Archaean Vent



Latitude: 12.939οN                  Longitude: 143.632οE             Depth: 3060 m bsl

The Archean site was discovered in 2004 at the top of a giant (50-m high) sulfide mound, located on the eastern flank of the Malano-Gadao Ridge spreading axis (Ishibashi et al., 2004) in the southern Mariana Trough. The site is an active hydrothermal system, with black smokers venting fluids as hot as 341°C (Yoshikwa et al., 2012). Chemistry of these fluids at that time was characterized by low pH, low Cl concentration (Ishibashi et al., 2006) and high H2S (Kato et al., 2010). The hydrothermal field has several discrete hydrothermal mounds with active and/or inactive chimneys (Ishibashi et al., 2006). On the basis of the associated geomorphological features, the Archean site is thought to have been created by prolonged hydrothermal activity (Yoshikawa et al., 2012). Biologically this site is enriched with different species of bacteria (Kato et al., 2010; Kato et al., 2012).

Table 1: Operations history for Archaean vent

Ship/ Platform Operation Year Dive Number References
TN-167A R/V Thompson/ ROPOS Not found 2004 March Not found YK05-09-Leg2 cruise report
YK05-09 Yokosuka/ Shinkai 6500 WHATS, ROCS, Bag with high temperature probe,  pH, pCO2, ORO sensors 2005 July-August 903, 905 YK05-09-Leg2 cruise report
YK10-10 Yokosuka/ Shinkai 6500 Not found 2010 August 1216, 1217 YK10-10 cruise report
YK10-11 Yokosuka/ Shinkai 6500 Not found 2010 September 1221, 1223, 1224 YK10-11 cruise report

Table 2: Vent activity and host rocks

Activity and Host Rocks References
Activity Active Yoshikawa et al., 2012, Ikehata et al., 2015; Kato et al., 2010
Host Rocks Basalt and Andesite Toki et al., 2015

Table 3: Vent fluid characteristics

Vent Fluids References
Temperature (οC) 93 οC-343 οC Toki et al., 2015; Ikehata et al., 2015
pH 3 (at 25 οC) Ishibashi et al., 2006
2.94 Toki et al., 2015
Composition K rich with low Cl concentrations and low pH. Ishibashi et al., 2004
High concentrations of H2S Ishibashi et al., 2006; Kato et al., 2010
CO2 (mM) 6.4-32.6 Toki et al., 2015
H2 (μM) 466 Toki et al., 2015
Mn (mM) 1.06-1.2 Toki et al., 2015
Fe (mM) 2.55-3.00 Toki et al., 2015
He (μM) 2.1 Toki et al., 2015
CH4 (μM) 115 Toki et al., 2015

Table 4: Vent Biology

General name Phylum Class / Order Family Genus/Species References
Bacteria Aquificae Aquificales Hydrogenothermaceae Persephonella Kato et al., 2012
Bacteria Proteobacteria Gammaproteobacteria Kato et al., 2010
Bacteria Proteobacteria Epsilonproteobacteria Campylobacterales Hydrogenimonas Kato et al., 2010;  Kato et al., 2012
Bacteria Proteobacteria Epsilonproteobacteria Campylobacterales Sulfurimonas Kato et al., 2010; Kato et al., 2012
Bacteroidetes Kato et al., 2010
Barnacle Arthropoda Multicrustacea Neoverrucidae Neoverruca brachylepadoformis Kumagai et al., 2015
Shrimp Arthropoda Malacostraca Alvinocarididae Chorocaris vandoverae Kumagai et al., 2015
Snail Mollusca Gastropoda Provannidae Alviniconcha hessleri Kumagai et al., 2015


Video Links:


  1. Ikehata,K., Suzuki, R., Shimada, K., Ishibashi, J., Urabe, T., 2015. Mineralogical and Geochemical Characteristics of Hydrothermal Minerals Collected from Hydrothermal Vent Fields in the Southern Mariana Spreading Center. In: Ishibashi, J., Okino, K., Sunamura, M. (Eds.), Subseafloor Biosphere Linked to Hydrothermal Systems: TAIGA Concept. Springer Japan, 275-287.
  2. Ishibashi, J., Suzuki, R., Yamanaka, T., Toki, T., Kimura, H., Noguchi, T., Urabe, T., 2006. Seafloor hydrothermal activity at offaxial seamounts of backarc spreading in southern Mariana Trough. Geochimica et Cosmochimica Acta 70 (18), A279-A279.
  3. Ishibashi, J., Yamanaka, T., Kimura, H., Hirota, A., Toki, T., Tsunogai, U., Gamo, T., Utsumi, M., Roe, K., Miyabe, S., Okamura, K. 2004. Geochemistry of Hydrothermal Fluids in South Mariana Backarc Spreading Center. American Geophysical Union, Fall Meeting 2004, abstract #V44A-05.
  4. Kato, S., Takano, Y., Kakegawa, T., Oba, H., Inoue, K., Kobayashi, C., Utsumi, M., Marumo, K., Kobayashi, K., Ito, Y., Ishibashi, J., Yamagishi, A., 2010. Biogeography and biodiversity in sulfide structures of active and inactive vents at deep-sea hydrothermal fields of the Southern Mariana Trough. Applied Environmental Microbiology 76 (9), 2968-2979.
  5. Kato, S., Nakamura, K., Toki, T., Ishibashi, J., Tsunogai, U., Hirota, A., Ohkuma, M., Yamagishi, A., 2012. Iron-based microbial ecosystem on and below the seafloor: a case study of hydrothermal fields of the Southern Mariana Trough. Frontiers in Microbiology 3, doi: 10.3389/fmicb.2012.00089.
  6. Kumagai, H., Watanabe, H., Yahagi, T., Kojima, S., Nakai, S., Toyoda, S., Ishibashi, J., 2015. Evaluating Hydrothermal System Evolution Using Geochronological Dating and Biological Diversity Analyses. In: Ishibashi, J., Okino, K., Sunamura, M. (Eds.), Subseafloor Biosphere Linked to Hydrothermal Systems: TAIGA Concept. Springer Japan, 49-59.
  7. Toki, T., Ishibashi, J., Noguchi, T., Tawata, M., Tsunogai, U., Yamanaka, T., and Nakamura, K., 2015, Chemical and Isotopic Compositions of Hydrothermal Fluids at Snail, Archaean, Pika, and Urashima Sites in the Southern Mariana Trough. In: Ishibashi, J., Okino, K., Sunamura, M. (Eds.), Subseafloor Biosphere Linked to Hydrothermal Systems: TAIGA Concept. Springer Japan, 587-602.
  8. Yoshikawa, S., Okino, K., and Asada, M., 2012. Geomorphological variations at hydrothermal sites in the southern Mariana Trough: Relationship between hydrothermal activity and topographic characteristics. Marine Geology 303-306, 172-182.

Website References:

  1. J-EDI JAMSTEC (Japan Agency for Marine Earth Science and Technology) E-library of Deep-sea Images: (accessed 08/20/2015)

Cruise Reports:

  1. Yokosuka Cruise Report YK05-09-Leg2 (accessed 11/26/2015)
  2. Yokosuka Cruise Report YK10-10 (accessed 11/26/2015)
  3. Yokosuka Cruise Report YK-10-11 (accessed 11/26/2015)