Growth of the second continent and mantle dynamics: Insights from a history of continental growth and tectonic erosion

2015 Fiscal Year Final Research Report

• Project/Area Number: 23224012
• Research Category: Grant-in-Aid for Scientific Research (S)
• Allocation Type: Single-year Grants
• Research Field: Geology
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Maruyama Shigenori 東京工業大学, 地球生命研究所, 特命教授 (50111737)
• Co-Investigator(Kenkyū-buntansha): YOKOYAMA Tetsuya 東京工業大学, 大学院理工学研究科, 准教授 (00467028) ; KAWAI Kenji 東京大学, 大学院総合文化研究科, 助教 (20432007) ; SENSHU Hiroki 千葉工業大学, 惑星探査研究センター, 研究員 (30359202) ; ZHAO Dapeng 東北大学, 理学研究科, 教授 (70304665) ; OMORI Soichi 放送大学, 教養学部, 准教授 (90267469) ; KOMABAYASHI Tetsuya エディンバラ大学, 地球科学科, 講師 (20444119)
• Project Period (FY): 2011-04-01 – 2016-03-31
• Keywords: 花崗岩質大陸地殻 / 構造浸食 / 沈み込み帯 / マントルダイナミクス / 第三大陸 / 原初大陸 / 大陸三層モデル

Outline of Final Research Achievements

This research demonstrates the presence of the second continent in the mantle transition zone, equivalent to ten times the volume of the continent. This is based on the quantitative evaluation of tectonic erosion through time and both the growth mechanism of granitic crust and quantification of its generation also through time. Furthermore, we revealed the history of dispersion and amalgamation of the 1.8 Ga supercontinent by radioactive heat effect of the third continent, and obtained evidence which strongly indicates that the third continent (fallen primordial continent, particularly KREEP basalt) is the main constituent of the “D” layer. Lastly, we proposed the model combining the three-layer model and the Earth history to systematize the mantle dynamics including that of the second continent. This model is to steer the research regarding the mechanism to generate the liquid core, which has not been unraveled by numerical computation of Earth’s convection, in a new direction.

Free Research Field

地質学的手法に基づく地球生命史