Chitinozoans from the Ordovician-Silurian Boundary Beds in the Eastern Cincinnati Region in Ohio and Kentucky

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Representatives of seven species of chitinozoans, one of which is new (Ancyrochitina belfastensis n. sp.), were isolated from samples of the lowermost Silurian Belfast Member and of slightly younger beds of the Brassfield Formation and of the Upper Ordovician Preachersville Member of the Drakes Formation at two localities in southern Ohio and north-central Kentucky in an attempt to determine the size of the stratigraphic gap at the Ordovician-Silurian paraconformity. Based on comparisons with successions in Estonia and on Anticosti Island, Quebec, the chitinozoans suggest that the stratigraphic gap between the systems, which is likely to be due to a global sea level drop associated with the Gondwana glaciation, represents an interval from the Ashgillian D. complanatus Zone to the early Llandoverian C. cyphus Zone and hence corresponds to about four graptolite zones. The present study is the first record of Silurian chitinozoans from Ohio.


Author Institution: Geological Survey of Sweden ; Department of Geology and Mineralogy, The Ohio State University



The Ohio Journal of Science. v85, n4 (September, 1985), 175-183