气候变化领域集成服务门户(CCPortal): Marine redox variability from Baltica during extinction events in the latest Ordovician

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DOI	10.1016/j.palaeo.2020.109792
	Marine redox variability from Baltica during extinction events in the latest Ordovician–early Silurian
	Young S.A.; Benayoun E.; Kozik N.P.; Hints O.; Martma T.; Bergström S.M.; Owens J.D.
发表日期	2020
ISSN	0031-0182
卷号	554
英文摘要	It is well documented that Upper Ordovician and Silurian successions record multiple marine turnover events – including the second-largest mass extinction in the Phanerozoic – widespread glaciation, and multiple global carbon cycle perturbations. Whereas causal mechanisms for the Late Ordovician major mass extinction event involving climate, paleoceanographic variation, and δ13C records have been published, similar records remain poorly constrained for subsequent extinction events in the early Silurian. Here, we present new organic matter carbon isotope (δ13Corg) chemostratigraphy and corresponding paleoredox proxies (Fe speciation, [Mn, V, Mo], and pyrite sulfur isotopes) from two organic-rich drill core sections in Sweden and Latvia that span the upper Katian through lower Wenlock stages (446–431 Ma). Pyritized Fe and bulk sedimentary Mn concentrations from Upper Ordovician strata in southern Sweden suggest a local redox shift to more reducing conditions in the late Hirnantian, possibly including euxinic (anoxic and sulfidic water column) conditions that coincide with the second mass extinction pulse. The new high-resolution δ13Corg and δ34Spyr datasets from the late Aeronian (early Silurian) interval within both drill cores show positive excursions that are broadly coincident with the associated Sandvika and sedgwickii extinction events. Independently, Fe speciation and bulk sedimentary trace metal data from this late Aeronian interval record locally euxinic conditions in both the deep basinal (Sweden) and distal shelf (Latvia) settings before and during the late Aeronian positive δ13C excursion. This multiproxy paleoredox dataset provides the first direct evidence for local to regional expansion of reducing marine conditions coincident with this early Silurian (late Aeronian) biotic event and positive δ13C excursion. Additionally, new δ34Spyr values spanning the Llandovery/Wenlock boundary interval in the Latvia core show a positive excursion coincident with Fe speciation and trace metal enrichments that imply a local redox perturbation with intermittently euxinic bottom waters during the rising limb of the Ireviken positive δ13C excursion. The combination of these geochemical data for local- to regional-scale (more data required for global interpretations) changes in marine redox conditions with paleobiological records and evidence for eustatic sea-level rise indicate that environmental stresses related to an expansion of anoxic to euxinic conditions were a probable driver for several extinction events during the latest Ordovician–early Silurian. © 2020 Elsevier B.V.
英文关键词	Anoxia; Euxinia; Hirnantian; Iron; Llandovery; Sulfur isotopes; Trace metals
语种	英语
scopus关键词	Baltica; carbon cycle; carbon isotope; environmental stress; extinction; marine environment; mass extinction; Ordovician-Silurian boundary; paleobiology; paleoceanography; perturbation; redox conditions; turnover; Latvia; Sweden
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150435
作者单位	Department of Earth, Ocean and Atmospheric Science and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, United States; Department of Geology, Tallinn University of Technology, Ehitajate tee 5, Tallinn, 19086, Estonia; School of Earth Sciences, The Ohio State University, Columbus, OH 43210, United States
推荐引用方式 GB/T 7714	Young S.A.,Benayoun E.,Kozik N.P.,等. Marine redox variability from Baltica during extinction events in the latest Ordovician–early Silurian[J],2020,554.
APA	Young S.A..,Benayoun E..,Kozik N.P..,Hints O..,Martma T..,...&Owens J.D..(2020).Marine redox variability from Baltica during extinction events in the latest Ordovician–early Silurian.Palaeogeography, Palaeoclimatology, Palaeoecology,554.
MLA	Young S.A.,et al."Marine redox variability from Baltica during extinction events in the latest Ordovician–early Silurian".Palaeogeography, Palaeoclimatology, Palaeoecology 554(2020).