Reconstruction of allochthonous salt emplacement from 3-D seismic reflection data, northern Gulf of Mexico

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

OSTI ID:6360413

Walters, R D ^[1]

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

Analysis of a 110 mi[sup 2] (284 km[sup 2]) three-dimensional (3-D) seismic survey located at the northern Gulf of Mexico continental shelf edge documents the emplacement history of an allochthonous salt structure. A listric, counter-regional growth fault bounds the updip salt edge and apparently soles into a detachment surface from which salt was evacuated. The counter-regional fault system served as the feeder stock for the dome. The current salt shape is an asymmetric, elongated wedge with a diameter of 20,000 ft (6.1 km) and maximum thickness of 13,000 ft (4.0 km). A steep fault/salt contact bounded by small, oval- shaped withdrawal subbasins on the landward side contrasts with a shallow-dipping basinward salt/sediment contact. A relatively thin sediment cover onlaps the shallow basinward salt flank. Regional seismic lines support the presence of a detachment surface in the area apparently separating Upper Cretaceous to lower Tertiary( ) sediments from upper Miocene (7.0--5.4 Ma) and younger sediments. During the first stage, an allochthonous salt sheet was emplaced during the hiatus and then segmented. From the middle to late Pliocene (4.0--2.2 Ma), the salt structure evolved by downbuilding, remaining close to the ocean floor surface and covered by only a thin sediment veneer. After the beginning of the Illinoian glacial stage (0.85 Ma), the deep source salt layer was depleted and the dome was buried by up to 1,700 ft (520 m) of sediment during the third stage. Seismic amplitude anomalies associated with structural disconformities indicate a possible salt evacuation surface or salt weld along the deep feeder stock. Geohistory diagrams indicate extremely rapid local subsidence in the withdrawal basin, which contains up to 12,000 ft (3.6 km) of Pleistocene sediment. Such acceleration subsidence, in conjunction with the fault/salt geometry, contributed to the development of hydrocarbon reservoirs near the dome flanks. 69 refs., 17 figs., 1 tab.

• OSTI ID: 6360413
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:5; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
GULF OF MEXICO
GEOPHYSICAL SURVEYS
SALT DEPOSITS
GEOLOGIC HISTORY
CONTINENTAL SHELF
CROSS SECTIONS
EVACUATION
EXPLORATION
FOSSIL FUELS
GEOMETRY
GROWTH
MEXICO
NATURAL GAS
PETROLEUM
SEDIMENTS
SEISMIC DETECTION
SHAPE
THICKNESS
ATLANTIC OCEAN
CARIBBEAN SEA
CONTINENTAL MARGIN
DETECTION
DEVELOPING COUNTRIES
DIMENSIONS
ENERGY SOURCES
FLUIDS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOLOGIC DEPOSITS
LATIN AMERICA
MATHEMATICS
NORTH AMERICA
SEAS
SURFACE WATERS
SURVEYS
020200* - Petroleum- Reserves
Geology
& Exploration