Textural and Heavy Mineral Distribution in the Alamparai Estuary, Marakkanam, Tamil Nadu, India: Implications for Depositional Environment

Abstract

The study analyzes sediment core samples collected from the Marakkanam estuary near Alamparai Fort, Tamil Nadu, India. The methodology involved core sampling using PVC pipes, subsampling at regular intervals, and subsequent analyses for grain size and heavy mineral distribution. The statistical parameters, including mean, standard deviation, skewness, and kurtosis, were calculated to interpret the depositional environment and transportation mechanisms. The study shows predominance of fine sand, a well to moderately well-sorted sediment texture and a mix of high-energy and low-energy environments. The granulometric analysis indicates mean sediment sizes ranging from 2.24 to 2.62, indicating fine sand prevalence. Standard deviation values ranging between 0.454 and 0.851 suggest moderately well to wellsorted sediments, likely due to wave reworking and alluvial processes. Skewness values from -0.093 to 0.118 indicate a transition from low to high-energy depositional environments. Kurtosis values, ranging from 1.079 to 1.465, classify the sediments as mesokurtic to leptokurtic, reflecting diverse sedimentary environments influenced by longshore currents and fluvial discharge. The frequency distribution curves exhibited bimodal patterns, signifying variable depositional conditions. The trilinear plot of sand-silt-clay fractions confirmed a predominantly sandy deposition environment. Heavy mineral analysis identified the presence of magnetite, ilmenite, zircon, garnet, tourmaline, rutile, and other minerals, with notable zircon (8.75-17.44%), tourmaline (1.98-20.95%), and rutile (8.56-24.49%) concentrations. The ZTR maturity index ranged from 12.58 to 62.71, indicating mature sediments derived from a mix of high-grade, igneous, reworked and low-rank metamorphic rocks. Overall, this research contributes to a better understanding of sedimentary processes and provenance analysis in estuarine environments.