气候变化领域集成服务门户(CCPortal): Iron-depleted pelagic water at the end-Permian mass extinction inferred from chemical species of iron and molybdenum in deep-sea sedimentary rocks

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DOI	10.1016/j.palaeo.2018.12.014
	Iron-depleted pelagic water at the end-Permian mass extinction inferred from chemical species of iron and molybdenum in deep-sea sedimentary rocks
	Takahashi S.; Nakada R.; Watanabe Y.; Takahashi Y.
发表日期	2019
ISSN	0031-0182
起始页码	384
结束页码	399
卷号	516
英文摘要	This study determined chemical species of iron (Fe) and molybdenum (Mo) in a pelagic deep-sea Permian–Triassic boundary section, that records redox variations across the severe mass extinction event. We applied X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) at the Fe K-edge and X-ray absorption near-edge structure (XANES) at the Mo K-edge to silicic sedimentary rock samples for analysis of the studied section. According to the EXAFS and XRD analyses, pyrite was the dominant Fe-bearing mineral in most samples, whereas ferric minerals such as hematite were absent throughout the Permian–Triassic transition. This result supports those of previous studies of other deep-sea Japanese Permian-Triassic boundary (PTB) sections. The Fe in pyrite mineral quantified by EXAFS spectra displayed synchronous variation with sulphide-sulphur (S sulphide ) but with total organic carbon content, which revealed the Fe-limited conditions for pyrite formation in the pelagic Panthalassa region. The XANES analysis indicated the presence of tetrahedral and octahedral configurations of Mo bonded to oxygen (O) and sulphur (S), which were referred to as MoO 4 2− , MoO 3 (as a possible alternative reference material of Mo in organic ligands), MoO 2 and MoS 2 . The MoS 2 species dominated in the end-Permian horizons, coinciding with high abundances of total Mo, which suggests a sulphidic depositional environment. The MoS 2 and MoO 3 species were the main contributors to these high Mo abundances in the end-Permian strata. The presence of the molybdenite (MoS 2 ) species in the studied section indicates that the samples were subjected to alteration under high temperatures, with sufficiently sulphidic and limited reactive Fe availability conditions for MoS 2 formation during late diagenesis. The Fe in pyrite decreased across the mass extinction boundary, which coincided with the highest total Mo amount with the MoS 2 and MoO 3 species. These trends reflected a decrease in reactive Fe in the sediments and contemporaneous seawaters under sulphidic conditions. The low reactive Fe condition could be due to massive pyrite formation under prolonged sulphidic water conditions in the pelagic and ambient continental margin regions in the end-Permian. © 2018 Elsevier B.V.
英文关键词	End-Permian mass extinction; Extended X-ray absorption fine structure (EXAFS); Japan; Pelagic deep sea; Redox conditions; X-ray absorption near edge structure (XANES)
语种	英语
scopus关键词	deep-sea sediment; iron; mass extinction; molybdenum; pelagic environment; Permian; redox conditions; sediment chemistry; sedimentary rock; XANES spectroscopy; Japan
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/151081
作者单位	Department of Earth and Planetary Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe 200, Nankoku, Kochi 783-8502, Japan
推荐引用方式 GB/T 7714	Takahashi S.,Nakada R.,Watanabe Y.,et al. Iron-depleted pelagic water at the end-Permian mass extinction inferred from chemical species of iron and molybdenum in deep-sea sedimentary rocks[J],2019,516.
APA	Takahashi S.,Nakada R.,Watanabe Y.,&Takahashi Y..(2019).Iron-depleted pelagic water at the end-Permian mass extinction inferred from chemical species of iron and molybdenum in deep-sea sedimentary rocks.Palaeogeography, Palaeoclimatology, Palaeoecology,516.
MLA	Takahashi S.,et al."Iron-depleted pelagic water at the end-Permian mass extinction inferred from chemical species of iron and molybdenum in deep-sea sedimentary rocks".Palaeogeography, Palaeoclimatology, Palaeoecology 516(2019).