Louisiana State University LSU Digital Commons LSU Master's Theses Graduate School 2010 Rare earth elements as an investigative tool into the source, age, and ecology of late Miocene to late Pleistocene fossils from the Tunica Hills, Louisiana Lindsey Theresa Yann Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_theses Part of the Earth Sciences Commons Recommended Citation Yann, Lindsey Theresa, "Rare earth elements as an investigative tool into the source, age, and ecology of late Miocene to late Pleistocene fossils from the Tunica Hills, Louisiana" (2010). LSU Master's Theses. 4290. https://digitalcommons.lsu.edu/gradschool_theses/4290 This Thesis is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Master's Theses by an authorized graduate school editor of LSU Digital Commons. For more information, please contact [email protected]. RARE EARTH ELEMENTS AS AN INVESTIGATIVE TOOL INTO THE SOURCE, AGE, AND ECOLOGY OF LATE MIOCENE TO LATE PLEISTOCENE FOSSILS FROM THE TUNICA HILLS, LOUISIANA A Thesis Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College In partial fulfillment of the Requirements for the degree of Master of Science in The Department of Geology by Lindsey Theresa Yann B.S., Virginia Polytechnic Institute and State University, 2008 August 2010 AKNOWLEDGMENTS I would like to thank my advisor, Dr. Judith Schiebout, and my committee members, Dr. Laurie Anderson and Dr. Barbara Dutrow for their thoughts and suggestions throughout my time at Louisiana State University. My committee was extremely helpful and understanding, both in and out of the classroom, which was vital to making my thesis enjoyable and a product I am proud of. I would also like to thank Dr. Suyin Ting for her help with preparation, identification, and curation of specimens, Wanda LaBlanc for allowing me to use the geochemistry facilities to process samples, and Drs. Laurie Anderson and Brian Marx for their help with the multivariate analysis. I thank Dr. Brad McPherson for his donated collection of vertebrate fossils that were the source material for Pleistocene fossils in my thesis, Bill Lee who collected many of the fossils from the Tunica Hills, Dr. Richard Hulbert for his invaluable help in the Florida Museum of Natural History vertebrate paleontology collection and Dr. Bruce MacFadden for his suggestions and tips to improve my thesis project. I thank Mary Lee Eggart for her help on the initial compilation of the geologic map and Clifford Duplechin, Jr. for his helpful Adobe Illustrator pointers. I also thank Ilia Rodushkin, and those at ALS Laboratory Group in Luleå, Sweden, for preparing my samples and running my rare earth element analysis. I would like to thank those who provided funding for my project, LSU Museum of Natural Science which funded my analysis through donated funds, as well as providing me a curatorial assistantship and the Geology and Geophysics Department for supporting me with a teaching assistantship. I would also like to thank the Gulf Coast Associations of Geological Societies, and the Geological Society of America for funding my trip to FLMNH to compare thesis samples. ii My friends have also been helpful the last few years. I would specifically like to thank Travis Atwood and Bill Lee for their help with field work. Without their help I would not have been able to find, or collect, all of the samples I needed for my research. Lastly I would like to thank my parents, my brother and my fiancé, Kevin Hoch, without their love, support, and encouragement I would not have made it this far. iii TABLE OF CONTENTS AKNOWLEDGMENTS ................................................................................................................. ii ABBREVIATIONS AND ACRONYMS ....................................................................................... v ABSTRACT .................................................................................................................................. vii CHAPTER 1. INTRODUCTION ................................................................................................... 1 1.1 Rare Earth Elements and Vertebrate Paleontology .............................................................. 3 1.2 Geologic Setting................................................................................................................... 8 CHAPTER 2. METHODS ............................................................................................................ 12 2.1 Field Methods .................................................................................................................... 12 2.2 Specimen Selection and Identification ............................................................................... 12 2.3 Rare Earth Elemental Analysis .......................................................................................... 13 CHAPTER 3. SYSTEMATIC PALEONTOLOGY ..................................................................... 16 CHAPTER 4. RESULTS .............................................................................................................. 41 CHAPTER 5. DISCUSSION ........................................................................................................ 67 5.1 Rare earth elements and the depositional environment ..................................................... 67 5.2 Paleoenvironmental interpretations ................................................................................... 74 CHAPTER 6. CONCLUSIONS ................................................................................................... 79 REFERENCES ............................................................................................................................. 83 APPENDIX: SPECIMEN IDS AND LOCALITY INFORMATION .......................................... 90 VITA ............................................................................................................................................. 91 iv ABBREVIATIONS AND ACRONYMS LSUMG – Louisiana State University Museum of Natural Science, Geosciences collection CCVC – Centenary College Vertebrate Collection FLMNH – Florida Museum of Natural History UF – University of Florida KC – Kimball Creek site LBS – Little Bayou Sara site TB – Tunica Bayou site TC and TH/K – TunicaHills/Kerry site TH – Tunica Hills site HC – Hinds County, MS site Vicks – Vicksburg, MS site CC – Clarks Creek Wilderness Area REE – rare earth elements La – lanthanum Ce – cerium Pr – praseodymium Nd – neodymium Sm – samarium Eu – europium Gd – gadolinium Tb – terbium Dy – dysprosium Ho – holmium v Er – erbium Tm – thulium Yb – ytterbium Lu - lutetium vi ABSTRACT Rare earth elements were investigated for their potential to determine provenance and depositional environments of vertebrate fossils found as float in creeks of the Tunica Hills region of Louisiana. Elemental analyses are used to test the hypotheses that fossils span multiple time periods, from late Miocene to late Pleistocene, and that elemental profiles can distinguish terrestrial depositional settings from possible estuarine deposits. In addition, the animals present were then used to test the hypothesis that Tunica Hills had late Pleistocene environmental conditions much like the modern Great Lakes region. This study is important because it provides new insight on the vertebrate fossils of Louisiana to better the current understanding of the paleontology of the central Gulf Coast region. Calcium is replaced by similar-sized rare earth elements in bone and tooth dentine very quickly upon death (10,000-30,000 years), and the signature is not altered by additional diagenetic effects. The change in source of sediment supply from the Tennessee River, a postulated source during the Miocene, to the average Midwest continental signature, during the late Pleistocene, would have affected the overall rare earth element compositions available during fossilization. The loess material may not have had enough to complete the uptake of REE, which would have an influence on the profiles seen. The 38 fossils analyzed from the Pascagoula Formation, Peoria Loess and intermediate beds included horses, mastodons, ground sloths, a rhinoceros, a large felid, a giant armadillo, and a grouse. The first occurrence of Synthetoceras in Louisiana is represented by one analyzed fossil specimen. Cluster analysis separated in situ fossils from loess deposits from the Pascagoula Formation fossils, based on rare earth element profiles. The results on lithologically diverse and stratigraphically complex intermediate deposits, including reworked Citronelle Formation, are vii less clear, and shell material and nodules analyzed were not useful for stratigraphic control. In situ samples from the Pascagoula Formation support an estuarine depositional environment in the Tunica Hills during the late Miocene or early Pliocene. Rare earth element analysis shows promise, but more comparative data is needed to help unravel the history Gulf Coast region. viii CHAPTER 1. INTRODUCTION The Tunica Hills region has yielded a large collection of fossil vertebrates as float in creeks, and a method of identifying the source of the fossils is needed. Rare earth element (REE) analysis is a relatively new tool in vertebrate paleontology, but it has become very useful in the study of depositional