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

Abstract

Granitoid pluton in the\rnorth of Golpayegan is located in10 kmnorth of Golpayegan at SanandajSirjan\rzone. Dominant rocks of this region include granite, syenite, and gabbro.\rGranite type is granular with medium to coarse crystals and its mineralogical\rcomposition contains alkali feldspar + quartz + plagioclase + biotite +\rsecondary minerals (opaque + sphene + apatite). Granite rocks have\rcalc-alkaline and metaluminous to\rperaluminous nature, relative enrichment of Rb over Sr, and relative enrichment\rof LILE over HFSE elements. These granites, which are type I, are derived from\rthe melting of metagreywackes and their tectonic setting is of upper\rcontinental crust and post-orogenic setting. Gabbroic type is older than other\rtypes of the pluton and is granular with medium to fine crystal. Mineralogical\rcomposition of these rocks is plagioclase + pyroxene + amphibole + biotite +\rsecondary minerals (opaque). Based on geochemical characteristics of tholeiitic\rand metaluminous nature, relative enrichment of Ba and Sr elements over Rb,\rrelative enrichment of LILE elements over HFSE, negative anomaly of Nb, Ba, and\rTa, and positive anomaly of Pb are observed. Origin of this type is probably\rfrom enriched mantle and in-plane tectonic setting.