Sedimentary basins of passive margins filled with sediments of river deltas and submarine fans

Rivers transport huge quantities of terrigenous material mobilized in their drainage areas and represented by rock fragments and grains of quartz, feldspars, and other weathering-resistant minerals. Large volumes of fine clay particles and organic components in the form of suspended matter and dissolved salts are also transported from the land to seas and oceans. This material is deposited in river deltas located on shelves and submarine fans, which are formed on the continental slope and at its foothill. Thick lenses of deltaic and submarine fan sediments turn gradually into oil-and gas-bearing basins, the largest among which is the Gulf of Guinea basin.