Pliocene-Pleistocene continental deposits in western Kentucky: A new look at regional stratigraphy and depositional history
Conference
·
· Geological Society of America, Abstracts with Programs; (United States)
OSTI ID:6137231
- Martin Marietta Energy Systems, Inc., Paducah, KY (United States)
Pliocene and Pleistocene age sediments of the northernmost Mississippi Embayment consist of a thick sequence of continental deposits which rest unconformably on Cretaceous through Eocene strata. The continental deposits have been tentatively correlated to the Pliocene Mounds Gravel and Pleistocene Henry and Equality Formations of southern Illinois. These sediments have previously been interpreted as representing alluvial fan and fluvial deposits. The continental deposits are generally divided into three lithofacies: (1) silt/clay dominated; (2) sand dominated, and (3) gravel dominated. A subsurface study utilizing approximately 300 soil borings has shown that (1) the continental deposits, particularly the gravel facies, exhibit significant local changes in thickness, (2) the upper portion of the sequence consists predominantly of finer-grained silt/clay lithofacies, and (3) sand and gravel lithofacies within the upper sequence often occur at predictable horizons. These observations indicate a paleovalley fill with distinct depositional episodes. As a result of Pleistocene base level fluctuations, stream systems became deeply entrenched in the Pliocene alluvial fan and older sediments. Fan deposits were initially transported and redeposited in a braided fluvial system. As valley alluviation continued and gradients decreased, the braided fluvial system evolved into a meandering system. During Woodfordian time, slackwater lakes created by glacial outwash dams produced extensive lacustrine deposits. At least two major episodes of lacustrine sedimentation are apparent. Significant fluctuations of lake level are recognized in the subsurface by local erosional surfaces overlain by coarser-grained sediments deposited in basinward-migrating channel and shoreline facies.
- OSTI ID:
- 6137231
- Report Number(s):
- CONF-921058--
- Conference Information:
- Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
- Country of Publication:
- United States
- Language:
- English
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Mon Aug 01 00:00:00 EDT 1988
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
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OSTI ID:5720086
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Sat Mar 31 23:00:00 EST 1984
· Am. Assoc. Pet. Geol., Bull.; (United States)
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OSTI ID:6434633
Neogene paleogeography of western Snake River plain, Idaho and Oregon
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Sat Mar 31 23:00:00 EST 1984
· Am. Assoc. Pet. Geol., Bull.; (United States)
·
OSTI ID:6376465