“Stratiform skarns” — A re-evaluation of three eastern Australian deposits

The tectonic setting, regional geology, regional geophysics, local geology, mineralogy, petrology and geochemistry of three eastern Australian stratiform skarns have been investigated. These skarns all show a close spatial relationship to granitic rocks, display multiphase spatial and temporal mineralogical zoning, contain minerals not commonly present in exhalites, contain fluid inclusions characteristic of metasomatic skarns, display textural evidence of replacement of limestone and fossils by calc-silicate minerals, and possess a major element chemistry unlike exhalites. Although some metamorphosed exhalites contain CaFeAlMgMn silicates, the Ban Ban, Brindabella and Willi Willi mineralized skarns formed from metasomatism associated with the emplacement of closely related granites. There is no evidence to suggest that these skarns represent isochemically metamorphosed calc-silicate rich beds of submarine exhalite origin.