basalt, high-K andesite, dacite, sediment
PMS, polymetallic sulfides & barite
Notes on Vent Field Description:
small vent field of approx. 10 sulfide and barite chimneys, 267-278 C, anhydrite chimneys venting clear fluid on barite-sulfide mound; Neptune Minerals Plc, 21 Feb. 2007, applications by Neptune Minerals Japan Kabushiki Kaisha: "Neptune's applications also cover the Minami-Ensei Knoll and Iheya North areas, both of which contain known SMS mineralisation."
Notes Relevant to Biology:
mussel (Bathymodiolus japonicus), Calyptogena, vestimentiferan tubeworms, bacterial mats; fauna summarized by Hashimoto et al. (1995)
Year and How Discovered (if active, visual confirmation is listed first):
1988 deep tow TV surveys followed by submersible Shinkai 2000; 1986 dredged Calyptogena shells
Discovery References (text):
[Chiba, et al. (1992) Chemistry and isotopic composition of bubbles emerging from the seafloor at the Minami-Ensei Knoll, Okinawa Trough. JAMSTECTR Deepsea Res., 8, 81-87 (in Japanese with English abst.)].
Other References (text):
Hashimoto et al. (1995) Microdistribution pattern and biogeography of the hydrothermal vent communities of the Minami-Ensei Knoll in the Mid-Okinawa Trough, Western Pacific. Deep-Sea Res. I 42: 577-598
Halbach et al., Geology and mineralogy of massive sulfide ores from the central Okinawa Trough, Japan, Econ. Geol., 88, 2210-2225, 1993.