Table 1 Adopted S-I-A-M classification

S-type

Melting of metasedimentary rocks

Strongly peraluminous, relatively potassic, high SiO₂ content (64–77%). Common minerals: muscovite, biotite, ilmenite, garnet and cordierite

Intracontinental collisional zones (syn-collisional granitoids), core of metamorphic belts. Example: Lachlan Fold Belt of eastern Australia

Chappell and White, 1974, 2001

I-type

Melting of mafic, meta-igneous sources

Metaluminous to weakly peraluminous, relatively sodic, wide range of SiO₂ content (56–77%). Common minerals: hornblende, biotite, sphene, magnetite

Continental subduction zones (volcanic arcs). Example: Lachlan Fold Belt of eastern Australia

Chappell and White, 1974, 2001

A-type

A₁ granites: differentiation of OIB-like

A₂ granites: continental tholeiitic basaltic magmas

Alkalinity, anhydrous characteristics. Relatively potassic, high SiO₂ content (60–80%), high FeO/(FeO + MgO), high F, Zr and other high field strength elements and REE

“Anorogenic” settings (post-orogenic granitoids). A₁ granites: Intraplate rift zones or within stable continental blocks (hot spots). A₂ granites: postcollisional granites and those that were emplaced at the end of a long period of apparently high heat flow and granitic magmatism. Example: A₁ granites: East African Rift system, White Mountain batholith (New Hampshire). A₂ granites: Gabo and Mumbulla, Lachland Fold Belt (Australia)

Loiselle and Wones, 1979; Eby, 1992

M-type

Mantle origin or partial melting of juvenile crust (technically I-type)

Relatively sodic, wide range of SiO₂ content (46–73%)

Island arcs, subduction zones

White, 1979