SIGNALS OF BARREMIAN (116-MA) OR YOUNGER OCEANIC-CRUST BENEATH THE BAY OF BENGAL ALONG 14-DEGREES-N LATITUDE BETWEEN 81-DEGREES-E AND 93-DEGREES-E

The magnetic profile along 14 degrees N in the Bay of Bengal, collecte d on board R.V. Samudra Manthan of the Geological Survey of India was procesed in the frequency domain. From the energy spectrum, the comput ed average thickness of sediment cover conies to 6 km and the average geothermal gradient to 20 degrees C/km. Analysis of the vertical magne tic structure by a singular point method yields a 'pseudosection' mark ed by four clear domains. The Eighty Five East ridge appears as a pair of strong magnetic features between 84 degrees E and 86 degrees E, wh ereas the Ninety East Ridge shows up as a narrow, well defined, vertic al magnetic feature at 92 degrees E. By match filtering technique, we extracted a magnetic profile of the basement which displays a number o f polarity reversals. The reversals between 81 degrees E and 84 degree s E appear to be records of Barremian or younger seafloor spreading, i nstead of M series reversals between 132 and 119 Ma. This is based on the fact that neither the basic lavas nor the marine sediments so far obtained from the basin margin are older than Barremian (116 Ma), Give n the uncertainty in APWP of the Indian landmass between 200 and 117 M a, the Rajmahal hot spot might have powered the rifting of India from Antartica from 117 Ma onwards. Initiation of rifting at 132 Ma, as rec onstructed by earlier workers, is not proved.