TOKONAMI Masayasu University of Tokyo, Faculty of Science, Professor, 理学部, 教授 (80029850)
OZAWA Tohru University of Tokyo, Faculty of Science, Lecturer, 理学部, 講師 (00011651)
芳賀 信彦 東京大学, 理学部, 助手 (60011748)
|Budget Amount *help
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1988: ¥3,500,000 (Direct Cost: ¥3,500,000)
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..