Granulometric analysis and heavy mineral distribution as proxies were used to investigate the depositional environment and provenance of sediments in the Thengapattanam estuary. The core sample was collected over a one-meter range, accompanied by sub samples at 4 cm intervals, for a total of 25 samples. The bivariate plot was plotted with the data obtained from the study to find the depositional environment, which reveals that the estuary contains beach type sands. The sorting of the sediments ranges from moderately well sorted to well sorted. The presence of beach-type sediments indicates that the estuary is current-dominated, with constant sediment reworking under a micro-tidal regime. The odd samples were chosen from the 25 subsamples to study the heavy mineral variation in order to determine the source rock for the sediments and the heavy mineral potential in Thengapattanam estuary sediments. The average percentage of opaque minerals is 65.5 percent, followed by sillimanite > garnet > augite > kyanite > tourmaline > zircon> monazite. The presence of a higher average percentage of metamorphic minerals (sillimanite, garnet, and kyanite) in the sediments clearly indicates that they derived from high-grade metamorphic rocks.