DOI: 10.1016/j.epsl.2018.05.018
Scopus记录号: 2-s2.0-85047065746
论文题名: Authigenic carbonate formation rates in marine sediments and implications for the marine δ13C record
作者: Mitnick E.H. ; Lammers L.N. ; Zhang S. ; Zaretskiy Y. ; DePaolo D.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 495 起始页码: 135
结束页码: 145
语种: 英语
英文关键词: authigenic carbonate
; carbon cycle
; carbon isotopes
; marine sediments
Scopus关键词: Carbonation
; Glacial geology
; Isotopes
; Oxygen
; Recrystallization (metallurgy)
; Sedimentology
; Sediments
; Submarine geology
; Anaerobic metabolism
; Authigenic carbonates
; Biogenic carbonates
; Carbon cycles
; Carbon isotopes
; Dissolved inorganic carbon
; Isotopic composition
; Marine sediments
; Organic carbon
英文摘要: Carbon isotope (δ13C) variations measured in carbonates have been attributed to large-scale phenomena throughout Earth history, such as changes in atmospheric oxygen or global glaciations. These interpretations follow from a model wherein the δ13C of marine dissolved inorganic carbon (DIC) is controlled by the relative sedimentary burial rates of biogenic carbonate (BC) and organic carbon (OC). A new model proposes authigenic carbonate (AC) as a third major sedimentary C pool, implying that δ13C anomalies are not necessarily indicative of extreme changes in the global carbon cycle and/or atmospheric oxygen. Two conditions are required for AC formation to significantly alter bulk carbonate δ13C: the AC isotopic composition must be at least ∼3‰ different from that of BC and the AC/BC ratio must be >0.1. We use pore fluid Ca and Sr concentrations to estimate rates of AC formation in Late Cenozoic marine sediments, then calculate relative fractions of AC, OC, and BC. Today AC is not expected to constitute a significant fraction of total sedimentary carbon (AC+OC+BC) globally; however, there are modern sites where local conditions promote elevated AC/BC and anaerobic metabolisms can alter the δ13C of pore fluids. We investigate these sites to determine what conditions might enable AC to alter δ13C of marine DIC. We find there is very little net addition of AC relative to BC, but large quantities of AC form today across many settings via recrystallization. In settings where remineralization of organic matter causes recrystallized carbonate to form with modified δ13C, AC/BC is generally too low for this recrystallization to significantly shift the δ13C of the bulk carbonate. However, exceptions are found in sites with very low BC and extensive methane oxidation, suggesting that this environment type would need to be globally extensive in the past in order for AC formation to change the δ13C of marine DIC. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109832
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 Science, University of California, Berkeley, CA 94720, United States; Earth and Environmental Science Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States; Department of Environmental Science, Policy & Management, University of California, Berkeley, CA 94720, United States; Houston, TX 77084, United States
Recommended Citation:
Mitnick E.H.,Lammers L.N.,Zhang S.,et al. Authigenic carbonate formation rates in marine sediments and implications for the marine δ13C record[J]. Earth and Planetary Science Letters,2018-01-01,495