島弧における初生マグマの含水量の推定：実験岩石学とメルト包有物分析からの制約

DOI Web Site 参考文献109件
  • 浜田 盛久
    東京工業大学大学院理工学研究科地球惑星科学専攻
  • 東宮 昭彦
    産業技術総合研究所地質調査総合センター

書誌事項

タイトル別名
  • Estimation of H2O concentration in primary arc magmas: constraints from melting experiments and analyses of melt inclusions
  • トウコ ニ オケル ショセイ マグマ ノ ガン スイリョウ ノ スイテイ ジッケン ガンセキガク ト メルト ホウユウブツ ブンセキ カラ ノ セイヤク

この論文をさがす

説明

  The slab-derived fluids and/or hydrous slab melts released from a subducted slab ascend into the mantle wedge, lower its melting temperature and thus induce generation of hydrous arc magmas. The estimation of H2O concentration in primary arc magmas provides an important constraint on pressure and temperature conditions of magma generation at subduction zones. This paper gives an overview of the estimation of H2O concentration in primary arc magmas by combining two petrological methods: experimental petrological studies and analyses of melt inclusions. Melting experiments of hydrous primary arc magmas have clarified that the P-T condition of magma generation shifts toward lower temperature and higher pressure with increasing H2O concentration. Another experimental constraint is that only primary magmas with low H2O (≤ 2 wt%) can erupt without modification of their primary composition by crystallization differentiation due to comparable dT/dP between olivine liquidus and basalt adiabat. However, this does not exclude presence of hidden H2O-rich primary magmas at depths. Indeed, the H2O concentrations in primary melt estimated from the analyses of primitive melt inclusions suggest wide variation (e.g., ~ 2 wt% at Kamchatka arc and ~ 4 wt% at Central American arc). H2O-rich primary magmas may ascend and erupt after differentiation and/or supply volatiles to magmas at shallower level and cause so-called “excess degassing”. Analyses of melt inclusions also clarified that the H2O concentration in primitive melt inclusions is almost constant or decrease from volcanic front to rear arc. This observation is opposite to a previous understanding that H2O concentration in primary melt increases as well as incompatible K2O across the arc.<br>

収録刊行物

  • 岩石鉱物科学

    岩石鉱物科学 40 (3), 91-100, 2011

    一般社団法人　日本鉱物科学会

参考文献 (109)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