Geology of continental shelf off Point Calimere, Tamil Nadu

摘要

The present work was carried out to understand the morphological features of the seabed through bathymetry, shallow seismic and magnetic surveys off northeast of Point Calimere, Tamil Nadu.The trend of bathymetric contours is in configuration with shoreline alignment, i.e., N-S to NNW-SSE direction. The inner-shelf is demarcated upto 19 m of water depth, the middle-shelf between 19 and 30 m and the outer shelf extends between 25 and 128 m of water depth and zone of continental shelf is so wide that shelf break could not be picked up in the area of study.The shallow seismic survey delineated wedge-shaped sediment in the inner shelf zone. A fault running in NNW-SSE direction around 25 m of isobath acts as divider between middle and outer shelf. In the mid-shelf region a basin-like feature is recorded parallel to coast. The analysis of magnetic data indicates that the area has been traversed by lineaments in different directions. These planes divide the area into several blocks. Depth of magnetic basement varies from 0.5 km to 2.6 km.The sedimentological studies indicate that the seabed sediments are classified into sand, clayey silt and silty sand in order of abundance. The sediments of the inner shelf are terrigenous-dominated and that of outer shelf is relict sand.