title: On the conditions of magma mixing and its bearing on andesite production in the crust.
abstract: Mixing between magmas is thought to affect a variety of processes, from the growth of continental crust to the triggering of volcanic eruptions, but its thermophysical viability remains unclear. Here, by using high-pressure mixing experiments and thermal calculations, we show that hybridization during single-intrusive events requires injection of high proportions of the replenishing magma during short periods, producing magmas with 55-58 wt% SiO2 when the mafic end-member is basaltic. High strain rates and gas-rich conditions may produce more felsic hybrids. The incremental growth of crustal reservoirs limits the production of hybrids to the waning stage of pluton assembly and to small portions of it. Large-scale mixing appears to be more efficient at lower crustal conditions, but requires higher proportions of mafic melt, producing more mafic hybrids than in shallow reservoirs. Altogether, our results show that hybrid arc magmas correspond to periods of enhanced magma production at depth.
authors.affiliation: ISTO, CNRS-Université d'Orléans-BRGM, 1a rue de la Férollerie, Orléans 45071, France.
authors.forename: Mickael
authors.initials: M
authors.lastname: Laumonier
authors.affiliation: ISTO, CNRS-Université d'Orléans-BRGM, 1a rue de la Férollerie, Orléans 45071, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Scaillet
authors.affiliation: ISTO, CNRS-Université d'Orléans-BRGM, 1a rue de la Férollerie, Orléans 45071, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Pichavant
authors.affiliation: ISTO, CNRS-Université d'Orléans-BRGM, 1a rue de la Férollerie, Orléans 45071, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Champallier
authors.affiliation: ISTO, CNRS-Université d'Orléans-BRGM, 1a rue de la Férollerie, Orléans 45071, France.
authors.forename: Joan
authors.initials: J
authors.lastname: Andujar
authors.affiliation: ISTO, CNRS-Université d'Orléans-BRGM, 1a rue de la Férollerie, Orléans 45071, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Arbaret