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Middle Valley, Bent Hill Massive Sulfide

Name Alias(es): 
Site 856, Middle Valley
MGDS_FeatureID lowest in hierarchy: 
Vent Sites: 
Maximum Temperature: 
Max Temperature Category: 
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: 
MORB, minor E-MORB, sediment-hosted
Deposit Type: 
PMS, polymetallic massive sulfides
Notes on Vent Field Description: 
[note: although Butterfield et al. (1994) say Bent Hill is active with temp. 265 C - this was measured at Lone Star vent at ODP Mound]; large inactive sulfide deposits within turbiditic sediments in a buried rift adjacent to Endeavour Ridge (several sulfide outcrops up to 100 m in diameter); Ocean Drilling Program (ODP) hole 856H penetrates through the massive sulfide
Notes Relevant to Biology: 
Year and How Discovered (if active, visual confirmation is listed first): 
1985 deposits only
Discovery References (text): 
(Middle Valley SMS deposits only) EE Davis et al. (1987) Massive sulfides in a sedimented rift valley, northern Juan de Fuca Ridge. Earth Planet Sci Let 82: 49–61.
Other References (text): 
[Ames, D.E., et al., 1993. Mineralogy and geochemistry of active and inactive chimneys and massive sulfide, Middle Valley, northern Juan de Fuca Ridge: an evolving hydrothermal system. Can. Mineral., 31:997-1024]
Butterfield et al., (1994) Geochemistry of hydrothermal vent fluids from Middle Valley, Juan de Fuca Ridge. In: Mottl, M.J., et al. (Eds.), Proc. ODP, Sci. Results, vol. 139, pp. 395–410
Teagle and Alt (2004) Hydrothermal Alteration of Basalts beneath the Bent Hill Massive Sulfide Deposit, Middle Valley, Juan de Fuca Ridge. Econ. Geol. 99: 561-584.