Geochemical and Paleontological Evidence
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THE EARLIEST FOREST AND ASSOCIATED WILDFIRES LINKED TO MARINE ANOXIA AND MASS EXTINCTIONS DURING THE LATE DEVONIAN: GEOCHEMICAL AND PALEONTOLOGICAL EVIDENCE by MAN LU YUEHAN LU, COMMITTEE CHAIR TAKEHITO IKEJIRI REBECCA TOTTEN MINZONI KIMBERLY GENAREAU RICHARD CARROLL JACK PASHIN A DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Geological Sciences in the Graduate School of The University of Alabama TUSCALOOSA, ALABAMA 2020 Copyright Man Lu 2020 ALL RIGHTS RESERVED ABSTRACT The diversification and radiation of vascular plants during the Devonian is a critical life event in geological history. The overarching goal of this dissertation is to reconstruct the evolution patterns of vascular plants through the Devonian and their impacts on terrestrial and marine environments. In Project I, I presented data from microscopic and geochemical analyses of the Upper Devonian Chattanooga Shale (Famennian Stage) in northeastern Alabama, USA. I found plant residues, molecular biomarkers and inorganic geochemical proxies increased throughout the section, suggesting that the southern Appalachian Basin, a region representing the southernmost Euramerica, became increasingly forested during the Late Devonian. Furthermore, the geochemical results were combined with a synthesis of vascular plant fossil records, showing a rapid southward progression of afforestation and pedogenesis along the Acadian landmass during the Late Devonian. In Project II, I established an ultra-high-resolution profile of an Upper Kellwasser (UKW) extinction interval from the Chattanooga Shale of Tennessee, USA. Through analyses of multiple paleoenvironmental proxies, I observed periodic, short-lived marine anoxia during UKW coinciding with variations in marine primary productivity, terrestrial nutrient inputs and sea level. My results suggest that anoxic episodes were caused by pulsed inputs of terrigenous organic matter that were, in turn, regulated by sea-level variations. Results from time-series analysis of Ti/Al ratios profile through Late Frasnian–Early Famennian strata demonstrates that obliquity mediated the cycle of sea-level changes, providing the first evidence that ii recurring, episodic environmental stresses on marine organisms during the UKW were paced by astronomical forcing. In Project III, I synthesized global fire occurrences based on three paleo-wildfire proxies—fossil charcoals, inertinites, and pyrogenic PAHs. Additionally, I performed a case study of reconstructing wildfire activities during the Late Devonian based on inertinites and pyrogenic PAHs abundances in the Chattanooga Shale of Tennessee. The results show that the wildfires increased dramatically and expanded rapidly across the Euramerica from the Frasnian to Famennian. I further analyzed the dispersal range, species, and key morphological features of vascular plants during the Devonian. The concurrent spatiotemporal expansion in wildfires and early tees through the Late Devonian suggest a rise in forest fires fueled by Archaeopteris. iii DEDICATION To my parents, to Xinguang iv LIST OF ABBREVIATIONS AND SYMBOLS F–F Frasnian–Famennian UKW Upper Kellwasser MN 13 Montagne Noire 13 sequence TOC Total organic carbon TP Total phosphorus δ13C Carbon isotope EF Enrichment factor XRF X-ray fluorescence XRD X-ray diffraction CIA Chemical Index of Alteration CPA Chemical Proxy of Alteration SiO2 Silicon dioxide Al2O3 Aluminium oxide Ti Titanium Al Aluminum Zr Zirconium Mo Molybdenum U Uranium DCM Dichloromethane v MeOH Methanol normal alkane n-alkane TAR Terrigenous-to-aquatic ratio PAHs Polycyclic aromatic hydrocarbons PZE Photic zone euxinia DBF Dibenzofuran C29/C30H C29/C30 αβ hopane Py Pyrene BaA Banzo[a]anthrene BeP Benzo[a/e]pyrene BF Benzo[b/k/j]fluoranthene MN Methylnaphthalene DMN Dimethylnaphthalene TMN Trimethylnaphthalene TeMN Tetramethylnaphthalene PMN Pentamethylnaphthalene MP Methylphenanthrene EP Ethylphenanthrene DMP Dimethylnaphthrene TMP Trimethylnaphthrene N Naphtharene Fl Fluoranthene vi Chry Chrysene O2 Oxygen CO2 Carbon dioxide pO2 Partial pressure of oxygen HF Hydrofluoric acid HNO3 Nitric acid HClO4 Perchloric acid HCl Hydrochloric acid ‰ Per-mille % Percentage mL/L Milliliter per liter ng/μL Nanogram/microliter ºC Degree Celsius min Minute μg/g Microgram per gram m/z Mass-to-charge ratio m Meter cm Centimeter mm Millimeter μm Micrometer v/v Volume per volume MTM Multi-taper method vii COCO Correlation coefficient FFT Fast Fourier transform CL% Confidence Level kyr Thousand years Ma Million years ago viii ACKNOWLEDGMENTS I would like to thank everyone who helped me complete the dissertation research. Especially, I want to thank my academic advisor, Dr. YueHan Lu, for providing me with a chance to