Preservation of coastal stratigraphy during the Holocene transgression, southwest Louisiana continental shelf
Compiled curves for the Gulf of Mexico show that sea level during the Holocene transgression rose continuously at varying rates on a scale of several thousand years. Within this primary variability, shorter term oscillations of sea level are indicated by the existence of multiple preserved depositional and erosional features on the southwest Louisiana continental shelf, recognizable on high resolution seismic reflection profiles. During the late Wisconsinan withdrawal, fluvial-deltaic systems extended themselves across the exposed continental shelf, ultimately reaching of the shelf margin. Initial transgression resulted in the eroding of a wave cut terrace from -100 to -70 m, a cypress stump from the northern edge of which was dated at 11,170 +/- 110 years B.P., and creating a composite fluvial system within pre-existing Late Wisconsinan stream channels. Resumed transgression reworked the Pleistocene deltaic sediments into a series of east-west trending sandy shoal deposits, each representing still stand positions. Several of these shoals are associated with east-west oriented lagoonal systems established in the submerged fluvial channels. Repeated erosion by the transgressing shoreface and reduced sediment supply caused by the eastward shift of the Mississippi depocenter has resulted in the subaqueous exposure of Pleistocene sediments being the sandy shoals and estuarine deposits. As sea level approached its present position, an early Holocene lobe of the Mississippi delta was deposited in the area. Its subsequent abandonment and reworking has produced a stratigraphic sequence resembling that on the outer shelf.
- Research Organization:
- Louisiana Geological Survey, Baton Rouge (USA)
- OSTI ID:
- 6273946
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580100* -- Geology & Hydrology-- (-1989)
CENOZOIC ERA
CONTINENTAL MARGIN
CONTINENTAL SHELF
DEPOSITION
EROSION
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGY
GEOPHYSICAL SURVEYS
LEVELS
LOUISIANA
NORTH AMERICA
QUATERNARY PERIOD
ROCKS
SEA LEVEL
SEDIMENTARY ROCKS
SEDIMENTS
SEISMIC SURVEYS
STRATIGRAPHY
SURVEYS
USA
VARIATIONS