Ocean Bottom Currents and Their Effects on Ordovician Brachiopods #2

This article submitted by Sarah Beasley, Jim Foley, Pete Rivizzigno [e-mail: ] on 10/7/97.

In our study we shall examine slabs of Ordovician sediment and the orentianion of the species on them. In our study we hope to
determine the relative set and drift of the Ordovician ocean currents and their role in shaping ocean floor life, specifically the lives of brachiopods. We expect slower currents to reveal smaller species with a concave orientation, and with a greater abundance of species. In faster currents we expect to see larger species with a convex orientation and a lower species density. We think that we will find this because faster currents will carry and distribute more, leaving a lower density of species. We plan to collect an undetermined amount of slabs from the arnheim, waynesville, liberty and whitewater formations. On each slab we will determine the orientation of the fossils (angle, direction, position), and the number of species in a controlled specified area on each slab. Problems might arise in
finding undisturbed slabs of sediment. We hope to find methods that will help us minimize this problem.

We feel that this study is important because it assists us in understanding the way the oceans behaved in the past. This in turn allows us to make inferences about the ecosytems and weather during that time period. Furthermore, these studies could help in predicting and understanding current and future oceanic processes. According to previous reaserch done by Reuben Ross(1975) on this subject, currents did have an affect on trilobyte distribution. Hannelore Krawinkel(1995) also found that, "fossil concentrations can be grouped into fossil concentrations produced by non-turbulent shelf currents..."

In order to collect our data, we will obtain 3 slabs per formation, we will then mark north on the slabs before removing them from their original positions. Then on each slab we will determine the frequency of species, their size, and orientation(concave, convex, and their angle). The following is a list of what will be included on our data sheet:
formation
location within formation
size of specemins
orientation of specemins
slab size
number of slabs taken from each formation
number of species per slab

Bibliography:

Krawinkle, Hannelore, and Seyfried Hartmut. "Sedimentologic, palaeoecologic, taphonomic and ichnologic criteria for high-resolution sequence analysis: a practical guide for the identification and interpretation of discontinuities in shelf deposits." Sedimentary Geology, 102(1996) 79-110.
Ross, Reuben James Jr. "Early Paleozoic trilobites, sedimentary faceis, lithospheric plates and ocean currents." Fossils and Strata, n.4 (1975) 307-329.

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