Stratigraphic interpretation of the Ordovician of the Appalachian Basin and implications for Taconian flexural modeling

Abstract

Models that reconcile the thicknesses of various Appalachian stratigraphic sequences in terms of subsidence associated with thrust loading are based on various assumptions about regional stratigraphy. Different assumptions, based on a different interpretation of Middle and Upper Ordovician stratigraphy, suggest that the geometry of lithospheric flexure due to Taconian thrust loading may have been different than predicted by existing models. Taconian flysch facies restricted to the eastern margin of the outcrop belt is the basis for identifying a thrust load‐induced foredeep. Coeval shallow marine facies were probably beyond the limit of thrust load influence. Stratigraphic thinning near the transition between the flysch and shallow marine facies is interpreted as a peripheral bulge and is located within the Valley and Ridge. Comparison is made with the Timor area north of Australia. Thrust load‐induced foredeeps and peripheral bulges predicted by this model are much narrower than predicted by previous models.