THE GEOLOGY OF SEA-FLOOR MASSIVE SULPHIDES
5
Introduction
Hydrothermal vents were first discovered at the Galapagos Rift in 1977 (Corliss
et al
. 1979). Observa-
tions made in 1979 from the manned submersible Alvin on the East Pacific Rise revealed vents where
superheated water was emerging from the sea-floor at temperatures exceeding 350°C. These vents
were actively formingmassive sulphide deposits rich inmetals. The resultant, chimney-shaped black
smokers – so called because they emit smoke-like plumes of dark particles – hosted a vent-adapted
biological ecosystem made up of a complex community of giant clams, tubeworms, and other previ-
ously undiscovered creatures that rely on chemosynthetic bacteria for their survival. The history of
early sea-floor hydrothermal-system research can be found in Lowell
et al
. (1995).
On land, massive sulphide deposits created through volcanic action are major sources of copper,
lead, and zinc. Many of the known deposits also contain significant amounts of gold and silver.
The recognition that these deposits originally formed in the ocean helped promote exploration to
discover marine sea-floor massive sulphide (SMS) deposits.
Flange crabs. Photo courtesy Chuck Fisher.
