A recent study suggested that the renowned Yellowstone supervolcano is likely sustained through entirely different means than many geologists previously believed. Instead of a potent hot column from the Earth’s depths (a mantle plume), tectonic processes within the crust and upper mantle may play the key role. This prompts researchers to re-examine the origin of magma in the region and potential future eruption scenarios. A team led by geologist Lixun Liu simulated the 3D evolution of the lithosphere and mantle beneath western North America over millions of years. The calculations incorporated plate motion, the structure of the mantle beneath Yellowstone, and the properties of the solid crust. It was revealed that the conduits through which magma ascends might have formed without the classic deep plume—they are “pulled” by competing forces stretching and tearing the lithosphere. One factor is related to the variable density of the crust under Yellowstone: heavier sections pull the Earth’s shell toward the western US coast, similar to stretching dough. The second relates to the subduction of the ancient Farallon plate beneath the central and eastern part of the continent, which tilts and draws down the lower crustal layers. It is the collision of these forces, according to Liu, that causes a fracture in the lithosphere below Yellowstone, opening a pathway for the magma. Thus, the volcanic system effectively connects the park’s surface to the layers beneath the crust and “draws” the melt upward. Independent observations align with this: geophysical data indicate that magma originates southwest of the current caldera, in the upper mantle, and then migrates northeastward beneath Yellowstone itself. The novel model explains why the magma follows this specific path. This is fundamentally important for forecasting future activity. If the magma reservoir is heated primarily by tectonics rather than a strong plume, it affects the rates of magma replenishment, the depth of its source, and the possible magnitude and frequency of eruptions. Jamie Farrell from the Yellowstone Observatory notes that in coming geological epochs, volcanic activity might shift to the area of colder and thicker crust east of the current park—the outcome will depend on which heat source is dominant. A similar modeling approach, the authors state, can now be applied to other large caldera systems—such as Toba in Southeast Asia, Taupo in New Zealand, and several active volcanoes in Northeast China.
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