Volume No. 1 (2013), Issue No. 4 (August) ISSN (Online): 2320-513X International Journal of Basic and Life Sciences www.ijmds.com 14 Textural Impact on the Sediments along the inner Continental shelf off Pondicherry and Cuddalore, Southeast Coast of India K. Sanjai Gandhi Research Scholar, Department of Geology, University of Madras, Maraimalai campus, Chennai, India V. Rammohan Professor, Department of Geology, University of Madras, Maraimalai campus, Chennai, India S. Srinivasalu Associate Professor, Department of Geology, Anna University, Guindy campus, Chennai, India Abstract The sediment deposited by the 26 th December 2004 Tsunami along the Tamil Nadu coast from Pondycherry to Cuddalore was sampled within a few weeks of the tsunami. The surface sediment in the tsunami inundated zone revealed significant salinity at that time. The sediment types varies from medium sand to fine sand, The salts and metals reveal high correlation to each other. For various metals, the geoaccumulation index has been calculated as a criterion to assess if their concentrations represent contamination levels or can be considered as background levels. The results show that metals concentrations in sediments can be considered near the background levels found in the study area. Using multivariate statistical analysis, we evaluate the possibility to distinguish the sampling stations, in relation to their geographical position. This study clearly indicates a serious environmental hazard exists in this region and there is a risk of migration of contaminants into groundwater and food chain. Samples of Surface sediments and waters were collected from the inner shelf extending from Pondicherry to Cuddalore over a 35 km coast length to understand the tsunamigenic process, and its impact on the near shore region. The geochemistry of the sediments of are examined along with samples collected during August, 2004 from Pondicherry – Cuddalore area to understand the changes that have taken place consequent to the tsunami. To assess the changes in the near shore environment a study of the characteristics of the sediments were examined and compared with the sediment characteristics prior to the tsunami. Comparison of the sand content of the near shore region off Pondicherry – Cuddalore area shows that the sand content has increased considerably in the near shore region of the shelf and on the other hand the sand content shows a decrease in the deeper depths investigated. The highest sand content is observed off Cuddalore which may be attributed to the input from the Ponnaiyar and Gadilam rivers that confluence in the area. Analysis of calcium carbonate content of the sediments collected an increase seaward as it is inversely proportional to sand content. However, decrease of calcium carbonate is found in the shore stations as the sand content in these areas have increased. It is possible that the calcium carbonate as it has less density might have been transported to the land and to support the idea on could observe considerable amount of shell debris in the beach. The post-tsunami sediments contain higher organin matter (OM) off the Pondicherry coast this may be due to the contribution from the domestic effluents transported from the Pondicherry town. Sand fraction with low silt and clay and this could be a contributing factor for the low concentration of the metals in the area investigated. Examination of temporal variation of the sediments in the Pondicherry – Cuddalore region, shows that the pattern is smoothened in the post-tsunami sediments as a result of agitation of the seafloor consequent to the advancing of the tsunami and backwash. Enrichment of iron is noticed may be attributed to the influence of heavy minerals. In many locations on the coastal zone, enrichment of heavy minerals are seen in the beaches. Key words: Tsunami Surface sediments, Pondicherry and Cuddalore, South east coast of India.