Methane migration from the Nankai Trough accretionary prism

Author(s): Toki, Tomohiro; Gamo, Toshitaka; Yamanaka, Toshiro; Ishibashi, Jun-ichiro; Tsunogai, Urumu; Matsubayashi, Osamu
Author Affiliation(s): Primary:
Hokkaido University, Division of Earth and Planetary Sciences, Sapporo, Japan
University of Tsukuba, Japan
Kyushu University, Japan
Geological Survey of Japan, Japan
Volume Title: Chishitsu Chosajo Geppo Bulletin of the Geological Survey of Japan
Source: Chishitsu Chosajo Geppo = Bulletin of the Geological Survey of Japan, 52(1), p.1-8. Publisher: Kogyo Gijutsu-in-Chishitsu Chosajo, Kawasaki, Japan. ISSN: 0016-7665 CODEN: CHCGAX
Note: In Japanese with English summary. 23 refs.; illus., incl. 1 table, sketch maps
Summary: Several major dissolved constituents and properties (pH, alkalinity, Ca, Cl, K, Mg, Na, Si (OH)4, NH4, SO4, CH4, and δ13C) were measured for interstitial waters retrieved from surface sediments of the Nankai Trough accretionary prism during the NGH99 cruise (Sept. 14-29, 1999). Detailed depth profiles of chemical components associated with early diagenesis indicate that sulfate reduction rapidly occurs to consume all sulfate within the upper 2 meters of the sediment column at one of five stations. It is suggested that the upward migration of methane plays an important role as a carbon source in addition to the sedimentary organic matter derived from the water column above. Based on the stable carbon isotope ratio of methane in the pore fluid (δ13CPDB≤70 per mil), methane is thought to be biogenic through bacterial CO2 reduction. Various sulfate distributions suggest a localized CH4 supply from deeper zones.
Year of Publication: 2001
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Accretionary wedges; Aliphatic hydrocarbons; Alkanes; C-13/C-12; Carbon; Chemical composition; Geochemical indicators; Geochemistry; Hydrocarbons; Isotope ratios; Isotopes; Leg 131; Marine sediments; Methane; Migration of elements; Nankai Trough; North Pacific; Northwest Pacific; Ocean Drilling Program; Organic compounds; Pacific Ocean; Sediments; Stable isotopes; Sulfates; West Pacific
Coordinates: N322105 N322111 E1345646 E1345634
Record ID: 2001075035
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