Kasuga-2 Vent



Latitude: 21.61οN                    Longitude: 143.64166οE                     Depth: 297 m bsl

Alternative names: Minami Kasuga, Daini Kasuga, Dai-ni Kasuga (InterRidge Vents Database Ver. 3.3)

Vent Sites: Barnacle Boulders, Crab Slope, Cracked Vent, Flat Bottom, Hairy Mat, Hairy Rock, Mat Ridge, Pinnacle, SW Eels, Whale Rock, Yellow Overlord (InterRidge Vents Database Ver. 3.3)

Kasuga-2 seamount is a heavily eroded caldera (Resing et al., 2009), located in the rear arc of Northern Seamount Province (Bloomer et al., 1989). Based on the freshness of lavas recovered from the volcano and active hydrothermal activity, Fryer et al., (1990) confirm that this volcano is active. Resing et al., (2009) identified two separate hydrothermal sources with distinct chemical signatures. The hydrothermal fluids are enriched in Mg2+, SO42- and depleted in Ca2+ relative to ambient seawater and those values are unusual compared to the fluids from other hydrothermal systems. Some bacteria, eukaryotes including worms, flatfish and even vertebrate shark make their habitat around Kasuga-2 seamount.

Table 1: Operations history for Kasuga 2 vent

Ship/ Platform Operation Year Dive Number References
TN-153 R/V T. G. Thompson EM 300 multibeam; CTD tow-yo 2003 February – March Not found Submarine Ring of Fire 2003
TN-167 R/V T. G. Thompson CTD tow-yo; ROPOS 2004 March- April R794 Submarine Ring of Fire 2004
Shinkai 2000 Not found 1997 November 990 JAMSTEC E-library of Deep-sea Images (JEDI) (note: Search “Kasuga 2”)

Table 2: Vent activity and host rocks

Activity and host rocks References
Activity Activity detected in 1987 and also in 2003

Fryer., 1990

Embley et al., 2004

Baker et al., 2008

Host Rocks

Calc-alkaline (medium-high K-basalts and absarokites) and subordinate andesites and dacites

Basalt and Andesite

Stern et al., 1993

Fryer et al., 1997

Table 3: Vent fluid characteristics

Vent Fluids References
Temperature (οC) 39

High Temperature

McMurtry et al., 1993 Resing et al., 2009
pH at 27οC 5.2 McMurtry et al., 1993
Composition Enriched in Mg2+, SO42- and dissolved Si and depleted in Ca2+, Cl and rich in CO2 relative to ambient seawater.

Degasses H2S

McMurtry et al., 1993

Plume depth (m) Shallow (355 m – 390 m) Deep (550 m – 650 m) Resing et al., 2009
ΔpH 0.813 0.313 Resing et al., 2009
Particulate Fe (nmol/kg) 24 263 Resing et al., 2009
TDMn (nM) 58 26 Resing et al., 2009
TDFe (nM) 180 810 Resing et al., 2009
Δ3He (fM) 15.5 3.8 Resing et al., 2009
ΔCO2 (mM) 265 24 Resing et al., 2009
CH4 (nM) 94 22 Resing et al., 2009

* ΔpH, ΔCO2 – Measured relative to the regional background; Δ3He – Measured above the background.

Table 4: Vent Biology

General name Phylum Species References
Chemosynthetic bacteria Bacteria Submarine Ring of Fire, 2006
Tube worms Annelida Submarine Ring of Fire 2004
Nematode worms Nematoda Submarine Ring of Fire 2006
Small flatfish Chordata Symphurus thermophilus Submarine Ring of Fire 2006

Tunniclife et al., 2010

Vertebrate- Shark Chordata Submarine Ring of Fire
Bythogreid crab Arthropoda InterRidge Vents Database
Barnacle Arthropoda InterRidge Vents Database
Tonguefish Chordata InterRidge Vents Database


Video Links:


  1. Baker, E. T., Embley, R. W., Walker, S. L., Resing, J. A., Lupton, J. E., Nakamura, K., de Ronde, C. E. J., Massoth, G. J., 2008. Hydrothermal activity and volcano distribution along the Mariana arc: Journal of Geophysical Research 113 (B8), 1-16.
  2. Bloomer, S. H., Stern, R. J., Fisk, E., Geschwind, C. H., 1989. Shoshonitic Volcanism in the Northern Mariana Arc. 1. Mineralogic and Major and Trace Element Characteristics. Journal of Geophysical Research 94 (B4), 4469-4496.
  3. Embley, R. W., Baker, E. T., Chadwick, W. W. JR., Lupton, J. E., Resing, J. A., Massoth, G. J., Nakamura, K., 2004. Explorations of Mariana Arc. Eos 85 (4), 37-44.
  4. Fryer, P., 1990. Recent Marine Geological Research in the Mariana and Izu-Bonin Island Arcs. Pacific Science 44 (2), 95-114.
  5. Fryer, P., Gill, J. B., Jackson, M. C., 1997. Volcanologic and tectonic evolution of the Kasuga seamounts. Journal of Volcanology and Geothermal Research 79, 277–311.
  6. McMurtry, G. M., Sedwick, P. N., Fryer, P., VonderHaar, D. L., Yeh, H. W., 1993. Unusual geochemistry of hydrothermal vents on submarine arc volcanoes Kasuga Seamounts, Northern Mariana Arc. Earth and Planetary Science Letters 114, 517-528.
  7. Resing, J. A., Baker, E. T., Lupton, J. E., Walker, S. L., Butterfield, D. A., Massoth, G. J., Nakamura, K., 2009. Chemistry of hydrothermal plumes above submarine volcanoes of the Mariana Arc. Geochemistry, Geophysics, Geosystems 10 (2), 1-23.
  8. Stern, R. J., Jackson, M. C., Fryer, P., Ito, E., 1993. O, Sr, Nd and Pb isotopic composition of the Kasuga Cross-Chain in the Mariana Arc: A new perspective on the K-h relationship. Earth and Planetary Science Letters 119, 459-475.

Website References:

  1. International cooperation in ridge-crest studies: InterRidge Vents Database Version 3; (accessed 11.19.2015)
  2. J-EDI JAMSTEC E-library of Deep-sea Images (accessed 12/02/2015)
  3. Submarine Ring of Fire 2004 (accessed 12/02/2015)
  4. Submarine Ring of Fire 2006 (accessed 11.19.2015)

Cruise Reports:

  1. Submarine Ring of Fire 2003 (accessed 11.19.2015)
  2. Submarine Ring of Fire 2004 (accessed 11.19.2015)