Continental Tectonics Inferred From High-Resolution Imaging of the Mantle Beneath the United States, Through the Combination of USArray Data Types

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 networks and USArray data. This data-driven modeling inverted a combination of regional waveform fits, teleseismic S delay times, and point 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 data set. Resolution in the upper mantle is achieved on the scale of ∼100 km, 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 related to lithospheric variations in the upper mantle between Proterozoic units.