Anomalies of bottom CH4 and trace metal concentrations associated with high heat flow at the Calyptogena community off Hatsu-shima Island, Sagami Bay, Japan: A preliminary report of Tansei Maru KT-88-1 cruise Leg-1

Toshitaka Gamo; Jun-ichiro Ishibashi; Kiminori Shitashima; Masataka Kinoshita; Masaharu Watanabe; Eiichiro Nakayama; Yoshiki Sohrin; Eun-Soo Kim; Toshiyuki Masuzawa; Kantaro Fujioka

doi:10.2343/geochemj.22.215

Anomalies of bottom CH₄ and trace metal concentrations associated with high heat flow at the Calyptogena community off Hatsu-shima Island, Sagami Bay, Japan: A preliminary report of Tansei Maru KT-88-1 cruise Leg-1

Toshitaka Gamo, Jun-ichiro Ishibashi, Kiminori Shitashima, Masataka Kinoshita, Masaharu Watanabe, Eiichiro Nakayama, Yoshiki Sohrin, Eun-Soo Kim, Toshiyuki Masuzawa, Kantaro Fujioka

Author information

Toshitaka Gamo
Ocean Research Institute, University of Tokyo
Jun-ichiro Ishibashi
Ocean Research Institute, University of Tokyo
Kiminori Shitashima
Faculty of Integrated Arts and Science, Hiroshima University
Masataka Kinoshita
Earthquake Research Institute, University of Tokyo
Masaharu Watanabe
Ocean Research Institute, University of Tokyo
Eiichiro Nakayama
Research Center for Instrumental Analysis, Faculty of Science, Kyoto University
Yoshiki Sohrin
The Institute for Chemical Research, Kyoto University
Eun-Soo Kim
Ocean Research Institute, University of Tokyo
Toshiyuki Masuzawa
Water Research Institute, Nagoya University
Kantaro Fujioka
Ocean Research Institute, University of Tokyo

JOURNAL FREE ACCESS

1988 Volume 22 Issue 5 Pages 215-230

DOI https://doi.org/10.2343/geochemj.22.215

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Abstract

Geochemical studies of bottom waters and sediments, including deep sea camera surveys and heat flow measurements, were conducted in the western Sagami Bay, central Japan, where dense clam (Calyptogena soyoae) communities had been previously located by submersible observations. The bottom waters above the communities contained an order of magnitude higher CH₄ (360∼4200 nl kg^-1) than those at nearby stations a few kilometers away from the community site (∼130 nl kg^-1), implying significant fluid venting rich in CH₄ from the bottom at the very community site. The mean life of the seepage CH₄ in seawater was estimated to be several days by using a simple vertical diffusion model. Weak correlations were observed between the concentrations of CH₄ and trace metals such as Fe, Mn, Al, and Zn. It was found that the community site is characterized by anomalously high heat flow up to 1680 mW m^-2, suggesting volcanic heat sources below the site.

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