Tectonic process resolved by geochemistry of submarine basalts
| Project/Area Number |
17K05715
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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 |
Geochemistry/Cosmochemistry
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| Research Institution | Tohoku University |
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Principal Investigator |
Hirano Naoto 東北大学, 東北アジア研究センター, 准教授 (00451831)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | アウターライズ / 太平洋プレート / プチスポット / アルカリ玄武岩 / 沈み込み / 日本海溝 / プレートの変形 / 単成火山 / リソスフェア / アセノスフェア / かんらん岩 / 二酸化炭素 / 海洋プレート / 海溝 |
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| Outline of Final Research Achievements |
Previous researches indicate that most of petit-spot erupted on concavely flexed plate are highly reacted with the depleted lithosphere during the magma ascending to surface. Geochemical composition of entrained xenolith from depleted mantle is disturbed by wall-rock interaction (Pilet et al., 2016). The research cruise KS-18-9, R/V Shinseimaru, in order to access the asthenosphere in August 2018 newly discovered the directly ascending petit-spot melt from asthenosphere (Sato, Hirano et al., 2018). The lavas, silica-poor and strongly alkaline with phenocrystic olivines, are completely discriminated from the majority of previous petit-spots. They selectively erupt atop the outer-rise wherein the lithosphere behaves entirely extensional during the ascent of melt from asthenosphere. Collaborated works with Univ. Bayreuth (Germany), Nanyang Tech. Univ. (Singapore), and Second Instit. Oceanogr. (China) provided several papers of Hirano et al. (2019), and Liu, Hirano et al. (2020).
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| Academic Significance and Societal Importance of the Research Achievements |
溶岩の産状・マグマ組成・噴出年代・マグマ上昇速度と、海底地形によるプレート構造およびその地理分布を照らし合わせ、プレートの変動履歴が明らかとなった。プレートの挙動が構成する岩石そのものから初めて示されるという点で大変意義深い。沈み込む海洋プレートの地殻構造や応力場の情報は、これまで海底音響探査や地震波を用いた構造探査、いくつかの過程を置いたシミュレーションなど、間接的な情報しか無かったが、本研究によりプレートの物質から直接的に得られた応力場・変動時期の情報として極めて貴重な成果が得られた。
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Report
(4 results)
Research Products
(39 results)
