Constraints on the Petrogenesis of Nosrat-Abad Ophiolite Extrusives, SE Iran

Nosrat-abad ophiolitic extrusive sequence, located in the sistan suture zone, in south eastern iran. the extrusive sequence, containspillow lava, sheet flow and related volcanic-clastic breccias which have undergone low-grade metamorphism. this association showscalc alkaline to tholeiitic affinities. interpretation of the geochemical data and behavior of the elements in different diagrams revealstwo distinct domains in the nosrat-abad ophiolitic extrusive sequence. the sheet flows are depleted in hfse similar to those of ssz.however, the enrichment of the pillow lavas in lile could be attributed to an enriched mantle source or melting of metasomatizedsediments above the subducted slab. it appears that two subduction components (fluids-melt), caused the diversity seen in thechemical composition of the study rocks. the morb to subduction chemical characteristics of the nosrat-abad ophiolitic extrusivesequence could be explained by a shift in the tectonic settings from the mid-ocean ridge to the marginal basin in sistan during thelate cretaceous period.