Microtextures on quartz grains in the Estuary sediments of Gurupura River, Dakshina Kannada district, Karnataka State, West coast, India.

Abstract

The present study focuses on the surface textures of the quartz grains derived from the granitic rocks in a fluvial regime on the west coast of India. The surface microtextures formed during transport due to their stable physical and chemical properties. The surface textures include information about source rock types, transporting force, sedimentary environment and evolution history of the sediment. For this purpose, eight samples were collected and investigated from the Gurupura River estuary of Dakshina Kannada District of Karnataka state west coast in India. The quartz grains show distinct surface textures with unique mechanical, chemical and morphological features. The mechanical features such as conchoidal fractures with arcuate steps indicate that the sand grains were derived from crystalline source rock (i.e., granite) and transported in a high-energy condition. The silica globule, overgrowth, and precipitation marks on the grain surfaces suggest action of chemical processes in a saturated silica environment, which is evident in the upper reaches of the Gurupura River. Surface textures of the quartz grains along the lower reaches of the Gurupura River display an array of mechanical features like a conchoidal fracture, V-shaped marks and impact pits, indicating the impact of mechanical processes. The overall pattern of the surface textures present on the quartz grains suggests moderate to high energy conditions in the Gurupura River.