Numerous Pb-Zn deposits formed during the Proterozoic, in contrast with the situation in the Archean. The largest examples, which are reviewed here, are McArthur, Mount Isa-Hilton, Sullivan, Gamsberg, and Broken Hill.

These huge stratiform deposits occur well above the bases of thick, predominantly sedimentary sequences which accumulated in major ensialic troughs. The sequences are dominated by carbonates or clastics, but the mineralization is localized within distinctive chemo-clastic facies which were deposited in basins of restricted extent. There is commonly evidence for synsedimentary faulting and for distal igneous activity. Biogenic sulfide was probably incorporated into some of the pyrite but is...