Abstract
The phase relations among calcite, wollastonite, clinopyroxene, grandite garnet, magnetite, quartz and other related minerals evaluate the role of carbon dioxide in the formation of ore-bearing skarns. The lowest CO2 content of skarn-forming fluid is represented by the assemblage calcite-wollastonite-quartz, while the upper limit is given by the assemblage calcite-andradite-hedenbergite-magnetite (or quartz).
The graphite mixing into the skarn-forming fluid is one of the important materials to drop oxygen fugacities. If the CO2-rich fluid generated from graphite-bearing limestone is lower in oxygen fugacity than the supplied aqueous fluid, hedenbergite occurs to close with limestone, as compared with andradite. On the contrary, when graphite is mixed into the aqueous fluid, the reversed zonal arrengement is expected.
These suggest that in the skarn formation water as well as carbon dioxide plays a important role.
