Lithofacies and Granulometric Analysis of Middle Siwalik Sandstones of Jammu, NW Himalaya, India

In the Northwest Himalaya, the Siwalik Group of rocks are exposed in the Suruin-Mastgarh anticlinal folded succession and has been classified into Lower, Middle and Upper subgroups. The Middle Siwalik Subgroup is exposed at various locations in the Jammu region and is primarily made up of multistoried sandstones embedded with thin beds of mudstone. In the present study, these rocks have been studied to understand the depositional history using the sediment size of sandstones and the lithofacies in addition to the paleocurrent analysis. The multistoried nature of the sandstone and the scour fills observed in these rocks imply that there were frequent and periodic strong stream encounters at the depositional site where saltation was the dominant process of transportation of sediments. The data obtained on grain size, lithofacies, cross beddings, and the type of contacts between different lithofacies suggest that the southerly flowing braided river system underwent multiple episodes of avulsion and abandonment of the channel system during the deposition of the Middle Siwalik subgroup in Jammu region.