Regional biostratigraphy and paleoenvironmental history of Miocene of onshore and offshore Alabama
- Geological Survey of Alabama, Tuscaloosa (USA)
Subsurface Miocene sediments of coastal Alabama and the adjoining state and federal waters consist of a clastic wedge varying in thickness from less than 1,000 ft in southern Alabama to a maximum of about 6,000 ft in the northeastern portion of the Main Pass area. Relatively deep-water and open-marine transgressive basal Miocene clays and shales unconformably overlie a gently southwestward-dipping late Oligocene-earliest Miocene carbonate platform. Middle and late Miocene sediments consist of a regressive offlapping sequence of sand and shale deposited in varying neritic paleoenvironments. Analysis of planktonic and benthonic foraminifera has resulted in a refined biostratigraphic zonation of these sediments, permitting the recognition of several regional time-equivalent datum levels, or biohorizons. These biohorizons are shown on a series of subsurface cross sections that show the dramatic southwestward thickening of middle and late Miocene sediments as well as illustrate the relationships of the producing intervals within the Cibicides carstensi and Discorbis 12 interval zones. The paleoenvironmental history of the Miocene has been reconstructed on a series of paleobathymetric maps drawn for selected regional biohorizons. Among other features, these maps have proven the existence and outlined the margins of previously unrecognized shallow-meritic deltaic sediments in southeastern Mobile County and in the Chandeleur and Viosca Knoll (north) areas. Analysis of sedimentation rates, which range from less than 25 to 1,370 ft/m.y., further aids in understanding the coastal shelf, deltaic, and open-marine depositional history of the Miocene of Alabama and the adjoining state and federal waters.
- OSTI ID:
- 5111730
- Report Number(s):
- CONF-8910221-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 73:9; Conference: Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM meeting, Corpus Christi, TX (USA), 25-27 Oct 1989; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALABAMA
GEOLOGIC HISTORY
STRATIGRAPHY
CARBONATE ROCKS
FORAMINIFERA
FOSSILS
PALEONTOLOGY
SHALES
TERTIARY PERIOD
ANIMALS
CENOZOIC ERA
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGY
INVERTEBRATES
MICROORGANISMS
NORTH AMERICA
PROTOZOA
ROCKS
SARCODINA
SEDIMENTARY ROCKS
USA
020200* - Petroleum- Reserves
Geology
& Exploration