Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan

Toshiro Yamanaka, Kotaro Maeto, Hironori Akashi, Jun Ichiro Ishibashi, Youko Miyoshi, Kei Okamura, Takuroh Noguchi, Yoshihiro Kuwahara, Tomohiro Toki, Urumu Tsunogai, Tamaki Ura, Takeshi Nakatani, Toshihiro Maki, Kaoru Kubokawa, Hitoshi Chiba

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Active hydrothermal venting from shallow seafloor (200-m depth) with talc chimneys has been discovered at the Wakamiko Crater floor in the Aira Caldera, southern Kyushu, Japan. The major chemical composition of the fluids suggests that the fluids are supplied from a single reservoir. The fluid is characterized by a low chloride concentration, low δD value, and a high δ18O value, suggesting that the endmember hydrothermal fluid is a mixture of seawater and andesitic water and possibly contribution of meteoric water and/or phase separation. Such noticeable magmatic input may be supported by high helium isotopic ratio (6.77 RA) of fumarolic gas discharging from the crater. Silica and alkaline geothermometers indicate that the fluid-rock interaction in the reservoir occurs in the temperature range of 230 to 250°C. The high alkalinity and high ammonium and dissolved organic matter concentrations in the fluid indicate interaction of the fluid with organic matter in sedimentary layers. At least three hydrothermal vents have been observed in the crater. Two of these have similar cone-shaped chimneys. The chimneys have a unique mineralogy and consist dominantly of talc (kerolite and hydrated talc) with lesser amounts of carbonate (dolomite and magnesite), anhydrite, amorphous silica, and stibnite. The precipitation temperature estimated from δ18O values of talc was almost consistent with the observed fluid temperature. Geochemical modeling calculations also support the formation of talc and carbonate upon mixing of the endmember hydrothermal fluid with seawater and suggest that the talc chimneys are currently growing from venting fluid.

Original languageEnglish
Pages (from-to)74-84
Number of pages11
JournalJournal of Volcanology and Geothermal Research
Volume258
DOIs
Publication statusPublished - May 15 2013

Fingerprint

Talc
chimneys
talc
Chimneys
hydrothermal activity
craters
crater
Japan
Fluids
fluid
Water
fluids
water
venting
hydrothermal fluid
Carbonates
Seawater
silica
Silicon Dioxide
Biological materials

Keywords

  • Aira caldera
  • Geochemical thermometer
  • Kagoshima Bay
  • Shallow seafloor hydrothermal system
  • Talc-dominated chimney
  • Thermodynamic calculation

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan. / Yamanaka, Toshiro; Maeto, Kotaro; Akashi, Hironori; Ishibashi, Jun Ichiro; Miyoshi, Youko; Okamura, Kei; Noguchi, Takuroh; Kuwahara, Yoshihiro; Toki, Tomohiro; Tsunogai, Urumu; Ura, Tamaki; Nakatani, Takeshi; Maki, Toshihiro; Kubokawa, Kaoru; Chiba, Hitoshi.

In: Journal of Volcanology and Geothermal Research, Vol. 258, 15.05.2013, p. 74-84.

Research output: Contribution to journalArticle

Yamanaka, T, Maeto, K, Akashi, H, Ishibashi, JI, Miyoshi, Y, Okamura, K, Noguchi, T, Kuwahara, Y, Toki, T, Tsunogai, U, Ura, T, Nakatani, T, Maki, T, Kubokawa, K & Chiba, H 2013, 'Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan', Journal of Volcanology and Geothermal Research, vol. 258, pp. 74-84. https://doi.org/10.1016/j.jvolgeores.2013.04.007
Yamanaka, Toshiro ; Maeto, Kotaro ; Akashi, Hironori ; Ishibashi, Jun Ichiro ; Miyoshi, Youko ; Okamura, Kei ; Noguchi, Takuroh ; Kuwahara, Yoshihiro ; Toki, Tomohiro ; Tsunogai, Urumu ; Ura, Tamaki ; Nakatani, Takeshi ; Maki, Toshihiro ; Kubokawa, Kaoru ; Chiba, Hitoshi. / Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan. In: Journal of Volcanology and Geothermal Research. 2013 ; Vol. 258. pp. 74-84.
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abstract = "Active hydrothermal venting from shallow seafloor (200-m depth) with talc chimneys has been discovered at the Wakamiko Crater floor in the Aira Caldera, southern Kyushu, Japan. The major chemical composition of the fluids suggests that the fluids are supplied from a single reservoir. The fluid is characterized by a low chloride concentration, low δD value, and a high δ18O value, suggesting that the endmember hydrothermal fluid is a mixture of seawater and andesitic water and possibly contribution of meteoric water and/or phase separation. Such noticeable magmatic input may be supported by high helium isotopic ratio (6.77 RA) of fumarolic gas discharging from the crater. Silica and alkaline geothermometers indicate that the fluid-rock interaction in the reservoir occurs in the temperature range of 230 to 250°C. The high alkalinity and high ammonium and dissolved organic matter concentrations in the fluid indicate interaction of the fluid with organic matter in sedimentary layers. At least three hydrothermal vents have been observed in the crater. Two of these have similar cone-shaped chimneys. The chimneys have a unique mineralogy and consist dominantly of talc (kerolite and hydrated talc) with lesser amounts of carbonate (dolomite and magnesite), anhydrite, amorphous silica, and stibnite. The precipitation temperature estimated from δ18O values of talc was almost consistent with the observed fluid temperature. Geochemical modeling calculations also support the formation of talc and carbonate upon mixing of the endmember hydrothermal fluid with seawater and suggest that the talc chimneys are currently growing from venting fluid.",
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T1 - Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan

