Archaean granites (including quartz monzonites) can be divided into three geochemical classes based chiefly on REE distributions. Geochemical model studies, initial 87Sr/86Sr ratios, and O-isotope data are consistent with an origin for most Archaean granites by partial melting (approx 20%) of one of three rock types in the lower crust with short crustal residence times: tonalite-trondhjemite, high-grade gneiss (of intermediate composition), or less likely, greywacke. Only a few percent of subcontinental mantle heat is needed to account for Archaean granite magma production by partial melting of the lower crust. (Author's abstract) J.A.H.
|Number of pages||11|
|Journal||Special Publication, Geological Society of Australia|
|Publication status||Published - 1981|