The silurian of central Kentucky, U.S.A. Stratigraphy, palaeoenvironments and palaeoecology

Frank R. Ettensohn, R. Thomas Lierman, Charles E. Mason, William M. Andrews, R. Todd Hendricks, Daniel J. Phelps, Lawrence A. Gordon

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Silurian rocks in Kentucky are exposed on the eastern and western flanks of the Cincinnati Arch, a large-wavelength cratonic structure separating the Appalachian foreland basin from the intracratonic Illinois Basin. The Cincinnati Arch area experienced uplift during latest Ordovician-early Silurian time, so that the exposed Silurian section is relatively thin due to onlap and post-Silurian erosional truncation on the arch. On both flanks of the arch, dolomitic carbonates predominate, but the section on the eastern side reflects a more shale-rich ramp that faced eastern Appalachian source areas. In the Silurian section on the western side of the arch, which apparently developed across a platform-like isolation-accommodation zone, shales are rare except during some highstand episodes, and rocks in the area reflect deposition across a broad, low-gradient shelf area, interrupted by structurally controlled topographic breaks. Using the progression of interpreted depositional environments and nearshore faunal communities, a relative sea-level curve, which parallels those of previous workers, was generated for the section in Kentucky. While the curve clearly shows the influence of glacial eustasy, distinct indications of the far-field, flexural influence of Taconian and Salinic tectonism are also present. In fact, at times, regional tectonic subsidence seems to have overwhelmed the effects of glacio-eustasy. Regional angular truncations in the section, as well as overlying bentonitic shales and a dysaerobic fauna in the deepest-water part of the section (Estill Shale), are best explained in terms of far-field tectonic subsidence accompanying the first tectophase of the Salinic Orogeny in the Appalachian area.

Original languageEnglish
Pages (from-to)159-189
Number of pages31
JournalMemoirs of the Association of Australasian Palaeontologists
Issue number44
StatePublished - 2013

Keywords

  • Appalachian basin
  • Basement structures
  • Cincinnati arch area
  • Depositional environments
  • Far-field tectonics
  • Faunal communities
  • Glacial eustasy
  • Kentucky
  • Salinic orogeny
  • Silurian
  • Taconian orogeny

ASJC Scopus subject areas

  • Paleontology

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