Gulf Coast Tertiary Depositional Units
1984. "Gulf Coast Tertiary Depositional Units", Structural and Depositional Styles of Gulf Coast Tertiary Continental Margins: Application to Hydrocarbon Exploration, Martin P.A. Jackson, William E. Galloway
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The overall depositional history of the Northwest Shelf of the Gulf of Mexico reflects multiple cycles of clastic influx (depositional episodes) punctuated by thin, occasionally regional transgressions. Regional stratigraphic analysis of the major clastic episodes shows two types (fig. 1).
Major episodes rapidly prograded to the existing continental margin and resulted in widespread construction of new continental platform. Slope off lap resulted.
Minor episodes of sediment input prograded the shoreline only partially across the extant submerged continental platform. The shelf margin remained a zone of slow pelagic sedimentation, sediment bypass, or possibly erosion. The slope may have been blanketed by spillover of distal prodelta and shelf suspended sediments or low-density turbidity currents. Little opportunity for deposition of sand at the shelf margin or onto the slope existed.
A tentative classification of -Tertiary depositional episodes is shown in figure 2. For comparison, the episodes, known subregional inner coastal plain unconformities, regional transgressive marine shales, and onlap or gorge fills (reflecting submarine erosion and deep marine deposition landward of the general continental margin) are plotted beside the Cenozoic cycle chart. It appears that in a depositionally active trailing-edge margin, such as the Northern Gulf, sediment supply or other controls supersede eustatic cycles in determining depositional history.
Principal sediment input shifted among three axes - the Rio Grande, Houston, and Mississippi embayments (fig. 3). Major delta systems prograded a sand-rich continental margin at the basinward margin of these depoaxes.
Major off lap episodes mobilize
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Structural and Depositional Styles of Gulf Coast Tertiary Continental Margins: Application to Hydrocarbon Exploration
The structure and genetic stratigraphy of the Gulf of Mexico continental margin are inextricably intertwined. As hydrocarbon exploration and exploitation advance into the deeply buried Tertiary basin fill, interpretation of the complex depositional and structural styles of the outer shelf and upper slope setting will increasingly challenge the interpreter. This publication provides a coherent summary of the key concepts, models, and tools that are needed to meet this exploration challenge, and includes chapters on: basic principles, submarine slope systems, models of growth faults, mechanics of diapir growth, petroleum traps, and techniques on analyzing normal faults and balancing cross sections with extended strata.