Petrography and geochemistry of igneous rocks and Sb and Au mineralization in Sefidsang and Dargiaban areas, southeastern Iran

The Sefidsang and Dargiaban areas are located in the Sistan suture zone. The geological units of the areas are flysch-like rocks, granitoid body, subvolcanic mass, acidic and intermediate dikes and recent deposit. The igneous rocks are granite, micro-granite, granodiorite, granodiorite porphyry and diorite porphyry. The phyllic and propylitic alterations observe with subvolcanic mass and argillic alteration occurs around the mineralized silicic veins. The important mineralization in the area is epithermal type quartz-stibnite veins. The phyllic and propylitic alterations and Cu, Pb and Zn anomalies associated with the subvolcanic rocks in the area are probably indication of a porphyry mineralization system. The Sefidsang granite is an S-type granitoid while the Dargiaban granite is an I-type granitoid and both of them are peraluminous. The igneous rocks are mainly calc-alkaline in magmatic series. Tectonic setting of the igneous rocks in the Dargiaban and Sefidsang is related to convergent zones and similar to those of the subduction, collisional and post-collisional environments. The S-type granite and microgranitic dikes were generated from partial melting of metagreywackes and subvolcanic bodies and intermediate dikes were generated from partial melting of amphibolite. The chondrite-normalized and primitive-normalized diagrams show the igneous rocks are characterized by LREE and LILE enrichment relative to HREE and HFSE. The enrichment of Th, Rb, K and Pb and the depletion of Zr, Ti and Nb are more consistent with melts generated from the metasomatized mantle and lower crust.