Mineralogical Studies of Carbonatites.

碳酸岩的矿物学研究。

基本信息

批准号：
63470044
负责人：
HORIUCHI Hiroyuki
金额：
$ 4.93万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

Studies on textures and chemical conpositions of constituent minerals of carbonatites and alkaline rocks were performed mainly using specimens obtained by the Monbusho International Scientific Research Program entitled "Studies on rare-earth and radioactive minerals of alkaline complexes in Brasil" (Head Investigator : Professor Masayasu TOKONAMI). Main subjects are the observations of following phenomena : (1) alteration of pyroxene into serpentine by a metamorphism at the contact of jacupirangite with carbonatite, (2) remarkable leaching phenomena of alkaline metal and alkaline-earth metal ions not only from carbonates but also from silicates, oxides, etc., (3) characteristic concentrations of rare-earth elements in such phosphate minerals as monazite, cheralith, etc., and concentrations into rhabdophane, crandallite, goyazite, etc. as a result of weathering.In this project, we also contributed to the development of a microarea X-ray diffraction technique. By applying this method, we can identify minerals up to the minimum of 5-10 mum crystalline phases without destroy of the specimen. Furthermore, it is possible to determine the crystallo-graphic orientation relationship among different crystalline phases which are observed in textures.Thus, this method will contribute to clarify various complicated mineralization processes such as solidification of carbonaceous magmas and its metamorphism with alkaline rocks, weathering processes, etc., by combined observations of an optical microscope, scanning electron microscope, etc..

主要利用文部省国际科学研究项目“巴西碱性复合体的稀土和放射性矿物的研究”获得的标本，对碳酸岩和碱性岩的构成矿物的结构和化学成分进行了研究（首席研究员：常波雅康教授））。主要研究对象是对以下现象的观察：（1）在碧铜矿与碳酸岩接触处通过变质作用将辉石转变为蛇纹石，（2）碱金属和碱土金属离子不仅从碳酸盐中而且从碳酸盐中显着的浸出现象硅酸盐、氧化物等，(3)独居石、铍石等磷酸盐矿物中稀土元素的特征浓度，以及杆状稀土元素的浓度，风化作用产生的辉辉石、菱沸石等。在这个项目中，我们还为微区X射线衍射技术的开发做出了贡献。通过应用这种方法，我们可以在不破坏样品的情况下识别至少 5-10 μm 晶相的矿物。此外，还可以确定在结构中观察到的不同晶相之间的晶体取向关系。因此，该方法将有助于阐明各种复杂的成矿过程，例如碳质岩浆的凝固及其与碱性岩的变质作用、风化过程等，通过光学显微镜、扫描电子显微镜等的组合观察。