| Project/Area Number |
15K05352
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Economic geology
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| Research Institution | Kitakyushu Museum of Natural History and Human History |
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Principal Investigator |
Shigeno Miki 北九州市立自然史・歴史博物館, 自然史課, 受託研究生 (90749558)
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| Co-Investigator(Kenkyū-buntansha) |
森 康 北九州市立自然史・歴史博物館, 自然史課, 学芸員 (20359475)
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| Research Collaborator |
Nishiyama Tadao
Kawamoto Tatsuhiko
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| Project Period (FY) |
2015-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2015: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 流体包有物 / 流体包有物の塩濃度 / スラブ流体 / ヒスイ輝石岩 / 曹長岩 / 蛇紋岩メランジ / 沈み込み帯 / 石英ヒスイ輝石岩 / 岩石・鉱物・鉱床学 |
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| Outline of Final Research Achievements |
Major components and salinity of fluid inclusions (liquid + gas bubble) in jadeite-quartz rocks, quartz-bearing jadeitite with albitite rind, albite-jadeitites from Japan were examined to find traces of slab-derived fluids in subduction-zone channels between the subducting slab and the mantle wedge.
The quartz-bearing jadeitite with albitite-rind developed along the slab-surface. Fluid inclusions in the both specimens showed low salinity (less than 5 wt% NaCl eq.). On the other hand, albite-jadeitites were formed by precipitation, when the slab-derived fluids went into the mantle wedge. Fluid inclusions in the albite-jadeitites showed higher salinity (more than 6 wt% NaCl eq.) and have small amount of methane. These results explain process of petrogenesis (origin, metamorphic condition and different appearance) of two types of jadeitite and two circulating paths of slab-derived fluids in subduction-zone channels.
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| Academic Significance and Societal Importance of the Research Achievements |
地球規模の物質循環の中で、プレート収束域において過去にヒスイの生成や発達に関わる物質移動に重要な役割を果たした、海水起源とされる塩水の情報を捉えた。
プレート収束域の地殻-マントル境界付近において、過去に地下深く沈み込んだヒスイ（日本産）と、その鉱物中に数ミクロンの微小な包有物としてカプセルのように保存された塩水を調べた。塩水の内容物と塩濃度の違いから、ヒスイの２つの成因を共に説明する新たなモデルを考案した。さらに、成因の異なるヒスイに封じ込められて運ばれた、地下深部の水の２つの循環経路を提唱し、国石としても知られるようになったヒスイの成因と科学的意義を示した。
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