Geological Society of America

31 D6. Sedimentary Geology (Posters)

Tuesday, 17 April 2018
8:00 AM - 5:30 PM
First Floor Lobby

STRATIGRAPHIC REVISION AND HIGH-RESOLUTION CHRONOSTRATIGRAPHIC CORRELATION OF THE SILURIAN BAINBRIDGE GROUP, ILLINOIS BASIN

Paper number: 31-8
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Neo E.B. McAdams Presenting Author
University of Iowa, Iowa City, IA
Bradley Cramer
University of Iowa Dept of Earth & Environmental Sciences, Iowa City, IA
Alyssa M. Bancroft
Indiana University, Bloomington, IN
Michael Melchin
St. Francis Xavier Univ, Antigonish, NS
Joseph Devera
Prairie Research Institute, University of Illinois, Carterville, IL
James Day
Illinois State University, Normal, IL

Abstract

The Illinois Basin contains a thick succession of poorly exposed Silurian strata, which, until recently, have been assigned to stratigraphically lumped formations and correlated only approximately at the series level. Recent work on the Schlamer #1 Core and several outcrops reveals the lithostratigraphic character and biostratigraphic content of the units, and demonstrates that they capture a series of global change events (Ireviken, Mulde, and Lau positive carbon isotope excursions). This new knowledge will enable stratigraphic revision and high-resolution global chronostratigraphic correlation of these strata. The ‘Bainbridge Formation’ should be revised as a group, with the former members elevated to formational status. The Bainbridge Group should contain the Seventy-Six Shale (uppermost Telychian-lowermost Sheinwoodian), St. Clair Formation (Sheinwoodian-Homerian), and the Moccasin Springs Formation (Gorstian-Pridoli). It is overlain by the Bailey Formation (?Pridoli-Devonian) and unconformably underlain by the Sexton Creek Formation (Aeronian-?Telychian). The Seventy-Six can be correlated into Arkansas, where it could replace the confusing term “’button shale’ of the Cason Fm.” The Moccasin Springs Fm. should be composed of four members: Greens Ferry, Sheppard Point, Lithium (new), and Randol members. Global series and stage boundaries can be correlated using integrated conodont-graptolite-carbon isotope bio-chemostratigraphy.

Geological Society of America Abstracts with Programs. Vol. 50, No. 4

doi: 10.1130/abs/2018NC-313090

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