Structure and tectonic evolution of the transitional region between the central Appalachian foreland and interior cratonic basins

• Published in: Tectonophysics 1999-05, Vol.305 (1), p.205-223
• Main Authors: Root, Samuel, Onasch, Charles M
• Format: Article
• Language: English
• Subjects: basement arch; craton; fault reactivation; forebulge
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/S0040-1951(99)00022-0

The transitional region between the central Appalachian foreland basin and Michigan and Illinois interior cratonic basins is characterized by first and second order structures related to plate convergent processes at the Laurentian plate margin. The first order structures are the Waverly and Cincinnati arches believed to be forebulges associated with the Taconic and Alleghanian orogenies, respectively. The second order structures are basement faults that exhibit a protracted history of recurrent displacements. First and second order structures are linked in that the basement faults have had a major effect in controlling the location and uplift history of the arches. The Waverly and Cincinnati arches share many similarities that suggest a common process of arch development. The Waverly arch developed over the low density rocks in the Central Metasedimentary belt of the Grenville province near its structural contact with the Central Gneiss belt. Uplift on the arch commenced during passive margin development in the Cambrian, but reached its maximum development at the end of the Middle Ordovician Taconic orogeny. Reactivation of faults along the arch continued as late as the Pennsylvanian. The Cincinnati arch as expressed in the Precambrian basement surface is coincident with the underlying Grenville front on a regional scale. The front is a major crustal suture which served to localize and control the history of the Cincinnati arch. Local deviations between the location of the arch and front are explained by the presence of Proterozoic rift basins filled with low density sedimentary rocks, by interactions between the developing Appalachian, Michigan, and Illinois basins, and by a northward decrease in Alleghanian tectonic loading. In a pattern similar to the Waverly arch, the Cincinnati arch began its history with a period of regional uplift as early as the Middle to Late Ordovician followed by maximum arch development in the Pennsylvanian in response to the Alleghanian orogeny. Neither arch showed significant migration following initial development as predicted by general models of forebulge development. We attribute this to the effect of preexisting basement anisotropies, such as lithotectonic boundaries, which served to control the initial location of the forebulge and affect its subsequent history. A third major arch, the Kankakee arch, occurs in the western part of the transitional region and is oriented at right angles to the other arches. Unlike the Wa