Protolith, metamorphism and exhumation tectonics of the eclogites from the Sambagawa metamorphic belt, southwest Japan

2014 Fiscal Year Final Research Report

• Project/Area Number: 24340124
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: Shimane University
• Principal Investigator: TAKASU Akira 島根大学, 総合理工学研究科(研究院), 教授 (00183848)
• Co-Investigator(Kenkyū-buntansha): KAMEI Atsushi 島根大学, 総合理工学研究科, 准教授 (60379691) ; ROSER Barry 島根大学, 総合理工学研究科, 准教授 (60325040) ; AKASAKA Maasahide 島根大学, 総合理工学研究科, 教授 (20202509) ; OHIRA Hiroto 島根大学, 総合理工学研究科, 准教授 (60273918)
• Research Collaborator: KABIR M.F. 島根大学, 総合理工学研究科, 研究員 ; OROZBAEV. R. キルギス科学アカデミ地質研究所, 研究員 ; JAVKHALAN O. 島根大学, 総合理工学研究科 ; MATSUURA Hiroaki 島根大学, 総合理工学研究科 ; KAINUMA Masaaki 島根大学, 総合理工学研究科
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: テクトニクス / 変成岩 / エクロジャイト / P-T経路 / 地質年代 / 三波川変成帯 / キルギス / モンゴル

Outline of Final Research Achievements

The metamorphism of the eclogites exposed in the Sambagawa metamorphic belt occurred for relatively short period between 120 Ma and 90 Ma, and it is divided into four major metamorphic events, i.e. i) high-T type metamorphic event, ii) two fold eclogitic metamorphic events, and iii) glaucophane schist to epidote amphibolite facies metamorphic event. These metamorphic events are correlated to the tectonic settins in the subduction zone, i) contact metamorphism due to the inception of an oceanic plate subduction, ii) obtaining the steady state low-geothermal gradient and subsequent ridge approaching resulting in relatively high-geothermal gradient in the subduction zone, and finally medium-P/T Sambagawa metamorphism and exhumation of whole metamorphic sequence probably due to the ridge subduction.

Free Research Field

変成地質学