DOI: 10.1111/gbi.12277
Scopus记录号: 2-s2.0-85042661859
论文题名: Bioturbation and directionality in Earth's carbon isotope record across the Neoproterozoic–Cambrian transition
作者: Boyle R.A. ; Dahl T.W. ; Bjerrum C.J. ; Canfield D.E.
刊名: Geobiology
ISSN: 1472-4677
EISSN: 1472-4669
出版年: 2018
卷: 16, 期: 3 起始页码: 252
结束页码: 278
语种: 英语
英文关键词: biogeochemistry
; bioturbation
; cambrian substrate revolution
; carbon isotope record
; evolution
; Neoproterozoic
Scopus关键词: Animalia
Scopus学科分类: Earth and Planetary Sciences: General Earth and Planetary Sciences
; Environmental Science: General Environmental Science
; Agricultural and Biological Sciences: Ecology, Evolution, Behavior and Systematic
英文摘要: Mixing of sediments by moving animals becomes apparent in the trace fossil record from about 550 million years ago (Ma), loosely overlapping with the tail end of the extreme carbonate carbon isotope δ13Ccarbonate fluctuations that qualitatively distinguish the Proterozoic geochemical record from that of the Phanerozoic. These Precambrian-scale fluctuations in δ13Ccarbonate (PSF-δ13Ccarbonate) remain enigmatic, due to their high amplitude and inclusion of global-scale negative δ13Ccarbonate values, below anything attributable to mantle input. Here, we note that different biogeochemical-model scenarios plausibly explaining globally synchronous PSF-δ13Ccarbonate converge: via mechanistic requirements for extensive anoxia in marine sediments to support sedimentary build-up of 13C-depleted carbon. We hypothesize that bioturbation qualitatively reduced marine sediment anoxia by exposing sediments to oxygenated overlying waters, which ultimately contributed to decreasing the carbon cycle's subsequent susceptibility to PSF- δ13Ccarbonate. Bioturbation may also have reduced the quantity of (isotopically light) organic-derived carbon available to contribute to PSF- δ13Ccarbonate via ocean crust carbonatization at depth. We conduct a comparative modelling exercise in which we introduce bioturbation to existing model scenarios for PSF- δ13Ccarbonate: expressing both the anoxic proportion of marine sediments, and the global organic carbon burial efficiency, as a decreasing function of bioturbation. We find that bioturbation's oxygenating impact on sediments has the capacity to prevent PSF- δ13Ccarbonate caused by authigenic carbonate precipitation or methanogenesis. Bioturbation's impact on the f-ratio via remineralization is partially offset by liberation of organic phosphate, some of which feeds back into new production. We emphasize that this study is semiquantitative, exploratory and intended merely to provide a qualitative theoretical framework within which bioturbation's impact on long-term, first-order δ13Ccarbonate can be assessed (and it is hoped quantified in more detail by future work). With this proviso, we conclude that it is entirely plausible that bioturbation made a decisive contribution to the enigmatic directionality in the δ13Ccarbonate record, from the Neoproterozoic–Cambrian boundary onwards. © 2018 John Wiley & Sons Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/85007
Appears in Collections: 影响、适应和脆弱性
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作者单位: Danish Institute for Advanced Study, University of Southern Denmark, Odense M, Denmark; Nordic Centre for Earth Evolution and Institute of Biology, University of Southern Denmark, Odense M, Denmark; Natural History Museum of Denmark, University of Copenhagen, København K, Denmark; Department of Geosciences and Natural Resource Management, University of Copenhagen, København K, Denmark
Recommended Citation:
Boyle R.A.,Dahl T.W.,Bjerrum C.J.,et al. Bioturbation and directionality in Earth's carbon isotope record across the Neoproterozoic–Cambrian transition[J]. Geobiology,2018-01-01,16(3)