Integrated Geophysical Study Off Goa, Central West Coast Of India

The western Indian offshore is characterized by several tectonic elements along its entire length. The prominent ones include the Laxmi Ridge (LR) and the Chagos-Laccadive Ridge (CLR) in the north and south, respectively. These ridges divide the western offshore into the western and eastern Arabian Basins, and have been attributed different evolution mechanisms and crustal types. The Goa offshore (14.7 -15.7 degrees N and 70.3 -71.2 degrees E), between the Laxmi Basin in the north and the CLR complex in the south, off the Central West Coast of India, may hold some clues of the connection/boundary between these diverse crustal domains. About 1550 km of gravity, magnetic, single and multibeam bathymetry data has been analyzed in the present study. The results indicate that the water depth varies between 2450 and 4000 m, and the region is characterized by similar to NW-SE to NNW-SSE trending broad wavelength gravity and magnetic anomalies. Forward modeling of the geophysical data under seismic constraints highlight the presence of similar to 6-9 km thick oceanic crust, while towards the east, the crust is thicker and contaminated with Deccan volcanic intrusions. Magnetic data analysis suggests that the age of the underlying oceanic crust varies between 63.9 and 68.7 Ma (Chron 29n to 31r).The present study indicates that the Goa offshore is an integral part of the Laxmi Basin. As such it is interpreted that a tectonic boundary between the oceanic crust in the north and the CLR complex in the south lies south of the study area. Further, this boundary may be associated with the Vengurla Arch and may have restricted the southward propagation of the Laxmi Basin spreading ridge.