Tectonics
and sedimentation are closely related in Bangladesh. The Ganges and Brahmaputra Rivers drain most of the
Himalayan Mountains bringing ~8% of the world’s annual sediment supply to
Bangladesh. These sediments have
built the world’s largest delta at the NE corner of the Indian plate. This delta, in turn, is being
overridden by two plate tectonic boundaries, the Burma Arc to the east and the
uplifted Shillong Plateau to the north.
The Shillong Plateau a piece of Indian basement that may represent the
beginning of a forward shift of the Himalayan Mountains to the south. The Burma Arc is the northward
extension of the plate boundary that experienced the 2004 M9.3 Sumatra-Andaman
earthquake and tsunami. Both of
these boundaries are partially buried by the sediments of the
Ganges-Brahmaputra Delta. This
both obscures the boundaries and preserves a record of the tectonics in the
sediments. Details on both the scientific issues and the methods we use to investigate them are on the pages for: Rivers & Sediments and Tectonics & Geophysics | Figure 1A) Drainage basin of the Ganges, Brahmaputra and Meghna (M) Rivers. The rivers, shown in yellow drain most of the Himalayan Mountains. B) Topography of the area surrounding the Ganges-Brahmaputra
Delta. Bangladesh is outlined in red. The Hinge Zone is the edge of
Indian Shield. Farther east is where the very thick sediments of the
delta have extended the continental margin. The major plate boundaries
are shown at black lines with triangles on the upper side of the thrust. |