2019 Fiscal Year Final Research Report
Crust-mantle interaction and compositional variation of continental lithosphere due to collision event
| Project/Area Number |
15H03748
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Economic geology
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| Research Institution | Yamaguchi University |
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Principal Investigator |
Owada Masaaki 山口大学, 大学院創成科学研究科, 教授 (50213905)
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| Co-Investigator(Kenkyū-buntansha) |
川嵜 智佑 愛媛大学, 理学部, 研究員 (50136363)
外田 智千 国立極地研究所, 研究教育系, 准教授 (60370095)
亀井 淳志 島根大学, 学術研究院環境システム科学系, 教授 (60379691)
志村 俊昭 山口大学, 大学院創成科学研究科, 教授 (70242451)
小山内 康人 九州大学, 比較社会文化研究院, 教授 (80183771)
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| Project Period (FY) |
2015-04-01 – 2020-03-31
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| Keywords | ゴンドワナ大陸 / 衝突帯 / 大陸地殻 / マントル / 変花崗岩 / ランプロファイアー / 海洋島弧 / 原生代 |
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| Outline of Final Research Achievements |
The Gondwana supercontinent was formed during the Late Neoproterozoic and included several suture zones. The Sor Rondane Mountains (SRM), East Antarctica, is situated within the suture zone of the Gondwana supercontinent, and is underlain by various kinds of the metamorphic and igneous rocks. The aim of this study is to reveal the time for formation of the SRM by the amalgamation of Proterozoic terranes and to address the crust and mantle interaction during the formation of suture zone.
Combined with the Nd isotopic values of the metagranitoids and the zircon U-Pb dating of the metamorphic rocks, the amalgamation of terranes in the SRM was established during 620 to 640 Ma. After that event, the high-K magmatism, lamprophyre and syenite, intruded into the SRM at ca. 550 Ma. The high-K magma could be produced by partial melting of the metasomatized mantle at least 60 km in depth. The source mantle of the high-K magma was modified by the subducted Proterozoic crust.
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| Free Research Field |
固体地球科学の諸現象を対象とした地質学
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| Academic Significance and Societal Importance of the Research Achievements |
大陸の成長は，マントルから付加される苦鉄質マグマの量と沈み込み帯からマントルへ運び込まれる大陸地殻の量によって決まる。大陸衝突帯は大陸同士が衝突し，一方の大陸がマントルへ潜り込むため，大陸がマントルへ運び込まれる直接証拠を得ることができる。本研究は，この課題に対して，大陸衝突帯に産する苦鉄質岩の化学的特徴から，衝突事変の後に活動したマグマが明らかに沈み込む大陸地殻と反応したことを明らかにした。
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