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Reevaluation of the Bedford-Berea Sequence in Ohio and Adjacent States: Forced Regression in a Foreland Basin

By
Jack C. Pashin
Jack C. Pashin
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Frank R. Ettensohn
Frank R. Ettensohn
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Published:
January 01, 1995

The Upper Devonian Bedford-Berea sequence provided an early basis for models of epeiric sedimentation, but controversy regarding the origin of the sequence has arisen in recent years. This study utilized outcrop and subsurface data to help resolve this controversy and to identify factors that control depositional architecture in foreland basins. The Bedford-Berea is a siliciclastic succession that was deposited in the Appalachian foreland basin during a relaxational phase of the Acadian orogeny. The sequence represents a spectrum of depositional systems ranging from alluvial valleys to an oxygen-deficient basin floor and formed in response to a major forced regression that separated deposition of the Catskill and Pocono clastic wedges.

Reevaluation of the Bedford-Berea sequence demonstrates that the depositional architecture and paleogeographic history of foreland basins are much more elaborate than is commonly recognized. Tectonism, relict topography, differential compaction, and relative sea-level variation functioned collectively to determine the complex depositional history and paleogeography of the Bedford-Berea sequence. Among the salient features of Bedford-Berea paleogeography are an eastern platform and a western basin. The platform was characterized largely by erosion of Catskill sediment and subsequent deposition of aggradational valley-fill sequences, whereas the basin was characterized mainly by progradational delta and shelf deposits that overlie conformably the distalmost part of the Catskill clastic wedge. The platform and basin were differentiated by topography inherited from Catskill deposition, compaction of organic-rich sediment, and reactivation of basement structures along the Catskill shelf margin.

Bedford-Berea depositional history is divided into two episodes: basin filling and delta destruction. Basin filling was characterized by regressive fluvial systems that eroded Catskill strata and supplied prograding deltaic and shelf sediment to the western basin in the form of a lowstand wedge. Delta destruction began after the basin was filled with sediment. At this time, the basin was apparently undergoing flexural relaxation, which modified the lowstand wedge and gave rise to unusual facies patterns. Delta-front deposits in the western basin were uplifted and reworked, and a shelf silt blanket prograded back onto the rapidly subsiding eastern platform where estuaries were forming in the incised valleys.

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GSA Special Papers

Reevaluation of the Bedford-Berea Sequence in Ohio and Adjacent States: Forced Regression in a Foreland Basin

Jack C. Pashin
Jack C. Pashin
Search for other works by this author on:
Frank R. Ettensohn
Frank R. Ettensohn
Search for other works by this author on:
Geological Society of America
Volume
298
ISBN print:
9780813722986
Publication date:
January 01, 1995

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