work with her. This dissertation is impossible to be completed without her help, support, and patient guidance. She brought me to the field of geochemistry and taught me how to do research, to be an independent thinker and researcher. She taught me how to organize research projects, how to make concise and readable presentations and writings, and even how to pronounce single English words correctly. Her knowledge and noble qualities will be lifetime wealth for me. I also want to thank another great mentor, Dr. Takehito Ikejiri. I learned a great deal of field research geology from him. I also appreciate that he is always willing to take a lot of time to discuss science with me, and these discussions have allowed enriching this dissertation. I also want to thank Dr. Lu and Dr. Ikejiri for their help in my life. Here, I would like to extend my sincere gratitude to my other committee members: Dr. Richard Carroll, Dr. Rebecca Minzoni, Dr. Kimberly Genareau and Dr. Jack Pashin for their commitment to serving on my committee and stimulating many constructive discussions. I also want to thank my coauthors: Dr. Yongge Sun, Dr. Thomas Algeo, Dayang Sun, Nicholas Hogancamp, Dr. Qihang Wu, Dr. Ibrahim Çemen and Dr. Elliot Blair for their insightful comments and revision that significantly improved the quality the manuscripts derived from my dissertation. I am very grateful to the Department of Geological Sciences for providing me the research opportunity and the teaching assistantships. ix I also want to thank all the people I met here. Especially, I would like to thank my former and current research group members and my friends Huijing Fang and Xiaoting Liu, for their great help in my research. Special thanks go to Shuo Chen and Yihuai Lou. They are always willing to help me when I have difficulty, and their friendship and companionship brings me a lot of joy in my Ph.D. life. I would like to express my gratitude and deepest love to my parents. I would never finish a Ph.D. without their endless love, encouragement, and support. Your supports make my life meaningful. I hope I have made you proud. I want to especially thank my fiancé, Xinguang Wang. You are always there, cheering me up and standing by me through the good and bad times. Finally, I would like to thank my cousin Yunyun, who encouraged me to pursue a Ph.D. Thank you for showing up in my life. I will miss you forever. x CONTENTS ABSTRACT ............................................................................................................................... ii DEDICATION .......................................................................................................................... iv LIST OF ABBREVIATIONS AND SYMBOLS ....................................................................... v ACKNOWLEDGMENTS ........................................................................................................ ix LIST OF TABLES ................................................................................................................... xv LIST OF FIGURES ................................................................................................................ xvi CHAPTER 1: INTRODUCTION .............................................................................................. 1 References .................................................................................................................................. 7 CHAPTER 2: GEOCHEMICAL EVIDENCE OF FIRST FORESTATION IN THE SOUTHERNMOST EURAMERICA FROM UPPER DEVONIAN (FAMENNIAN) BLACK SHALES .................................................................................................................... 11 2.1 Abstract .............................................................................................................................. 11 2.2 Introduction ........................................................................................................................ 12 2.3 Material and methods ......................................................................................................... 15 2.3.1 Samples ................................................................................................................... 15 2.3.2 X-ray diffraction (XRD), X-ray fluorescence (XRF) and Scanning Electron Microscope (SEM) ........................................................................................................... 16 2.3.3 Trace element .......................................................................................................... 16 2.3.4 Organic petrography ............................................................................................... 17 2.3.5 TOC and stable carbon isotope of TOC .................................................................