Metasomatic process of the mantle wedge recorded in basal peridotites from the Oman ophiolite

• Project/Area Number: 16K05606
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Hiroshima University (2018); Kyoto University (2016-2017)
• Principal Investigator: Yoshikawa Masako 広島大学, 理学研究科, 研究員 (00378605)
• Co-Investigator(Kenkyū-buntansha): Python Marie 北海道大学, 理学研究院, 助教 (30533278) ; 田村 明弘 金沢大学, 地球社会基盤学系, 博士研究員 (80401884)
• Research Collaborator: Arai Shooji ; Shibata Tomoyuki ; Mohamed Khedr Zaki
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000); Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: オフィオライト / 基底部かんらん岩 / メタモルフィックソール / 微量元素組成 / Sr-Nd同位体比 / 上部マントル / 沈み込み帯 / かんらん岩 / 沈み込み帯マントル / 交代作用 / オマーンオフィオライト / 沈み込みたいマントル / スラブ由来成分 / 初期島弧

Outline of Final Research Achievements

We estimated Sr-Nd isotope ratios and trace element compositions were newly obtained from clinopyroxenes in the basal peridotites of the central Sarami block and a harzburgite in the central Hilti block of the Oman ophiolite in order to directly observe the chemical composition change of the upper mantle by the subducting slab. The basal peridotites of the northern and central blocks show chemical characteristics of residual peridotites and the influence of components derived from the subducting slabs. On the other hand, our results suggest that basal peridotites in the southern Wadi Tayin block and the harzburgite in the central Hilti block were formed by melt-peridotite reaction, and melt involved in the reaction should have a similar composition to the mid-ocean ridge basalt.

Academic Significance and Societal Importance of the Research Achievements

岩石やその構成鉱物の微量元素・Sr-Nd 同位体組成は、一般に、分化過程や混合過程などのプロセスやそれらが起こった場や年代、起源物質についてより詳細な情報を与えている。しかしオフィオライトを構成するかんらん岩のデータの蓄積は非常に遅れていた。本研究では、変質に強く目的元素が濃集する単斜輝石の微量元素・Sr-Nd 同位体組成を測定した。その結果、南部と北部ブロックの基底部かんらん岩で観察される組成差は、北部ブロックでの沈み込んだスラブ由来成分の付加と南部ブロックの中央海嶺玄武岩と類似するメルトの流入で説明できることが明らかとなり、海洋でのメルト形成過程解明に貢献できた。

Research Products

• [Journal Article] Compositional heterogeneity of a websterite xenolith from Kurose, southwest Japan: insights into the evolution of lower crust beneath the Japan Arc (2019)
  • Author(s): Tamura Akihiro、Arai Shoji、Takeuchi Miyuki、Miura Makoto、Pirnia Tahmineh
  • Journal Title: European Journal of Mineralogy Volume: 31 Issue: 1 Pages: 35-47
  • DOI: 10.1127/ejm/2018/0030-2803
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Dunite channels within a harzburgite layer from the Horoman peridotite complex, Japan: Possible pathway for magmas (2018)
  • Author(s): Yoshikawa Masako、Niida Kiyoaki、Green David H.
  • Journal Title: Island Arc Volume: 28 Issue: 1
  • DOI: 10.1111/iar.12279
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Petrology of Peridotites and Nd-Sr Isotopic Composition of Their Clinopyroxenes from the Middle Andaman Ophiolite, India (2018)
  • Author(s): Morishita Tomoaki、Yoshikawa Masako、Tamura Akihiro、Guotana Juan、Ghosh Biswajit
  • Journal Title: Minerals Volume: 8 Issue: 9 Pages: 410-410
  • DOI: 10.3390/min8090410
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Mantle Evolution from Ocean to Arc: The Record in Spinel Peridotite Xenoliths in Mt. Pinatubo, Philippines (2018)
  • Author(s): Payot Betchaida、Arai Shoji、Yoshikawa Masako、Tamura Akihiro、Okuno Mitsuru、Rivera Danikko
  • Journal Title: Minerals Volume: 8 Issue: 11 Pages: 515-515
  • DOI: 10.3390/min8110515
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Clinopyroxenite dykes within a banded unit in the basal mantle section of the northern part of the Oman ophiolite: A record of the latest deep-seated magmatism. (2017)
  • Author(s): Ishimaru, S., Arai, S. and Tamura, A.
  • Journal Title: Lithos Volume: 292-293 Pages: 334-347
  • DOI: 10.1016/j.lithos.2017.09.022
  • Peer Reviewed
• [Journal Article] Aqueous fluids and sedimentary melts as agents for mantle wedge metasomatism, as inferred from peridotite xenoliths at Pinatubo and Iraya volcanoes, Luzon arc, Philippines (2016)
  • Author(s): Yoshikawa M, Tamura A, Arai S, Kawamoto T, Payot BD, Rivera DJ, Bariso EB, Mirabueno MHT, Okuno M, Kobayashi T
  • Journal Title: Lithos Volume: 262 Pages: 355-368
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Compositional variations in spinel-hosted pargasite inclusions in the olivine-rich rock from the oceanic crust-mantle boundary zone (2016)
  • Author(s): Tamura A, Morishita T, Ishimaru S, Hara K, Sanfilippo A, Arai S
  • Journal Title: Contributions to Mineralogy and Petrology Volume: 171 Pages: 39-40
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Petrogenesis of basal peridotites from the Oman ophiolite, Mantle heterogeneisits and trapped melts contribution (2018)
  • Author(s): Python, M., Yoshikawa, M., Suzuki, T. Tamura, A., Arai, S.
  • Organizer: 3rd Korea-Japan Joint Workshop on Isotope-ratio Mass Spectrometry
  • Int'l Joint Research
• [Presentation] Petrographical and chemical evolution of a troctolites rich section of oceanic crust located directly above a spreading centre, example from Wadi Mahram, Oman ophiolite (2017)
  • Author(s): Python, Marie, Charles, Claire, Ito, Natsumi, Arai, Shoji,
  • Organizer: JpGU-AGU Joint Meeting
• [Presentation] オマーンオフィオライトの中部Sarami・Wuqbahブロックと南部Wadi Tayinブロックの基底部かんらん岩の岩石学・地球化学的特徴 (2017)
  • Author(s): 芳川雅子・錦蛇真理・田村明弘・柴田知之・
  • Organizer: 日本地質学会第124年学術大会
• [Presentation] オマーンオフィオライトのマントルソース：マントルセクションにおける輝石岩溶融とその他の火成プロセス (2016)
  • Author(s): 日下 葵 ・マリ ピトン
  • Organizer: 日本鉱物科学会年会
  • Place of Presentation: 金沢市
  • Year and Date: 2016-09-23