Lowstand versus highstand eustatic models for peat preservation: The coal-bearing rocks of the Breathitt Group, Eastern Kentucky
- Univ. of Kentucky, Lexington, KY (United States). Kentucky Geological Survey
Stratigraphic and chronologic studies suggest that the alternation between major coal beds and clastic rocks of the Lower and Middle Pennsylvanian Breathitt Group (Central Appalachian Basin) resulted from glacial eustacy. The typical Coal-Clastic cycle starts at the top of a major coal bed and consists of a coarsening-upward sequence of marine or brackish-water strata which is commonly truncated and overlain by a fining-upward sequence. The fining-upward sequence is overlain by a rooted paleosol which is overlain by a coal bed. In one scenario, the peat is deposited during the stable highstand period. Because of subsidence, the highstand peat deposit is drowned and covered by marine sediments. During the subsequent lowstand the marine strata are eroded to varying degrees and bare channels are developed, causing an erosional unconformity surface on the marine strata. During transgression, the rise in base-level causes sediments to aggrade within the channels, creating fining-upward sequences above the marine strata. Paleosol development and peat deposition begin again at the next highstand. In another scenario peats are deposited in a coastal setting during lowstand. As transgression proceeds from lowstand, channels backfill and all low-lying areas including peat are covered by coarsening-upward sequences. Peats are then deposited on exposed platforms during highstand. During the subsequent drop in sea level, channels are incised and highstand peats and part of the coarsening-upward sediment package is eroded. The second scenario implies a preservation bias to cyclothems caused by eustatic rates being greater than subsidence rates. Peats are probably deposited during both lowstand and highstand, but lowstand peats are more likely to be preserved.
- OSTI ID:
- 5818426
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COAL DEPOSITS
STRATIGRAPHY
KENTUCKY
PEAT
DEPOSITION
EROSION
FLUCTUATIONS
GEOLOGIC MODELS
GROUND SUBSIDENCE
SEA LEVEL
DEVELOPED COUNTRIES
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
GEOLOGY
LEVELS
MATTER
MINERAL RESOURCES
NORTH AMERICA
ORGANIC MATTER
RESOURCES
USA
VARIATIONS
011000* - Coal
Lignite
& Peat- Reserves
Geology
& Exploration