Magma chemistry sampled in plutonic and volcanic rocks (including their crystal cargoes) reflects combinations of processes that operate in their sources (e.g. metasomatism and tapping of various mantle components) as well as during differentiation in the crust (e.g. fractional crystallization, crustal assimilation, mixing/mingling, replenishment of magma reservoirs and chambers, and crustal melting). The fundamental questions addressed by this session concern how igneous systems operate in different tectonic settings and the principal controls on primary, parental and derivative magma compositions. This session thus invites contributions focussing on the generation and differentiation of magmas in the mantle and the crust. We particularly encourage reports on field studies, petrology, geochemistry, experimental petrology, and thermodynamic and geochemical modelling.