Geophysical studies for the evaluation of offshore placer deposits and basement configuration

Abstract

The marine geophysical studies carried out on the inner continental shelf of the central west coast of India suggested the offshore extension of onshore placer deposits upto 12 m water depths, and beyond these depths sands are overlainEd. by recent soft clays in further offshore regions. The total magnetic anomaly map reveals smooth and broad wavelength anomalies. Over riding them are a) high frequency short wavelength and low amplitude anomalies, b) short wavelength and large amplitude anomalies and c) medium to long wavelength and large amplitude anomalies. Besides, the anomaly map is characterisEd. by N-S, NW-SE and WNW-ESE trending magnetic lineaments. The presence of high frequency and short wavelength magnetic anomalies is due to the occurrance of different Fe-Ti oxide assemblages. A reasonably good correlation between magnetic anomalies and the percentage of magnetite was established