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DOI	10.1016/j.epsl.2019.115976
	Extensive marine anoxia associated with the Late Devonian Hangenberg Crisis
	Zhang F.; Dahl T.W.; Lenton T.M.; Luo G.; Shen S.-Z.; Algeo T.J.; Planavsky N.; Liu J.; Cui Y.; Qie W.; Romaniello S.J.; Anbar A.D.
发表日期	2020
ISSN	0012821X
卷号	533
英文摘要	The global Hangenberg Crisis near the Devonian-Carboniferous boundary (DCB) represents one of the major Phanerozoic mass extinction events, which shaped the roots of modern vertebrate biodiversity. Marine anoxia has been cited as the proximate kill mechanism for this event. However, the detailed timing, duration, and extent of global marine redox chemistry changes across this critical interval remain controversial because most of the studies to date only constrain changes in local or regional redox chemistry. Thus, opinions on the significance of anoxia as a kill mechanism are variable—from anoxia being a primary driver to being relatively unimportant. In this study, we explore the evolution of global marine redox chemistry using U isotopes of marine limestones. The δ238U trends at Long'an section in South China document systematic oscillations with three negative shifts punctuated by two positive events in between. The magnitude of the δ238U oscillations implies that the sediments do not record contemporaneous seawater with a constant offset at all times. The lack of covariation between δ238U data and diagenetic indicators (e.g., Mn and Sr contents, Mn/Sr ratio, δ18O) suggests that the δ238U trends are not produced by the same post-depositional diagenetic processes. Instead, trace-metal enrichments suggest that more reducing conditions prevailed during the deposition of the two positive events. We present plausible model scenarios that fit the observed δ238U trends in the context of redox-sensitive trace metal data suggesting marine anoxia expanded in the latest Devonian oceans to cover >5% of the continental shelf seafloor area. The rapid expansion of marine anoxia coincident with the onset of the Hangenberg Crisis supports marine anoxia as an important kill mechanism. Biogeochemical modeling of the coupled C-P-U cycles suggests that intensified continental weathering, for example, assisted by the spread of seed plants with deeper root systems at this time, could have triggered expansion of marine anoxia and other global changes (e.g., positive excursion in δ13Ccarb and decrease in sea surface temperature) in the latest Devonian. The anoxic event is inferred to have been transient as climatic cooling would have reduced weathering fluxes. © 2019 Elsevier B.V.
关键词	biogeochemical model Devonian-Carboniferous Hangenberg Crisis marine anoxia mass extinction uranium isotopes
英文关键词	Biodiversity; Biogeochemistry; Deposition; Expansion; Isotopes; Lime; Nuclear fuels; Oceanography; Seed; Surface waters; Weathering; Biogeochemical modeling; Devonians; Hangenberg Crisis; marine anoxia; Mass extinction; Uranium isotopes; Trace elements; anoxia; Carboniferous; chemical weathering; chemostratigraphy; Devonian; isotopic composition; limestone; mass extinction; paleoenvironment; redox conditions; trend analysis; uranium isotope; China; Spermatophyta; Vertebrata
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203002
作者单位	School of Earth Sciences and Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China; Globe Institute, University of Copenhagen, København K, Denmark; Department of Geology and Geophysics, Yale University, New Haven, CT 06511, United States; Global Systems Institute, University of Exeter, Exeter, EX4 4QE, United Kingdom; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei 430074, China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei 430074, China; Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, United States; Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, United States; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, 210008, China; School o...
推荐引用方式 GB/T 7714	Zhang F.,Dahl T.W.,Lenton T.M.,et al. Extensive marine anoxia associated with the Late Devonian Hangenberg Crisis[J],2020,533.
APA	Zhang F..,Dahl T.W..,Lenton T.M..,Luo G..,Shen S.-Z..,...&Anbar A.D..(2020).Extensive marine anoxia associated with the Late Devonian Hangenberg Crisis.Earth and Planetary Science Letters,533.
MLA	Zhang F.,et al."Extensive marine anoxia associated with the Late Devonian Hangenberg Crisis".Earth and Planetary Science Letters 533(2020).