Reevaluation of generation condition for hydrothermal petroleum at seafloor hydrothermal system

2014 Fiscal Year Final Research Report

• Project/Area Number: 24340135
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Science of ore deposit
• Research Institution: Okayama University
• Principal Investigator: YAMANAKA TOSHIRO 岡山大学, 自然科学研究科, 准教授 (60343331)
• Co-Investigator(Kenkyū-buntansha): CHIBA Hitoshi 岡山大学, 大学院自然科学研究科, 教授 (30144736) ; ISHIBASHI Jun-ichiro 九州大学, 大学院理学研究院, 准教授 (20212920) ; MURAKAMI Hiroyasu 独立行浩康政法人産業技術総合研究所, 地圏資源環境研究部門, 主任研究員 (40371083) ; YONEZU Kotaro 九州大学, 大学院工学研究院, 助教 (90552208)
• Co-Investigator(Renkei-kenkyūsha): YONEZU Kotaro 九州大学, 大学院工学研究院, 助教 (90552208) ; NOGUCHI Takuro 海洋研究開発機構, 海洋工学センター, 特任技術研究員 (90600643) ; MIYOSHI Yoko 独立行浩康政法人産業技術総合研究所, 特任研究員 ; FUJINO Keiko (株)マリンワークジャパン, 社員
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 海洋資源 / 海底熱水系 / 熱水性石油 / oil window / 鹿児島湾

Outline of Final Research Achievements

Although hydrothermal petroleum had been considered to require a high temperature (higher than 250 degree C) for its generation, we sampled core sediments and reevaluated the generation condition at the actual site occurred the petroleum. As a result, petroleum generation from matured organic matter was confirmed at about 10 m depth below seafloor. At that depth significant intrusion of hydrothermal fluid was not observed and alteration clay mineral occurred at high temperature and hydrothermal clay minerals were rarely found. It suggests that the sediment at that depth dose not experience high temperature over 100 degree C. The temperature estimated by biomarker maturation indies is about 120 degree C , it is also comparable with the observation. In conclusion, it was confirmed that hydrothermal petroleum is generated at the temperature range (oil window) similar to conventional petroleum generation.

Free Research Field

宇宙地球化学