New Insights Into the Tectonic Framework & Geologic Features of the Bengal Basin, Bangladesh

In this research, high-resolution SRTM-based NASA Digital Elevation Models (DEM) data and published literature have used to gain new insights regarding South-east Asian surficial geology, fluvial geomorphology, and tectonics, focusing on the Bengal Basin. Seismic databased discovery of shallow, down-warping and \u3e30 km thick Indian crust challenges prior knowledge of crustal origin, which was thought to be oceanic rather than continental in origin due to high-angle subduction. Furthermore, the collapse of the Indian passive margin beneath the Shillong Plateau may have formed a 20 km thick Surma Basin on top and has led to substantial earthquake risks. To update the surficial geology of Bangladesh, located in the central part of the Bengal Basin, dry season Sentinel-2 satellite imagery with published conventional maps was utilized. The lithological variations over the past three decades were attributed to river avulsion and sea-level fluctuations, with the paths of the Ganges and Brahmaputra rivers largely influenced by active tectonics and adjusting landscapes. The Meghna estuary coast was found to be vulnerable to sea-level rise despite significant land accretion. Alternatively, the mangrove forest coast (Sundarban) was found to be relatively stable. The research findings, including an updated geologic map of Bangladesh, can be crucial in natural resource management and hazard mitigation. However, a further tectonic investigation is needed to validate the crustal and basin thickness around the Bengal Basin, which could be accomplished by seismic tomography, gravity and/or magnetic anomaly analyses including field-based observations