Thermomechanical Modeling of the Formation of a Multilevel, Crustal‐Scale Magmatic System by the Yellowstone Plume

Abstract

Abstract Geophysical imaging of the Yellowstone supervolcano shows a broad zone of partial melt interrupted by an amagmatic gap at depths of 15–20 km. We reproduce this structure through a series of regional‐scale magmatic‐thermomechanical forward models which assume that magmatic dikes stall at rheologic discontinuities in the crust. We find that basaltic magmas accumulate at the Moho and at the brittle‐ductile transition, which naturally forms at depths of 5–10 km. This leads to the development of a 10‐ to 15‐km thick midcrustal sill complex with a top at a depth of approximately 10 km, consistent with geophysical observations of the pre‐Yellowstone hot spot track. We show a linear relationship between melting rates in the mantle and rhyolite eruption rates along the hot spot track. Finally, melt production rates from our models suggest that the Yellowstone plume is ~175°C hotter than the surrounding mantle and that the thickness of the overlying lithosphere is ~80 km.