| Co-Investigator(Kenkyū-buntansha) |
FUJII Toshitsugu Tokyo Univ., Earthquake Research Inst.Professor, 地震研究所, 教授 (00092320)
OHTANI Eiji Tohoku Univ., Inst.Mineral.Petrol. & Economic Geol.Professor, 理学部, 教授 (60136306)
TATSUMI Yoshiyuki Kyoto Univ., Fac.Integrated Human Studies Professor, 総合人間学部, 教授 (40171722)
TAKAHASHI Eiichi Tokyo Inst.Tech., Dept.Earth & Planet Sci.Professor, 理学部, 教授 (40144779)
KAWAMURA Katsuyuki Tokyo Inst.Tech., Dept.Earth & Planet Sci.Professor, 理学部, 教授 (00126038)
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| Research Abstract |
During the three-year profect, so many developments have been made in the following fields, physical properties of magma, genesis of magmas, dynamics of magma generation, origin of volcanic activity, magmatic activities in the Earth's history. Collaborative works by scientists in different disciplines resulted in the establishment of a new discipline, magmalogy. The selected results may be summarized as follows.
・High pressure experiments confirmed that the density of magma becomes higher than those of mantle minerals at pressure, 13-15 GPa. As this significant property of magma was determined, the crystallization process within the magma ocean in the early stage of the Earth could be simulated by computer calculation.
・Combining various observations including seismic array experiments, geological survey of intrusive bodies, and petrological and geochemical analyzes of volcanic rocks, a comprehensive model on the crustal magma-feeding system of typical subduction zone volcano has been pr
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oposed.
・Compositional variation of partial melts of mantle peridotite were determined precisely using diamond aggregates method as function of pressure, temperature and melt fraction. As such a precise data set became available, quantitative discussions on the genesis of basaltic magmas at various tectonic settings has become possible.
・Experimental determination of the partition coefficients for lithophile elements between mantle minerals and magmas at high pressure indicates that the chondritic relative abundance of lithophile elements in the primitive upper mantle could be explained by the fractionation of the high pressure phase in the deep magma ocean extending to the depth of lower mantle.
・Composition of aqueous fluid coexisting with mantle minerals has been determined experimentally, and it was shown that the fluid contains large amount of silicate components, and that the fluid might be called as secondary magma. This indicates the possibility that aqueous fluid might have playd a significant role in the process of magma genesis. Less
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