Provenance studies of Chirala coastal glass sand deposit, east coast of India

Abstract

Mineralogy and chemical and optical properties of Chirala coastal glass sand deposit have been studied. Common hornblends and epidotes are predominant among nonopaque minerals. Euhedral zircons are common. Hornblende and epidote abundance and their chemical and optical properties suggest that Nellore schist belt as the chief source for these sands. Shape and length-breadth ratios of zircons further support the schist belt provenance. Low presence of garnets, sillimanites, rounded zircons and zircon high-elongation frequencies indicate minor contribution from khondalites and charnockites. Major confinement of Gundlkamma river to Dharwarian schistose rocks and Archaean granitic gneisses suggest that the Nellore schist belt might have been actively eroded and contributed the sediment to a large extent to this coastal sand belt.