Clam field (= Clam Site) (includes Calyptogena site and Pyramid chimney)
basalt, high-K andesite, dacite, sediment
Notes on Vent Field Description:
Calyptogena site did not have shimmering water; Pyramid site 200 m N of Calyptogena has clear smokers 100-220 C, fluid emanation from fissures; 1987 strong plume anomaly in western Natsushima 84 deep (Ishibashi et al. 1988); Ishibashi et al. (2015): "highest temperature was recorded as 220 C in 1988. Venting was ceased in 1990, and since then, dive studies have not been conducted in this field"
Notes Relevant to Biology:
Calyptogena okutanii, Neolepas-type scalpellid barnacles, tubeworms; fauna less abundant at Pyramid than Calyptogena
Year and How Discovered (if active, visual confirmation is listed first):
1988 submersible Shinkai 2000; 1987 plume only
Discovery References (text):
[Tanaka et al. (1989) Shinkai 2000 diving surveys in the east of Iheya Small Ridge of the central Okinawa Trough. JAMSTECR Deep-Sea Res. 267-281 (in Japanese with English abstract)]
(plume only) Ishibashi et al. (1988) Geochemical evidence for hydrothermal activity in the Okinawa Trough. Geochemical Journal 22: 107-114.
Other References (text):
Ohta, S. and Kim, D. (2001) Submersible Observations of the Hydrothermal Vent Communities on the Iheya Ridge, Mid Okinawa Trough, Japan. J. Oceanogr. 57: 663-677
Halbach et al., Econ. Geol., 88, 2210-2225, 1993.
Ishibashi, J., et al. (2015) Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization. pp. 337-359 in Ishibashi, J. et al. (eds) Subseafloor Biosphere Linked to Hydrothermal Systems. Springer. doi:10.1007/978-4-431-54865-2_27.