Quartz surface microtextural studies of Cauvery River sediments, Tamil Nadu, India

Abstract

The spatially distributed sand samples of the Cauvery River sediments in Tamil Nadu were investigated with respect to their surface microtextural features in north-east (NE) and south-west (SW) monsoon rainfall seasons. The quartz grains show distinct surface microtextures with unique mechanical, chemical and morphological features with respect to the sedimentation process. The mechanical features like conchoidal fractures with arcuate steps indicate that the sand grains were derived from crystalline rocks. The abundance of angular grains supports that the grains were transported long distance by fluvial process. The silica globule, overgrowth and precipitation marks on the grain surfaces decipher the chemical process in silica saturated environment. Similarly, the solution pits in sand grains near Poombugar indicate the influence of sea water. The chatter mark trails suggest the wet tropical climate. The abundance of mechanical features and smooth surface microtextures suggest that the grains were transported in high-energy conditions. The NE monsoon sediments are coarse grained to medium grained and SW monsoon sediments are medium to fine sand size, which are attributed to the high and moderate energy conditions, respectively.