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Magmatic evolution creates crystal cumulates. In the current paradigm for the genesis of evolved magmas, cumulate crystal mushes dominate trans-crustal magma systems that feed volcanoes erupting intermediate and felsic magmas. Both melts and cumulates may show broad compositional variation with depth, from mafic/ultramafic near the base of the crust to more evolved at shallow depths. Upward movement of melt through the system (recharge) thus brings relatively mafic magmas into contact with fusible cumulate mush left over by more evolved magma. Recharge mobilizes and melts such mush zones, thus contributing to the total mass of crystal-poor eruptible magma in the system, generates compositional zoning, and may trigger eruptions. By their nature, cumulate mushes compositionally resemble, for most elements, melts higher on the liquid line of descent in any one system, hence the chemical imprint …