Offshore Extension of the Structural Element at Udipi, Confirmation from Marine Magnetics

Abstract

The isomagnetic anomaly map (1: 3,00,000) reflects conspicuous E-W, NW-SE, WNW-ESE, NE-SW and N-S trends which are similar to that of the onshore Dharwar trend. The map also shows short wavelength, high amplitude anomalies off Coondapoor, broad wavelength anomalies off Mangalore and relatively smooth zone further south to Kasaragod. A prominent WNW-ESE structural element (fault) south off Coondapoor is observed in the three eastern profiles (A-A', B-B' and C-C') which was not reflected in the western profiles (D-D', E-E' and F-F') and this can be extrapolated towards the adjacent coast to join an onshore structural element trending in the same direction. This structural element perhaps represents the offshore extension of the fault at Udipi. The broad wavelength anomalies off Mangalore and Malpe may be generated from sources composed at a depth of around 4 km. The observed magnetic smooth zone south off Mangalore is interpreted in terms of insignificant magnetization contrast in the crystalline basement.