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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Controls on the iron isotopic composition of global arc magmas
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Controls on the iron isotopic composition of global arc magmas

机译：对全球弧岩棉的铁同位素组成的控制

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摘要

We determined the iron isotope composition of 130 mafic lavas from 15 arcs worldwide with the hypothesis that the results would reflect the relatively high oxidation state of arc magmas. Although this expectation was not realized, this Fe isotope data set reveals important insights into the geodynamic controls and style of the melting regimes in the sub-arc mantle. Samples are from oceanic arcs from the circum-Pacific, the Indonesian Sunda-Banda islands, Scotia and the Lesser Antilles as well as from the eastern Pacific Cascades. Their mean delta Fe-57 value is +0.075 +/- 0.05 parts per thousand, significantly lighter than MORB (+0.15 +/- 0.03 parts per thousand). Western Pacific arcs extend to very light delta Fe-57 (Kamchatka = -0.11 +/- 0.04 parts per thousand). This is contrary to expectation, because Fe isotope fractionation factors (Sossi et al., 2016, 2012) and the incompatibility of ferric versus ferrous iron during mantle melting, predict that melts of more oxidized sources will be enriched in heavy Fe isotopes. Subducted oxidation capacity flux may correlate with hydrous fluid release from the slab. If so, a positive correlation between each arc's thermal parameter (phi) and delta(57) Fe is predicted. On the contrary, the sampled arcs mostly contribute to a negative array with the phi value. High phi arcs, largely in the western Pacific, have primary magmas with lower delta(57) Fe values than the low phi, eastern Pacific arcs.
机译：我们确定了从全世界15个弧度的130毫米熔岩的铁同位素组成，并认为结果将反映弧形岩浆的相对高的氧化状态。虽然没有意识到这种期望，但这种FE同位素数据集揭示了对亚弧地幔中熔化制度的地球动力控制和风格的重要见解。样品来自循环太平洋，印度尼西亚的Sunda-Banda岛，斯科罗基和较小的安妥尔兹以及东太平洋瀑布的海洋弧。它们的平均delta fe-57值为+0.075 +/- 0.05份，比Morb更轻（+0.15 +/- 0.03份）。西太平洋弧扩展到非常轻的Delta Fe-57（堪察加= -0.11 +/- 0.04零件）。这与预期相反，因为Fe同位素分级因子（Sossi等，2016,2012）和Ferric对熔融期间的铁熔铁与铁铁的不相容性，预测更多氧化来源的熔体将富含重的Fe同位素。底电氧化能力通量可以与从板坯中释放的含水流体释放相关。如果是，则预测每个弧的热参数（PHI）和DELTA（57）FE之间的正相关。相反，采样弧主要有助于具有PHI值的负阵列。高Phi弧线主要在西太平洋，有初级毛岩石，比迪尔特拉（57）Fe值低于低Phi，东太平洋弧。

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