Paragenetic mineral assemblages have been established based on
mineralogical, chemical, and isotope (S, Pb) studies, and the sequence
of deposition has been defined in hydrothennal sulfide structures in a
typical back-arc basin. The ores in the Manus basin have a prominent
Zn specialization (sphalerite, würtzite, and fe-sphalerite). An association
of Fe-spbalerite and galena with Ag sulfosalts is noted that is not
characteristic of typical midocean ridge hydrothennal systems. The
average 34S in the sulfide minerals is 3.5%o, which corresponds to the
medium-temperature sphalerite stage in hydrothermal mineral fonnation.
It is suggested that the metal source is located in the relatively acid
rocks of the island-arc tholeiitic series and possibly in sediments
