Influences of Modern Pedogenesis on Paleoclimate Estimates From Pennsylvanian and Permian Paleosols, Southeast Ohio

Abstract

Exposed paleosols are subject to modern pedogenic processes which, over time, are expected to alter paleosol chemistry and subsequent paleoclimate estimates to better reflect the environment at the time of exposure rather than the time of formation. Although paleosols are widely used in paleoclimatic reconstruction, current research typically does not address the degree of influence that modern weathering has on the bulk geochemistry of paleosols. Previously described Pennsylvanian and Permian paleoVertisols and paleoInceptisols with known durations of exposure were described and sampled from five roadcuts in southeastern, Ohio. Samples were collected at depths of 0, 25, 50, 100, and 150 cm from the outcrop surface, and then analyzed via XRF for major oxides (Ca, Fe, K, Mg, Na, Al, Si, Mn, P, and Ti). These data were used in molecular weathering ratios to characterize paleosol properties and calculate MAP and MAT. Results indicate that although oxide geochemistry often differs between sampling depths, the differences do not occur in a pattern that supports that recent pedogenesis is a driving factor. Rather, this study may be capturing naturally occurring geochemical variations that are the result of small-scale differences in formational environment. Additionally, decade-level exposure time along these roadcuts may limit the extent of pedogenesis. Ultimately, for geochemical studies on paleosols in outcrops located on young roadcuts in ACKNOWLEDGMENTS First, I need to thank my adviser, Daniel Hembree, for forcing me to consistently meet his expectations and live up to my potential through a combination of encouragement, patience, and pressure. I would like to thank my committee members, Gregory Springer, Alycia Stigall, and Craig Grimes, for providing a secondary source of guidance and expertise. Many thanks to my field assistants, Alexander Hartman and Kelsey McGuire, who were willing to dig holes for money, and Emma Swaninger, who was willing to dig holes for free. Without you I would probably still be on a roadcut. I would like to thank Rob Michitsch at the University of Wisconsin-Stevens Point, if we never met, this thesis would probably have been about deer. Finally, I would like to thank my friends and family for their unwavering support, particularly my fiancé, Bradley Kuehn, who sacrificed both his career and his computer to further my education. I would also like to thank the following funding sources that made this project possible: the