We report evidence for a ≥13-km-diameter Permian caldera associated with a renowned
section through the continental crust comprising the Ivrea-Verbano Zone and Serie dei
Laghi of northwest Italy. Correlation of ages of volcanic and middle to deep crustal plutonic
rocks suggests that they constitute an unprecedented exposure of a subcaldera magmatic
plumbing system to a depth of 25 km, and points to a cause and effect link between
intrusion of mantle-derived basalt in the deep crust, and large-scale, silicic volcanism.
