Fresh water seepage and pore water recycling on the seafloor: Sagami Trough subduction zone, Japan

U. Tsunogai, Junichiro Ishibashi, H. Wakita, T. Gamo, T. Masuzawa, T. Nakatsuka, Y. Nojiri, T. Nakamura

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

We collected 19 samples of bottom sea water (including 8 samples of shimmering fluid), using the Japanese submersible Shinkai 2000, in the bathyal Calyptogena community area (the Hatsushima area) along Sagami Trough, at the northern end of the Philippine Sea plate, in order to clarify the source of fluid seepage. Shimmering fluid samples showed a maximum temperature of 11.6°C, which is about 9°C higher than the ambient sea water. The fluid chemistry of these samples is summarized as follows: (1) alkalinity, H2S, SiO2, NH4, ΣCO2 and CH4 show enrichment and Cl, SO4, K, Na, Mg and Ca show depletion compared with ambient sea water; (2) Cl depletion is about 20%; and (3) the content and 3He/4He ratio of dissolved helium show little anomaly compared with ambient sea water. The observed chemical composition and temperature of the fluid is well explained by mixing of sea water, pore water and land-derived groundwater with a temperature of about 40°C and a seeping flux of about 400 m3 per day. A preliminary estimation of the global chemical flux implies that groundwater discharge to the ocean (including pore water recycling) is an important factor in controlling ocean chemistry.

Original languageEnglish
Pages (from-to)157-168
Number of pages12
JournalEarth and Planetary Science Letters
Volume138
Issue number1-4
Publication statusPublished - Jan 1 1996
Externally publishedYes

Fingerprint

Water recycling
seepage
fresh water
sea water
Seepage
recycling
troughs
subduction zone
Japan
porewater
trough
seafloor
seawater
porosity
fluid
Water
fluids
Fluids
water
ground water

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Tsunogai, U., Ishibashi, J., Wakita, H., Gamo, T., Masuzawa, T., Nakatsuka, T., ... Nakamura, T. (1996). Fresh water seepage and pore water recycling on the seafloor: Sagami Trough subduction zone, Japan. Earth and Planetary Science Letters, 138(1-4), 157-168.

Fresh water seepage and pore water recycling on the seafloor : Sagami Trough subduction zone, Japan. / Tsunogai, U.; Ishibashi, Junichiro; Wakita, H.; Gamo, T.; Masuzawa, T.; Nakatsuka, T.; Nojiri, Y.; Nakamura, T.

In: Earth and Planetary Science Letters, Vol. 138, No. 1-4, 01.01.1996, p. 157-168.

Research output: Contribution to journalArticle

Tsunogai, U, Ishibashi, J, Wakita, H, Gamo, T, Masuzawa, T, Nakatsuka, T, Nojiri, Y & Nakamura, T 1996, 'Fresh water seepage and pore water recycling on the seafloor: Sagami Trough subduction zone, Japan', Earth and Planetary Science Letters, vol. 138, no. 1-4, pp. 157-168.
Tsunogai, U. ; Ishibashi, Junichiro ; Wakita, H. ; Gamo, T. ; Masuzawa, T. ; Nakatsuka, T. ; Nojiri, Y. ; Nakamura, T. / Fresh water seepage and pore water recycling on the seafloor : Sagami Trough subduction zone, Japan. In: Earth and Planetary Science Letters. 1996 ; Vol. 138, No. 1-4. pp. 157-168.
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