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THE STRUCTURES AND PHYSICAL PROPERTIES OF MAGMAS

岩浆的结构和物理性质

基本信息

批准号：
09044069
负责人：
OKUNO Masayuki
金额：
$ 2.11万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09044069/
关键词：
magma glass structure analysis X-ray diffraction method Raman spectroscopy volcanic glass plagioclase 灰長石

项目摘要

Principle results on the structures of feldspar and volcanic glasses for analyzing structures and physical properties of magmas under high temperature and pressure conditions were followed.a) The shock-wave densification of SiO2 glass was analyzed by X-ray diffraction and Raman spectroscopy. SiO2 glass was densified up to 25GPa and the density decreased upper pressure by high residual temperature.b) Feldspar (NaAlSi_3O_8 CaAl_2Si_2O8) glasses were compressed under 500^OC/4GPa and 7.7GPa by cubic press apparatus. The structures of these glasses were analyzed by Raman spectroscopy. From these observations, it was evident that the structure of plagioclase glass has smaller ring structure of TO_4 tetrahedra and the coordination numbers of Al atoms change from 4 to 6 under high temperature and high pressure conditions. Shock experiment for CaAl_2Si_2O_8 glass was also performed to reveal the density increase was smaller than that of SiO2 glass and this density increase was based on the increase of three membered rings of TO_4 tetrahedra. The annealing process of shock-wave denshified CaAl_2Si_2O_8 glass was also investigated by in-situ Raman spectroscopy. These results are very important to understand Al bearing magma.c) The structures of densified volcanic glasses obtained by shock and static compressions were investigated by Xray diffraction and Raman spectroscopy techniques. The densification of volcanic glass (about 9%) by 500^OC/7.7GPa static compression may be due to change from 6 and 5 membered ring of TO_4 tetrahedra dominant structure to 4 and 3 meinbered ring dominant structure. On the other hand, crystallites in the obsidian vitrified by shock-wave compression and the density did not increase but decrease at higher shock pressure(25 and 35GPa).d) These results were discussed in Japan and France by all project members and we prepared some scientific papers.

利用X射线衍射和拉曼光谱分析了SiO2玻璃的冲击波致密化过程。B）用六面顶压机在500 ℃/4GPa和7.7GPa下对长石（NaAlSi_3O_8、CaAl_2Si_2O_8）玻璃进行了压缩。用拉曼光谱分析了玻璃的结构。结果表明，在高温高压条件下，斜长石玻璃具有较小的TO_4四面体环状结构，Al原子的配位数从4变为6。对CaAl_2Si_2O_8玻璃进行了冲击实验，发现其密度增长小于SiO_2玻璃，这种密度增长是基于TO_4四面体三元环的增加。用原位拉曼光谱研究了冲击波致密化CaAl_2Si_2O_8玻璃的退火过程。这些结果对认识含铝岩浆具有重要意义。c）用X射线衍射和拉曼光谱技术研究了冲击压缩和静态压缩得到的致密化火山玻璃的结构。火山玻璃经500^OC/7.7GPa静态压缩后的致密化（约9%）可能是由于由TO_4四面体的六元环和五元环结构为主转变为四元环和三元环结构为主。另一方面，黑曜石中的微晶通过冲击波压缩而玻璃化，并且密度在更高的冲击压力（25和35 GPa）下没有增加而是减少。d）这些结果由所有项目成员在日本和法国讨论，并且我们准备了一些科学论文。