Minerals Report - International Seabed Authority

The main areas of occurrence are fast-, intermediate-, and slowspreading
mid-ocean ridges, on- and off-ridge volcanoes and seamounts,
in sedimented rifts adjacent to continental margins and in volcanoes and
spreading ridges related related to deep-ocean trenches (Rona, 1988; Rona
and Koski, 1985; Herzig, 1999; Herzig and Hannington, 2000). Hightemperature
hydrothermal activity and large accumulations of
polymetallic sulphides are known at some 25 different sites world-wide
(Figure 10).
Small oceanic basins related to deep-ocean trenches are important
sites for PMS mineralisation. For example, the “PACMANUS”
hydrothermal deposits are scattered along a 10 km-long crest of an active
volcanic ridge in the Eastern Manus Basin, Papua New Guinea. Here,
chimneys dominated by chalcopyrite and sphalerite, with barite and some
bornite, have average compositions of 11 wt% Cu, 27% Zn, 230 ppm Ag
and 18 ppm Au (Moss et al., 1997; Scott and Binns, 1995; Binns et al., 1993).
The shallow depths (less than 1,500 m) and high gold content make such
sites potentially viable for mining.
INTERNATIONAL SEABED AUTHORITY 693