Petrogenesis and Sr-Nd isotope Geochemistry of Neogene Igneous Rocks in the Goloumak Area, South of Kerman, Iran

The study area is near Goloumak village, 30 km south of Kerman. These rock units consist of acidic rhyolite and dacite, as well as intermediate andesite, basalt, and trachy-andesite. Mafic igneous rocks are alkaline, and intermediate rocks are calc-alkaline to transition range. Volcanic rocks exhibit depletion in Ba, Ti, Nb, and Ta, as well as enrichment in K, Rb, and Th. Basaltic rocks were formed by partial melting of the mantle, based on 87Sr/86Sr and 144Nd/143Nd isotopic ratios. Samples show relative enrichment of 87Sr/86Sr in the mantle array on the Sr-Nd isotope correlation diagram. Mafic rocks are affected by subduction of lithospheric slab or mantle crust metasomatism, as per the comparison of studied samples in the 143Nd/144Nd isotope correlation diagram versus 87Sr/86Sr. Based on Sr-Nd geochronological data, the rocks were formed at 12.5 ±2.0 Ma, corresponding to the Miocene for the basaltic rocks. All samples are in a continental arc margin and post-collision volcanic arc. The magma source is from low to intermediate partial melting of the mantle, as indicated by the LREE/HREE ratio of the mafic and intermediate rocks. LREE enrichment is due to low partial melting of mantle source and magma contamination by crust materials. Basalts show a low melting degree of the mantle for magma formation. Depletion of these rocks of HREE in the source shows garnet in genesis. La and Sm abundance in the studied composition is similar to magma derived from the enriched mantle, comprising about 1-5% of lherzolitic garnet.