Grain size analysis and characterization of sedimentary environment along Thiruchendur coast, Tamilnadu, India

Abstract

Thiruchendur coast of southern Tamilnadu, India has been studied for grain-size spectrum and textural parameters namely mean, sorting, skewness and kurtosis. The grainsize spectrum shows a marked variation in the berm, high tide line (HTL) and low tide line (LTL) stretches. Variation in energy condition is controlled by geomorphology of the sedimentary beach. Textural pattern shows complicated profile as a result of the fluctuation in the physicochemical conditions due to the sediments and the marine interactions. Abundance of the medium sand to fine sand shows the prevalence of comparatively moderate- to low-energy condition in the Thiruchendur area. Linear discriminate function of the samples indicates an aeolian, shallow marine deposition environment and less influence of fluvial (7 %) process. CM diagram (C 0 one percentile in microns M 0 medium in microns) of Thiruchendur coast sediments suggests that deposition takes place by (1) rolling, (2) bottom suspension, (3) graded suspension. This is also supported by the wave energy in different stretches in beach line and also tractive current figure implies the sediments disturbed by the tractive and turbidity currents. The heavy minerals are concentrated in the berm (average, 11.8 %) and high tide line (average, 11.2 %) because of highenergy condition and aeolian action. Quartz microtextures show the mechanical action due to high-energy condition in Manapad and Kuduthalai areas, the chemical action because of to low-energy condition along the Thiruchendur, Kallamozhi areas.