Published:January 01, 1978
Arnold H. Bouma, George T. Moore, James M. Coleman, 1978. "Introduction", Framework, Facies, and Oil-Trapping Characteristics of the Upper Continental Margin, Arnold H. Bouma, George T. Moore, James M. Coleman
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The Marine Geology Committee of the American Association of Petroleum Geologists presented its first workshop “Finding and Exploring Ancient Deltas in the Subsurface” at the 1975 annual meeting at Dallas. Because the deltaic system provides a major source of hydrocarbons, the workshop’s purpose was to offer a rationale to provide the geologist with a better understanding of his geologic tools and the sedimentary complex to which they have to be applied.
The overwhelming interest in this workshop resulted in the organization of a second short course by the Marine Geology Committee for the 1976 annual meeting. It seemed proper to combine an evolving frontier area with an extension of the previous workshop theme. Under the title “Beyond the Shelf Break, ” a series of 10 papers was presented to provide an in-depth study of many facets of the upper continental slope. Nine contributions focused on the Gulf of Mexico, and one dealt with the oil-trapping characteristics of turbidites with examples from California.
Several environmental settings are favorable to the accumulation of oil and gas, one of them being the continental slope. The slope in the northern Gulf of Mexico was drilled in 1966 by a combine of oil companies (Exxon, Chevron, Mobil, Gulf) to depths of 1,000 feet (305 m) with the drilling vessel Caldrill I. The proprietary rights expired after 10 years, and release of these data as part of a workshop rather than as individual abstracts and papers was felt to be of greater service to the geologic profession. As a consequence, many papers presented in the short course originated from petroleum company research on the continental slope.
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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.