Clay input from the red sediments of Visakhapatnam Coast

Abstract

Red sediments of recent age are commonly seen in association with the khondalite hill ranges and also found towards the coast in Visakhapatnam District, Andhra Pradesh, India. These red sediments comprise sand (quartz + heavies), silt and clay. X-ray data on clays reveal that kaolinite (70-94%) and illite (6-22%) are the dominant types in the red sediments. Smectite and chlorite are rare. Variation of clay mineral percentages in the red sediments is due to varying amounts of altered detrital sillimanite and orthoclase derived from the khondalites. The clays from the inner shelf have considerable proportion of illite and kaolinite along Visakhapatnam Coast, which indicates that the fluvial input of clays from the red sediments and lateritic soils is significant.