DOI: 10.1016/j.epsl.2017.10.037
Scopus记录号: 2-s2.0-85033598890
论文题名: The role of microbial iron reduction in the formation of Proterozoic molar tooth structures
作者: Hodgskiss M.S.W. ; Kunzmann M. ; Poirier A. ; Halverson G.P.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 482 起始页码: 1
结束页码: 11
语种: 英语
英文关键词: carbonate
; illitisation
; iron isotopes
; molar tooth structures
; Proterozoic
; smectite
Scopus关键词: Carbon
; Carbonates
; Carbonation
; Iron
; Isotopes
; Organic carbon
; Sedimentary rocks
; Sediments
; illitisation
; Iron isotopes
; Molar teeth
; Proterozoic
; Smectites
; Clay minerals
; carbon isotope
; carbonate
; concentration (composition)
; illitization
; iron
; iron-reducing bacterium
; isotopic composition
; organic carbon
; oxygen isotope
; Proterozoic
; smectite
; sulfur
英文摘要: Molar tooth structures are poorly understood early diagenetic, microspar-filled voids in clay-rich carbonate sediments. They are a common structure in sedimentary successions dating from 2600–720 Ma, but do not occur in rocks older or younger, with the exception of two isolated Ediacaran occurrences. Despite being locally volumetrically significant in carbonate rocks of this age, their formation and disappearance in the geological record remain enigmatic. Here we present iron isotope data, supported by carbon and oxygen isotopes, major and minor element concentrations, and total organic carbon and sulphur contents for 87 samples from units in ten different basins spanning ca. 1900–635 Ma. The iron isotope composition of molar tooth structures is almost always lighter (modal depletion of 2‰) than the carbonate or residue components in the host sediment. We interpret the isotopically light iron in molar tooth structures to have been produced by dissimilatory iron reduction utilising Fe-rich smectites and Fe-oxyhydroxides in the upper sediment column. The microbial conversion of smectite to illite results in a volume reduction of clay minerals (∼30%) while simultaneously increasing pore water alkalinity. When coupled with wave loading, this biogeochemical process is a viable mechanism to produce voids and subsequently precipitate carbonate minerals. The disappearance of molar tooth structures in the mid-Neoproterozoic is likely linked to a combination of a decrease in smectite abundance, a decline in the marine DIC reservoir, and an increase in the concentration of O2 in shallow seawater. © 2017 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110145
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 Earth & Planetary Sciences, Geotop, McGill University, Montréal, QC, Canada; Department of Geological Sciences, Stanford University, Stanford, CA, United States; CSIRO Mineral Resources, Australian Resources Research Centre, Kensington, WA 6151, Australia; Northern Territory Geological Survey, Darwin, NT 0800, Australia; Département des sciences de la Terre et de l'atmosphère, Geotop, Université du Québec à Montréal, Montréal, QC, Canada
Recommended Citation:
Hodgskiss M.S.W.,Kunzmann M.,Poirier A.,et al. The role of microbial iron reduction in the formation of Proterozoic molar tooth structures[J]. Earth and Planetary Science Letters,2018-01-01,482