Geological significance of high-K adakitic granite and syenite complex in the early stage of continental break-up

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05312
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: Shimane University
• Principal Investigator: Kamei Atsushi 島根大学, 総合理工学研究科, 教授 (60379691)
• Co-Investigator(Kenkyū-buntansha): 柴田 知之 広島大学, 理学研究科, 教授 (40332720) ; 大和田 正明 山口大学, 大学院創成科学研究科, 教授 (50213905) ; 外田 智千 国立極地研究所, 研究教育系, 准教授 (60370095) ; 小山内 康人 九州大学, 比較社会文化研究院, 教授 (80183771) ; 高須 晃 島根大学, 総合理工学研究科, 教授 (00183848)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: アダカイト / 閃長岩 / 超大陸分裂 / ゴンドワナ / 原生代末 / 南極

Outline of Final Research Achievements

Latest Neoproterozoic magmatism of high-K adakitic granite and syenite complex is observed in Sor Rondane Mountains, East Antarctica. The aim of this study is to reveal the petrogenesis of the complex and to make clear the geological significance of this igneous activity. SHRIMP U-Pb zircon dating of the complex suggests their simultaneous activities of several high-K adakitic magmas and syenite magma happened at around 550 Ma. Geochemical investigations offer that the high-K adakite magmas were derived from partial melting of volcanic arc type basalt under high pressure conditions such as 2.0 GPa or more. On the other hand, the syenite originated from the melting of the underlying mantle. Therefore, the igneous activity of the high-K adakitic granite and syenite complex means the beginning of "re-break-up" the thickened suture zone, which formed by collision of volcanic arcs accompanying with the Gondwana amalgamation.

Free Research Field

地球惑星科学・地質学