A Late Glacial-Early Holocene Paleoclimate Signal from the Ostracode
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A LATE GLACIAL-EARLY HOLOCENE PALEOCLIMATE SIGNAL FROM THE OSTRACODE RECORD OF TWIN PONDS, VERMONT A thesis submitted To Kent State University in partial Fulfillment of the requirements for the Degree of Master of Arts By Kevin J. Engle May 2015 © Copyright All Rights Reserved Except for previously published materials Thesis Written by Kevin Engle B.S. Shawnee State University, 2011 M.S. Kent State University, 2015 Approved by Alison Smith Dr. Alison Smith, Professor, Ph.D., Geology, Masters Advisor Daniel Holm Dr. Daniel Holm, Professor, Ph.D., Chair, Department of Geology Dr. James Blank, Professor, Ph.D., Dean, College of Arts and Sciences ii TABLE OF CONTENTS TABLE OF CONTENTS ....................................................................................................... iii LIST OF FIGURES ………………………………………………………………………………………………………… vii LIST OF TABLES…………………………………………………………………………………………………………….. x ACKNOWLEDGEMENTS……………………………………………………………………………………………….. xi CHAPTERS I. Introduction ………………………..………………..……………………………………………… 1 Regional Geologic Setting …………………...……….………………….…………………… 1 Bølling-Allerød Interstadial ……………………….……………..…………………………. 9 Younger Dryas ………………………………………………………………….…………………. 10 Post-Younger Dryas Climate Interval …………………………………………………… 19 9.2 kya Event ...………………………………………………………………………….………… 24 8.2 kya Event ………………………………………………………………………….…………… 27 II. Methods …………………………………………………………………………………………..... 31 iii Ostracode Bleaching Procedure ……..………………………………………………..... 34 Running Samples on the Kiel ..……………………………………………..……………… 36 Reporting ……………………………………………………………………………………………. 37 Statistical Analysis ……………….……………………………………………..…..………..… 40 Cluster Analysis ………………………………………………………………….………….……. 41 Principal Components Analysis ……………………………………..…….……………… 41 II. Results ….…………..…………………………………………….…………………………….…… 43 Multi-Proxy Work…………………………………………………………………………..…… 43 Age Model.……………………………………………………………………………………………43 Bulk Carbonate δ18O ……….……………………………………………………………….…..47 Loss on Ignition …………………………………………………..……………………………... 50 Ostracode Abundances ………………………………………………..…………………..… 53 Candona ohioensis ……………………………………………..…………………… 53 Candona candida ……………………………………………..…………………….. 54 Candona paraohioensis …………………………………………………………... 55 Pseudocandona stagnalis ……………………………………..………………… 56 iv Cyclocypris ampla …………………………………………………………………… 57 Cypridopsis vidua ……………………………………………………….……..……. 58 Darwinula stevensoni ………………………………………………..……....….. 59 Cyclocypris globosa …………………………………………………………….…… 60 Cluster Analysis--Ostracode Zones ……………………………………..………….…… 65 P. stagnalis Zone ………………………………………………….……….………… 67 C. ampla Zone …………………………………………………………………………. 69 D. stevensoni Zone …………………………………………………………….……. 71 Nektic Zone ……………………………….………………………………..………..… 73 C. ohioensis Zone ……………………………………..……………………………… 75 Principal Components Analysis (PCA) ……………………..………………………..… 77 Isotopes ……………………………………………………………………………………………… 86 Benthic δ18O vs. ostracode abundances ……………..………………………………. 91 Benthic Ostracode δ18O vs. Bulk Carbonate δ18O ……………………….……….. 93 Post-Younger Dryas Interval ……………………………………………………………….. 95 v IV. Discussion …………………………………………………………………………………………… 97 Conclusion ……………………..………………………………………………………………………………….…… 102 References .……..………………………………………………………………………………………………….…….104 Appendices A. Isotope Input Data …………………………………………………………………………………...127 B. VPDB values ………………………………………………….………………………..…………….….133 C. VSMOW Values for a Range of Temperatures ………………………….…….………. 137 D. Ostracode Counts …………………………………………………………………………….….……140 vi LIST OF FIGURES Figure 1. Generalized Geologic Map of Vermont ……………………………………………………..…. 2 Figure 2. Topographic Maps of Twin Ponds, Vermont ……………………………………………..…. 4 Figure 3. Google Earth View of Twin Ponds, Vermont ……………………………………………..…. 6 Figure 4. Climate events following the Last Glacial Maximum from a central European pollen record …………………………………………..………………………………………………………………... 10 Figure 5. Effects of the Younger Dryas seen in various records around the globe …..…. 16 Figure 6. Example of a strong Jet Stream ……………………………………………….…………………. 19 Figure 7. Post-Younger Dryas climate effects across North America ……………...…..……. 20 Figure 8. Example of a weak Jet Stream ……………………………………………………………………. 22 Figure 9. Routing of Lake Agassiz overflow to the oceans …………………………………………. 25 Figure 10. Age Model …………………………………….………………………………………....……………… 45 Figure 11. Time gap in core ……………………………………………………………………………..………..46 Figure 12. Bulk carbonate δ18O profile of Twin Ponds ……………………………...…….………… 49 Figure 13. Loss on Ignition profile of Twin Ponds ………………………………………….....………. 51 vii Figure 14. Comparison of a typical core section with the Younger Dryas section of the core ………………………………………………………………………………………………………………….