102 Paleontology (Posters) III - Diversity and Paleoecology

Monday, 1 November 2010
8:00 AM - 6:00 PM
Hall D

USING FAUNAL GRADIENT ANALYSIS TO RECONSTRUCT FINE-SCALE, REGIONAL PALEOENVIRONMENTAL HISTORY IN THE KOPE FORMATION (CINCINNATIAN SERIES, UPPER ORDOVICIAN) OF OHIO AND KENTUCKY

Paper number: 102-18
Program: Technical Sessions
Time: 8:00 AM – 6:00 PM

Authors

Abstract

In the Kope Formation (Cincinnatian Series), gradient analysis has been effective in quantifying subtle, environmentally-related variations in the stratigraphic and geographic distributions of marine assemblages. The outcomes of these studies are useful for establishing stratigraphic correlations and for reconstructing a regional history of paleoenvironmental change at broad-scales. However, small-scale patterns are obscured by variability in biotic composition caused by patchiness in the distribution of fossils across beds. Previous work has shown that patchiness can be smoothed by 1) collecting multiple samples from each bed at one locality, and 2) grouping samples from individual beds into bedsets. This has proven to be an effective way to examine biological signals from the Kope Formation at scales less than one meter. Up to now, this sampling protocol has only been applied to one relatively small interval within the Kope Formation (Alexandria Submember, approximately 8 m thick) at a single locality.

The goal of this project is to expand upon this by sampling a larger stratigraphic interval at multiple localities. This will: 1) provide a further test of the utility of this sampling protocol to capture fine-scale biotic signals; 2) determine whether small-scale shifts in composition are uniform among localities and thus provide a basis for small-scale correlations; and 3) enable the establishment of a highly-resolved reconstruction of paleoenvironmental change that can serve as a foundation for other studies in the Kope Formation. Results show that this technique for removing patchiness maintains its utility in detecting subtle biotic signals when applied across the region. With this, a high-resolution reconstruction of paleoenvironment is produced that conveys more information than relying on lithofacies alone. Although stratigraphic trends among localities are not completely uniform, there are recognizable patterns from outcrop to outcrop that serve as vital corroboration for small-scale stratigraphic correlations. Differences among localities likely reflect localized shifts in environment over time.