Late Quaternary shelf margin deltas, northwest Gulf of Mexico

Conference · Sun Apr 01 04:00:00 EST 1984 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6528820

Suter, J R; Berryhill, H L

Deltaic deposition during a eustatic sea level fall occurs in two phases, each controlled primary by the morphology of the sea floor and the rate of subsidence. The initial, or shelf phase of deposition, produces deposits similar to most modern deltas, although the rates of progradation are enhanced by the cumulative effects of sedimentation and absolute sea level fall. Such deposits are relatively thin and widespread, and internally are characterized by low angle clinoform reflections. The second, or shelf margin phase, results when sea level reaches the shelf edge and deposition occurs on the upper continental slope, where steeper sea floor gradients and more rapid subsidence produce a more localized deposit. Interpretations of over 35,000 km of single channel high-resolution seismic profiles of the continental shelf and upper continental slope of the northwest Gulf of Mexico indicate the existence of 5 late Wisconsinan shelf margin deltas, including the ancient Rio Grande and Mississippi deltas. The deltas were recognized by geomorphic pattern, high angle clinoform seismic reflections, and association with buried river systems. Isopach patterns show that the deltas range in size up to 5000 km/sup 2/ (1930 mi/sup 2/) and reach thicknesses of over 160 m (525 ft). The deposits are elongate parallel to depositional strike, indicating subsidence of the shelf margin as a whole, as well as reworking by marine processes. Internal reflection patterns show the deltas to be fluvially dominated. Multiple lobes can be recognized in most of the deltas studied, resulting both from short term eustatic sea level fluctuations and delta switching.

• Research Organization: Louisiana Geological Survey, Baton Rouge
• OSTI ID: 6528820
• Report Number(s): CONF-8405216-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 68:4
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALLUVIAL DEPOSITS
ATLANTIC OCEAN
CARIBBEAN SEA
CENOZOIC ERA
CONTINENTAL MARGIN
CONTINENTAL SHELF
DEPOSITION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
GULF OF MEXICO
QUATERNARY PERIOD
SEAS
SEDIMENTATION
SEISMIC SURVEYS
SURFACE WATERS
SURVEYS