IAB, low-K andesite, dacite, rhyolithe
Notes on Vent Field Description:
just east of Bayonnaise Rocks; Bayonnaise Rocks is barely exposed rim of largely submarine 9-km wide caldera; Myojin-sho is post-caldera lava dome on NE rim of this caldera; Iizasa et al. (1992): "This is the first discovery of extensive base metal sulfide mineralization in a volcanic front environment;" volcanically active in historical time; Carey and Sigurdsson (2007): "The loss of the Japanese survey vessel Kaio-maru in 1952 from an eruption of the shallow Myojinsho volcano underlines the dangers of submarine eruptions that reach the surface"; Neptune Minerals Plc, 21 Feb. 2007, applications by Neptune Minerals Japan Kabushiki Kaisha: "Neptune's applications also cover the Myojin and Myojinsho Knolls, and the Suiyo and Kaikata Seamounts, all of which contain known SMS mineralisation."
Notes Relevant to Biology:
Year and How Discovered (if active, visual confirmation is listed first):
1988 deposits only; 2005 plume only
Discovery References (text):
(deposits only) Iizasa, K., et al., Mineralogy and geochemistry of volcanogenic sulfides from the Myojinsho submarine caldera, the Shichito-Iwojima Ridge, Izu-Ogasawara Arc, northwestern Pacific. Mar. Geol., 108, 39-58, 1992
(plume only) Okamura, K., et al (2005) Hydrothermal plumes at the Myojinsho submarine caldera, the Shichito-Iwojima Ridge, Izu-Bonin Arc. American Geophysical Union, Fall Meeting 2005, abstract #V51C-1499
Watanabe, H., pers. comm., 2009: "Dr. K. Iizasa in AIST conducted a cruise of R/V Natsushima and ROV HyperDolphin"
Other References (text):
Fiske, R. et al. (1998) Tephra dispersal from Myojinsho, Japan, during its shallow submarine eruption of 1952–1953. Bull. Volcanology 59: 262-275
[Glasby, GP et al. (2000) Submarine hydrothermal mineralization on the Izu-Bonin Arc, South of Japan: An overview. Marine georesources & geotechnology 18: 141-176]
Carey, S. and Sigurdsson, H. (2007) Exploring submarine arc volcanoes. Oceanography 20(4): 80-89.