--> Abstract: Stratigraphic, Paleoenvironmental, and Structurally Related Aspects of Middle and Upper Mississippian Rocks (Newman and Pennington Formations), East-Central Kentucky, by Frank R. Ettensohn; #90975 (1976).
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Abstract: Stratigraphic, Previous HitPaleoenvironmentalNext Hit, and Structurally Related Aspects of Middle and Upper Mississippian Rocks (Newman and Pennington Formations), East-Central Kentucky

Frank R. Ettensohn

New exposures of upper Valmeyeran and Chesterian rocks in east-central Kentucky reveal complex lithofacies, biofacies, and sedimentary features deposited in subterrestrial to open-marine environments during transgressional and progradational events. These complexities were compounded by synsedimentary tectonic activity on the north-south Waverly arch and an east-west basement-fault zone.

Previous HitAnalysisTop of regional stratigraphy and tectonics indicates that the Newman and Pennington Formations represent five separate transgressions and a progradational event. The lower Newman Formation represents three westerly transgressions onto the cratonic shelf from the Appalachian basin; each was ended by uplift on the Waverly arch. The upper Newman Formation and parts of the lower Pennington Formation represent a westerly Mississippian transgression onto the cratonic shelf followed by a westerly clastic progradation. The progradation was interrupted by a brief marine incursion. Upper Newman Formation carbonate rocks were deposited on a low-angle, southeasterly dipping ramp formed on exposed lower Newman Formation carbonate strata. This surface was low in relief, pitted with microkarst, and covered with a thin residual soil.

Depositional environments in the late Newman Formation transgressive phase apparently are related to the interaction of wave base and gently dipping bottom. Each upper Newman member represents a more or less distinct depositional environment. As these environments migrated westward with transgression and progradation, their lithologic members developed a sheetlike geometry with widespread distribution. Transgressive-phase members represent in ascending order terrigenous-carbonate intertidal mud-flat (Cave Branch), lagoonal (Armstrong Hill), carbonate sandbelt (Beech Creek), shallow open-marine (Haney), and deeper open-marine (lower Hardinsburg) environments. Progradational-phase members represent in ascending order shallow open-marine (upper Hardinsburg), carbonate sandbelt (lower Gle Dean), shallow, back-sandbelt marine (upper Glen Dean), lagoonal (Rowan Member, Pennington Formation), and clastic tidal channel-tidal flat (Carter Caves Sandstone Member, Pennington Formation) environments. Probable subsidence and a brief transgression (Licking River Limestone Member, Pennington Formation) interrupted the progradational event throughout the region. The overlying sandy shales, predominantly red and green in color (Bernstadt Member, Pennington Formation), represent renewed progradation with deposition in lagoonal and tidal mud-flat environments. The uppermost Pennington Member is largely absent in northern parts of the outcrop belt because of structural influence. The disconformably overlying Pennsylvanian clastic rocks represent a later, unrelated progradation in the re ion.

Many aspects of Newman and Pennington stratigraphy, such as depositional and erosional thinning, internal disconformities, disjunct-unit distribution, and different facies on opposite sides of structural features, are related to synsedimentary tectonic activity along the Waverly arch and a basement-fault zone. Although the Mississippian-Pennsylvanian boundary appears to be everywhere disconformable in the area, progressively more of the Mississippian section is absent as the structural features are approached. The most complete sections are south and east of these structures.

AAPG Search and Discovery Article #90975©1976 GCAGS- GC Section SEPM Annual Meeting Shreveport, Louisiana