Revised sequence stratigraphy of the upper Katian Stage (Cincinnatian) strata in the Cincinnati Arch reference area: Geological and paleontological implications

Comparisons of Late Ordovician ecosystem dynamics before and after the Richmondian invasion reveal consequences of invasive species in benthic marine paleocommunities

“…Geologic Setting.-During the Late Ordovician, the Cincinnati Basin of modern Ohio, Indiana, and Kentucky was located along a gently dipping carbonate ramp in a shallow (∼30 m) epeiric sea (Holland 1993), situated distal to the Taconic foreland basin, approximately 20°S (Scotese and McKerrow 1990). The region consists primarily of interbedded fossiliferous limestones and shale originally divided into third-order stratigraphic sequences, C1-C6 (Holland and Patzkowsky 1996), and more recently revised and split into eight sequences representing 7 Myr (Brett et al 2020). Here we use the revised nomenclature of Brett et al (2020) when referring to sequences (C1-C8) ( Fig.…”

“…The region consists primarily of interbedded fossiliferous limestones and shale originally divided into third-order stratigraphic sequences, C1-C6 (Holland and Patzkowsky 1996), and more recently revised and split into eight sequences representing 7 Myr (Brett et al 2020). Here we use the revised nomenclature of Brett et al (2020) when referring to sequences (C1-C8) ( Fig. 1).…”

“…1). Today, the region consists primarily of fossiliferous limestones and shale, and four depositional environments are widely recognized within each sequence: offshore, deep subtidal, shallow subtidal, and peritidal (Frey and Pemberton 1985;Brett and Baird 1986;Holland 1993;Holland and Patzkowsky 1996;Holland et al 2001;Brett et al 2015Brett et al , 2020. Previous studies have argued that ecological stability (i.e., low turnover) existed throughout the C1-C3 sequences across onshore/offshore gradients, with a subsequent breakdown in the C4 sequence and gradient reestablishment in the C5-C7 sequences (Holland and Patzkowsky 2007).…”

“…The invasion is preserved in the Sunset through the Clarksville Members of the Cincinnatian Series (C4 and C5B lithostratigraphic units of Brett et al [2020]). The invasion was a pulsed event, with the most significant phase occurring abruptly in the C5, in the Clarksville-middle Rowland Member (C5B; Brett et al 2020). Brief, unsuccessful repeated invasions occurred in the C4 sequence and resulted in the extinction of incumbent taxa (Brett et al 2020).…”

“…The dark gray area represents the extent of Ordovician rock exposed at the surface in the region. The simplified stratigraphic column is modified after Brett et al (2020). See also Holland and Patzkowsky (1996).…”