A plume is a still theoretical abnormality that lies at the boundary between the Earth’s core and the mantle, and rises through the mantle into the crust — an abnormality that would exist as a vertical stream of magma. Well these researchers from the University of Texas claim they have found a new evidence of a plume beneath Yellowstone National Park and further propose that the plume is part of a zone that runs to the park all the way from Mexico.
The prospect of a plume beneath Yellowstone has been strongly debated. Some have suggested a plume would explain the source of the heat that drives so much surface activity in the park. Others disagree pointing out that it could just as easily be explained by shallow subduction or lithospheric processes.
The researchers found what they describe as “a long, thin, sloping zone” (approximately 72 by 55 kilometers in size) inside of the mantle where seismic waves were traveling slower than the areas around them. This suggests a section of the mantle that is approximately 600 to 800° C degrees warmer than surrounding areas, and offers strong evidence of a plume.
The new paper suggests that there is likely a thin plume stretching from the core-mantle boundary beneath the park and that it is responsible for the volcanism seen at Yellowstone.
For example, the the world’s tallest geyser – the Steamboat Geyser at Yellowstone – has erupted on March 15, 2018 after more than 4 years – September 3, 2014 – of calm:
Video of Steamboat Geyser taken on March 16, more than 24 hours after an eruption documented by seismic and thermal sensors in the Norris Geyser Basin. pic.twitter.com/ZY4FRAxDO5
— YellowstoneNPS (@YellowstoneNPS) March 19, 2018
Here the abstract of the new scientific study:
The Yellowstone hotspot, located in North America, is an intraplate source of magmatism the cause of which is hotly debated. Some argue that a deep mantle plume sourced at the base of the mantle supplies the heat beneath Yellowstone, whereas others claim shallower subduction or lithospheric-related processes can explain the anomalous magmatism. Here we present a shear wave tomography model for the deep mantle beneath the western United States that was made using the travel times of core waves recorded by the dense USArray seismic network. The model reveals a single narrow, cylindrically shaped slow anomaly, approximately 350 km in diameter that we interpret as a whole-mantle plume. The anomaly is tilted to the northeast and extends from the core–mantle boundary to the surficial position of the Yellowstone hotspot. The structure gradually decreases in strength from the deepest mantle towards the surface and if it is purely a thermal anomaly this implies an initial excess temperature of 650 to 850 °C. Our results strongly support a deep origin for the Yellowstone hotspot, and also provide evidence for the existence of thin thermal mantle plumes that are currently beyond the resolution of global tomography models.