Opaque mineralogy and mafic mineral chemistry of I- and S-type granites of the Lachlan fold belt, Southeast Australia

A systematic survey of opaque mineral assemblages and mafic mineral chemistry was undertaken to clarify the relationship between the descriptive magnetite- and ilmenite-series granite classification and the petrogenetic I- and S-type granite classification. I- and S-type granites may belong to either the magnetite or ilmenite series. However, the bulk of I-type granites are magnetite series, and the bulk of S-type granites are ilmenite series. The fO2 in a granitic magma may be more important than the nature of the granitic source rocks in controlling the type of associated mineral deposits.