Holocene Sediment Geochemistry of Continental Slope and Intraslope Basin Areas, Northwest Gulf of Mexico
Published:January 01, 1978
T.R. Mckee, L.M. Jeffrey, B.J. Presley, U.G. Whitehouse, II, 1978. "Holocene Sediment Geochemistry of Continental Slope and Intraslope Basin Areas, Northwest Gulf of Mexico", Framework, Facies, and Oil-Trapping Characteristics of the Upper Continental Margin, Arnold H. Bouma, George T. Moore, James M. Coleman
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Slope topography has a major effect on the geochemical properties of near-surface sediment on the Texas-Louisiana Slope. Sediment in intraslope basins accumulates faster than in areas outside the basins, leading to a more anoxic character for basin sediment. One basin was found to be partly filled with a high-density brine, resulting in completely anoxic water and sediment, undisturbed by benthic organisms. Iron and manganese are mobilized in the sediment column, and recrystallize in patterns depending on sediment accumulation rates and redox conditions.
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Framework, Facies, and Oil-Trapping Characteristics of the Upper Continental Margin
The Gulf of Mexico covers an area of more than 1,500,000sq km, has a maximum depth of about 3,700m, and includes many of the geomorphic features of large oceans.The continental shelf, slope, rise, and abyssal plain comprise the major physiographic provinces of the guldf and contain avariety of subprovinces distinguished by topographic character and geomorphic history.
The gulf shelf is a relatively smooth, gently sloping surface marked locally bylow-relief featuresformed by sea-level fluctuation during the Pleistocene, reef growth, near-surface movement of diapiric salt and mud, and faulting. Shelf width varies from about 280km off the Florida and Yucatan Peninsulas to less than 10km at the Mississippi Delta. The continental slope consists of a considerable variety of physiographic subprovinces and individual features that encircle the deep gulf floor.
The distinctive subprovinces of the gulf slope have evolved in response to reef building and constructional sedimentation on the Florida and Yucatan carbonate platforms; erosion, nondeposition, slumping, and fault ing in the Straits of Florida and Yucatan Channel; salt diapirism and differential sedimentation in the region off Texas and Louisiana; the largeaccumulation of mainly Pleistocene sediment on a former continental slope seaward of the Mississippi Delta; tectonic uplift and diapirism in theGolfo de Campeche; and shale mobilization of feastern Mexico. In contrast to the greatly varied, irregular topography of the continental slope,thedeep seafloor of the gulf (composed of continental rise and abyssal plainprovinces) is an almost featureless plain smoothed by turbidite and pelagic sedimentation and marked locally bylow-relief knolls, sedimentary aprons, and small-leveed channels.