DOI: 10.1016/j.epsl.2021.116754
论文题名: Pulsed oxygenation events drove progressive oxygenation of the early Mesoproterozoic ocean
作者: Luo J. ; Long X. ; Bowyer F.T. ; Mills B.J.W. ; Li J. ; Xiong Y. ; Zhu X. ; Zhang K. ; Poulton S.W.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 559 语种: 英语
中文关键词: Fe speciation
; Mesoproterozoic
; molybdenum isotopes
; ocean oxygenation
; palaeoredox
英文关键词: Biology
; Geochemistry
; Isotopes
; Molybdenum
; Oceanography
; Organic carbon
; Seawater
; Trace elements
; Water levels
; Biological evolution
; Geochemical proxies
; Isotope signatures
; Isotopic composition
; Major and trace elements
; North China Craton
; Organic carbon fluxes
; Oxygenation dynamics
; Oxygenation
; carbon isotope
; iron
; isotopic composition
; molybdenum
; oxygenation
; paleoceanography
; Proterozoic
; seafloor
; speciation (chemistry)
; China
; North China Block
英文摘要: The Mesoproterozoic era has long been considered a time of relative environmental and biological stasis. However, emerging insight suggests that this period may have been more dynamic than previously considered, both in terms of oxygenation and potential consequences for biological evolution. Nevertheless, our understanding of this immense period of time remains limited. To provide more detailed constraints on oxygenation dynamics, we report a multiproxy geochemical study of an early Mesoproterozoic (∼1600–1540 million years ago, Ma) carbonate-dominated succession from the North China craton. We include inorganic carbon isotope (δ13Ccarb), iron-speciation, and major and trace element data, in addition to molybdenum isotopic compositions (δ98/95Mo). These geochemical data support previous inferences of persistent anoxic and ferruginous deeper water conditions in the earliest Mesoproterozoic ocean, with limited oxygenation of surface waters. However, the behaviour of these redox-sensitive geochemical proxies reveals pulsed oxygenation events, with each event increasing the maximum depth of oxygenation, leading to overall progressive oxygenation of the ocean. During these pulsed oxygenation events we find the lightest Mo isotope signatures ever measured in the rock record, which we attribute to initial drawdown of isotopically light Mo in association with extensive Mn and Fe (oxyhydr)oxide precipitation, followed by diagenetic recycling. However, shallower water sediments deposited after the pulses of deeper water oxygenation more faithfully record the Mo isotopic composition of coeval seawater. For these samples, we utilise a single reservoir Mo cycling model, constrained by an updated estimate of Mesoproterozoic seawater Mo concentration, and scaled using a function associated with differential organic carbon flux between the shelf and basin. When scaled to modern rates of Mo accumulation under variable marine redox conditions, our modelling estimates suggest a minimum oxic seafloor area of ∼30% of the total seafloor area at ∼1540 Ma. It remains unclear whether the oxygenation observed across this ∼60 million year interval represents a progressive transition to a more persistently oxygenated ocean, or whether oceanic oxygen levels fluctuated considerably through the later Mesoproterozoic. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165580
Appears in Collections: 气候变化与战略
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作者单位: State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an, 710069, China; School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom; State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; MNR Key Laboratory of Isotope Geology, MLR Key Laboratory of Deep-Earth Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361005, China
Recommended Citation:
Luo J.,Long X.,Bowyer F.T.,et al. Pulsed oxygenation events drove progressive oxygenation of the early Mesoproterozoic ocean[J]. Earth and Planetary Science Letters,2021-01-01,559