Compositional and Geochemical Signatures of Oligocene volcanoclastic sandstones of Abbasabad-Kahak area, NE Iran: Implications for provenance relations and paleogeography

Abstract

Petrography and geochemistry of sandstone for the lower Oligocene volcanic-related sandstones of Abbasabad-Kahak area, NE Iran, are detected to decipher provenance, tectonic setting and paleo-weathering of source areas. Lower Oligocene sandstones are grey in colour and host copper mineralization as bedded and lenticular, vein-veinlets and disseminated textures and structures. Texturally, sandstones are medium to coarse grained, moderately to poorly sorted and compositionally have abundance of volcanic lithic fragments. Sandstones are lithofeldspathic to feldspatholithic, leading to a provenance from the progressive dismantling of a magmatic arc. Geochemical signatures suggest a derivation from mafic-to-intermediate volcanic sources. CIA values (56–61 with the average of 57) indicate a low level of chemical weathering in source areas, which may reflect arid to semi-arid climatic conditions in source terrains. These sandstones, deposited in a remnant backarc basin, are the results of the post-Eocene extensional stage of a dismantling magmatic arc.