Shelf processes most effective in transporting bed-load sediment are related to tides, storm waves and surge, and wind-forced currents.
In a Mediterranean basin, such as the Gulf of Mexico, tide range is limited and tidal processes have likely been of minor importance.
Below fair-weather wave base, which establishes the depth of the shoreface (typically about 30 ft or 10 m in modern and Tertiary Gulf Coast), storm waves may entrain and transport sediment to depths of a few hundred feet. Hummocky crossbedding is now popularized as a key sedimentary structure indicative of storm wave action on the shelf.
Storm surge occurs when wind and barometric pressure pile water against the shore. With passage of the storm, return flow also generates bottom currents capable of sand transport.
Wind-forced currents are produced at shallow to moderate depths as storm winds pile water against the shore. Unlike storm surge, flow may continue for several days. Flow is deflected along strike by the shoreface. Combined offshore transport (ebb surge) and strike transport (wind-forced currents) may play a major role in sand deposition in water depths below normal current action and at the shelf edge. Such processes rapidly lose their impact in deeper water beyond the shelf edge, however.
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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.