Imaging and Modeling the Yellowstone Plume

Session: Advances in Seismic Imaging of Earth’s Mantle and Core and Implications for Convective Processes
Type: Oral
Date: 4/29/2020
Time: 10:45 AM
Room: 120 + 130
Description: 

The Yellowstone Hotspot is an intraplate source of magmatism whose cause has been highly debated. Some argue that a deep mantle plume supplies the heat beneath Yellowstone while others claim 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 by carefully measuring the travel times of SKS/SKKS waves recorded by the dense USArray seismic network. Using core waves is ideal for imaging short wave length sub vertical features in the lower mantle. The model shows a narrow (~350 km diameter) cylindrically shaped slow anomaly extending from the core-mantle boundary to beneath Yellowstone that we interpret as a whole mantle plume. The anomaly is strongly tilted to the northeast and extends from the core-mantle boundary beneath San Diego to the surficial position of the Yellowstone Hotspot. We perform numerical computations of plumes deflected in large-scale mantle flow to find if a set of realistic model parameters exist that can fit our observations. For a plume head reaching the surface 17 Ma, corresponding to the start of the Columbia River Flood Basalts, we are able to match the shape and location of the conduit, using a range of current global tomography models scaled to density, if the rise time is ~80 Myrs or longer.

Presenting Author: Stephen P. Grand

Authors