Revising the Geological Time Scale: A Multi-Clade CONOP9 Composite from the Middle Ordovician Rocks of Newfoundland
Katherine Gayle Michel
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.
Primary Advisor's Department
Stander Symposium project
"Revising the Geological Time Scale: A Multi-Clade CONOP9 Composite from the Middle Ordovician Rocks of Newfoundland" (2018). Stander Symposium Projects. 1370.