DEPOSITIONAL ENVIRONMENTS AND STRATIGRAPHY OF THE PENNINGTON FORMATION (UPPER VISEAN-NAMURIAN A), EAST-CENTRAL KENTUCKY, U.S.A.
Ettensohn, Frank R., and Chesnut, Donald R., Department of Geology and Kentucky Geological Survey, University of Kentucky, Lexington, Kentucky U.S.A. 40506

The Pennington Formation is poorly exposed, Upper Mississippian shaley unit,
0 to 60 m. thick, representing transition between dominantly transgressive
Middle and Upper Mississippian carbonates below and dominantly regressive
Pennsylvanian clastics above in east-central Kentucky.
	Basal parts of the Pennington form a regressive, near-shore, environmental
continuum with upper parts of the underlying Newman carbonates. Dark,
fossiliferous shales at the base of the Pennington intertongue with the
underlying Newman carbonates and represent an open, channel lagoon east of a
carbonate shoal-complex represented by the upper Newman Limestone. Lower
Pennington dark shales grade upward into a tidal-flat sequence known as the
clastic member in the north and dolostone member in the south. To the north
the sequence is dominated by sparsely fossiliferous, fining-upward clastics
with many tidal features and reflects a clastic source to the northeast. To
the south, the same interval is dominated by laminated dolostones and
brecciated calcilutites; fossils are sparse and subaerial exposure horizons
are common. Overlying the clastic and dolostone members is a thin, widespread
fossiliferous limestone; it is interpreted to represent renewed eastward
transgression of a shallow sea. This limestone is overlain by a thick
sequence of silty red and green shales containing brecciated and mudcracked
dolostone lens and siltstone layers; it is unconformably overlain by lower
Pennsylvanian clastics. This upper shale unit is interpreted to represent a
lagoonal environment filled with prodelta and interdelta deposits derived from
shoal-water deltas to the east. We suspect that the Pennington was originally
gradational with overlying shoal-water delta deposits equivalent in age to the
Pochontas Formation (lower Pennsylvanian) to the east. A widespread episode
of post-Pochontas uplift and erosion, however, has destroyed upper parts of
the Pennington and any possible Pocahontas equivalents resulting in a
prominent systemic unconformity.