DOI: 10.1016/j.epsl.2018.04.009
Scopus记录号: 2-s2.0-85046162437
论文题名: Vanadium isotope compositions of mid-ocean ridge lavas and altered oceanic crust
作者: Wu F. ; Qi Y. ; Perfit M.R. ; Gao Y. ; Langmuir C.H. ; Wanless V.D. ; Yu H. ; Huang F.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 493 起始页码: 128
结束页码: 139
语种: 英语
英文关键词: hydrothermal alteration
; magmatic differentiation
; oceanic basalts
; oxygen fugacity
; vanadium isotopes
Scopus关键词: Basalt
; Clay alteration
; Melting
; Oceanography
; Structural geology
; Submarine geology
; Vanadium
; Altered oceanic crusts
; Back-arc basin basalts
; Hydrothermal alterations
; Isotope compositions
; Isotope fractionation
; Mid ocean ridge basalts
; Oceanic basalts
; Oxygen fugacity
; Isotopes
; fugacity
; hydrothermal alteration
; igneous geochemistry
; isotopic composition
; isotopic fractionation
; lava
; magmatism
; melting
; mid-ocean ridge
; mid-ocean ridge basalt
; oceanic crust
; oxygen
; vanadium
; Anatahan
; East Pacific Rise
; Hekla
; Iceland
; Mariana Islands
; Northern Mariana Islands
; Pacific Ocean
英文摘要: Vanadium isotope compositions of igneous rocks have the potential to constrain variations of physico-chemical conditions such as oxidation states during magmatism. Here, we present V isotope data for 27 fresh lavas (ranging from basaltic to dacitic compositions) from mid-ocean ridges, 31 altered basalts and gabbros from IODP site 1256 near the East Pacific Rise (EPR), and 2 back arc basin basalts (BABB). Our analyses of fresh mid-ocean ridge basalt (MORB) provide new constraints on the V isotope composition of MORBs, i.e. δ51V=−0.84±0.02‰ (2SE, n=22). In addition, the mean δ51V of MORBs from individual segments is correlated with the mean ridge depth and Na8.0 of the segment, which might reflect the effect of melting extent on V isotope fractionation during mantle melting. The mafic profile of intact altered oceanic crust (AOC) from the IODP site 1256 has δ51V ranging from −1.01 to −0.77‰, similar to that of fresh MORBs, suggesting that V isotope fractionation is limited during alteration of oceanic crust. These results also indicate the V isotopic homogeneity of the bulk oceanic crust with average δ51V of −0.85±0.02‰ (2SE, n=53), which is unaffected by ocean water and hydrothermal fluid alteration. Our results provide a guideline for application of V isotopes into studies of low and high temperature geochemical processes. The evolved lavas (basaltic andesites, andesites, and dacites) from the East Pacific Rise (EPR) show apparent shifts towards heavy δ51V values with increasing degree of differentiation, which can be explained by the crystal–liquid fractionation during crystallization with an inferred isotope fractionation factor of Δ51Vmineral-melt=−0.15×106/T2. The enrichment of 51V with increasing differentiation degree for the 9°N Overlapping Spreading Center (OSC) lavas is consistent with direction of the isotope shift observed in lavas from Anatahan Island (Northern Mariana Arc) and Hekla Volcano (Iceland), but the magnitude (0.3‰) is much smaller than that (2‰) reported in Prytulak et al. (2017). Modeling of V isotope fractionation between mineral and melt shows that variations in redox condition are important for controlling V isotope fractionation, but insufficient to explain the dramatically different Δ51Vmineral-melt between 9°N OSC lavas and Anatahan/Hekla suites. More studies are necessary for better understanding of mechanisms of V isotope fractionation during magmatism. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109882
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: CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China; Department of Earth, Ocean and Atmospheric Science, Florida State University, TallahasseeFL, United States; Department of Geological Sciences, University of Florida, Gainesville, FL, United States; Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, United States; Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States; Department of Geosciences, Boise State University, Boise, ID, United States
Recommended Citation:
Wu F.,Qi Y.,Perfit M.R.,et al. Vanadium isotope compositions of mid-ocean ridge lavas and altered oceanic crust[J]. Earth and Planetary Science Letters,2018-01-01,493