Modeling the nature and development of major paleozoic clastic wedges in the Appalachian Basin, USA

The Paleozoic stratigraphic succession of the Appalachian Basin is punctuated by several major clastic wedges of Middle Ordovician to Permian age, which have been interpreted to represent "deltas" in classic literature on the basin. So-called deltas like the Blount, Queenston, Bloomsburg, Catskill, Bedford-Berea, Price-Pocono-Borden, and Allegheny may contain deltaic components, but in fact represent delta complexes or clastic wedges that may have extended laterally more than 1000 km along basin strike and contain a variety of terrestrial, marginal-marine, and open-marine facies. These complexes commonly developed in post-orogenic, compressional, tectonic regimes and are related to them through provenance and the flexurally generated accommodation space, which they filled. Specifically, those complexes that developed in concert with early subduction-type orogenies are characterized by a predominance of marine sediments and one or more, distinctive, four-part, stratigraphic sequences, whereas the final Alleghenian delta complex, which developed during continent-continent collision, is characterized by largely terrestrial sediments that lack the distinctive sequence. Because the timing, character, and distribution of stratigraphic sequences in a delta complex may largely reflect lithospheric flexural responses to deformational loading and relaxation in the adjacent orogen, sequence characteristics can be potentially useful in corroborating the nature and presence of past compressional regimes, as well as the likely intervention of extra-orogenic influences like eustacy.