DOI: 10.1016/j.epsl.2018.02.006
Scopus记录号: 2-s2.0-85044777549
论文题名: Iron isotope fractionation during pyrite formation in a sulfidic Precambrian ocean analogue
作者: Rolison J.M. ; Stirling C.H. ; Middag R. ; Gault-Ringold M. ; George E. ; Rijkenberg M.J.A.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 488 起始页码: 1
结束页码: 13
语种: 英语
英文关键词: Black Sea
; Great Oxidation Event
; iron isotope fractionation
; paleo-redox proxy
; pyrite formation
; redox-sensitive trace metal
Scopus关键词: Atmospheric chemistry
; Isotopes
; Oceanography
; Redox reactions
; Sedimentology
; Trace elements
; Water levels
; Black sea
; Great Oxidation Event
; Iron isotopes
; paleo-redox proxy
; Pyrite formation
; Trace metal
; Pyrites
英文摘要: The chemical response of the Precambrian oceans to rising atmospheric O2 levels remains controversial. The iron isotope signature of sedimentary pyrite is widely used to trace the microbial and redox states of the ocean, yet the iron isotope fractionation accompanying pyrite formation in nature is difficult to constrain due to the complexity of the pyrite formation process, difficulties in translating the iron isotope systematics of experimental studies to natural settings, and insufficient iron isotope datasets for natural euxinic (i.e. anoxic and sulfidic) marine basins where pyrite formation occurs. Herein we demonstrate, that a large, permil-level shift in the isotope composition of dissolved iron occurs in the Black Sea euxinic water column during syngenetic pyrite formation. Specifically, iron removal to syngenetic pyrite gives rise to an iron isotope fractionation factor between Fe(II) and FeS2 of 2.75 permil (‰), the largest yet reported for reactions under natural conditions that do not involve iron redox chemistry. These iron isotope systematics offer the potential to generate permil-level shifts in the sedimentary pyrite iron isotope record due to partial drawdown of the oceanic iron inventory. The implication is that the iron stable isotope signatures of sedimentary pyrites may record fundamental regime shifts between pyrite formation under sulfur-limited conditions and pyrite formation under iron-limited conditions. To this end, the iron isotope signatures of sedimentary pyrite may best represent the extent of euxinia in the past global ocean, rather than its oxygenation state. On this basis, the reinterpreted sedimentary pyrite Fe isotope record suggests a fundamental shift towards more sulfidic oceanic conditions coincident with the ‘Great Oxidation Event’ around 2.3 billion years ago. Importantly, this does not require the chemical state of the ocean to shift from mainly de-oxygenated to predominantly oxygenated in parallel with the permanent rise in atmospheric oxygen, contrary to other interpretations based on iron isotope systematics. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109992
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Department of Chemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand; Centre for Trace Element Analysis, University of Otago, P.O. Box 56, Dunedin, New Zealand; Antarctic Climate and Ecosystems CRC, University of Tasmania, Private Bag 80, Hobart, TAS 7001, Australia; Royal Netherlands Institute for Sea Research, Department of Ocean Systems (OCS), Utrecht University, PO Box 59, Den Burg, Texel, AB 1790, Netherlands; Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States
Recommended Citation:
Rolison J.M.,Stirling C.H.,Middag R.,et al. Iron isotope fractionation during pyrite formation in a sulfidic Precambrian ocean analogue[J]. Earth and Planetary Science Letters,2018-01-01,488