Abstract

The lead-zinc ores occur in a shear zone in Precambrian metasediments. The shear zone is later than the two recognized generations of folds, and contemporaneous with wall-rock alteration and subsequent mineralization. Flow directions of mineralizing solutions are deduced from the mineral zoning pattern; galena follows sphalerite paragenetically and lead-rich zones are assumed to lie farther from the two inferred centers of mineralization at cross faults. The zonal fronts are not parallel to isotherms as determined by sphalerite geothermometry. Microscopic observations and theoretical considerations indicate that the wall-rock alteration was caused by a gaseous medium, and that the ore metals were probably carried as complexions.

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