Submarine caldera formation and forearc IODP cores in the Izu arc

Abstract

Izu calderas that have produced only rhyolite have no mantle roots beneath the crust, but dikes from adjacent basalt volcanoes might provide the heat source to partially melt the surrounding middle crust (Tamura et al., 2009). The middle crust is deemed to be andesitic in composition, which have been produced when the crust was thin (Tamura et al., 2016) and, thus, only in the early stage of arc crust evolution. In the later stage of the Izu arc, we suggest that only basalt magmas are produced in the mantle wedge, which could be the heat source to melt the andesitic middle crust.