PALEOMAGNETIC RESULTS FROM THE CRETACEOUS BAGH GROUP IN THE NARMADA BASIN, CENTRAL INDIA - EVIDENCE OF PERVASIVE DECCAN REMAGNETIZATION ANDITS IMPLICATIONS FOR DECCAN VOLCANISM

A palaeomagnetic study of 115 samples (328 specimens) from 22 sites of the Mid- to Upper Cretaceous Bagh Group underlying the Deccan Traps i n the Man valley (22 degrees 20'N, 75 degrees 5'E) of the Narmada Basi n is reported. A characteristic magnetization of dominantly reverse po larity has been isolated from the entire rock succession, whose deposi tional age is constrained within the Cretaceous Normal Superchron. Onl y a few samples in the uppermost strata have yielded either normal or mixed polarity directions. The overall mean of reverse magnetization i s D-m = 144 degrees, I-m = 47 degrees (alpha(95) = 2.8 degrees, k = 15 2, N = 18 sites) with the corresponding S-pole position 28.7 degrees S , 111.2 degrees E (A(95) = 3.1 degrees) and a palaeolatitude of 28 deg rees S+/-3 degrees. The characteristic remanence is carried dominantly by magnetite. Similar magnetizations of reverse polarity are also exh ibited by Deccan basalt samples and a mafic dyke in the study area. Th is pole position falls near the Late Cretaceous segment of the Indian APWP and is concordant with poles reported from the Deccan basalt flow s and dated DSDP cores (75-65 Ma) of the Indian Ocean. It is therefore concluded that the Bagh Group in the eastern part of the Narmada Basi n has been pervasively remagnetized by the igneous activity of Deccan basalt effusion. This overprinted palaeomagnetic signature in the Bagh Group indicates a counter-clockwise rotation by 13 degrees+/-3 degree s and a latitudinal drift northwards by 3 degrees+/-3 degrees of the I ndian subcontinent during Deccan volcanism.