Geochemistry and Petrogenesis of Intrusive Pluton in North of Golpayegan (Central Part of Sanandaj-Sirjan Zone)

摘要

Granitoid pluton in the north of Golpayegan is located in10 kmnorth of Golpayegan at SanandajSirjan zone. Dominant rocks of this region include granite, syenite, and gabbro. Granite type is granular with medium to coarse crystals and its mineralogical composition contains alkali feldspar + quartz + plagioclase + biotite + secondary minerals (opaque + sphene + apatite). Granite rocks have calc-alkaline and?metaluminous to peraluminous nature, relative enrichment of Rb over Sr, and relative enrichment of LILE over HFSE elements. These granites, which are type I, are derived from the melting of metagreywackes and their tectonic setting is of upper continental crust and post-orogenic setting. Gabbroic type is older than other types of the pluton and is granular with medium to fine crystal. Mineralogical composition of these rocks is plagioclase + pyroxene + amphibole + biotite + secondary minerals (opaque). Based on geochemical characteristics of tholeiitic and metaluminous nature, relative enrichment of Ba and Sr elements over Rb, relative enrichment of LILE elements over HFSE, negative anomaly of Nb, Ba, and Ta, and positive anomaly of Pb are observed. Origin of this type is probably from enriched mantle and in-plane tectonic setting.