Oxygen isotope variations in magmatic differentiation processes of the volcanic rocks in Japan
Oxygen isotope variations in magmatic differentiation processes of the volcanic rocks in Japan
复制标题
日本火山岩岩浆分异过程中的氧同位素变化
DOI：
--
复制
发表时间：
1973
期刊：
影响因子：
--
通讯作者：
Hitoshi Sakai
中科院分区：
文献类型：
--
作者：
Y. Matsuhisa;O. Matsubaya;Hitoshi Sakai
本文分析了日本伊豆箱根地区、隐岐道后岛、浅间火山和木曾翁竹火山的35个火山岩的18 O/16 O比值。各岩系在结晶分异过程中，岩浆中~（18）O富集。拉斑玄武岩系列岩浆的固液同位素分馏幅度与碱性岩系列相近，钙碱性岩系列的表观同位素分馏幅度大于上述两个系列。伊豆-箱根地区拉斑玄武岩岩浆的δ 18 O值相对于SMOW为+5.7‰，表明其起源于新鲜的上地幔物质。浅间火山钙碱性岩系的原始岩浆的δ 18 O值与伊豆箱根原始岩浆的δ 18 O值相近或略高。岛弧大陆一侧的冲岛-道后岛的碱性岩系比伊豆-箱根岩系重1‰。这可能意味着隐岐-道后岩系可能与富含18 O的地壳物质交换了氧，或者它们可能起源于富含18 O的上地幔物质。
The 18O/16O ratios were analyzed for 35 volcanic rocks from the Izu-Hakone region, Oki-Dogo Island, Asama Volcano and Kiso-Ontake Volcano in the Japanese Islands. The 18O-enrichment in magma during crystallization differentiation is recognized in every rock series. The magnitude of solid-liquid isotope fractionation in the magma of tholeiite series is similar to that of alkali rock series, while the apparent isotope fractionation of calc-alkali rock series is larger than that of the above two series. The δ18O value of the tholeiite magma in the Izu- Hakone region is +5.7‰ relative to SMOW, which suggests its origin from the fresh upper mantle material. The primary magma of the calc-alkali rock series in Asama Volcano is assumed to have the δ18O value similar to or slightly higher than that of the Izu-Hakone primary magma. The alkali rock series of Oki-Dogo Island in the continental side of the island arc is by 1‰ heavier than the Izu-Hakone rock suite. This may imply that Oki-Dogo rock series might have exchanged their oxygen with 18O-rich crustal materials, or they might have originated from somewhat 18O-rich upper mantle material.