeitic and calc -alkaline affinities and reside in supra-subduction related arc settings in tectonic discrimination diagrams. Studying the geochemical behavior of elements by using various petrogenetic diagrams suggest the occurrence of two different mantle sources for Robat volcanic rocks: 1) a mantle source which was affected slightly to moderately by slab fluids and/or melts and is responsible for arc island tholeitic series, 2) a mantle source which is highly effected by melts derived from melting of sediments associated with subducting slab, and is responsible for calc -alkaline series. It seems that the emplacement of the volcanic rocks in the Robat ophiolitic sequence was probably the result of processes related to the initial subduction process, upwelling and partial melting of subducted sediment and asthenospheric fluids in the source, along with differentiation and melting of portions of the oceanic crust.