Neogene to recent evolution of the Southern Gulf of Mexico basin: Tectonic controls on deep-water sediment dispersal systems

Newly available two-dimensional (2D) and limited three-dimensional (3D) reflection seismic data coupled with publicly available well and core data were used to generate the first comprehensive regional basin evolution model for the deep-water Neogene to recent southern Gulf of Mexico (GoM). This evolution is presented in the context of contemporaneous onshore tectonic drivers and predecessor basin tectonic history. Dynamic uplift to the west in North America, transpression to the south and tectonically influenced salt tectonics to the east served to collapse the margins of the southern Gulf of Mexico Basin throughout the late Neogene and into the modern. This collapse and salt inflation served to shut off efficient sediment transport into the axial deep basin. Newly developed nearshore extensional accommodation along both the western margin of the basin and salt-rooted orogenic structures to the south and east appear to have baffled coarser-caliber sediment input from southern (Mexican) sediment sources into the deep Gulf of Mexico Basin beginning in the late Miocene. This sequence is recorded in the southern GoM basin by a transition from large early-mid Miocene submarine channel belts to late Miocene-recent sediment wave fields and mass transport deposits. Improved resolution of new 2D and 3D subsurface seismic reflection data shows that sediment waves of the southern Gulf of Mexico are supercritical bedforms, long wavelength antidunes and cyclic steps, not contourites. These supercritical bedforms are among the most spatially expansive and morphologically largest documented globally. The location and evolution of these bedforms appears closely tied to the tectonically driven history of margin collapse, salt inflation and the starving of the deep basin of coarse-grained sediment. Cumulatively, the tectonic drivers that intuitively should have increased sediment flux into the deep southern Gulf of Mexico acted to 'pinch off' the basin, starving it of sediment supplied from southern sediment sources.

Automated summary

The study utilized newly available two-dimensional and limited three-dimensional seismic data, combined with well and core data, to reveal the basin evolution model of the deep-water Neogene to recent southern Gulf of Mexico. The tectonic drivers such as dynamic uplift, transpression, and salt tectonics led to collapse of the basin margins and limited sediment transport into the deep basin. Additionally, the newly developed nearshore sediment systems affected sediment input into the deep basin.