A CHEMOSTRATIGRAPHIC INVESTIGATION OF THE LATE ORDOVICIAN GREENHOUSE TO ICEHOUSE TRANSITION: OCEANOGRAPHIC, CLIMATIC, AND TECTONIC IMPLICATIONS DISSERTATION Presented in Partial Fulfillment of the Requirements For the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Seth Allen Young, M.S. ***** The Ohio State University 2008 Dissertation Committee: Dr. Matthew R. Saltzman, Adviser Dr. Kenneth A. Foland Dr. William I. Ausich Dr. Andrea G. Grottoli ABSTRACT The latest Ordovician (444 million years ago) was a critical period in Earth history. This was a time of significant climatic global change with large-scale continental glaciation. Moreover, the end-Ordovician mass extinction is recognized as the second- most devastating mass extinction to have affected the Earth. The anomalous Late Ordovician icehouse period has perplexed many researchers because all previous model and proxy climate evidence suggest high levels of atmospheric CO2 during the Late Ordovician glaciation. Also associated with this period is a large positive carbon isotope (δ13C) excursion (up to +7‰) that represents a global perturbation of the carbon cycle. Additionally, a large decrease (0.001) in seawater 87Sr/86Sr occurs several million years prior (~460 million years ago); this could reflect an increase in atmospheric CO2 uptake due to weathering of volcanic rocks involved in uplift of the early Appalachian Mountains. To address these Ordovician anomalies, well-studied, thick, and continuous Late Ordovician limestone sequences from eastern West Virginia, south-central Oklahoma, central Nevada, Quebec (Canada), Estonia, and China have been sampled. Carbon and strontium isotopic ratios have been measured on samples from these localities of which Estonian and Chinese sample sites represent separate paleocontinents (Baltica and South ii China) and are compared with other data sets from North America. These data test previous interpretations that the well-documented latest Ordovician carbon isotope excursion coincides with maximum glaciation. They support a hypothesis that the large positive carbonate carbon isotope excursion was coincident with a warm interglacial (high CO2 levels) period that separated two major glacial advances (with lowered CO2 levels). There are clear parallels between the Late Ordovician and the Late Cenozoic (the most recent) greenhouse to icehouse transitions, with silicate weathering providing the initiator and positive feedback on changes in atmospheric CO2 levels. The results lead to a more complete understanding of climatic and biotic events of this critical interval, which will certainly help the understanding of the period of global climatic and biotic change affecting Earth today. iii ACKNOWLEDGMENTS I would like to thank my advisor, Dr. Matthew R. Saltzman and for all of his advice, stimulating discussions, encouragement, and supervision throughout the duration of my doctoral degree. His time and involvement was given freely, and I am very grateful for his guidance. Thanks to Dr. Kenneth A. Foland, Dr. William I. Ausich, and Dr. Andrea G. Grottoli for serving on my committee and their support and advice throughout the dissertation process. I also thank Dr. Stig M. Bergström for his very helpful support, guidance, discussions, and collaborations over the last four years. I am grateful for stimulating discussions, assistance in the field, and collaborations with Dr. Stephen A. Leslie (James Madison University), Dr. Dimitri Kaljo (Tallinn Technical University), Dr. Mats Eriksson (Lund University), Dr. Birger Schmitz (Lund University), Dr. Lee R. Kump (Pennsylvania State University), Dr. Berry Lyons (The Ohio State University), and Dr. Loren E. Babcock (The Ohio State University). Many thanks to laboratory technicians Jeff Linder, Yohei Matsui, and Frtiz Hubacher for their assistance with sample preparation and mass spectrometer operations in the Radiogenic Isotopes and Stable Isotope Biogeochemistry Laboratories here at The Ohio State University. I thank my group members and the following graduate students at OSU for useful discussions, field and lab assistance: Alyssa Bancroft, Brad Cramer, Abbey Chrystal, Scott Drew, iv Steve Goldsmith, Jeremy Gouldey, Alex Lin, Ryan Moyer, Alexa Sedlacek, Kate Tierney, and Branwen Williams. I would like to express sincere thanks to my fiancé Jessica R. Lucas for her unyielding academic, personal, and financial support of me throughout this process. I also thank my parents Deborah Poe and Doyle Young for their encouragement and support during my life as a graduate student. My dissertation research was funded by grants from Friends of Orton Hall Fund (OSU), Office of International Affairs Grant (OSU), Alumni Research Grant (OSU), and a GraduateStudent Research Grant from The Geological Society of America. Additional funding was provided by the National Science Foundation Grants to M.R. Saltzman, K. A. Foland, and W. I. Ausich. Thanks to the School of Earth Sciences for providing me with a Graduate Teaching Assistantship through the first three years of my graduate studies. The last year of my Ph.D. program I was supported by a University Presidential Fellowship from The Ohio State University. v VITA March 27, 1978 ……………………………………..Born-Little Rock, Arkansas Fall, 2000………….