Provenance discrimination and geodynamics analysis of open and island coasts, South East coast of India: Inference on heavy minerals and hydrodynamics

Abstract

AbstractThe coastal sediments contain heavy minerals originating from the offshore and hinterland. We investigated the heavy minerals on different sediment layers of three trenches such as the Dhanushkodi open coast and Manoli island beach in India to identify the pervasiveness and depositional environment of the sediments. The primary objectives of this study are to identify the source rock and to establish the impact of hydrodynamics on the vertical textural trends of heavy mineral distribution. This is in conjunction with sediment deposits. The mineral array consists mainly of ilmenite, sillimanite, garnet, and pyroxene. Both surface and sub‐surface sediments indicate their origin, primarily from metamorphic and igneous rocks. To achieve the goal of the present study, during the low tide time, three shallow‐depth trenches, such as Trench‐1 (Palk Bay Side) and Trench‐2 (Gulf of Mannar side) were dug at Dhanushkodi beach and Trench‐3 excavated at Manoli island beach. The tip of the Dhanushkodi is called Arichalmunai and it is a continuously growing dynamic sandspit whereas Manoli Island has massive reefs with both live and dead corals on its Southern and Northern borders and it includes lagoonal lakes and extensive mudflats. The fine and very fine sand fractions of Trenches 1 and 2 contain a high concentration of ilmenite and sillimanite. Due to high energy sorting by the wave action, Trench 3 contains relatively high concentrations of mineral assemblages with very fine sand particles. Provenance relationships are established based on the mineralogical contents of trench sediments, and the observation of down‐core variation of heavy mineral assemblages implies that they were sourced from various igneous and metamorphic rocks of nearby land areas, such as the East and West coasts of India, as well as the Sri Lankan coast.