Geochemical modeling of dehydration and partial melting of subducting lithosphere: Toward a comprehensive understanding of high‐Mg andesite formation in the Setouchi volcanic belt, SW Japan
Geochemical modeling of dehydration and partial melting of subducting lithosphere: Toward a comprehensive understanding of high‐Mg andesite formation in the Setouchi volcanic belt, SW Japan
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DOI：
10.1029/2003gc000530
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发表时间：
2003-09
期刊：
影响因子：
3.7
通讯作者：
Y. Tatsumi;T. Hanyu
中科院分区：
文献类型：
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作者：
Y. Tatsumi;T. Hanyu
通过脱水、部分熔融和熔-固反应的地球化学表述，研究了地幔来源的高镁安山岩岩浆产生的可能机制，包括（1）俯冲岩石圈水溶液的加入使地幔楔橄榄岩部分熔融，（2）俯冲沉积物和蚀变洋壳部分熔融，以及随后的熔体-地幔相互作用。模拟结果表明，这两种机制都可以合理地解释日本西南部Setouchi火山带高Mg安山岩的不相容微量元素特征。然而，地幔楔橄榄岩的简单水合熔融不能解释这种安山岩的Sr-Nd-Pb-Hf同位素组成。相反，后一种机制与濑户内火山带下方的热结构一致，可以很好地再现这些高镁安山岩的同位素特征。
Possible mechanisms for the production of mantle‐derived, high‐Mg andesite magmas, including (1) partial melting of mantle wedge peridotite by addition of aqueous fluids from the subducting lithosphere and (2) partial melting of the subducting sediments and altered oceanic crust, and subsequent melt‐mantle interaction, were examined by geochemical formulation of dehydration, partial melting and melt‐solid reactions. The modeling results demonstrate that both mechanisms can reasonably explain the incompatible trace element characteristics of high‐Mg andesites in the Setouchi volcanic belt, SW Japan. However, simple hydrous melting of mantle wedge peridotite cannot account for the Sr‐Nd‐Pb‐Hf isotopic compositions of such andesites. By contrast, the latter mechanism, which is consistent with thermal structures beneath the Setouchi volcanic belt, can well reproduce the isotopic signature of those high‐Mg andesites.