Mid-Ocean ridge peridotites revisited: homogeneity/heterogeneity and the nature of the Oceanic plate

2016 Fiscal Year Final Research Report

• Project/Area Number: 26287134
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Kanazawa University
• Principal Investigator: Morishita Tomoaki 金沢大学, 自然システム学系, 教授 (80334746)
• Co-Investigator(Kenkyū-buntansha): 仙田 量子 国立研究開発法人海洋研究開発機構, 地球内部物質循環研究分野, 研究員 (50377991) ; 浜田 盛久 国立研究開発法人海洋研究開発機構, 地球内部物質循環研究分野, 研究員 (60456853) ; 鈴木 勝彦 国立研究開発法人海洋研究開発機構, 海底資源研究開発センター, グループリーダー (70251329) ; 針金 由美子 国立研究開発法人産業技術総合研究所, 地質情報研究部門, 研究員 (90569360)
• Co-Investigator(Renkei-kenkyūsha): TAMURA Akihiro 金沢大学, 自然システム学系, 博士研究員 (80401884)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 海洋プレート / 海洋マントル / 部分溶融 / かんらん岩

Outline of Final Research Achievements

Results of this research on the sub-oceanic mantle peridotites are summarized as follows. 1)　We suggested possibility of existence of ancient melted residue in abyssal peridotites recovered from mid-ocean ridge system (Indian Ocean) and its “crustallization” processes by melt-residual peridotite interactions. Addition to this, melting processes selectively accumulated ancient melting geochemical signatures by melt-rock interactions. 2) We clarified mid-ocean ridge type peridotite origin for mantle section of the Eastern end of the Jurassic-Cretaceous ophiolite belt (Tethys ophiolite belt), Andaman Ophiolite, and its modification at subduction setting during the initiation of subduction. 3) We examined back-arc magmatic processes deduced from peridotite xenolith in back arc region (Japan Sea). Our results suggest that the late stage of magma process is similar to those expected beneath Mid-ocean ridge setting, resulting in the similar depleted peridotites in both tectonic settings.

Free Research Field

岩石学