DOI: 10.1016/j.epsl.2018.08.017
Scopus记录号: 2-s2.0-85051556598
论文题名: Sulfur isotopic compositions of deep arc cumulates
作者: Lee C.-T.A. ; Erdman M. ; Yang W. ; Ingram L. ; Chin E.J. ; DePaolo D.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 500 起始页码: 76
结束页码: 85
语种: 英语
英文关键词: arc
; mantle
; pyroxenite
; redox
; sulfur
; sulfur isotopes
Scopus关键词: Budget control
; Isotopes
; Lithology
; Seawater
; Sulfur
; Sulfur compounds
; Altered oceanic crusts
; Isotopic composition
; Isotopic signatures
; mantle
; pyroxenite
; redox
; Sierra Nevada batholith
; Sulfur isotope
; Iron
; cumulate
; igneous geochemistry
; isotopic composition
; mantle
; pyroxenite
; redox conditions
; slab
; sulfur isotope
; California
; Sierra Nevada [California]
; United States
英文摘要: Heavy sulfur isotopic compositions of arc lavas suggest a seawater component in the sulfur budget of arc lavas, but whether the seawater signature derives from the subducting slab or from magma interactions with lithologies in the upper plate is unclear. To see through the effects of degassing or crustal processing, a study was conducted on the S isotopic composition of deep arc cumulates from 45–90 km beneath the Sierra Nevada batholith in California, a Cretaceous continental arc. These cumulates represent the crystal line of descent from magmatic differentiation of hydrous arc basalts. The deepest (up to 60–90 km) and most primitive cumulates are low in Fe and have high molar Mg/(Mg + Fe), whereas the shallow and more evolved cumulates are high in Fe and have low Mg/(Mg + Fe). Bulk rock δ34S correlates with Fe and negatively with Mg/(Mg + Fe). The most primitive cumulates are isotopically similar to the Earth's mantle whereas the more evolved cumulates are heavier by 6‰ in the direction of seawater sulfate. The mantle-like S isotopic signatures of the primitive cumulates indicate that the contribution of slab-derived sulfate to arc lavas may not be as large as widely thought. Heavy S isotopic signatures are seen only in the evolved arc cumulates, which suggests that the seawater signature of arc lavas may not all derive directly from the slab, but perhaps during magma interaction with pre-arc crust. In continental arcs, pre-arc crust is dominated by accreted marine metasediments and metabasalts, and in island arcs, by seawater altered oceanic crust in the upper plate. The limited contribution of slab sulfate to the mantle source of Sierran arc magmas, if generalizable, suggests that sulfate in the subducting slab is efficiently released well before the arc magmatic front. Such a scenario would be consistent with the higher solubility of sulfate in aqueous fluids compared to that of sulfide. In summary, it is suggested here that the upper plate, in the form of seawater altered crust and sediments, may be as or more important for the sulfur budget in arc magmas than the subducting slab. Early loss of sulfate from the slab during subduction suggests that the dominant S species transported to the deep mantle is in the reduced form – sulfide. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109688
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 Science, MS-126, Rice University, 6100 Main St., Houston, TX 77005, United States; United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States; Center for Stable Isotope Biogeochemistry, University of California, CA, Berkeley, 94720-4767, United States; Department of Earth and Planetary Sciences, University of California, CA, Berkeley, 94720-4767, United States; Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, Mail Code 0212, La Jolla, CA 92093-0212, United States
Recommended Citation:
Lee C.-T.A.,Erdman M.,Yang W.,et al. Sulfur isotopic compositions of deep arc cumulates[J]. Earth and Planetary Science Letters,2018-01-01,500