………….………….………….B.S. Geology, University of Arkansas at Little Rock Fall, 2003…………...…………...…………...………M.S. Geological Sciences, The Ohio State University Fall, 2001-Fall, 2003……………..………………….Graduate Teaching Associate, The Ohio State University (M.S.) Winter, 2004-Spring, 2007…………...……………...Graduate Teaching Associate, The Ohio State University (Ph.D.) Summer, 2007-present……………..………………...Presidential Fellowship, The Graduate School, The Ohio State University (Ph.D.) PUBLICATIONS Research Publications Young, S.A., Saltzman, M.R., Ausich, W.I., & Kaljo, D., 2007, A global change in δ13C of organic matter during the Late Ordovician (Hirnantian): Implications for atmospheric CO2 levels and glaciation. Geological Society of America, Abstracts with Programs, 39 (6): 84. Bergström, S.M., Xu, Chen, Young, S.A., Schmitz, B., & Saltzman, M.R., 2007, The First Record of The Ordovician Guttenberg δ13C excursion (GICE) in Asia: Chemostratigraphy of the Pagoda Limestone and Yanwashan Formations in South-eastern China. Geological Society of America, Abstracts with Programs, 39 (6): 144. Saltzman, M. R., Young, S.A., Gill, B., Lyons, T., Kump, L., & Runnegar, B., 2007, Increased Carbon Isotopic Fractionation during the Late Cambrian SPICE Event vi and a Pulse of Atmospheric Oxygen. Geological Society of America, Abstracts with Programs, 39 (6): 24. Bergström, S. M., Young, S.A., Schmitz, B., Barta, N., & Saltzman, M.R., 2007, Katian and Hirnantian (Upper Ordovician) δ13C chemostratigraphy in North America and Baltoscandia: A trans-Atlantic comparison. WOGOGOB 2007. SGU Rapporter och meddelanden . No. 128, 80-81. Goldman, D., Leslie, S. A., Nõlvak, J., Young, S., Bergström, S.M., and Huff, W.D., 2007, The Global Stratotype Section and Point (GSSP) for the base of the Katian Stage of the Upper Ordovician Series at Black Knob Ridge, Southeastern Oklahoma, USA. Episodes, v. 30, p. 258-270 Bergström, S. M., Young, S.A., Schmitz, and Saltzman, M.R., 2007, Upper Ordovician δ13C chemostratigraphy: A trans-Atlantic comparison. Acta Palaeontologica Sinica 46: 37-39. Young, S.A., Saltzman, M.R., Bergström, S.M., 2005, Upper Ordovician (Mohawkian) carbon isotope (δ13C) stratigraphy in eastern and central North America: Regional expression a perturbation of the global carbon cycle. Palaeogeography, Palaeoclimatology, Palaeoecology 222: 53-76. Young, S. A., Saltzman, M. R., Foland, K. A., Linder, J.S., 2006, A large, rapid 87Sr/86Sr drop across the Middle to Late Ordovician boundary: Implications for paleoceanography & weathering of the Taconic highlands. Geological Society of America, Abstracts with Programs, 38 (7): 478. Bergström, S. M., Young, S.A., Schmitz, B., & Saltzman, M.R., 2006, A detailed δ13C curve through the Cincinnatian Series (Upper Ordovician) in its type area: significance for regional chemostratigraphic correlations. Geological Society of America, Abstracts with Programs, 38 (7): 146. Young, S.A., Bergström, S. M., Schmitz, B., & Saltzman, M.R., 2006, Trans-atlantic correlation of Upper Ordovician δ13C excursions. Geological Society of America, Abstracts with Programs, 38 (4): 73. Saltzman, M.R., Young, S.A., 2005, Long-lived glaciation in the Late Ordovician? Isotopic and sequence-stratigraphic evidence from western Laurentia. Geology 33 (2): 109-112. vii Young, S.A., Saltzman, M.R., Ausich, W.I., 2005, Hirnantian-Llandovery (uppermost Ordovician-lowermost Silurian) carbon isotope (δ13C) stratigraphy from Anticosti Island, Quebec: implications for oceanography, glaciation, and organic carbon burial. The Dynamic Silurian Earth: Subcommision on Silurian Stratigraphy Field Meeting 2005. SGU Rapporter och meddelanden . No. 121, 97-98. Young, S.A., Saltzman, M.R., Ausich, W.I., 2005, Richmondian-Hirnantian (Upper Ordovician) carbon isotope (δ13C) stratigraphy from Anticosti Island, Quebec: implications for oceanography, glaciation, and organic carbon burial. Abstracts for the Second International Symposium of IGCP503 on Ordovician Palaeogeography and Palaeoclimate. Insight, A Milwaukee Public Museum Series in Natural History. (2) 40. Young, S.A., 2004, Carbon isotope stratigraphy; a gateway to the past, present, and future. Sedimentary Record 2 (2): 11 p. Young, S. A., Saltzman, M. R., Foland, K. A., Linder,