Tracing origin and transportation mechanism of subducted water into the mantle by simultaneous determination of halogens and noble gases

2014 Fiscal Year Final Research Report

• Project/Area Number: 23340169
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geochemistry/Astrochemistry
• Research Institution: The University of Tokyo
• Principal Investigator: SUMINO Hirochika 東京大学, 理学(系)研究科(研究院), 助教 (90332593)
• Co-Investigator(Kenkyū-buntansha): MIZUKAMI Tomoyuki 金沢大学, 自然システム学系, 助教 (80396811) ; WALLIS R・Simon 名古屋大学, 環境学研究科, 教授 (30263065) ; KAGI Hiroyuki 東京大学, 大学院理学系研究科, 教授 (70233666)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: ハロゲン / 希ガス / 沈み込み / スラブ流体 / 質量分析 / 中性子照射 / マントル / 水

Outline of Final Research Achievements

We have developed an analytical method for simultaneous determination of ultratrace-amounts of halogens and noble gases by using neutron-irradiation and noble gas mass spectrometry. Halogens and noble gases in mantle-derived peridotite xenoliths from subduction zones shares sedimentary pore-fluid-like signature with mantle peridotites and serpentinites from the Sanbagawa metamorphic belt in Shikoku, southwest Japan. Eclogites and metasediments from the Sanbagawa metamorphic belt contain a Cl-rich component, which is typical of altered oceanic crust, in addition to the sedimentary pore-fluid-like component. These observations indicate that mantle wedges beneath subduction zones are significantly and widely metasomatized by subducted components with respect to halogens and noble gases.

Free Research Field

同位体地球化学