Separate granite plutons in southeasthern Australia can commonly be grouped into suites on the basis of shared similarities in field, petrographic and compositional data. Granites in different plutons of the same suite share common properties or exhibit a sequence of such features. Rocks of the same suite are cogenetic, but the details of their genesis need not be known or agred on, to group granite units in such a way. These rocks are cogenetic in the sense that they shared a similar petrogenesis and were derived from source materials of essentially the same composition, whereas differences between suites reflect analogous differences in their source rocks. The term suite is lithologic or lithodemic in a stratigraphic sense and is closely analogous to the lithostratigraphic term group. As such, the plutons within a suite need not be of the same age, and age is not a factor in recognising a suite. However, the fact that the petrogenesis of the components of a suite resulted in such similar products means that their ages are likely to be similar. Granite plutons that share many similar features, but which also show distinct differences and which may be assigned to more than one suite, may be grouped into supersuites. The allocation of granites to suites is fundamental to understanding their petrogenesis. Suites vary in the complexity of their compositional variation. Simple suites show variations in element abundances that are highly correlated and the dispersion of composition within such suites is considered to result from varying degrees of fractionation of entrained restite from a melt. Intricate suites vary in composition in more complex ways and their variation is considered to be a consequence of processes such as fractional crystallisation. Any mineralisation is generally associated with intricate suites, and the occurrence of mineralisation and its precise character is generally specific to particular suites.
- Lachlan Fold Belt
- Source rocks