Physiographic and bathymetric characteristics of the continental slope, northwest Gulf of Mexico

Bryant, William R.; Bryant, John; Feeley, Mary H.; Simmons, Gregory R.

doi:10.1007/bf02431065

Cited by 54 publications

(24 citation statements)

References 8 publications

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“…1). The seismic line crosses the Louisiana shelf, the salt minibasin province on the continental slope, and the Sigsbee Escarpment (Bryant et al, 1990;Hall, 2002). Unlike GUMBO Line 3 and Line 4, the south end of GUMBO Line 2 does not cross the east-west-trending extinct spreading center, which lies ~40 km farther south Nguyen and Mann, 2016).…”

Section: Seismic-refraction Datamentioning

confidence: 91%

Structure and origin of the rifted margin of the northern Gulf of Mexico

et al. 2018

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The wide continental margin of southern Louisiana borders Paleozoic terranes that accreted to Laurentia before Jurassic rifting formed the Gulf of Mexico. It is unclear whether continental rifting here involved widespread or localized crustal extension, or how seafloor spreading in the Gulf of Mexico started. To improve our understanding of this rifting episode, we gathered marine seismic-refraction data along a 396-km-long transect from the continental shelf 50 km off the western Louisiana coast to the central ocean basin as part of the Gulf of Mexico Basin Opening (GUMBO) program. Using travel-time tomography, we imaged the compressional seismic-velocity structure from the shallow sediments to the uppermost mantle. In our geophysical model, the crust tapers in thickness from ~11 km near the Louisiana coast to ~8 km in the deep water of the central Gulf of Mexico. The compressional seismic velocity increases from 5.7 to 5.9 km/s in the shallow basement to 6.8-7.2 km/s above the Moho. The thickness and average wave speed of crust beneath the modern Louisiana coast and continental shelf suggest the presence of uniformly stretched continental crust that was intruded by mantle-derived melts during extension before continental breakup. South of the Sigsbee Escarpment, the crust is thinner with a higher seismic velocity, which is more consistent with thick oceanic crust. A comparison of our seismic-velocity model with coincident seismic-reflection data indicates that the voluminous Louann Salt was likely deposited on rifted continental crust shortly before the onset of seafloor spreading in the Gulf of Mexico.

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Section: Seismic-refraction Datamentioning

confidence: 91%

Structure and origin of the rifted margin of the northern Gulf of Mexico

et al. 2018

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“…Middle Jurassic Louann salt that was deposited during rifting or early postrifting time became mobilized in middle Cenozoic time (Diegel et al, 1995;Salvador, 1991) and has controlled formation of much of the gross surface morphology and stratigraphy of minibasins and intervening structural highs in the northern Gulf (Diegel et al, 1995;Ewing, 1991;Peel et al, 1995). Remobilization occurred in Plio-Pleistocene time owing to differential loading of the shelf as sediment depocenters migrated back and forth across the continental shelf in response to changing sea level (Bryant et al, 1990). During sea level low stands, sediments bypassed the continental shelf into shelf-edge deltas that channeled terrigenous deposits into slope basins and fans (Suter and Berryhill, 1985;Lee et al, 1996).…”

Section: Geologic Setting Of the Northern Gulf Of Mexicomentioning

confidence: 99%

“…Lithology and structure, together with the sometimes complicated history of deposition and deformation, are known to affect the distribution and concentration of hydrate (Expedition 311 Scientists, 2006;Reidel et al, 2006;Trehu et al, 2004). Although the northern Gulf of Mexico (hereafter referred to simply as the Gulf) is a passive continental margin, the continental slope is remarkably complex and heterogeneous because of widespread salt tectonism, differential Pleistocene sediment loading, and consequent large variations in sediment patterns and structural style (Bryant et al, 1990;Diegel et al, 1995;Peel et al, 1995). Hence, understanding the geologic setting around the Joint Industry Project (JIP) drill holes sets the stage for understanding the factors affecting distribution of gas hydrate within the sedimentary section.…”

Section: Introductionmentioning

confidence: 99%

Geologic framework of the 2005 Keathley Canyon gas hydrate research well, northern Gulf of Mexico

