Solidification process of crustal magma chamber

Research Project

Project/Area Number	15K05337
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Petrology/Mineralogy/Economic geology
Research Institution	Tohoku University
Principal Investigator	Simura Rayko 東北大学, 多元物質科学研究所, 助教 (90420009)
Project Period (FY)	2015-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000) Fiscal Year 2017: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2016: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2015: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Keywords	板状貫入岩体 / 岩石組織 / 偏光顕微鏡 / マグマ溜まり / マグマ熱進化過程 / 結晶分化 / 熱進化過程 / 貫入岩
Outline of Final Research Achievements	Crystal size distributions of groundmass minerals of the Nosappumisaki intrusion were analyzed using a polarization film rotating thin section observation system. This system produces maps of mineral retardation and primary-axis direction in thin section samples. Mineral types observed in thin sections were identified using the generated retardation maps, and the grain boundaries were delimited using primary-axis direction maps. The data reveal that there is a systematic variation in the crystal sizes of constituent alkali feldspar (plagioclase), biotite, and magnetite that suggests solidification by thermal conduction originating near the lowermost contact surface with the host rock, and proceeding toward the inner region of the Nosappumisaki magma chamber.