Do microcrystalline dolomite inclusions provide fossil evidence for the onset of gas hydrate formation?: Isotopic and biogeochemical investigations of methane hydrate in Joetsu Basin, Sea of Japan.

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05712
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Meiji University
• Principal Investigator: Snyder Glen 明治大学, 研究・知財戦略機構(駿河台), 研究推進員 (90751777)
• Co-Investigator(Kenkyū-buntansha): 鈴木 庸平 東京大学, 大学院理学系研究科(理学部), 准教授 (00359168) ; 松本 良 明治大学, 研究・知財戦略機構(駿河台), 特任教授 (40011762) ; 佐野 有司 東京大学, 大気海洋研究所, 教授 (50162524) ; 戸丸 仁 千葉大学, 大学院理学研究院, 准教授 (80588244)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: gas hydrate / Sea of Japan / microdolomite / Bacteriodetes / helium / stable isotopes

Outline of Final Research Achievements

Microbial life has been found in a variety of extreme environments such as hot springs, glaciers, and in deep marine sediments. Researchers at Meiji’s GHRL recovered the first long cores of massive gas hydrate from the seafloor in Joetsu Basin, just southwest of the Japan’s port city of Niigata in order to study this unconventional energy resource. While melting the hydrate to study methane gas, a fine microdolomite powder was discovered which consists of microscopic spheroids with dark cores. Further research revealed a unique, microenvironment where microbial life is able to metabolize complex macromolecules to produce extracellular polymeric substance that promote the formation of spheroidal microdolomites. In addition, the noble gases helium and neon were also measured, permitting the discovery that gases from the mantle are involved in the migration of methane in the region which eventually accumulates as gas hydrate in shallow marine sediments.

Free Research Field

Isotope geochemistry, marine chemistry

Academic Significance and Societal Importance of the Research Achievements

Meters-thick gas hydrate was recovered from marine sediments and the role of mantle gases in methane migration and gas hydrate growth in the sea of Japan was documented. Microbial life was discovered inside of the gas hydrate, living within spheroidal aggregates of microdolomite.