Geochemistry and geodynamic setting of the intrusive units in Chahargonbad, Northeastern of Sirjan- Kerman

The Chahargonbad area is located in Northeast of Sirjan (Kerman Province) and in the Urumieh- Dokhtar magmatic belt. These Oligocene- Miocene intrusive bodies (granite and quartzdiorite porphyry) are intruded into the volcanic rocks (andesite basaltic, trachyandesite and dacite) of Eocene. The main texture of these rocks is porphyritic and granular. Plagioclase, quartz, alkali feldspar, pyroxene and amphibole are the main minerals in these magmatic rocks. Non-equilibrium thermodynamics or magma mixing occurrences of magma have created the sieve texture, oscillatory zoning in plagioclase phenocrysts, opacity of ferromagnesian minerals and various tissues in the rocks. In terms of geochemical characteristics, the rocks studied are calc-alkaline affinity and ranges metaluminous- peraluminous character. All magmatic sequences show similar trace element and REE pattern. Enrichment of LILE (Sr, Rb, Th ) and LREE relative to HFSE and HREE, low Ce / Pb and Nb / U ration and high Ba / Nb reveal that the rocks under study were originated in an active continental margin subduction related tectonic setting. It seems that the lithospheric mantle source beneath the rocks was metasomatized by subducted NeoTethys oceanic lithosphere derived fluids. The negative anomalies of Ti, Nb and P on the spider diagram also confirm this fact.