IDENTIFYING CYCLICITY AND PROVENANCE THROUGH THIN SECTION PETROLOGY OF SHALLOW MARINE DEPOSITS IN THE INDO-BURMAN RANGES

The creation of a massive fluvial system by tectnic forces has generated a stratigraphic record within the Indo-Burman ranges (IBR) in Eastern India containing Miocene-Pliocene-aged deltaic and shallow marine deposits. The mechanical properties of these sedimentary bodies will help in understanding the tectonically active megathrust fault that poses a potential for a major earthquake in a densely populated area. The rise of the Himalayas and a simultaneous closing of the remnant ocean basin created a coupled tectonic-sedimentary suture-type delta, which controls sediment distribution and long-term evolution of the delta. We analyzed hand samples and thin sections from the M2 facies of the Surma group extracted from a quarry in Aizawl, Mizoram, India for grain size, mineralogy, and cyclicity. Our mineralogy results are compared to previous detrital zircon provenance data in the IBR and the Bengal and Nicobar Fans, thus filling a spatial and temporal knowledge gap in a dynamic system. We identify numerous scales of cyclicity within the M2 facies to determine the sediment accumulation rate within the subaqueous delta. Ultimately, these data will aid the characterization of IBR stratigraphy and how the different units may respond in the event of a megathrust earthquake.