Published:January 01, 1978
Regional sparker lines across the continental slope of the northern Gulf of Mexico demonstrate the close relation between salt movement and sediment deposition.
Salt features on the outer slope are not as well developed as those near the shelf because sedimentation has been much less on the slope. Salt-generated structures in the eastern part of the gulf are more mature than those in the western gulf because of higher rates of sedimentation. The youngest salt features on the outer slope are much larger than domes on the shelf.
Seismic data from the outer slope suggest that salt dome growth in this area was initiated by southward salt flowage caused by sediment loading updip. The Sigsbee Escarpment appears to be a salt scarp (formed by this gulfward salt flowage) that has extruded over younger sediments for a considerable distance.
Areas of salt diapirs in the Gulf of Mexico, with the exception of diapirs on much of the lower continental slope, are considered to be areas of original thick salt deposition. It is suggested that these areas of thick salt were deposited in one central rift in Jurassic time, and have moved to their present position by seafloor spreading. The present Red Sea is a model for the Gulf of Mexico at the time of Mesozoic breakup.
Figures & Tables
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.