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Iheya Ridge

Name Alias(es): 
Iheya Small Ridge
Vent Sites: 
Clam field (= Clam Site) (includes Calyptogena site and Pyramid chimney)
Maximum Temperature: 
220
Latitude: 
27.5417
Longitude: 
126.9750
Location on map: 
Ocean: 
National Jurisdiction: 
Maximum or Single Reported Depth (mbsl): 
1430
Minimum Depth (mbsl): 
1390
Tectonic setting: 
Full Spreading Rate (mm/a): 
28.8
Volcano Number (if applicable): 
Host Rock: 
basalt, high-K andesite, dacite, sediment
Deposit Type: 
LTH
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.