The Yellowstone plume has been tomographically imaged as a tilted body extending from 80 km depth at the Yellowstone Plateau to 660 km depth beneath western Montana. Geodynamic modeling of the plume finds that the plume is up to 120 K hotter than the surrounding mantle, with a maximum of 2.5% melt and a small buoyancy flux of 0.25 MG/s, properties of a cool, weak plume. Mantle flow modeling is used to constrain the evolution of the hotspot: the Yellowstone plume initially ascended vertically through the mantle beneath the thin, accreted lithosphere of the Columbia Plateau and was responsible for the 17 Ma flood basalts there. At 12 Ma, the plume passed beneath the thicker North American lithosphere and became entrained in eastward upper mantle return flow, resulting in a shift of volcanic activity to the southeast and the onset of rhyolitic eruptions caused by melting in the lithosphere. As the North America plate moved southwest, hotspot volcanism propagated northeast, and the resulting tectonic and magmatic interactions produced the 700-km-long Yellowstone-Snake River Plain magmatic system.

Credit: University of Utah Seismology and Active Tectonics Research Group

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