Oxidation State of Arc Mantle Revealed by Partitioning of V, Sc, and Ti Between Mantle Minerals and Basaltic Melts
Oxidation State of Arc Mantle Revealed by Partitioning of V, Sc, and Ti Between Mantle Minerals and Basaltic Melts
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V、Sc、Ti在地幔矿物与玄武岩熔体之间的分配揭示了弧地幔的氧化态
DOI：
10.1029/2018jb016731
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发表时间：
2019-05
影响因子：
3.9
通讯作者：
Liu Xingcheng
中科院分区：
文献类型：
--
作者：
Wang Jintuan;Xiong Xiaolin;Takahashi Eiichi;Zhang Le;Li Li;Liu Xingcheng
弧幔是否比洋幔氧化程度更高一直存在争议。多价钒（V）的行为是氧逸度（fO 2）敏感的，并且V与同价元素（例如，Sc、Ti或Yb）常用作fO 2代用指标。弧玄武岩和洋中脊玄武岩之间类似的比值，如V/Sc，以前被认为是地幔来源中类似fO 2的证据。然而，这种说法可能存在问题，因为元素比主要由分配系数（D值）控制，而分配系数（D值）又进一步受到各种因素的影响。在典型的弧T-P-H2O条件和可变fO 2s条件下，我们确定了地幔矿物和玄武岩熔体之间V和其他过渡元素的D值。结合实验结果与公布的数据，fO 2，T，P，和相组成的DV，DSc，和DTi橄榄石，斜方辉石（opx），单斜辉石（cpx），和尖晶石的影响进行了评估，使用多元线性回归。结果表明，这4种矿物的DV值均随fO 2和温度的降低而增大，在fO 2一定的情况下，低温时DV/DSc和DV/DTi比高于高温时。因此，弧玄武岩和洋中脊玄武岩之间相似的V/Sc和V/Ti比反映了由于其较低的熔化温度而相对氧化的弧地幔。鉴于Ti在地幔熔融过程中的高度不相容行为，V-Ti系统被认为在fO 2估计中比V-Sc系统更上级。使用V-Ti系统学的部分熔融模拟结果显示，弧地幔的fO 2平均比大洋地幔高约0.9个对数单位。
Whether arc mantle is more oxidized than oceanic mantle is persistently debated. The behavior of multivalent vanadium (V) is oxygen fugacity (fO2) sensitive, and the ratios of V to a homovalent element (e.g., Sc, Ti, or Yb) in basalts were commonly used as fO2 proxies. Similar ratios, such as V/Sc, between arc basalts and mid‐ocean ridge basalts were previously taken as evidence for similar fO2s in their mantle sources. However, this claim may be problematic because elemental ratios are primarily controlled by partition coefficients (D values), which are further affected by various factors. Here we determined D values of V and other transition elements between mantle minerals and basaltic melts at typical arc T–P‐H2O conditions and variable fO2s. Combining experimental results with published data, the effects of fO2, T, P, and phase compositions on DV, DSc, and DTi for olivine, orthopyroxene (opx), clinopyroxene (cpx), and spinel were evaluated using multiple linear regressions. The results show that DV values for these four minerals all increase with decreasing fO2 and temperature, leading to higher DV/DSc and DV/DTi ratios at low temperatures than those at high temperatures given a certain fO2. Thus, similar V/Sc and V/Ti ratios between arc basalts and mid‐ocean ridge basalts reflect a relatively oxidized arc mantle due to its lower melting temperatures. In light of the highly incompatible behavior of Ti during mantle melting, V‐Ti systematics are regarded to be more superior than V‐Sc systematics in the fO2 estimation. Partial melting modelling results using V‐Ti systematics reveal that arc mantle is, on average, ~0.9 log units higher in fO2 than oceanic mantle.
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影响因子：
3.5
作者：
Vladimir Matjuschkin;R. Brooker;B. Tattitch;J. Blundy;C. C. Stamper-C.
通讯作者：
Vladimir Matjuschkin;R. Brooker;B. Tattitch;J. Blundy;C. C. Stamper-C.
影响因子：
5.3
作者：
Berry, Andrew J.;Stewart, Glen A.;Mosselmans, J. Fred W.
通讯作者：
Mosselmans, J. Fred W.
影响因子：
5
作者：
T. Sisson;C. Bacon
通讯作者：
T. Sisson;C. Bacon
影响因子：
3.5
作者：
KRESS, VC;CARMICHAEL, ISE
通讯作者：
CARMICHAEL, ISE
影响因子：
3.9
作者：
P. Jugo;R. Luth;J. Richards
通讯作者：
P. Jugo;R. Luth;J. Richards