TIMING OF DEPOSITION IN MARWAR BASIN, RAJASTHAN, INDIA, USING GEOCHRONOLOGY AND PALEOMAGNETISM

Peninsular India includes numerous ancient (Purana) sedimentary basins, many of which have ages of deposition that are still unclear. Located in Rajasthan in Northwest India, the Marwar Basin is a Purana basin where the age of deposition can be determined with precision using a combination of geochronologic and paleomagnetic data. Existing constraints on the age of Marwar deposition are poor, especially for the onset, and there is currently a 250 million year range from the beginning of Marwar deposition to its termination if the Cambrian. The Marwar Supergroup unconformably overlies the well-dated Malani igneous rocks (750-800 Ma), and the top of the Marwar section has trace fossils that are Early to Middle Cambrian in age. Further knowledge of the Marwar Basin is important when considering the tectonic evolution of India as well when making global correlations to other sedimentary units/basins that formed during the process of Gondwana assembly (Davis et al., 2013; Meert et al., 2003). Our study targets the lowermost section of the Marwar Supergroup at Chhotti Khatu where the sediments contain interbedded felsic flows and tuffs. The felsic units will be used for U-Pb dating and paleomagnetism (Meert et al., 2013) to help establish the depositional range for this important basin in India.