Long-term deformation of the Tohoku Arc: constraints from multi-thermochronometiries

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03736
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geology
• Research Institution: Kyoto University
• Principal Investigator: Tagami Takahiro 京都大学, 理学研究科, 教授 (80202159)
• Co-Investigator(Kenkyū-buntansha): 堤 昭人 京都大学, 理学研究科, 助教 (90324607)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 熱年代学 / 東北日本弧 / 隆起 / 削剥 / 冷却 / (U,Th)/He法 / フィッショントラック法

Outline of Final Research Achievements

Recent progress of low-temperature thermochronology, e.g., developments of (U-Th-Sm)/He method and fission-track inversion modeling, enables to analyze uplift-denudation-cooling histories of the island-arc mountains with good confidence. This is particularly fruitful for studying the topographic evolution of the Japan Arc, because many of the Japanese mountains are started to uplift in recent time (e.g., late Pliocene to Quaternary) after an extended period of relative tectonic quiescence, and hence the resultant smaller amount of total denudation is only resolvable by low-temperature thermochronology. We conducted (U-Th-Sm)/He and fission-track analyses of the NE Japan Arc. We found following cooling episodes based on the dating results: (1) >50Ma in the forearc, (2) ~10- 5Ma in the backarc, and (3) ~1-2Ma in the central Ou backbone range. These results suggest contrasting uplift-denudation-cooling histories among the regions.

Free Research Field

地球年代学