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UNIVERSITY OF CINCINNATI _____________ , 20 _____ I,______________________________________________, hereby submit this as part of the requirements for the degree of: ________________________________________________ in: ________________________________________________ It is entitled: ________________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ Approved by: ________________________ ________________________ ________________________ ________________________ ________________________ Methodological advances in the use of faunal gradient analysis for regional paleoecological investigations in the type Cincinnatian Series (Upper Ordovician) A dissertation submitted to the Division of Research and Advanced Studies of the University of Cincinnati in partial fulfillment of the requirements for the degree of DOCTORATE OF PHILOSOPHY (Ph.D.) in the Department of Geology of the College of Arts and Sciences 2003 by Andrew J. Webber B.S., College of William and Mary, 1995 M.S., University of Cincinnati, 1999 Committee Chair: Dr. Arnold I. Miller Abstract The purpose of this research is to refine established applications of faunal gradient analysis as a tool of regional high-resolution correlation, using the type Cincinnatian Series as a natural laboratory. Comparisons of stratigraphically arranged, quantified faunal patterns have been employed to establish stratigraphic correlations at regional scales, and have provided a foundation for regional paleoecological studies at high resolution. There are three primary objectives to this research: 1) to assess the meaning of fine-scale stratigraphic change in faunal composition; 2) to extend the lateral breadth of correlations for a more regional coverage; and 3) to assess local spatial variation in the distribution of fossils, and examine the effects this patchiness has on the fine-scale signal of biological variation in the Cincinnatian. Results of this work show that lithofacies-defined meter-scale cycles in the Cincinnatian do not correspond with water-depth related stratigraphic trends in biotic composition. Therefore, these cycles are likely not caused by small-scale fluctuations in sea-level. Second, previously established correlations, at scales greater than one meter, can be extended farther across the region, and examining the patterns in biotic composition for small stratigraphic intervals rather than individual strata is a promising technique for drawing correlations at scales of less than a meter. Finally, this research has shown that even though local patchiness and differences in the amount of time-averaging with lithology limits the use of faunal gradient analysis when comparing fine-scale (bed-by-bed) trends of biological variation among Cincinnatian localities, patterns at scales greater than a few beds are robust across the region. Acknowledgements I would like to acknowledge those who helped me bring this project together. I thank my dissertation committee, who gave me invaluable suggestions and reviews, and kept me on track. I owe a very special thanks to my dissertation committee chair, Dr. Arnold Miller, who generously provided guidance and support, and without whom this project would not have been possible. I am grateful to the other members of my dissertation committee: Dr. Steven Holland, for his helpful insight and prompt feedback; Dr. Carlton Brett, for discussions and debate; Dr. Thomas Algeo, and Dr. David Meyer. This research was funded by grants from The Paleontological Society, the Geological Society of America, and the Dry Dredgers. I thank the Geology Department at the University of Cincinnati for providing a terrific environment in which to learn and to conduct scientific research. I am indebted to those who served as field assistants: Karen Layou, Heather Ellington, Brenda Hunda, Bill Garcia, Kim Koverman, and Eric Winhusen. I thank Mark Patzkowsky, three anonymous reviewers, and the editors of PALAIOS for their reviews of the first chapter of this dissertation. Finally, I am grateful for the loving and continual support of my family, especially my wife, LeAnna, and my son, Avery, over the years it took me to work on this project. 