Cenozoic depositional history of the Gulf of Mexico basin

Abstract

A Geographic Information System (GIS) database incorporating information from 241 publications, theses, and dissertations; well logs and paleontologic reports; and interpreted University of Texas Institute for Geophysics (UTIG) deep-basin seismic lines was used to map and interpret 18 basinwide genetic stratigraphic sequences that form the Gulf of Mexico basin Cenozoic fill. Eight principal extrabasinal fluvial axes provided the bulk of the sediment infill in the basin. First-order temporal and spatial use of these axes reflects four continent-scale phases of crustal uplift. Abundant sediment supply has prograded the northern and northwestern basin margin 150 to 180 mi (240 to 290 km) from its inherited Cretaceous position. Margin outbuilding has been locally and briefly interrupted by hypersubsidence due to salt withdrawal and mass wasting. Three depositional systems tracts characterize Cenozoic genetic sequences: (1) fluvial --> delta --> delta-fed apron, (2) coastal plain --> shore zone --> shelf --> shelf-fed apron, and (3) delta flank --> submarine fan. One or more examples of the fluvial --> delta --> delta-fed apron systems tract occur in each of the major genetic sequences. Immense volumes of sand have bypassed the shelf margin to be deposited in slope and base-of-slope systems, primarily within fluvial --> delta --> delta-fed apron system tracts, during all major Paleogene and Neogene depositional episodes. Deposition and preservation of volumetrically significant coastal plain --> shore zone --> shelf --> shelf-fed apron tracts is typical of Paleogene through Miocene depositional episodes only. Fan system origin was commonly associated with major continental margin failures, but large submarine canyons occur mainly in Pleistocene sequences. Thick, potential reservoir sand bodies occur in offlapping delta-fed slope and subjacent basin floor aprons, in autochthonous slope aprons and related infills of slide scars and canyon cuts, and in submarine fans.