Granitic magmatism, from source to emplacement: a personal view

Abstract

This personal view tracks the phenomenon of granitic magmatism from the source materials through partial melting, melt segregation, magma ascent and emplacement to the mechanisms by which granitic plutons acquire their main chemical heterogeneities. Readers should bear in mind that, although the work deals specifically with plutonic felsic magmatism, most of the conclusions also apply to the genesis and evolution of felsic volcanic magmas. Major conclusions are that: the majority of granitic magmas are formed mainly by crustal melting under fluid-absent conditions; the magmas segregate rapidly and efficiently from their solid residues, initially carrying small amounts of peritectic crystals; they ascend by fracture pathways and in pulses to inflate mainly tabular bodies that we call batholiths; and that the main internal variations in these bodies are not due to differentiation or magma mixing, but are inherited from the heterogeneous magma pulses that reflect source melting reactions and peritectic mineral entrainment.