AU - Yamanaka, Toshiro

AU - Maeto, Kotaro

AU - Akashi, Hironori

AU - Ishibashi, Jun Ichiro

AU - Miyoshi, Youko

AU - Okamura, Kei

AU - Noguchi, Takuroh

AU - Kuwahara, Yoshihiro

AU - Toki, Tomohiro

AU - Tsunogai, Urumu

AU - Ura, Tamaki

AU - Nakatani, Takeshi

AU - Maki, Toshihiro

AU - Kubokawa, Kaoru

AU - Chiba, Hitoshi

PY - 2013/5/15

Y1 - 2013/5/15

N2 - Active hydrothermal venting from shallow seafloor (200-m depth) with talc chimneys has been discovered at the Wakamiko Crater floor in the Aira Caldera, southern Kyushu, Japan. The major chemical composition of the fluids suggests that the fluids are supplied from a single reservoir. The fluid is characterized by a low chloride concentration, low δD value, and a high δ18O value, suggesting that the endmember hydrothermal fluid is a mixture of seawater and andesitic water and possibly contribution of meteoric water and/or phase separation. Such noticeable magmatic input may be supported by high helium isotopic ratio (6.77 RA) of fumarolic gas discharging from the crater. Silica and alkaline geothermometers indicate that the fluid-rock interaction in the reservoir occurs in the temperature range of 230 to 250°C. The high alkalinity and high ammonium and dissolved organic matter concentrations in the fluid indicate interaction of the fluid with organic matter in sedimentary layers. At least three hydrothermal vents have been observed in the crater. Two of these have similar cone-shaped chimneys. The chimneys have a unique mineralogy and consist dominantly of talc (kerolite and hydrated talc) with lesser amounts of carbonate (dolomite and magnesite), anhydrite, amorphous silica, and stibnite. The precipitation temperature estimated from δ18O values of talc was almost consistent with the observed fluid temperature. Geochemical modeling calculations also support the formation of talc and carbonate upon mixing of the endmember hydrothermal fluid with seawater and suggest that the talc chimneys are currently growing from venting fluid.

AB - Active hydrothermal venting from shallow seafloor (200-m depth) with talc chimneys has been discovered at the Wakamiko Crater floor in the Aira Caldera, southern Kyushu, Japan. The major chemical composition of the fluids suggests that the fluids are supplied from a single reservoir. The fluid is characterized by a low chloride concentration, low δD value, and a high δ18O value, suggesting that the endmember hydrothermal fluid is a mixture of seawater and andesitic water and possibly contribution of meteoric water and/or phase separation. Such noticeable magmatic input may be supported by high helium isotopic ratio (6.77 RA) of fumarolic gas discharging from the crater. Silica and alkaline geothermometers indicate that the fluid-rock interaction in the reservoir occurs in the temperature range of 230 to 250°C. The high alkalinity and high ammonium and dissolved organic matter concentrations in the fluid indicate interaction of the fluid with organic matter in sedimentary layers. At least three hydrothermal vents have been observed in the crater. Two of these have similar cone-shaped chimneys. The chimneys have a unique mineralogy and consist dominantly of talc (kerolite and hydrated talc) with lesser amounts of carbonate (dolomite and magnesite), anhydrite, amorphous silica, and stibnite. The precipitation temperature estimated from δ18O values of talc was almost consistent with the observed fluid temperature. Geochemical modeling calculations also support the formation of talc and carbonate upon mixing of the endmember hydrothermal fluid with seawater and suggest that the talc chimneys are currently growing from venting fluid.

KW - Aira caldera

KW - Geochemical thermometer

KW - Kagoshima Bay

KW - Shallow seafloor hydrothermal system

KW - Talc-dominated chimney

KW - Thermodynamic calculation

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