Thick crust, hydrous magmas, and the paradox of voluminous cold magmatism

Andesites are refined and “cold” magmas compared to their basaltic parents, yet large volumes of andesites generated at continental arcs. We show that andesitic plutons favored when arc crust attains a thickness ~60 km while mafic small is thin. Using simple thermal models, we large, long-lived relatively cold partially molten zones, sustained by recharge hydrous magmas, depth thick due the reduced efficiency heat loss with increasing crustal thickness. Thin drier favor hotter thinner zones. Our study provides an explanation for apparent paradox most voluminous in settings cold. The origin may be linked interplay between magmatic differentiation, availability water, processes control