A strontium isotopic study of the volcanic rocks of the Myoko volcano group, central Japan
A strontium isotopic study of the volcanic rocks of the Myoko volcano group, central Japan
复制标题
日本中部妙高火山群火山岩的锶同位素研究
DOI：
10.1007/bf00375577
复制
发表时间：
1977
影响因子：
3.5
通讯作者：
K. Hayatsu
中科院分区：
文献类型：
--
作者：
K. Ishizaka;T. Yanagi;K. Hayatsu
从Myoko火山群，其中包括一个火山链的四个独立的火山第四纪到最近的年龄的31个选定的火山岩进行了87 Sr/86 Sr比值分析。在Myoko火山群中最古老的lizuna火山的岩石具有更高的87 Sr/86 Sr比值，并且比其他火山的岩石具有更大的分散度，范围从0.70437到0.70556。黑姬火山岩的87 Sr/86 Sr比值范围有限（0.70403 ~ 0.70435）。87 Sr/86 Sr比值的Myoko火山岩几乎相同的平均黑姬火山岩，虽然有些变化范围为0.70378至0.70461。对八重山火山岩的一次分析得出87 Sr/86 Sr比值为0.70427。87 Sr/86 Sr比值在Myoko火山群的火山活动中呈现出一种特征性的变化模式，即87 Sr/86 Sr比值在火山活动的早期较高，然后下降到较低的值，而在火山活动的晚期，87 Sr/86 Sr比值基本保持不变。Iizuna火山岩石中87 Sr/86 Sr与Rb/Sr的负相关和87 Sr/86 Sr与Sr的正相关表明存在高87 Sr/86 Sr比值（>0.7056）、低Rb/Sr比值（<0.01）和高Sr含量（>300 ppm）物质的混染。硅铝质地壳污染可能只起了很小的作用。
Thirty-one selected volcanic rocks from the Myoko volcano group which comprises a volcanic chain of four independent volcanoes of Quaternary to Recent age are analyzed for 87Sr/86Sr ratios. The rocks of the lizuna volcano, the oldest among the Myoko volcano group, have higher 87Sr/86Sr ratios and show a larger scatter ranging from 0.70437 to 0.70556 than those of other volcanoes. The Kurohime volcanic rocks have a restricted range of 87Sr/86Sr ratios (0.70403∼0.70435). 87Sr/86Sr ratios of the Myoko volcanic rocks are almost the same in average to those of the Kurohime volcanic rocks, although somewhat varied ranging from 0.70378 to 0.70461. A single analysis of the Yakeyama volcanic rock yielded a 87Sr/86Sr ratio of 0.70427. A characteristic pattern in 87Sr/86Sr ratios is observed through the volcanic activity of the Myoko volcano group; 87Sr/86Sr ratios are high in the early stage of the volcanic activity and then decrease to low values, the late eruptives being characterized by constant 87Sr/86Sr ratios. The negative correlation between 87Sr/86Sr and Rb/Sr, and positive correlation between 87Sr/86Sr and Sr found in the rocks of the Iizuna volcano are interpreted to show the occurrence of contamination by materials with high 87Sr/86Sr ratios (>0.7056), low Rb/Sr ratios (<0.01) and high Sr contents (>300 ppm). Sialic crustal contamination may have played only a minor role.