Widespread Arkose along the Northern Margin of the Proterozoic Kaladgi Basin, Karnataka: Product of Uplifted Granitic Source or K-metasomatism?

The basal conglomerate and sandstone all along the northern margin of the Proterozojc Kaladgi basm are highly enriched in K-feldspar ranging m size from sand to pebble They are believed to have undergone K-metasomatism by earlier workers However, the present study shows that K-feldspar grains present in these rocks are predominantly temgenous detrital This is indicated by sympathetic relation between constituent quartz and feldspar in size, presence of fresh rounded microcline with or without authigenic overgrowth, typical arkosic texture and geochemistry of the rocks, and their sharp erosional contact with the underlying granitoids An uplifted, restncted source, dominantly consisting of K-rich granitoids and pegmatites to the north of the basin supplied the immature arkosic detritus possibly under humid and warm climatic condition The testimony for the presence of a highly K-rich source weakens the theory of K-metasomatism in the Kaladgi basin as proposed by some earlier authors.