Oceanic Transform as a water inlet to earth's interior

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05263
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: The University of Tokyo
• Principal Investigator: OKINO KYOKO 東京大学, 大気海洋研究所, 教授 (30313191)
• Co-Investigator(Kenkyū-buntansha): 町田 嗣樹 千葉工業大学, 次世代海洋資源研究センター, 上席研究員 (40444062) ; 川口 慎介 国立研究開発法人海洋研究開発機構, 深海・地殻内生物圏研究分野, 研究員 (50553088)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: トランスフォーム断層 / 海洋地殻 / 蛇紋岩 / 水

Outline of Final Research Achievements

The contribution of seawater infiltration along oceanic transform faults is not negligible in global water flux, however, the degree and spatial extent of serpentinization around the faults system remain poorly constrained. The R/V Hakuho-maru cruise was conducted in early 2016, investigating the nature of these long-offset oceanic transform faults (OTF) as a water inlet into earth's interior. 1) Detailed bathymetry and gravity measuremen reveals the detailed fault distribution and evolutionary process of OTF and a possible density increase beneath the OTF, indicating sepentinization of lithospheric mantle. 2) Surface magnetic survey is used to reconstruct the seafloor spreading history of the area. Deep-tow mangetic survey across the OTF shows no clear anomalous signature. 3) Major and minor compositions of dredged rock samples and their alteration processes are studied. 4) Anomalous water mass is detected in deeper part of the OTF valley. Methane analysis is now going on.

Free Research Field

海洋底地球物理