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ABSTRACT Title of Dissertation: AUTHIGENESIS ABSTRACT Title of Dissertation: AUTHIGENESIS, BIOMINERALIZATION, AND CARBON-SULFUR CYCLING IN THE EDIACARAN OCEAN Huan Cui Doctor of Philosophy, 2015 Dissertation directed by: Dr. Alan J. Kaufman Department of Geology Fossil record of the Ediacaran Period (635-541 Ma) reveals unprecedented rise of early animal life (metazoan) in Earth history. Coupled with this evolutionary milestone, the Earth’s atmosphere and hydrosphere experienced dramatic redox fluctuations. In order to better constrain the redox architecture of the Ediacaran ocean margin, an integrated chemostratigraphic correlation of the Doushantuo Formation in basin scale was conducted (see Chapter 2). The revised redox model suggests that euxinic conditions on the platforms were mainly restricted in lagoonal settings, which helps us to better understand Ediacaran fossil distributions and fluctuated δ13C records in the Ediacaran strata in South China. One of the most distinct features of the Ediacaran chemostratigraphy is the δ13C negative excursion (i.e. Shuram Excursion, or SE) reported globally, which is the largest known C cycle anomaly in Earth history. In order to understand the biogeochemical processes that gave rise to the SE expressed in the upper Doushantuo Formation, systematic petrographic and geochemical investigations were conducted for the outer shelf sections in the Yangtze block (see Chapter 3). Methane-derived authigenic calcite cements and nodules with extreme 13C-depletion were discovered and interpreted as the first empirical evidence of authigenic mineralization associated with the SE. In light of these novel observations, it is proposed that the globally distributed SE may be formed by widespread syndeposition of authigenic carbonates in a sulfate-methane transitional zone positioned at the sediment-water interface in response to a global seawater sulfate increase. Finally, to provide environmental context for the terminal Ediacaran biomineralization of animals, we conducted a high-resolution elemental and isotopic study of the richly fossiliferous Gaojiashan Member (see Chapter 4). Coincident with the first appearance of Cloudina are significant C-S-Ca-Sr cycle anomalies. It is proposed that the onset of calcarious biomineralization of animals may have coincided with an increase in terrestrial weathering fluxes of sulfate, alkalinity, and nutrients to the depositional basin. Enhanced concentration of Ca ion in seawater may have promoted the calcarious biomineralization of the early animals. Integrated chemo-, bio- and litho-stratigraphy of the Doushantuo and Dengying formations presented in this dissertation emphasized intimate co-evolution of Earth-life system during the Ediacaran Period. AUTHIGENESIS, BIOMINERALIZATION, AND CARBON-SULFUR CYCLING IN THE EDIACARAN OCEAN by Huan Cui Dissertation submitted to the Faculty of the Graduate School of the University of Maryland, College Park, in partial fulfillment of the requirements for the degree of Doctor of Philosophy 2015 Advisory Committee: Professor Alan J. Kaufman, Chair Professor Shuhai Xiao Professor Roberta L. Rudnick Professor James Farquhar © Copyright by Huan Cui 2015 Preface Studies presented in this dissertation cannot be completed without the support of the following collaborators and grant institutions. Here I would like to sincerely acknowledge them. Chapter 2: Cui, H., Kaufman, A.J., Xiao, S., Zhu, M., Zhou, C., Liu, X-M., 2015. Redox architecture of an Ediacaran ocean margin: Integrated chemostratigraphic (δ13C–δ34S–87Sr/86Sr–Ce/Ce*) correlation of the Doushantuo Formation, South China. Chemical Geology, 405: 48-62. I acknowledge Richard Walker, Igor Puchtel, Jingao Liu and Katherine Bermingham for the guidance of Sr isotope measurements in the UMD Isotope Geochemistry Laboratory. I also thank Yongbo Peng, Mike Evans, Rebecca Plummer, and Brittney Gaeta for their assistance in the UMD Paleoclimate CoLaboratory. This research was supported by funding from NASA Exobiology (NNX12AR91G), National Basic Research Program of China (2013CB835000), NSF Sedimentary Geology and Paleontology program (EAR0844270), an Explorers Club Exploration Fund Grant, an International Association of Sedimentologist (IAS) Graduate Student Research Grant, and an Society of Economic Geologists (SEG) Student Research Grant. Chapter 3: Cui, H., Kaufman, A.J., Xiao, S., Zhou C., A Global Authigenic Response to Ediacaran Surface Oxidation. About to be submitted soon. ii I thank Rebecca Plummer and Mike Evans for their assistance in the UMD Paleoclimate CoLaboratory, Peter Zavalij for the assistance on XRD analysis in the UMD X-ray Crystallographic Center, Phil Piccoli for the assistance on BSE imaging in the UMD Electron Probe Microanalyzer Laboratory, Timothy Rose for the assistance on cathodoluminescence imaging in the Smithsonian Institution, Richard Walker and Igor Puchtel for the guide on Sr isotope analysis in the UMD Isotope Geochemistry Laboratory, and Chengguo Guan for his help in sample collections. This research was funded by NASA Exobiology (NNX12AR91G to AJK and NNX15AL27G to SX), NSF Sedimentary Geology and