Detection of Oceanic Plateau magmatism lasting for ~100 million years

2017 Fiscal Year Final Research Report

• Project/Area Number: 26302010
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 海外学術
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: National Museum of Nature and Science, Tokyo
• Principal Investigator: Sano Takashi 独立行政法人国立科学博物館, 地学研究部, グループ長 (40329579)
• Co-Investigator(Kenkyū-buntansha): 石川 晃 東京大学, 大学院総合文化研究科, 助教 (20524507) ; Tejada Maria・L・G 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 (40598778) ; 中西 正男 千葉大学, 大学院理学研究院, 教授 (80222165)
• Co-Investigator(Renkei-kenkyūsha): HANYU Takeshi 海洋研究開発機構, 地球内部物質循環研究分野, 主任研究員 (50359197) ; SHIMIZU Kenji 海洋研究開発機構, 高知コア研究所, 技術研究員 (30420491) ; MIURA Seiichi 海洋研究開発機構, 地震津波海域観測研究開発センター, グループリーダー (00371724) ; SUZUKI Katsuhiko 海洋研究開発機構, 海底資源研究開発センター, センター長代理 (70251329)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 火山 / 岩石・鉱物・鉱床学 / 地殻・マントル物質 / 地球化学 / 固体地球科学 / 地質学 / 地球・惑星内部構造

Outline of Final Research Achievements

Our targets were two super volcanoes (oceanic plateaus) that are located in the Pacific Ocean: Ontong Java Plateau and Shatsky Rise. Previous workers proposed that thermal plume heads hit against the plate boundaries to generate the voluminous magmas that were erupted to form the oceanic plateaus. The thermal plume model favors volcanism over geologically short periods. However, post-emplacement volcanoes, which are present as seamounts, are likely present. To test our hypothesis, we conducted research of the seamounts during four scientific cruises (KR14-07, KR16-04, KH-17-J01, KR17-13) to carry out geological surveys and rock sample collection by dredge. Our investigations show that durations of magmatic activity of the oceanic plateaus are longer than the prediction of the plume model. Geochemical examinations indicate that a simple thermal plume model cannot explain the magma genesis of the two oceanic plateaus, and more complex (e.g., thermochemical) models should be introduced.

Free Research Field

地球科学