The PACMANUS and Jade deposits are two active hydrothermal fields that are forming massive sulfide deposits at the
Pacific rim margin. Both are associated with felsic submarine volcanic rocks and both occur in back-arc settings.
However, PACMANUS is associated with almost sediment-free dacites and lies on the crest of a volcanic ridge, whereas
Jade occurs in a heavily-sedimented tectonic depression associated with a basement of pumiceous rhyolite. The
PACMANUS deposit is richer in Cu and Au, and Jade in Pb. Zinc, Ag, As and Sb contents are similar. Sulfide textures at
PACMANUS suggest formation of Cu and Zn sulfides by simultaneous double-diffusion involving inwards-moving
seawater mixing with outwards-moving hydrothermal fluid. By contrast, at Jade there is a more complex history of
formation where initial growth of barite on the sediment surface, probably associated with microbial activity, formed an
impervious cap which trapped higher temperature hydrothermal solutions.