Eruptive dynamics reflect crustal structure and mantle productivity beneath volcanoes

Abstract

Abstract Volcanoes exhibit a wide range of eruptive and geochemical behavior, which has significant implications for their associated risk. The suggested first-order drivers of intervolcanic diversity invoke a combination of crustal and mantle processes. To better constrain mantle-crustal-volcanic coupling, we used the well-studied Lesser Antilles island arc. Here, we show that melt flux from the mantle, identified by proxy in the form of boron isotopes in melt inclusions, correlates with the long-term volcanic productivity, the volcanic edifice height, and the geophysically defined along-arc crustal structure. These features are the consequence of a variable melt flux modulating the pressure-temperature-composition structure of the crust, which we inverted from xenolith mineral chemistry. Mafic to intermediate melts reside at relatively constant temperature (981 ± 52 °C; 2σ) in the middle crust (3.5–7.1 kbar), whereas chemically evolved (rhyolitic) melts are stored predominantly in the upper crust (<3.5 kbar) at maximum depths that vary geophysically along the arc (6–15 km). Our findings are applicable worldwide, where we see similar correlations among average magma geochemistry, eruptive magnitude, and rate of magma input.