Depositional history and petroleum potential of Middle and Upper Ordovician of Alabama Appalachians

Conference · Thu Sep 01 00:00:00 EDT 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6555459

Benson, J D; Mink, R M

Middle and Upper Ordovician deposits occupy a significant position in the Paleozoic sequence in the southern Appalachians, since they represent a transition from passive margin carbonate to active margin clastic deposition. Middle Ordovician units show a transition from shallow-water deposits in the west to deeper water basinal deposits in the east. West of the Helena fault the Middle Ordovican is represented by peritidal to shallow subtidal lithologic characteristics of the Chickamauga Limestone. East of the Helena these shallow-water deposits are replaced by deeper water carbonates of the Lenoir and Little Oak Limestones and graptolitic shales of the Athens Formation. Red-green mudrocks of the Greensport Formation were deposited in shallow-shelf to tidal-flat environments and were in turn overlain by quartz arenites of the Colvin Mountain Sandstone, deposited as part of a shallow-barrier system. With continued uplift during the Late Ordovician, additional clastics prograded westward over the filled basin. Early Late Ordovician shallow-shelf to tidal-flat mudrocks of the Sequatchie Formation grade westward into shallow-water carbonates of the Inman and Leipers Formations. With continued input, Sequatchie clastics prograded westward and over-rode the westerly carbonates. A relative sea-level rise during the late Late Ordovican was accompanied by deposition of open-marine shelf, bioclastic limestones of the Sequatchie throughout much of the western Valley and Ridge. The petroleum potential of the Middle and Upper Ordovician sequence in the Alabama Appalachians appears to range from marginal to moderate. The existence of significant reservoirs in this area appears dependent upon the development of fracture porosity associated with Appalachian structures.

• Research Organization: Univ. of Alabama, University
• OSTI ID: 6555459
• Report Number(s): CONF-8310301-
• Journal Information: Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:9; Conference: American Association of Petroleum Geologists eastern section meeting, Carbondale, IL, USA, 3 Oct 1983
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ALABAMA
GEOLOGIC HISTORY
PETROLEUM DEPOSITS
RESOURCE POTENTIAL
EXPLORATION
APPALACHIAN MOUNTAINS
CARBONATE ROCKS
DEPOSITION
FRACTURES
GEOLOGIC FAULTS
ORDOVICIAN PERIOD
SEDIMENTARY BASINS
TECTONICS
FAILURES
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
MINERAL RESOURCES
MOUNTAINS
NORTH AMERICA
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA
020200* - Petroleum- Reserves
Geology
& Exploration