Holocene relative sea level rise and subsidence in northern Gulf of Mexico
The analysis of more than 90 tidal gauge records, 10,000-km high resolution seismic profiles, 500 vibracores, and 250 radiocarbon dates led to the development of a new sea level history for the Louisiana coastal zone and adjacent continental shelf for the last 8000 years. Now re-interpreted, the original single delta plain is seen as actually two individual, imbricated shelf-phase delta plains deposited at different sea levels. Termed the modern and late Holocene, these two delta plains are separated by a regional shoreface refinement surface, which can be traced updip to the relict-transgressive Teche shoreline. The Late Holocene delta plain was deposited during a seal level stillstand 6 m below the present, 3000-7200 years ago. A 5 to 6-m eustatic-enhanced relative rise in sea level 2500-3000 years ago at a rate of 101.2 cm/yr led to the complete transgressive submergence of the lower late Holocene delta plain. Sea level reached its approximate position about 2500 years ago, and since then the Mississippi River has built the modern delta plain consisting of the abandoned St. Bernard and Lafourche delta complexes and the active Balize and Atchafalaya delta complexes. In the abandoned delta complexes, a subsidence-enhanced relative sea level rise between 0.60 and 0.65 cm/yr in young sediments (500-1000 years B.P.) and 0.30 and 0.35 cm/yr in older sediments (1000-2000 years B.P.) is occurring. These subsidence rates compare well to the relative sea level rise in rates of 0.25-0.55 cm/yr recorded by the Louisiana tide gauges between 1930 and 1960. Since 1960, these gauges have recorded a dramatic acceleration in the rate of relative sea level rise, on the order of 1.25-1.50 cm/yr. These rates are consistent with the EPA forecast of relative sea level rise acceleration due to global warming.
- Research Organization:
- Louisiana Geological Survey, Baton Rouge (USA)
- OSTI ID:
- 5794118
- Report Number(s):
- CONF-880301-
- Journal Information:
- AAPG Bull.; (United States), Vol. 72:2; Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20-23 Mar 1988
- Country of Publication:
- United States
- Language:
- English
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