1. Mid Ocean Ridge Ore Deposits
Patrick Loury and Olivia Miller

2. Processes of Ore Formation
Exhalative deposition
Related to submarine hot-springs or fumaroles
Mineralizing fluids pour onto the seafloor or raise to some height before deposition
Deposit characteristics are a function of:
Water depth, temperature, and salinity
Distance from vent
Proximal ore deposits
Intermediate volcanic processes and products
Distal ore deposits
Lateral transmission of ore forming fluids through seawater
Host rocks: volcanic tuffs and seafloor sediments

3. Volcanogenic Massive Sulfide (VMS) Deposits
Lenses of polymetallic massive sulfides that form in submarine volcanic environments
Distribution:
800 known deposits worldwide
Age: Archean to present day
Classification based on chemical composition and host rock lithology:
Cu-Zn, Zn-Cu and Zn-Pb-Cu groups
Mafic dominated, bimodal mafic, siliciclastic mafic, bimodal felsic, high sulfidation bimodal felsic, siliciclastic felsic groups

4. Sp, sphalerite; Gn, galena; Py, pyrite; Ba, barite; Cpy, chalcopyrite; Po, pyrrhotite; and Hem, hematite
(Taylor et al., 1995)

5. $862 million cleanup VMS deposits provide:
at least 22% of the world's Zn
6% of the world's Cu
9.7% of the world's Pb
8.7% of it's Ag
2.2% of it's Au
World’s Most Acidic Water
$862 million cleanup
(Galley et al., 2007, Nordstron et al., 2000)