REFINED RICHMONDIAN STRATIGRAPHY OF CENTRAL TENNESSEE

A third-order sequence stratigraphic framework for the Richmondian Stage (late Ordovician, late Katian) has been established for the Nashville Dome for more than two decades and was established by the seminal work of Holland and Patzkowsky. However, this framework can be further amended and refined to provide researchers with an improved temporal scaffolding for studies in the region. To this end, the fourth-order sequence stratigraphic framework of Brett et al. (2020; Palaeo-3) for the Richmondian Stage of the Jessamine Dome, Kentucky has been extended to central Tennessee via integrated stratigraphy (sequence stratigraphy, chemostratigraphy, and biostratigraphy). Although most classic sections are now poorly exposed a series of five major roadcuts and newly excavated 18-meter industrial park succession provides an outstanding composite section for the Arnheim-Sequatchie succession. A series of key surfaces and marker beds including ferruginous firmgrounds and phosphatic pebble beds, distinct shell-rich limestones, and two widespread deformed (seismite) horizons permit high-resolution correlation and recognition of about 10 small-scale (4^th order?) depositional sequences. A combination of the newly identified sequence stratigraphic surfaces and marker beds, conodont biostratigraphic data, carbon stable isotope data, and macrofaunal assemblages. permits the following tentative correlation with the classic Cincinnati Arch reference section.

1. a) "Arnheim Formation" of the Nashville Dome is in part correlative with the Arnheim Formation of the Jessamine Dome (sequences C4A and C4B) and in part correlative with the Waynesville Formation (sequences C5A–C5C); a major faunal change occurs at the distinctive phosphatic corrosion surface forming the C5C boundary
2. b) The Sequatchie Formation of central Tennesse is correlated with the upper Waynesville/Rowland Formation (sequence C6A).
3. c) Lower grainstones and lime mudstones of the Fernvale Formation are probably equivalent to the Liberty and Whitewater Formations of the Jessamine Dome (sequences C6B–C7B).
4. d) The upper locally fossiliferous mudstone siltstone unit of the Fernvale Formation ( the Mannie Shale Member) is equivalent to the Elkhorn Formation (sequences C8A and C8B) of the Cincinnati Arch.