Paleontology (EAR0844270 and EAR1528553 to AJK; EAR1528553 to SX), Chinese Academy of Sciences (KZZD-EW-02 to CZ), and multiple graduate student research grants to HC, including the Mineralogical Society of America (MSA) Grant for Student Research in Mineralogy and Petrology, the Society of Economic Geologists (SEG) Student Research Grant, the Explorers Club Exploration Fund Grant, International Association of Sedimentologists Graduate Student Research Grant, and financial support from International Geoscience Program (IGCP) 587: Identity, Facies and Time - The Ediacaran Puzzle (PI: Patricia Vickers-Rich). Chapter 4: Cui, H., Kaufman, A.J., Xiao, S., Peek, S., Cao, H., Min, X., Cai, Y., Siegel, Z., Liu, X-M., Peng, Y., Schiffbauer, J.D., Martin, A.J., Environmental iii context for the terminal Ediacaran biomineralization of animals. In review for Geobiology. I thank Mike Evans and Brittney Gaeta for their assistance in the UMD Paleoclimate CoLaboratory. This research is supported by funding from the NASA Exobiology Program (NNX12AR91G) to AJK, the NSF Sedimentary Geology and Paleontology program (EAR0844270 and EAR1528553) to AJK, the AAPG Grants- In-Aid Program to HC, and the Explorers Club Washington Group Exploration and Field Research Grant to HC. iv Acknowledgements In the past several months, I have been thinking on how to write this acknowledgement for many times with mixed feelings. For each time, it ends with a different version. My past four years in UMD was an adventure with joy, enrichment, gratitude, perhaps also including some frustration and depression. Here I would like to sincerely thank my advisor Dr. Alan Jay Kaufman, who led me into this research field, and trained me hand by hand from scratch. Jay’s passion on this research field, and on presenting the beauty of science to the students, has always inspired, and will continue to inspire me in my future career. Lots of memories pop up into my mind. I still remember how Jay showed me the Ediacara-type fossil for the first time in an afternoon in Novosibirsk, with sunset casting light on the specimen surface. I still remember one day in Jay’s office, he held a glacial drop stone sample collected from Namibia in front me, introducing an amazing world of the Snowball Earth to me. Memory also leads me into another day along the shore in Newfoundland, Jay kneed down for a long time on a surface of an outcrop, scrutinizing the soft-bodied animal impressions for a long time, as if that was the whole world at that moment. I also would not forget Jay’s beautifully-outlined teaching slides for his Biogeochemistry course, which always made me feel so enjoyable when sitting in his class. Jay’s creativity in teaching science, and the devotion to his students makes me feel so lucky in the past four years working with him. I sincerely thank Jay for his tremendous efforts, great passion and patience in guiding me into this exciting research field. v It’s a great fortune in my life to have Drs. Shuhai Xiao, Roberta Rudnick, and James Farquhar in my Ph.D. committee. They are all my role models in my future career. Collaborating with Shuhai in several projects was a great experience, during which I have been deeply influenced by Shuhai in so many ways. Shuhai’s thoughtful ideas, detailed field notes, considerable efforts on the student’s research and manuscripts, nice attitude in front of everyone, comprehensive knowledge on both palaeontology and geochemistry have inspired me deeply in the process working with him. Every time when I think of Roberta, her big smile emerges in my mind. Roberta’s considerate attitude to everyone around her, realistic, serious and decisive style when at work, have influenced me significantly. I deeply appreciate Roberta’s considerable efforts on directing my Ph.D. program as my committee member. I feel lucky to have the chance to teach the High Temperature Geochemistry course with Roberta as a teaching assistant. Roberta’s class is always full of fun with lots of pleasant interaction among the students. I benefit so much as the TA for Roberta. I also feel a little sad when realizing that I could hardly see Zella and Sunny (the two four-legged sweeties) any more after graduation. It is always fruitful when having coffee talks or email communications with Dr. James Farquhar. James’ emphasis on basic derivation from scratch of the equations or formula in both class and resserch inspired me a lot. Thanks James for vi sharing your own experience in research with me! Your advice and suggestions make our talks very helpful. I deeply appreciate your support! Thanks to William (Bill) McDonough for his inspiring and encouraging advises. Bill’s perspectives on leadership, working attitude, and research styles have deeply impacted me. Bill, thank you so much! I really appreciate! I also want to thank my research collaborators and labmates, including Chuanming Zhou (NIGPAS), Maoyan Zhu (NIGPAS), Yaoping Cai (NWU), Yongbo Peng (UMD, now in LSU), Xiaoming Liu (UMD, now in UNC), Rebecca Plummer (UMD), Sara Peek (UMD, now in USGS), Palma Jean Jarboe (UMD, now in USGS), Aaron Martin (UMD, now in IPICYT), Iadviga N.
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