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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 >The mechanism of Re enrichment in arc magmas: evidence from Lau Basin basaltic glasses and primitive melt inclusions
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The mechanism of Re enrichment in arc magmas: evidence from Lau Basin basaltic glasses and primitive melt inclusions

机译：弧岩浆中稀土富集的机理：来自刘盆地盆地玄武岩玻璃和原始熔体包裹体的证据

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Rhenium and other trace element data were obtained in situ by laser ablation ICP–MS analysis of submarine-erupted volcanic glasses and olivine-hosted melt inclusions from the Valu Fa Ridge, the south tip of the Lau Basin, in the southwestern Pacific Ocean. The chemistry of the Lau Basin basaltic glasses changes systematically from compositions similar to MORB in the Lau Spreading Centers, to more arc-like compositions in the Valu Fa Ridge, providing geochemical profiles both along the Lau Spreading Centers (ridges) and across the Valu Fa Ridge. The east seamount samples of the Valu Fa Ridge have diagnostic trace element ratios (Ba/Nb, Nb/U, Ce/Pb) close to global arc averages, with high Ba/La, indicating addition of considerable amounts of subduction-released fluids. In contrast, samples from the west seamount and the Lau Spreading Centers show a smaller influence from subduction fluids. The variable degrees of subduction influences apparent in the chemistry of these suites provide an ideal means to explore the mechanisms of Re enrichment in undegassed arc magmas. All of the analyzed arc melts have significantly higher Re concentrations than previously published, largely subaerially erupted samples, confirming that high Re is a characteristic of undegassed arc magmas. The east seamount samples are characterized by higher Re and lower Yb/Re than the more MORB-like Lau Spreading Center lavas. The lack of correlation between Yb/Re and Fo of host olivine suggests that low Yb/Re is not due to magmatic differentiation. When the Lau Basin sample suite is plotted together with MORB data, Yb/Re is positively correlated with Ce/Pb and Nb/U, and negatively correlated with Ba/Nb, indicating that Re is much more mobile than Yb during dehydration of subducted slabs. Thus, Re enrichment in arc magmas is likely due to addition of Re via fluids released from subducted slabs; the recognition of high Re in arcs favors arguments for a slab origin of radiogenic ~(187)Os/~(188)Os components in arc rocks.
机译：laser和其他微量元素数据是通过激光烧蚀ICP-MS对西南太平洋劳流盆地南端Valu Fa Ridge的海底喷发火山玻璃和橄榄石包裹的熔体包裹体进行原位分析而获得的。劳盆地盆地玄武岩玻璃的化学成分从劳氏扩散中心的MORB相似的成分系统地变化为Valu Fa Ridge的弧状成分，从而沿劳氏扩散中心（脊）和整个Valu Fa提供了地球化学剖面岭。 Valu Fa Ridge的东海山样品的诊断痕量元素比率（Ba / Nb，Nb / U，Ce / Pb）接近全球弧平均值，且Ba / La较高，表明添加了大量的俯冲释放流体。相反，来自西海山和劳氏传播中心的样本显示出的俯冲流体影响较小。这些套件的化学作用中明显的不同程度的俯冲影响为探索无脱弧岩浆中的Re富集机理提供了理想的手段。所有已分析的电弧熔体的Re浓度均显着高于以前发表的大部分通过地下气溶胶喷发的样品，这证实了高Re是不脱气电弧岩浆的特征。东海山样品的特征是比起更像MORB的Lau Spreading Center熔岩的更高的Re和更低的Yb / Re。宿主橄榄石的Yb / Re和Fo之间缺乏相关性，这表明低的Yb / Re不是由于岩浆分化。当将Lau盆地样品套件与MORB数据一起绘制时，Yb / Re与Ce / Pb和Nb / U正相关，而与Ba / Nb负相关，这表明在俯冲板块脱水过程中Re比Yb流动得多。 。因此，弧岩浆中的Re富集很可能是由于通过俯冲板释放的流体添加了Re而引起的。电弧中高Re的认识有利于论证弧岩中放射源〜（187）Os /〜（188）Os的平板起源。

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