DISTRIBUTION OF HEAVY MINERALS IN PARANGIPETTAI (PORTO-NOVO) BEACH, TAMIL-NADU

Studies on the sediments of Parangipettai (Porto Novo) beach and its s urrounding environments (Vellar river, estuary and nearshore environme nt) reveal that all the environments show texturally different charact ers but similarity in heavy mineral assemblages with varying percentag e of occurrence. The river sediments are coarser (1.48 phi) and modera tely sorted than estuarine sediments which are finer (4.22 phi) and po orly sorted. The beach sediments fall in the size range 2.25 phi to 2. 61 phi in the southern region and 2.56 phi to 2.71 phi in the northern region, and are well to moderately sorted. In nearshore, sediments of the northern region are finer (3.50 phi) and poorly sorted than those of the southern region, which are coarser (2.98 phi) and moderately s orted. Sediments of river, bermcrest and backshore of southern beach a nd bermcrest of northern beach represent near symmetrical skewness and the other remaining beach environments have coarse skewness. Nearshor e and estuarine sediments register fine and strongly fine skewed natur e. In all the environments, the sediments are leptokurtic except those at low water mark of southern region where they are platykurtic. Thes e variations are due to the physicochemical conditions, impact of tida l action and longshore movements on the different environments. Conspi cuous changes are noticed in the individual heavy mineral concentratio ns. Based on the mineral assemblage in the riverine environment, it is inferred that the main sources for these minerals are the rock types present in the catchment area of the river. The enrichment of some hea vy minerals in the beach and nearshore environments suggest that the i ncrement may be due to the addition of these minerals from some other sources like paleo sediments and the present day offshore sediments.