ABSTRACT

The bathymetry of the continental slope of the northern Gulf of Mexico is very complex. This is mainly due to 15 km of sediments have been deposited on top of over 3 km of salt since Late Jurassic. The buoyancy of the salt accompanied with sediment differential loading and salt gravity spreading has pushed the salt through the overlying sediment as well as moving basinward. Many of the resulting allochthonous salt structures are very close to the seafloor, and basins that are hundreds of meters in relief were formed in between salt domes or overlying salt withdrawal massifs. The seafloor morphology was further complicated by the salt-sediment interplay caused faults and sea level fluctuations resulted shifts in sediment sources.

Recently compiled multibeam and digitized seismic data has detailed the bathymetry of the northern Gulf of Mexico slope and deep water areas. Based on this bathymetry and a watershed basin analysis model, land like drainage paths in the underwater environment have been generated. Four drainage systems have been identified: western, central, northeastern, and southeastern continental slope areas. These drainage systems coincide with the major sediment sources in the west (Rio Grande River system), in the northwest (Brazos and Colorado Rivers systems), and in the north (Mississippi River system). The carbonate-dominated platforms in the eastern and southern Gulf of Mexico show few drainage pathways. On a regional scale, these drainage paths are the primary conduits of turbidity currents and debris flows during periods of low sea stand.

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