PRELIMINARY PALEOMAGNETIC DATA FROM RAJAHSTAN: IMPLICATIONS FOR RODINIA PALEOGEOGRAPHY

The Neoproterozoic Mt. Abu granitic pluton of southern Rajahstan, India, is crosscut by steeply-dipping, sub-parallel mafic dikes. Paleomagnetic measurements from the dikes have identified a steeply dipping high temperature component of magnetization. Both pluton and dikes are poorly dated but the age of magnetization probably ranges between 800 and 900 Ma; we await 40Ar/39Ar mica and U/Pb zircon ages to fully interpret the paleomagnetic data. Previous palaeomagnetic data from the 750 Ma Malani rhyolites (NW Rajahstan) yielded intermediate northerly latitudes for India during the Neoproterozoic, and India along with Madagascar and the Seychelles were separated from East Antarctica and Australia at this time. The presumably older palaeomagnetic data from the Mt. Abu dikes suggest that India occupied high northerly latitudes between 800-900 Ma (65-87oN) and subsequently drifted rapidly southward to reach subtropical latitudes at c. 750 Ma. This demonstrate that the Rodinia was not a static and equatorially cantered Supercontinent during the Neoproterozoic and break-up probably commenced at around 850 Ma.