Volatile element isotope systematics at Ontake volcano, Japan
Volatile element isotope systematics at Ontake volcano, Japan
复制标题
日本御岳火山的挥发性元素同位素系统学
DOI：
10.2343/geochemj.37.299
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发表时间：
2003
影响因子：
0.8
通讯作者：
Y. Sano
中科院分区：
文献类型：
--
作者：
N. Takahata;R. Yokochi;Y. Nishio;Y. Sano
从1996年6月至2000年6月，在日本本州中部的Ontake火山的温泉和矿泉中采集了23个气体样品。用气相色谱仪、惰性气体质谱仪和稳定同位素质谱仪分别测定了样品的化学组成、He、Ar、C和N同位素比值。3 He/4 He比值随距离的增加而减小，CO2的δ 13 C值随距离的增加而增大。这种趋势与文献中1981年11月至1993年6月的观测结果一致，表明岩浆氦和碳的来源位于火山锥下方，并不断向周围排放。N2的δ 15 N值随距离的增加而增加，而40 Ar/36 Ar比值大多与大气值相近。岩浆中的氮也可能被流经火山碎屑岩的流体携带，并被地壳中的氮稀释。在1984年9月6.8级地震形成的断层附近，观测到1996 ~ 2000年3 He/4 He比值的显著增加，这与1981年11月~ 1993年6月3 He/4 He比值的变化相吻合。1993年6月至2000年6月在白川观测点观测到δ 13 C值异常增高。这种变化不能用岩浆和地壳端元之间简单的双组分混合来解释，可能需要另一种具有三个端元（地幔、石灰岩和沉积物）的模型。
Twenty three gas samples were collected from hot and mineral springs associated with Ontake volcano in central Honshu, Japan from June 1996 to June 2000. The chemical compositions, He, Ar, C and N isotopic ratios were measured using a gas chromatography, noble gas and stable isotope mass spectrometers, respectively. The 3He/4He ratio decreased with increasing distance from the central cone of the volcano to the sampling site, while δ13C value of CO2 increased with the distance. Such trends are consistent with those observed from November 1981 to June 1993 in the literature, suggesting that source of magmatic helium and carbon is located beneath the volcanic cone and they are continuously emitted into surroundings. The δ15N value of N2 increased with the distance while most 40Ar/36Ar ratios were similar to the atmospheric value. Magmatic nitrogen may also be carried by a fluid flowing through the volcanic edifice and diluted by crustal nitrogen. Significant increase of 3He/4He ratio from 1996 to 2000 was observed at the site close to the fault formed by a M6.8 earthquake that occurred in September 1984, which agrees well with the 3He/4He change from November 1981 to June 1993. Anomalous increase of δ13C value was observed at Shirakawa site from June 1993 to June 2000. The change cannot be explained by a simple two-component mixing between magmatic and crustal end-members and may require another model with three end-members, mantle, limestone and sediment.
影响因子：
4
作者：
SANO, Y;WAKITA, H
通讯作者：
WAKITA, H