Glacial eustatic mechanism (marine ice sheet decoupling) for isolation of shelf sand bodies
The formation of shelf sand bodies requires a mechanism for delivering sand to the offshore environment (below wave base or ravinement depth). The distribution of these sand bodies (sheetlike versus patchy distribution) is greatly influenced by the rate of shoreline translation. Holocene sand bodies of the north Texas shelf illustrate these influences well, as does a map depicting the thickness and lateral extent of sand bodies that would be formed were sea level to rise rapidly again. Preliminary observations imply that wave-dominated deltas have actively (via plume mechanisms) and passively (via transgressions) been key factors in delivering very fine to fine sands to the offshore environment. Other sand bodies may be relict shoreline deposits that, like the modern Galveston Island barrier, prograded into the offshore environment so that their roots were preserved beneath the ravinement surface. Recently gathered evidence from the Antarctic continental shelf indicates that ice sheets were formerly grounded to the shelf edge and that the retreat of these ice sheets from the shelf was rapid but sporadic. The subsequent ''drawdown'' of marine ice sheets and the associated eustatic rise in sea level during any single event was probably on the order of 5-10 m in a few centuries. Such a sea level rise would manifest itself in rapid translations of the shoreline of about 10-25 km on the Texas shelf. Several of these eustatic events are believed to have occurred during the Holocene, and were probably instrumental in isolating shelf sand bodies. Sand bodies associated with the most recent rapid rise occur within 30 km of the present shoreline and their origin is being investigated using high-resolution seismic (uniboom) profiling and coring.
- OSTI ID:
- 6633694
- Report Number(s):
- CONF-880301-
- Resource Relation:
- Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20 Mar 1988
- Country of Publication:
- United States
- Language:
- English
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03 NATURAL GAS
ANTARCTIC REGIONS
GLACIERS
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
ORIGIN
CONTINENTAL SHELF
EXPLORATION
GEOLOGIC HISTORY
GEOPHYSICS
ICE CAPS
OCEANOGRAPHY
OFFSHORE SITES
PETROLEUM GEOLOGY
SANDSTONES
SEA LEVEL
SEISMIC SURVEYS
SHORES
TERTIARY PERIOD
TEXAS
CENOZOIC ERA
CONTINENTAL MARGIN
FEDERAL REGION VI
GEOLOGIC AGES
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GEOPHYSICAL SURVEYS
ICE
LEVELS
MINERAL RESOURCES
NORTH AMERICA
POLAR REGIONS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
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USA
020200* - Petroleum- Reserves
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030200 - Natural Gas- Reserves
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