Time scale and cause of initiation of subduction of oceanic plate

2016 Fiscal Year Final Research Report

• Project/Area Number: 25287133
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Ishizuka Osamu 国立研究開発法人産業技術総合研究所, 活断層・火山研究部門, 主任研究員 (90356444)
• Co-Investigator(Kenkyū-buntansha): 海野 進 金沢大学, 自然システム学系, 教授 (30192511) ; 谷 健一郎 独立行政法人国立科学博物館, 地学研究部, 研究員 (70359206) ; 森下 知晃 金沢大学, 自然システム学系, 教授 (80334746) ; 針金 由美子 国立研究開発法人産業技術総合研究所, 地質調査総合センター地質情報研究部門, 主任研究員 (90569360)
• Co-Investigator(Renkei-kenkyūsha): KUSANO Yuki 国立研究開発法人産業技術総合研究所, 活断層・火山研究部門, 研究員 (00635972)
• Research Collaborator: TAYLOR Rex N. University of Southampton, Senior Lecturer ; MAFFIONE Marco Utrecht University, Post doctoral fellow
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: プレートの沈み込み / オフィオライト / 高精度年代測定 / 地球化学 / 島弧

Outline of Final Research Achievements

The initiation of subduction and the subsequent birth and early development of island arcs are still poorly understood. Exposed forearcs, such as Izu-Bonin-Mariana forearc, are valuable for understanding how subduction zones start. We conducted submarine geological survey in Izu and Mariana forearcs as well as analyses of samples collected by ocean drilling in the ancient reararc side of this arc. Geochemical characteristics and age of the collected rocks revealed magmatic and tectonic processes at and immediately after subduction initiation. Ophiolite sections exposed on land are also suitable targets to study subduction initiation. Our target of fieldwork included ophiolite sections of Vourinos (Greece), Khoy (Iran), Troodos (Cyprus), and Mersin (Turkey). Geochemical, structural and geochronological study of crustal and mantle sections of these ophiolites revealed commonality and differences in magmatic and mantle processes at subduction initiation among these studied sections.

Free Research Field

年代学，地質学