basalt, high-K andesite, dacite, sediment
Notes on Vent Field Description:
Southernmost Part of Okinawa Trough; westernmost vent field within Japanese waters; "20 active hydrothermal vents are aligned along an elongated depression and fluid circulation occurs within accumulated terrigenous sediments"; Inagaki et al. (2006): "The hydrothermal field is characterized by two active black smoker vents (Tiger and Lion chimneys), with vent fluid temperatures up to 323°C"; known for liquid CO2; Lee (1999): " Seven out of the 68 identified volcanoes have shown an active hydrothermal venting from the high-frequency EK500 records"; Gamo et al. (2010) clarified the hydrocasts SPOT-1 through SPOT-5, with SPOT-5 being the closest; see maps in Okino et al. (2002) and Hongo et al. (2007); Okino et al. (2002): "Station SPOT-5 (Fig.3) showed the highest light transmission anomaly up to ~5% within 300 m above the seafloor."; Matsumoto et al. (2001): "The area was surveyed by R/V YOKOSUKA and DSV SHINKAI 6500 in July-August 2000 (Lequios Cruise: Cruise ID=YK00-06 Leg2) after the succession of the previous l'Atalante cruise in 1996 in the SPOT Area (east of Taiwan). ... Two active hydrothermal sites were newly located through 10 dives in the study area. One is located in the SPOT area and the other on the axial zone of the Okinawa Trough off the northern coast of Miyako Island. Maximum temperature was 170.DEG.C. in the former case and 150.DEG.C. in the latter case. Both sites are characterised by active chimneys associated with sulphide deposits and chemosynthetic communities."
Notes Relevant to Biology:
Bathymodiolus mussels, bythograeid crabs; image in Inagaki et al. (2006) indicates high density crabs
Year and How Discovered (if active, visual confirmation is listed first):
2000 submersibles Shinkai 2000 and Shinkai 6500
Discovery References (text):
[Fujikura, K. et al., Report on the investigation of hydrothermal vent ecosystems by the crewed submersible ‘Shinkai 2000’ on the Dai-yon (No. 4) Yonaguni Knoll and the Hatoma Knoll, the Okinawa Trough. JAMSTEC J. Deep Sea Res. 19 (2001), pp. 141-154 (in Japanese with English abstract)]
Matsumoto et al. (2001) Volcanic and hydrothermal activities and possible "segmentation" of the axial rifting in the westernmost part of the Okinawa Trough. Preliminary results from the YOKOSUKA/SHINKAI 6500 Lequios Cruise. JAMSTEC Journal of Deep Sea Research 19: 95-107.
Lee, C.-S. (1999) Active collision and backarc extension in the southernmost part of the Okinawa Trough. EOS, American Geophysical Union Transactions, 80, 46, AGU Fall Meeting abstract #T51B-06.
Other References (text):
Kishida, K. et al. (2004) Tungsten enriched in submarine hydrothermal fluids. Earth and Planetary Science Letters 222: 819-827
Inagaki et al. (2006) Microbial community in a sediment-hosted CO2 lake of the southern Okinawa Trough hydrothermal system. PNAS 103: 14164-14169
Konno et al. (2006) Liquid CO2 venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough. American Geophysical Union, Fall Meeting 2006, abstract #V23B-0606
Hongo et al. (2007) Rare Earth Elements in the hydrothermal system at Okinawa Trough back-arc basin. Geochemical Journal 41: 1-15
Suzuki et al. (2008) Diverse Range of Mineralization Induced by Phase Separation of Hydrothermal Fluid: Case Study of the Yonaguni Knoll IV Hydrothermal Field in the Okinawa Trough Back-Arc Basin. Resource Geology 58:267-288.
Okino et al. (2002) Deep-tow sonar “WADATSUMI” survey in the Okinawa Trough. InterRidge News 11(2): 38-41.
Gamo, T. et al. (2010) Microbial carbon isotope fractionation to produce extraordinarily heavy methane in aging hydrothermal plumes over the southwestern Okinawa Trough. Geochemical Journal 44: 477-487.