The Early Earth Mantle-Crust Differentiation History through in-situ Analysis of Zr Minerals in Archean Ultramafic Rocks

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14571
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: University of Toyama (2023); Japan Agency for Marine-Earth Science and Technology (2020-2022)
• Principal Investigator: Sawada Hikaru 富山大学, 学術研究部都市デザイン学系, 助教 (10845100)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: ジルコン / 太古代 / バデレアイト / 超苦鉄質岩 / かんらん岩 / 蛇紋岩 / 地殻 / マントル

Outline of Final Research Achievements

In our study, as we recovered and analyzed various heavy minerals from different ultramafic and mafic rocks, it became evident that zircon minerals in these rocks are relatively prone to dissolution and reprecipitation due to the formation of strongly alkaline hydrothermal fluids during serpentinization reactions. Deciphering the early history of the Earth's mantle and crust, our initial objective, has proven to be exceedingly challenging. Over the past year, there has been a surge in reports regarding the properties of zircon in ultramafic rocks, leading to conclusions similar to those of our research project. Through studies conducted by representatives, we have been able to catch up with global research trends.

Free Research Field

鉱物学

Academic Significance and Societal Importance of the Research Achievements

超苦鉄質岩は日本列島でも一般的な岩石であり、その蛇紋岩化反応はプレート沈み込み帯で顕著に起こっている現象である。これらの岩石から希少なアクセサリー鉱物を抽出し、様々な局所分析を行った本研究の手法や議論の方向性は、太古代のような地球史初期の地質解読ばかりでなく、日本列島の比較的若い年代の岩石に対しても有効であり、それらの分析によって今後の防災科学に対する知見が広がることも期待できる。