Hutchinson

Hart

Collett

et al. 2008

Marine and Petroleum Geology

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a b s t r a c tThe Keathley Canyon sites drilled in 2005 by the Chevron Joint Industry Project are located along the southeastern edge of an intraslope minibasin (Casey basin) in the northern Gulf of Mexico at 1335 m water depth. Around the drill sites, a grid of 2D high-resolution multichannel seismic data designed to image depths down to at least 1000 m sub-bottom reveals 7 unconformities and disconformities that, with the seafloor, bound 7 identifiable seismic stratigraphic units. A major disconformity in the middle of the units stands out for its angular baselapping geometry. From these data, three episodes of sedimentary deposition and deformation are inferred. The oldest episode consists of fine-grained muds deposited during a period of relative stability in the basin (units e, f, and g). Both the BSR and inferred gas hydrate occur within these older units. The gas hydrate occurs in near-vertical fractures. A second episode (units c and d) involved large vertical displacements associated with infilling and ponding of sediment. This second interval corresponds to deposition of intercalated fine and coarse-grained material that was recovered in the drill hole that penetrated the thin edges of the regionally much thicker units. The final episode of deposition (units a and b) occurred during more subdued vertical motions. Hemipelagic drape (unit a) characterizes the modern seafloor. The present-day Casey basin is mostly filled. Its sill is part of a subsiding graben structure that is only 10-20 m shallower than the deepest point in the basin, indicating that gravity-driven transport would mostly bypass the basin. Contemporary faulting along the basin margins has selectively reactivated an older group of faults. The intercalated sand and mud deposits of units c and d are tentatively correlated with Late Pleistocene deposition derived from the western shelf-edge delta/depocenter of the Mississippi River, which was probably most active from 320 ka to 70 ka [Winker, C.D., Booth, J., 2000. Sedimentary dynamics of the salt-dominated continental slope, Gulf of Mexico: integration of observations from the seafloor, near-surface, and deep subsurface. In: Proceedings of the GCSSEPM Foundation 20th Annual Research Conference, Deep-water Reservoirs of the World, pp. 1059-1086]. The presence of sand within the gas hydrate stability zone (in units c and d) is not sufficient to concentrate gas hydrate even though dispersed gas hydrate occurs deeper in the fractured mud/clay-rich sections of units e and f.Published by Elsevier Ltd.

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“…From these various sources of data, several bathymetric maps have been published, some covering the entire Gulf while others cover only a portion of it (e.g., Gealy 1955; Uchupi 1967;Sorensen 1975;Martin and Bouma 1978;Perry 1984;Bryant et al 1990Bryant et al , 1991aNOAA 1992). Bryant et al (1990) provided a detailed bathymetry of the entire Texas-Louisiana slope, using a multitude of single-beam sounding sources.…”

Section: Introductionmentioning

confidence: 99%

“…Bryant et al (1990) provided a detailed bathymetry of the entire Texas-Louisiana slope, using a multitude of single-beam sounding sources. The National Ocean Service (NOS) of the National Oceanic and Atmospheric Administration (NOAA) commenced a multibeam survey of the US Exclusive Economic Zone (EEZ) in response to a 1983 presidential proclamation.…”

Section: Introductionmentioning

confidence: 99%

Physiographic features on the northern Gulf of Mexico continental slope

Bouma

Bryant

1994

Geo-Marine Letters

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AbstraetThe continental slope of the northern Gulf of Mexico is diapirically controlled and is comprised of coalescing salt sheets, salt withdrawal basins, salt ridges, salt tongues and sills, and submarine canyons. Bathymetric information from single-beam data has resulted in several published maps. Many of the map areas have been remapped, using multibeam surveys, by the US National Ocean Service, and names have been given to the major physiographic features. The multibeam program was discontinued before complete coverage of the slope was accomplished. We provide charts of the remaining areas with

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Physiographic and bathymetric characteristics of the continental slope, northwest Gulf of Mexico

Cited by 54 publications

References 8 publications

Structure and origin of the rifted margin of the northern Gulf of Mexico

Structure and origin of the rifted margin of the northern Gulf of Mexico

Geologic framework of the 2005 Keathley Canyon gas hydrate research well, northern Gulf of Mexico

Physiographic features on the northern Gulf of Mexico continental slope

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