PRELIMINARY PALEOMAGNETIC DATA FROM THE UPPER VINDHYAN SUPERGROUP OF PENINSULAR INDIA

East Gondwana (India, Seychelles, Madagascar, Sri Lanka, East Antarctica and Australia) was traditionally treated as a largely coherent unit during the Neoproterozoic-early Paleozoic assembly of Gondwana. This notion is challenged by the presence of Cambrian age orogenic belts that traverse the East Antarctic craton along with the identification of similar-age belts in Australia and India. The Indian craton is featured as the largest part of a proto-East Gondwana continent during the Neoproterozoic, placing India alongside Madagascar and parts of coastal East Antarctica. Therefore, paleomagnetic data from India during the 1000-550 Ma interval are crucial in testing these proposals hinting at a younger assembly of East Gondwana.

Existing paleomagnetic database for the Neoproterozoic interval in India, mainly from the Vindhyan Supergroup, is problematic. Although dual polarity paleomagnetic directions were reported in each of the Upper Vindhyan (Kaimur, Rewa and Bhander Groups) neither the paleomagnetic directions nor the ages of the poles are well-constrained. Paleomagnetic poles from the Bhander-Rewa fall on the combined Gondwana apparent polar wander path (APWP) near Vendian/Cambrian poles with ages of ~550 Ma. Results from Kaimur fall close to the 750 Ma pole of the Malani rhyolites and may have resulted from a remagnetization during the Malani igneous event. Because the previous paleomagnetic studies do not show detailed demagnetization and paleomagnetic field tests, we cannot, without further work, determine if these directions are primary.

Here we will present new paleomagnetic and rockmagnetic data from the Son Valley and SE Rajasthan parts of the Upper Vindhyan. The sampled sequence preserves strata of varying thicknesses and ages that collectively may span a significant portion of the Meso (Kaimur) -Neoproterozoic interval (Rewa and Bhander). Our paleomagnetic study accompanied with rock magnetic data will have excellent potential in providing a strong temporal framework and APWP for the Meso-Neoproterozoic succession in Eastern Gondwana.