MCLAUGHLIN, PATRICK I., University of Cincinnati Dept. of Geology, Cincinnati, OH

ABSTRACT: This study represents a detailed analysis of the process sedimentology and stratigraphic architecture of a transgressive systems tract in a storm dominated depositional succession within the Bromley Shale

Point Pleasant Formationlower Kope Fulton beds succession (Upper ShermanianEdenian). The study interval includes a succession of strata approximately 30 meters thick which is well exposed in closely spaced outcrops for over 130 kilometers to the south of Cincinnati. Until recently the detailed regional stratigraphy of these rocks was little explored, and no detailed correlated framework existed for this supposedly mosaic interval. Conversely, high-resolution sequence stratigraphic analysis indicates that individual beds or bed bundles show considerable lateral continuity. Event stratigraphy of hardgrounds, k-bentonites and seismites within the Point Pleasant Formation has also been implemented to corroborate correlations. The correlations permit regional delineation of facies trends that have refined the orientation of depositional strike along the southeast margin of the Sebree Trough, during the time interval represented by this succession. The paleogeography of the Late Ordovician Cincinnati Arch region is presently under major revision and this study has further aided in that revision. This research has recognized regional depositional patterns and cyclicity within this succession. Finally, using these data we have reconstructed the patterns of environmental and tectonic change of the study interval. Results of this study challenge existing literature that suggests that there is no cyclicity within these units. In fact, these data permit recognition of similar stratal patterns in Ohio-Kentucky and the Taconic foreland in New York and Ontario.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid