Use of Sequence Stratigraphic Concepts to Correlate Across Nonmarine Successions without thick Coals in the Pennsylvanian of Southeastern Ohio
Kevin D. Kallini¹ and Elizabeth H. Gierlowski-Kordesch²
¹TRC Environmental Corporation, Cincinnati OH 45242, [email protected]
²Dept. of Geological Sciences, Ohio University, Athens OH 45701, [email protected]
Traditional approaches to mapping the Pennsylvanian strata within the Appalachian foreland basin of the eastern United States have been based on the tracing of key marine zones and coal beds. This is difficult where thick coal beds and marine limestones are mostly absent in some portions of the continental strata of the late Pennsylvanian in the northern Appalachian basin. The subdivision and mapping of marine/terrestrial strata based on unconformity-bounded sequences using sequence-stratigraphic methods can potentially produce good stratigraphic correlations. Sequence stratigraphic applications to solely nonmarine rocks have involved floodplain facies using paleosol horizons as unconformity-bounded sequences, but this requires detailed geochemical work and extensive core/outcrop data. The recognition of three types of nonmarine systems tracts of (1) channel-dominated, low-accommodation, (2) paleosol-dominated, low- accommodation, and (3) lacustrine-dominated, high-accommodation system tracts indicates that lacustrine sequences can be considered for stratigraphic correlation.
The Stewart Quadrangle in Athens County, situated in southeastern Ohio, contains Pennsylvanian to Permian rocks of the upper Conemaugh, Monongahela, and Dunkard Groups characterized as “cyclothems” that are interpreted as low-gradient distal deposits of a foreland basin containing siliciclastic and carbonate rocks with rare thin coals. The siliciclastics comprise paleosols, siliciclastic lake deposits, and channel sandstones while the carbonates are interpreted as lacustrine and palustrine limestones. The correlation potential of the freshwater limestones has never been studied.
A detailed, bedrock-geologic map of the Stewart 7.5-minute Quadrangle in Athens County, Ohio, was prepared in order to test the application of nonmarine sequence- stratigraphic methods for correlation. Mapping data included measured stratigraphic sections, geologic maps, drillers’ logs, continuous bedrock core descriptions, and aerial photographs. In order to identify similar sequences from one location to the next, logs were evaluated based on the presence of siliciclastic vs. carbonate lithologies. Limestones were identified as lacustrine-dominated system tracts with the other discontinuous siliciclastic lithologies grouped into one package of paleosol- and channel-dominated system tracts because differentiation between these system tracts is difficult. Correlation across this quadra
AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012