1 Table of Contents Introduction 4 Chapter 1: High-Resolution Faunal Gradient Analysis and an Assessment of the Causes of Meter-Scale Cyclicity in the Type Cincinnatian Series (Upper Ordovician) 8 Abstract 8 Introduction 9 Stratigraphic Framework 13 Development of Analytical Framework 15 Data Collection 15 Quantitative Analysis 17 Comparing Faunal Scores to Meter-Scale Cycles 19 Results and Implications 28 Conclusions 32 Chapter 2: Methodological advances in the use of faunal gradient analysis for regional high- resolution correlation in the type Cincinnatian Series (Upper Ordovician) 34 Abstract 34 Introduction 35 Background 38 The Study Interval 38 Correlation in the Cincinnatian 39 Methods 44 Data collection 44 Data Analysis 45 Results and Discussion 48 Broad-scale correlation 48 Fine-Scale Correlation 52 Conclusions 60 Chapter 3: The Effects of Spatial Patchiness on the Stratigraphic Signal of Biotic Composition in the Type Cincinnatian Series (Upper Ordovician) 62 Abstract 63 Introduction 63 The Study Interval 67 Methods 68 Data Collection 68 Data Analysis 71 Results and Discussion 73 Local Variation 73 Regional Variation 86 Implications 87 Conclusions 93 Final Remarks 94 Bibliography 95 Appendix: Locality Descriptions 108 2 List of Figures Chapter 1 1.1 Photograph of meter-scale cyclicity in the Kope Formation at the K445 locality 10 1.2 Interpretations of meter-scale cyclicity in the type Cincinnatian Series 11 1.3 Location map 16 1.4 Generalized position of major Cincinnatian taxa along DCA axis 1 21 1.5 Stratigraphic position of meter-scale cycles and DCA axis 1 scores at K445 22 1.6 Binning protocols 26 Chapter 2 2.1 Map of outcrop localities of the Kope and lower Fairview Formations used in faunal gradient analysis 37 2.2 Stratigraphic position of sample ordination scores at K445 41 2.3 A comparison of smoothed ordination curves from K445 and Holst Creek 42 2.4 Large-scale correlation of ordination curves from six Cincinnatian localities 49 2.5 A comparison of the Maysville smoothed ordination curve with the curves from K445 and Holst Creek 51 2.6 A comparison of the raw ordination curve with the smoothed curve and the binned curve from the Maysville locality 55 2.7 Fine-scale correlation of ordination curves for K445, Holst Creek, and Maysville, binned into 0.5 m thick intervals 56 2.8 Fine-scale correlation of ordination curves for K445, Holst Creek, and Maysville, binned according meter-scale cycles 59 Chapter 3 3.1 Graphical depiction of the stratigraphic position of quantified biological Composition for K445 as calculated by gradient analysis 64 3.2 Comparisons of quantified faunal patterns for K445 and Maysville 65 3.3 Map of outcrop localities used in faunal gradient analysis 69 3.4 Composite stratigraphic column of the study interval at the Maysville locality 70 3.5 Graphical depiction of the stratigraphic position of raw DCA Axis 1 ordination scores for the four Maysville sublocalities 74 3.6 Generalized stratigraphic columns of the study interval for each of the four Maysville sublocalities 77 3.7 The stratigraphic position of binned DCA Axis 1 ordination scores for the four Maysville sublocalities 80 3.8 The differences in binned DCA Axis 1 ordination scores between each sublocality and the mean plotted according to stratigraphic position 81 3.9 Raw DCA Axis 1 ordination scores for Maysville and K445 88 3.10 Stratigraphic column of the study interval at K445 89 3.11 DCA Axis 1 ordination scores binned according bedsets 90 3 List of Tables Chapter 1 1.1 Axis 1 ordination scores of taxa 20 1.2 Faunal patterns within meter-scale cycles for each binning protocol 29 Chapter 2 2.1 Axis 1 ordination scores of taxa 46 Chapter 3 3.1 Axis 1 ordination scores of the 47 taxa included in DCA 72 3.2 List of the primary taxonomic composition of each bin, in order of abundance 82 4 Introduction The richly fossiliferous rocks of the type Cincinnatian Series have been well studied for over a century. The abundance and diversity of fossil remains, along with numerous outcrops covering a wide geographical area, make Cincinnatian strata an ideal setting for high-resolution paleoecological studies. However, these investigations require an understanding of subtle biotic transitions over broad areas. This has been problematic in the Cincinnatian, where the stratigraphic features necessary for high-resolution correlation are not easily recognizable, and which historically has not been well-correlated at high resolution as a result of difficulties in tracing individual sedimentological horizons among outcrops (Miller et al., 2001; but see Brett and Algeo, 2001a). In an effort to establish a highly resolved chronostratigraphic framework for the Lower Cincinnatian (Kope and lower Fairview Formations), Holland et al. (2001) and Miller et al. (2001) compared high-resolution stratigraphic changes in fossil composition among localities. To do this, these authors recorded the abundance of taxa from every fossiliferous horizon, and subjected these data to gradient analysis, procedures frequently used by ecologists and paleoecologists to quantify variations in biotic composition. Using gradient analysis, Holland et al. (2001) and Miller et al. (2001) found that the quantified faunal composition of Cincinnatian