Geochemistry and geochronology of Upper Cretaceous, magnetite series granitoids, Arghash-GhasemAbad, NE Iran

The Arghash gold prospect occurs in the northeastern of Central Iranian domain. It is located in Sabzevar zone, north of Darouneh fault. The exposed rocks in the study area consist of volcanic rocks (andesite and dacite), plutonic rocks mostly diorite, quartz diorite, quartz monzodiorite, granodiorite and granite with minor sedimentary rocks (limestone, sandstone and conglomerate). We focus on a suite of hbl-bearing granitoid rocks consisting of diorite, quartz diorite, quartz monzodiorite and granodiorite. The rocks are metaluminous, medium K, calc-alkaline belonging to Magnetite-series granitoids (I-type). They are related to small numbers of iron bodies and veins. They show low TiO2, P2O5, Nb, La, Zr. Initial 87Sr/86Sr ratios and initial εNd are 0.703755 and +4.74, respectively. U/Pb zircon dating of this suite, using laser inductively coupled plasma mass spectrometry (LA-ICP-MS) yielded mean age of 92.8 ± 0.9 Ma (Turonian). Their chemical compositions as well as initial isotope ratios of 87Sr/87Sr strongly suggest that the original magma formed in a depleted mantle in the subduction zone in Sabzevar Paleoocean.