Relationship between paleotopographic surface of Cambrian-Ordovician Knox Group and oil and gas entrapment in Kentucky
Cambrian-Ordovician dolostones of the Knox Group constitute one of the largest occurrences of this rock type known in the US. In Kentucky, the Knox carbonate sequence attains thicknesses of more than 3500 ft. Mudstone and wackestone are dominant in the upper Knox, with lesser amounts of packstone and grainstone. The Upper Cambrian to Lower Ordovician carbonate sequences in Kentucky resulted from carbonate sedimentation on a cratonic platform in shallow, low-energy marine environments. Relative structural quiescence existed during this time. The thick sequence of shallow-water carbonates suggests that the rate of deposition generally kept pace with subsidence of the craton. Geologic environments and climatic conditions during this period were similar to those of the Bahamas today. Warm climate, sporadic rainfall, and dry trade winds probably accounted for the net loss of water by evaporation and the resulting hypersaline conditions. The paleotopographic surface that developed on top of the Knox Group is of considerable economic importance because of potential hydrocarbon entrapment at or near the unconformity. Areas where permeable and porous zones developed on the exposed Knox surface due to erosion and weathering provide reservoir conditions; also, the unconformable surface of the Knox was sealed by an overlapping impermeable formation capable of entrapping hydrocarbons. Because of pressures exerted, hydrocarbons driven by fluids or gas may migrate along the eroded Knox surface laterally and upward onto paleotopographic highs. These conditions increase the probability of finding commercial oil and gas deposits in the Cambrian-Ordovician Knox in Kentucky.
- Research Organization:
- Univ. of Kentucky, Lexington
- OSTI ID:
- 5867172
- Report Number(s):
- CONF-8710197-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 71:9; Conference: American Association of Petroleum Geologists Eastern Section meeting, Columbus, OH, USA, 7 Oct 1987
- Country of Publication:
- United States
- Language:
- English
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Sedimentological cross section of Cambro-Ordovician carbonate shelf (Knox group, Conasauga Formation) in central Alabama: facies, diagenesis, potential reservoirs
Sedimentological cross section of Cambro-Ordovician carbonate shelf (Knox group, Conassauga Formation) in central Alabama: facies, diagenesis, potential reservoirs
Related Subjects
03 NATURAL GAS
KENTUCKY
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
EXPLORATION
GEOLOGIC TRAPS
CAMBRIAN PERIOD
DOLOMITE
GEOLOGIC FORMATIONS
ORDOVICIAN PERIOD
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERAL RESOURCES
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PALEOZOIC ERA
RESOURCES
USA
020200* - Petroleum- Reserves
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& Exploration
030200 - Natural Gas- Reserves
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& Exploration