TRILOBITE FAUNAS, SEDIMENTARY FACIES AND SEQUENCE STRATIGRAPHY OF THE UPPER ORDOVICIAN (SANDBIAN-KATIAN) SUCCESSION OF MISSOURI

Abstract

The late Sandbian-Katian interval (Upper Ordovician) was a time of major environmental change across Laurentia with highest recorded sea levels of the Paleozoic. While sequence stratigraphy, environmental change and faunal turnover are generally well studied in the foreland basin of Laurentia, the mid-continent has received less attention. The Upper Ordovician units of eastern Missouri offer the opportunity to examine depositional patterns and trilobite faunas. New collections are made from the Kimmswick Limestone of Missouri that revise the trilobite systematics and biostratigraphy for the study region. The trilobite genera Raymondites, Achatella received in-depth systematic revision and phylogenetic analysis. This dissertation attempts to answer the following questions: 1) How are sedimentary facies and important erosional surfaces expressed in the shallow continental interior? 2) How do the depositional sequence boundaries identified in eastern Laurentia correlate with the mid-continent? 3) How do trilobite faunas in the mid-continent compare to other basins across Late Ordovican Laurentia? 4) Do they offer new information on the age and correlation of the Upper Ordovician succession?