High-resolution imaging of continental tectonics in the mantle beneath
the United States, through the combination of USArray data sets
Abstract
A comprehensive North American upper mantle seismic-tomographic model,
NA13, was inferred from a combination of several decades of seismic data
from early North American seismic models and USArray data. This
data-driven modeling inverted a combination of regional waveform
misfits, teleseismic S delay times, and constraints on Moho
depths. The joint inversion model combines the contrasting and
overlapping resolving power of the different data sets, and demonstrates
enhanced resolution over regional models created with a single
geophysical dataset. Resolution in the upper mantle is achieved on the
scale of ~100km, although travel time delay studies
suggest that anomalies in parts of the western United States are
smaller. In NA13, velocities beneath the Yellowstone plume are low
enough to require the presence of partial melt. NA13 also models a
variety of smaller scale velocity variations beneath the Central and
Eastern United States that reveal remnant velocity anomalies in the
upper mantle from Mesozoic and Cenozoic tectonics.