Recognition of Continental-Slope Seismic Facies, Offshore Texas-Louisiana
Published:January 01, 1978
J. B. Sangree, D. C. Waylett, D. E. Frazier, G. B. Amery, W. J. Fennessy, 1978. "Recognition of Continental-Slope Seismic Facies, Offshore Texas-Louisiana", Framework, Facies, and Oil-Trapping Characteristics of the Upper Continental Margin, Arnold H. Bouma, George T. Moore, James M. Coleman
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From analysis of a high-resolution arcer survey of the young sediments in the western clastic region of the Gulf of Mexi cocontinental slope, and study of 29 300-m core holes, six facies type shave been defined from their appearance on seismicsections. The sedimentary facies that correspond to these seismic-facies type shave been interpreted and some progress has been made in identifying the transportation deposition processes responsible for each facies. The six seismic facies and their sedimentary equivalents are: (1)divergent and parallel layered, avaried, deposited in uniform layers; (2)sheet drape—hemipelagic deposits; (3)on lapping fill—probably both high-energy and low-energy turbidites; (4)sigmoid progradational— varied, mainly low-energy submarine deposits formed by out building from relatively shallow to relatively deep water; (5)oblique progradational— shelf-margin delta sand related marine facies; (6)mounded chaotic—submarine creep-and-slump deposits, mass-transport facies.
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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.