Jacob Covault, Zoltan Sylvester, Daniel Carruthers, Dallas Dunlap

Large meandering submarine-channel systems are important conduits for mass transfer to continental margins; wider and deeper channels, with larger meanders, reflect larger sediment discharge. Some large meandering channel systems are known to receive voluminous sediment from the largest rivers in the world, such as the Ganges-Brahmaputra, Amazon, Indus, Mississippi, and Zaire (Congo); however, smaller rivers draining rapidly uplifting landscapes can also contribute significant terrigenous mass to continental margins. Here, we use three-dimensional seismic-reflection data from >2 km water depth in the Campos basin, offshore Brazil, to interpret the stratigraphy of a Late Cretaceous submarine-channel system within a deep-water salt-tectonic province. We mapped three regional seismic-reflection horizons, which define a sequence of at least 16 downstream-translating channel elements ~1 to >1.5 km wide with wavelengths ranging from 8 to 24 km. These are among the largest meandering channel forms and deposits in the world. Increased sediment discharge through submarine channels during the Late Cretaceous, driven by dynamic uplift along the humid and warm coast of southeastern Brazil, promoted the development of these large meandering channels. Analogous settings characterized by rapid uplift of coastal mountains and unstable, narrow shelves might promote large sediment supply to continental margins, producing giant submarine canyon-channel-fan depositional systems and petroleum reservoirs.