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South Cleft

Name Alias(es): 
southern Cleft segment
southern Rift A
southern Area 1
MGDS_FeatureID lowest in hierarchy: 
Vent Sites: 
Vent 1
Vent 3
Maximum Temperature: 
Location on map: 
National Jurisdiction: 
Maximum or Single Reported Depth (mbsl): 
Minimum Depth (mbsl): 
Tectonic setting: 
Full Spreading Rate (mm/a): 
Volcano Number (if applicable): 
Host Rock: 
Deposit Type: 
PMS, polymetallic massive sulfides
Notes on Vent Field Description: 
Plume (44 38.5'N), Vent 1 (44 40'N), Vent 3 (44 41'N); Vent 1 is longer and more complex than Plume site; axial cleft not as distinct at Vent 1 as at Plume site; Vent 3 is intermediate in character between Plume and Vent 1 sites; Note: Plume, Vent 1, and Vent 3 are sites within a larger South Cleft field - Kappel and Normark (1987): "It was speculated after the intensive photogeologic mapping of the cleft during the 1983 field season that the cleft was, in fact, continuous at least through the recognized vent areas"; southern Area 1 in Crane et al. (1985)
Notes Relevant to Biology: 
extensive hydrothermal biota
Year and How Discovered (if active, visual confirmation is listed first): 
1981 deep-tow photographs; 1984 submersible Alvin
Discovery References (text): 
(camera tow) Normark, WR et al. (1983) Active hydrothermal vents and sulfide deposits on the southern Juan de Fuca Ridge. Geology 11: 158-163
USGS Juan de Fuca Study Group, Submarine fissure eruptions and hydrothermal vents on the southern Juan de Fuca Ridge: Preliminary observations from the submersible Alvin, Geology, 14, 823-827, 1986
Normark, W.R. et al. (1987) Submersible Observations Along the Southern Juan de Fuca Ridge: 1984 Alvin Program. Journal Geophysical Res. 92(B11): 11283-11290.
Other References (text): 
[Bischoff et al., Econ Geol Bull Soc Econ Geol, 78, 1711-1720, 1983, Sea-floor massive sulfide deposits from 21 degrees N East Pacific Rise, Juan de Fuca Ridge, and Galapagos Rift: bulk chemical composition and economic implications]
(towed thermistors indicated geothermal region only) Crane et al., J. Geophys. Res., 90, 727-744, 1985, The Distribution of Geothermal Fields on the Juan de Fuca Ridge, doi:10.1029/JB090iB01p00727
(plume only) Baker and Hammond (1992) Hydrothermal Venting and the Apparent Magmatic Budget of the Juan de Fuca Ridge. J. Geophys. Res. 97(B3): 3443-3456.