A petrographic study of Precambrian quartzites from Goa coast

Abstract

A petrographic and heavy minerals study of quartzites along the Goa Coast, India has been undertaken to decipher their sediment history. The quartzite outcrops exhibit well preserved primary sedimentary structures like current bedding and ripple marks. From the petrographic studies, the present quartzites are classified as micaceous and sericitic arkosic wacke. The composition of earlier sandstones prior to the metamorphism is inferred as clayey sandstone arkosic wacke. The heavy minerals like tourmaline, topaz, zircon, rutile, fluorite, apatite and hornblende lead to a source of acidic composition. The introduction of tourmaline and fluorite in the wacke, the grade of metamorphism and the source of the wacke have been discussed