DOI: 10.1007/s00531-012-0782-3
Scopus记录号: 2-s2.0-84908566661
论文题名: Nitrogen recycling in subducted mantle rocks and implications for the global nitrogen cycle
作者: Halama R. ; Bebout G.E. ; John T. ; Scambelluri M.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2014
卷: 103, 期: 7 起始页码: 2081
结束页码: 2099
语种: 英语
英文关键词: N isotopes
; Nitrogen
; Recycling
; Subduction
; Ultramafic rocks
Scopus关键词: harzburgite
; isotopic composition
; mantle plume
; nitrogen cycle
; nitrogen isotope
; serpentinite
; subduction
; ultramafic rock
; Italy
; Spain
英文摘要: The nitrogen concentrations [N] and isotopic compositions of ultramafic mantle rocks that represent various dehydration stages and metamorphic conditions during the subduction cycle were investigated to assess the role of such rocks in deep-Earth N cycling. The samples analyzed record low-grade serpentinization on the seafloor and/or in the forearc wedge (low-grade serpentinites from Monte Nero/Italy and Erro Tobbio/Italy) and two successive stages of metamorphic dehydration at increasing pressures and temperatures (high-pressure (HP) serpentinites from Erro Tobbio/Italy and chlorite harzburgites from Cerro del Almirez/Spain) to allow for the determination of dehydration effects in ultramafic rocks on the N budget. In low-grade serpentinites, δ15Nair values (−3.8 to +3.5 ‰) and [N] (1.3–4.5 μg/g) are elevated compared to the pristine depleted MORB mantle (δ15Nair ~ −5 ‰, [N] = 0.27 ± 0.16 μg/g), indicating input from sedimentary organic sources, at the outer rise during slab bending and/or in the forearc mantle wedge during hydration by slab-derived fluids. Both HP serpentinites and chlorite harzburgites have δ15Nair values and [N] overlapping with low-grade serpentinites, indicating no significant loss of N during metamorphic dehydration and retention of N to depths of 60–70 km. The best estimate for the δ15Nair of ultramafic rocks recycled into the mantle is +3 ± 2 ‰. The global N subduction input flux in serpentinized oceanic mantle rocks was calculated as 2.3 × 108 mol N2/year, assuming a thickness of serpentinized slab mantle of 500 m. This is at least one order of magnitude smaller than the N fluxes calculated for sediments and altered oceanic crust. Calculated global input fluxes for a range of representative subducting sections of unmetamorphosed and HP-metamorphosed slabs, all incorporating serpentinized slab mantle, range from 1.1 × 1010 to 3.9 × 1010 mol N2/year. The best estimate for the δ15Nair of the subducting slab is +4 ± 1 ‰, supporting models that invoke recycling of subducted N in mantle plumes and consistent with general models for the volatile evolution on Earth. Estimates of the efficiency of arc return of subducted N are complicated further by the possibility that mantle wedge hydrated in forearcs, then dragged to beneath volcanic fronts, is capable of conveying significant amounts of N to subarc depths. © 2012, Springer-Verlag. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84908566661&doi=10.1007%2fs00531-012-0782-3&partnerID=40&md5=1a30aee57a990c946cb2edf2d8da922b
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70458
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Institut für Geowissenschaften and SFB 574, Universität Kiel, Ludewig-Meyn-Str. 10, Kiel, Germany; Department of Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, PA, United States; Institut für Mineralogie, Universität Münster, Corrensstr. 24, Münster, Germany; Dipartimento per lo Studio del Territorio e delle sue Risorse, Università di Genova, Corso Europa 26, Genova, Italy
Recommended Citation:
Halama R.,Bebout G.E.,John T.,et al. Nitrogen recycling in subducted mantle rocks and implications for the global nitrogen cycle[J]. International Journal of Earth Sciences,2014-01-01,103(7)