Open AccessV P and V S structure of the Yellowstone hot spot from teleseismic tomography: Evidence for an upper mantle plume
Author(s) -
Waite Gregory P.,
Smith Robert B.,
Allen Richard M.
Publication year - 2006
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jb003867
Subject(s) - geology , transition zone , mantle (geology) , lithosphere , mantle plume , hotspot (geology) , volcano , caldera , plume , volcanism , seismology , seismic tomography , upwelling , geophysics , tectonics , oceanography , physics , thermodynamics
The movement of the lithosphere over a stationary mantle magmatic source, often thought to be a mantle plume, explains key features of the 16 Ma Yellowstone–Snake River Plain volcanic system. However, the seismic signature of a Yellowstone plume has remained elusive because of the lack of adequate data. We employ new teleseismic P and S wave traveltime data to develop tomographic images of the Yellowstone hot spot upper mantle. The teleseismic data were recorded with two temporary seismograph arrays deployed in a 500 km by 600 km area centered on Yellowstone. Additional data from nearby regional seismic networks were incorporated into the data set. The V P and V S models reveal a strong low‐velocity anomaly from ∼50 to 200 km directly beneath the Yellowstone caldera and eastern Snake River Plain, as has been imaged in previous studies. Peak anomalies are −2.3% for V P and −5.5% for V S . A weaker, anomaly with a velocity perturbation of up to −1.0% V P and −2.5% V S continues to at least 400 km depth. This anomaly dips 30° from vertical, west‐northwest to a location beneath the northern Rocky Mountains. We interpret the low‐velocity body as a plume of upwelling hot, and possibly wet rock, from the mantle transition zone that promotes small‐scale convection in the upper ∼200 km of the mantle and long‐lived volcanism. A high‐velocity anomaly, 1.2% V P and 1.9% V S , is located at ∼100 to 250 km depth southeast of Yellowstone and may represent a downwelling of colder, denser mantle material.