Attributes and origins of ancient submarine slides and filled embayments: Examples from the Gulf Coast basin

Journal Article · Tue Jun 01 00:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5755150

Morton, R A ^[1]

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1. Univ. of Texas, Austin (United States)

Large submarine slides and associated shelf margin embayments represent an intermediate member in the continuum of unstable shelf margin features. On seismic profiles, they may resemble submarine canyons, but are different in their size, morphology, origin, and hydrocarbon exploration potential. Two large Neogene submarine slides, located in the northwestern Gulf Coast Basin, formed on the upper slope and flanks of prominent shelf-margin deltas. The basal detachment surface of each slide is a structural discontinuity that may be misinterpreted as an erosional unconformity and misidentified as a stratigraphic boundary separating depositional sequences. Regional stratigraphic correlations indicate that both slides were initiated after the continental platform was flooded. The condensed sections deposited during the rise in relative sea level contain the basal detachment surfaces. The relationships between the slides and sea level fluctuations are uncertain. The shelf-margin embayments created by the slides apparently were partly excavated during periods of lowered relative sea level and were filled during sea level rise and highstand. Eventually the preslide morphology of the shelf margin was restored by coalsced prograding deltas. Submarine slides exhibit landward dipping, wavy, mounded, and chaotic seismic reflection that are manifestations of slump blocks and other mass transport material. Composition of these internally derived slide deposits depends on th composition of the pre-existing shelf margin. Embayment fill above the slide consists mostly of externally derived mudstones and sandstones deposited by various disorganized slope processes, as well as more organized submarine channel-level systems. Thickest slope sandstones, which are potential hydrocarbon reservoirs, commonly occur above the basal slide mudstones where seismic reflections change from chaotic patterns to overlying wavy or subhorizontal reflections. 46 refs., 10 figs., 1 tab.

• OSTI ID: 5755150
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:6; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
CONTINENTAL SHELF
LANDSLIDES
US GULF COAST
EXPLORATION
COASTAL WATERS
HYDROCARBONS
PETROLEUM DEPOSITS
RESERVOIR ROCK
SANDSTONES
SEDIMENTATION
CONTINENTAL MARGIN
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
MINERAL RESOURCES
NORTH AMERICA
ORGANIC COMPOUNDS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SURFACE WATERS
USA
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences