An overview of sedimentation on the amazon continental shelf

Sedimentological, geochemical, and physical-oceanographic studies of the Brazilian continental shelf near the Amazon River help provide a broad understanding of this major sediment dispersal system. Amazon River sediment accumulates as a subaqueous delta, with the most rapid accumulation (10 cm/yr) occurring near the seaward edge of the topset beds and in the foreset beds. Amazon River sediment is dispersed northwestward along the shelf and is transported beyond the Brazilian border. Radiographic studies of sediment cores delineate three sedimentary environments: interbedded mud and sand, faintly laminated mud, and bioturbated mud. The distribution of these environments is a function of proximity to the river mouth and of sediment accumulation rate.