| Summary: | The Geological Time Scale is a fundamental tool for geoscientists that is revised and republished every eight years. It is a representation of the geologic record - a system composed of radioisotope dates interpolated into fossil successions that can be used to correlate rocks, used a standard to which local successions can be compared, and as a framework for the rate calculations needed in geologic and evolutionary studies. The current Geologic Time Scale for the Ordovician Period (GTS 2012) is composed of a sequence of species ranges from a group of fossils called graptolites with interpolated radiometric dates. Building a global geologic time scale requires correlating between different biofacies. These correlations are difficult because the fossil organisms used to demonstrate time equivalency may live in non-overlapping environments, as well as other biases inherent in the fossil record. In this thesis I will attempt to combine stratigraphic range data from different kinds of Ordovician fossils in order to improve the precision and usefulness of the Ordovician time scale. I will integrate the range data from graptolites (deep water biofacies), chitnozoans and conodonts (shallow water biofacies) in the Middle Ordovician rocks of Newfoundland. I will conduct field studies to make new, detailed fossil collections and use these in conjunction with already published literature. In particular I will look for unusual co-occurrences of both types of fossils on single bedding planes, which have been reported in the geologic literature from Newfoundland. I plan to use the computer-assisted graphic correlation program CONOP9 to create composite taxon ranges from many localities based on the first and last appearance data for each species and then construct a more precise correlation network between sections that represent disparate biofacies. This correlation network can be used in the revision of the Ordovician Time Scale for 2020.
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