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Petrology and Geochemistry of Schists, Gneisses and Leuco-granites in the East-northern Part of the Hida Metamorphic Belt, Central Japan.

日本中部飞驒变质带东北部片岩、片麻岩和隐色花岗岩的岩石学和地球化学。

基本信息

批准号：
60470053
负责人：
AKIRA Fujiyoshi
金额：
$ 4.74万
依托单位：
SHIZUOKA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

1. (i) Bernas' method that powder sample was decomposed with hydrofluoric acid in a sealed Teflon vessel was a little modified to make a clean solution easily.(ii) A simple method by atomic absorption spectrometry without adding large amounts of other elements for suppressing the interference of coexisting elements was investigated for the determination of major elements in silicates.2. In the Tateyama-gawa of the upper Hayatsuki-gawa area, two discordant temperatures, 610-650゜C and 700-780゜C from different sample were estimated by cordierite-garnet and garnet-biotite geothermometry. The metamorphic temperature of 700-780゜C might correspond to an earlier stage of metamorphism characterized by spinel, corundum, Mg-rich garnet and others; the metamorphism of 610-650゜C might have been caused by migmatization related to the leuco-granites and be characterized by andalusite and cordierite.3. The metamorphic grade increases from staurolite-kyanite zone of the amphibolite facies in the Kurobe-gawa area to the transition zone of the amphibolite-granulite facies in the Tateyama-gawa. With the increase of the metamorphic grade, chemical change is as follows: <SiO_2> decreases, <Na_2O> , <K_2O> , MgO, MnO and <TiO_2> increase, and <Al_2O_3> , FeO and CaO remain hardly unchanged.4. The results of chemical analyses of leuco-granites in calcareous, pelitic and basic gneisses indicates that the migmatites in the calcareous and plitic gneisses are formed in situ more easily than those in the basic gniesses.

1. (i)本文对Bernas提出的在聚四氟乙烯密封容器中用氢氟酸分解粉末样品的方法作了一些改进，使之易于配制干净的溶液。(ii)研究了一种不需加入大量其它元素抑制共存元素干扰的原子吸收光谱法测定硅酸盐中主量元素的方法.在早月川上部的立山川，用堇青石-石榴石和石榴石-黑云母地质测温法，从不同样品中估算出两个不一致温度，分别为610-650 ℃和700-780 ℃。700-780 ℃的变质温度可能对应于以尖晶石、尖晶石、富镁石榴石等为特征的早期变质作用; 610-650 ℃的变质作用可能是与浅色花岗岩有关的混合岩化作用，以红柱石和堇青石为特征.从黑部川地区角闪岩相的十字石-蓝晶石带到立山川地区角闪岩-麻粒岩相的过渡带，变质程度逐渐增加。随着变质程度的增加，化学变化表现为：<SiO_2>减少、<Na_2O>、<K_2O>、MgO、MnO和<TiO_2>增加，而<Al_2O_3>、FeO和CaO几乎保持不变.钙质、泥质和基性片麻岩中浅色花岗岩的化学分析结果表明，钙质和泥质片麻岩中的混合岩比基性片麻岩中的混合岩更容易就地形成。