…..…… 52 Figure 15. Ostracodes found in the Twin Ponds core ………………………………………..….…...62 Figure 16. Ostracode abundance profile ………………………………….………..……………….……. 64 Figure 17. Dendrogram showing 5 zones identified in the core from the late Glacial to early Holocene ………………………………………………………………………..…………………….…...……. 66 Figure 18. PCA Scatterplot of Axis 1 vs. Axis 2 ………………………..……………………......……… 81 Figure 19. Scree Plot summarizing eigenvalues ………………………………………………….……..82 Figure 20. PCA Case Scores vs. Depth in Core…………………………………………………….……… 83 Figure 21. PCA Scatterplot of Axis 1 vs. Axis 3…………………………………………………..………. 84 Figure 22. PCA Scatterplot of Axis 2 vs. Axis 3…………………………………………………..…..….. 85 Figure 23. Twin Ponds benthic ostracodes δ18O compared with depth in the core..…... 87 Figure 24. Twin Ponds benthic ostracodes δ18O compared with radiocarbon dates of the core ………………………………………………………………………………………………………………..…..….… 88 Figure 25. Twin Ponds nektic ostracodes δ18O compared with depth in the core ……..……………………………………………………………………………….……………………………….…………..89 viii Figure 26. Twin Ponds nektic ostracodes δ18O compared with age from radiocarbon dates of the core …………………………………………………………………………………………….….…….. 90 Figure 27. Ostracode abundance profile vs. benthic ostracode δ18O profile …………………………………………………………………………………………………………………………....….… 92 Figure 28. Correlation of benthic ostracode δ18O with bulk carbonate δ18O and GRIP δ18O ……………………………………………………………………………………………………………………….…. 94 Figure 29. Correlating the information from Figure 25 with the Post-Younger Dryas interval ……………………………………………………………………………………………………………………… 96 ix LIST OF TABLES Table 1. The timing of the 9.2 kya event ………………………………….………………………..………27 Table 2. The recommended number of ostracode valves for isotope analysis ……………33 Table 3. The minimum and maximum temperatures for air, surface water and bottom water for the area in which each ostracode species was collected …………………...……….39 Table 4. Abundances of ostracodes in the P. stagnalis Zone ………………….………..……..…68 Table 5. Abundances of ostracodes in the C. ampla Zone ……………………………...………….70 Table 6. Abundances of ostracodes in the D. stevensoni Zone ……………….……...………….72 Table 7. Abundances of ostracodes in the Nektic Zone………………………………..….…….…..74 Table 8. Abundances of ostracodes in the C. ohioensis Zone …………………….……………….76 Table 9. Eigenvalues and variance explained by the first 4 axes and the PCA variable loadings from the PCA analysis of the Twin Ponds core ………………………….……..…………..80 x Acknowledgements Growing up in the country and working on a farm I had never really considered myself “college material.” I surprised myself while earning my undergraduate degree at Shawnee State University when I realized how much I loved geology. Even after doing well while earning my Bachelor’s I still didn’t quite believe that I was cut out for school, so I decided to apply for jobs instead of furthering my education. The job search was not going very well, so I figured I would just apply to graduate school and see what happens. And to my surprise I received an amazing offer from Kent State, which I happily accepted. So I would like to thank the Kent State Geology Department for giving me a chance, helping me to believe in myself and opening up a whole new world for me. I would like to thank my parents, Tim and Heidi Engle, who have been there for me every step of the way. I would not be where I am today without their love and support. To my advisor, Dr. Alison Smith, you also showed me a whole new world under the microscope, which I will never forget. Thank you for everything, your attitude and passion for your work really inspired me and helped me to finish this even when it seemed impossible. xi To my committee members Dr. Palmer and Dr. Ortiz, thank you both for giving me a chance to be in this program. Both of you have helped and challenged me to be a better student throughout my time at Kent State, and I thank you for it. Lastly, thank you to the Katherine Moulton Scholarship and to the SGE Scholarship Committee. The financial support I received was vital to completing my research and I would not have been able to do so without it. xii Introduction North America was greatly affected by an abrupt global cooling event known as the Younger Dryas stadial, which occurred from about 12.9-11.5 kyr ago, based upon research done on Greenland ice cores (Rasmussen et al., 2006). Regions adjacent to the North Atlantic were directly affected by the abrupt cooling while regions further inland were affected by changes in atmospheric circulation (Shuman et al., 2002). Areas such as Maine and Nova Scotia were directly affected by the cooling of the North Atlantic and showed a cool, dry climate during the Younger Dryas (Diffenbacher-Krall and Nurse, 2005; Stea and Mott, 1989). Also directly affected were sites in