Shelf sedimentation off the Ganges-Brahmaputra river system: Evidence for sediment bypassing to the Bengal fan

The nature of shelf sedimentation seaward of the world's largest sediment dispersal system is examined by using sedimentological and geochronological techniques on a unique suite of sediment cores and grab samples. Sediments from the Ganges-Brahmaputra river system are currently accumulating on the shelf in water depths of less than about 80 m, forming a clinoform-like deposit similar to subaqueous deltas found off other major river systems. The highest sediment accumulation rates on the shelf occur near the head of the Swatch of No Ground, a major submarine canyon that indents the shelf west of the present river mouths. This observation, together with textural data, suggests that river sediments are transported seaward and westward and that the Swatch of No Ground is currently a major conduit for the transport of sediments from the Bengal shelf.