The Cincinnati Arch: A Stationary Peripheral Bulge during the Late Ordovician

Abstract

Shallow-water features, including peritidal carbonate complexes, tidally-influenced shoal-water facies, biostromes, and coincident subaerial unconformities on the peritidal complexes are restricted to the Cincinnati Arch during the Late Ordovician Taconic Orogeny. Persistence of these features along the Cincinnati Arch indicate this area experienced decreased subsidence relative to surrounding areas, forming the peripheral bulge within the Taconic foreland basin.These shallow-water features are surrounded on all sides by deeper water, shallow subtidal to deep subtidal facies. The Jessamine and Nashville Domes were prominent topographic highs on the arch and were the locus of shallow-water deposition and subaerial erosion, but many of these shallow-water features also occur in the subsurface between these two domes.The shallow-water features and unconformities on the Cincinnati Arch occur in a narrow band repeatedly throughout the Late Ordovician. The width of these features is much too narrow to have formed solely by flexure of the lithosphere and their persistent formation in the same location indicates they did not form as a viscoelastic response to orogenesis. Rather the boundary between the Grenville Front and the Eastern Granite-Rhyolite Province acted as a focusing mechanism for the orogenic load stresses to the east, producing a relatively stationary peripheral bulge. A temporal and spatial change in the stratigraphy and subsidence on the Nashville and Jessamine Domes during the Edenian likely records a northward shift of loading, possibly sedimentary loading, during the Taconic Orogeny.

Niche conservatism along an onshore-offshore gradient

“…This study focuses on the Upper Ordovi cian of the Cincinnati Arch region (Holland andPatzkowsky 2004, 2007;Patzkowsky and Holland 2007). These strata were deposited on a northward-dipping, storm-dominated, mixed carbonate-siliciclastic ramp situated at approximately 20°S (Holland 1993;Pope and Read 1997;Pope et al 2009). The region preserves facies from a wide array of depositional environments, three of which are used in this study because they are abun dantly fossiliferous and occur through much of the study interval.…”

Ocean Temperatures in the Late Ordovician: A Clumped Isotope Study of Brachiopods and Cements

“…Cincinnatian strata within the study area deposited along the crest of the Jessamine Dome contain cool, temperate water, subtidal, and peritidal carbonates (figure 3A). The interbedded carbonate and shale of the Sebree and Rome troughs surround the carbonate strata on the dome (Aucoin and Brett, 2015;Brett et al, 2012;Kolata et al, 2001;Patzkowsky and Holland, 1993;Read, 1997, 1998;Pope et al, 2012).…”

“…Subduction and the Taconic Orogeny along eastern Laurentia created the Appalachian foreland basin, and the Cincinnati Arch was a peripheral bulge within this foreland basin. The major structural components of this arch (figure3B) were the Nashville and Jessamine domes on the crest, the Rome trough to the south, and the Sebree trough to the north(Ettensohn et al, 2004;Kolata et al, 2001;Pope and Read, 1998;Pope et al, 2012).…”

Reassessment of ocean paleotemperatures during the Late Ordovician

“…The Cincinnati Arch was a peripheral bulge within that basin (Fig. 1) (Pope et al, 2012). Cool-water subtidal and peritidal carbonates were deposited on the Jessamine Dome of the Cincinnati Arch throughout the Late Ordovician (Kolata et al, 2001).…”