Hackberry Embayment – Slope Onlap Wedge
1984. "Hackberry Embayment – Slope Onlap Wedge", 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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A deep-water marine wedge, the Hackberry slope system, extends from the eastern flank of the Houston delta system along strike into western Louisiana. The Hackberry consists of a lower sequence containing sands and an upper sequence dominated by shale (fig. 1). The unit is floored by a widespread unconformity that truncates middle, and locally lower, Frio shelf and paralic deposits. The unconformity displays considerable channeling and local truncation of underlying Frio section exceeds 1,000 ft (600 m). Hackberry sandstones occur mainly within the incised canyons.
Fill of the canyons contains a well-described bathyal fauna. Sands display sedimentary features typical of slope systems.
Upper Frio deltaic and shore-zone systems prograde across the Hackberry wedge (fig. 1). Actual time represented by slope canyon cut and fill is thus limited to about 2 to 3 million years.
Though not obviously related to a regional transgressive shale, such as the middle Wilcox Yoakum gorge, the Hackberry occupies a common site of submarine canyon cutting - the flank of a major delta system. Similarly located submarine canyon fills are found on the flanks of the Tertiary Niger delta system.
The upper slope canyon system is quite complex (fig. 2). Canyon fill onlaps the underlying unconformity, showing that the gorges were scoured and then backfilled, much like their Quaternary counterparts flanking the Mississippi delta system. Gorge-fill sand geometry is controlled by the canyon topography and syndepositional structural development (fig. 3). Sand-rich pockets occur within the upper slope. Although
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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.