Facies stratigraphy and relative sea-level history - Upper Cretaceous Eutaw formation, central and eastern Alabama
- Auburn Univ., AL (USA)
The Upper Cretaceous (late Santonian-early Campanian) Eutaw Formation crops out in an east west-striking belt in the inner Coastal Plain of Alabama. Facies arrangement within the Eutaw indicates a regional paleoshoreline having depositional strike approximately parallel to and coincident with the present outcrop belt. The Eutaw Formation (40 to 120 m thick) rests disconformably on incised valleys (a type 1 unconformity) occurring at the top of the underlying Cenomanian-early Turonian nonmarine Tuscaloosa Formation. The Eutaw is topped by an erosional discontinuity that has slight relief and a discontinuous conglomeratic lag. In the outcrop and shallow subsurface, the Eutaw Formation has four main paralic and nearshore facies that are arranged in two discontinuity-bounded genetic packages of facies (or parasequences) both of which developed in a single eustatic cycle. The Eutaw facies are: carbonaceous and ostried-rich clayey silts (= back barrier); planar, trough, and low-angle cross-bedded medium-fine sands (= barrier island); fossiliferous bioturbated fine sands (= lower shoreface); and calcareous clays, silts, and sands (= inner shelf). The lower genetic package of the Eutaw Formation is bounded below by the tuscaloosa disconformity (a flooding surface) and is bounded above by a low-relief intraformational facies discontinuity. The intraformational facies discontinuity is likely a parasequence boundary developed at maximum eustatic high-stand in latest Santonian. The lower genetic package is mainly a transgressive sequence of back-barrier, barrier-island, lower-shoreface, and inner-shelf facies. The upper genetic package is mainly a progradational sequence encompassing the same set of facies as the lower genetic package.
- OSTI ID:
- 6130229
- Report Number(s):
- CONF-9010204-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:9; Conference: Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM (Society of Economics, Paleontologists, and Mineralogist) meeting, Lafayette, LA (USA), 17-19 Oct 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
ALABAMA
PETROLEUM DEPOSITS
RESERVOIR ROCK
CRETACEOUS PERIOD
DEPOSITION
DIAGENESIS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
SEA LEVEL
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC DEPOSITS
LEVELS
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
RESOURCES
USA
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences