Petrology and tectonics on the mantle peridotite from southern Mariana fore arc

2015 Fiscal Year Final Research Report

• Project/Area Number: 25400492
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: Fukada Geological Institute
• Principal Investigator: Ishii Teruaki 公益財団法人深田地質研究所, その他部局等, 研究員 (80111582)
• Co-Investigator(Kenkyū-buntansha): Ohara Yasuhiko 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, 招聘主任研究員 (10470121)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 南部マリアナ海溝 / 海底地質断面 / 蛇紋岩冷湧水系 / 南東マリアナ前弧リフト / しんかい湧水域 / 深海生物群集 / 橄欖岩海嶺 / ブルーサイトチムニー

Outline of Final Research Achievements

The 3000 km long Izu-Bonin-Mariana (IBM) arc system is an outstanding example of a nonaccretionary intraoceanic convergent plate margin. The trench inner wall (forearc) exposes so similar lithologies found in many land ophiolites, the igneous rocks exposed in the IBM forearc represents an in situ supra-subduction zone ophiolite. Along the southern Mariana trench inner wall (forearc), we have been investigating using the DSV Shinkai 6500. The discovery includes (A) a very young volcanic region of forearc rifting unusually close to the trench axis in SSW of Guam; the Southeast Mariana Forearc Rift (SEMFR), (B) a serpentinite-hosted deep sea ecosystem near the Challenger Deep; the Shinkai Seep Field (SSF), (C) a very shallow peridotite ridge consists of fresh mantle rocks, near trench axis in west of the Challenger Deep, of which ridge may be induced by colliding Caroline Ridge.

Free Research Field

海洋地質学