Seismic analysis of the Rocky Mountain Front and Great Plains using transportable array data

USArray seismic data along the Rocky Mountain Front and Great Plains was downloaded from the Incorporated Research Institutions for Seismology (IRIS) to map lithosphere boundaries including the Mohorovičić discontinuity (Moho), Hales discontinuity (Hales), and lithosphere-asthenosphere boundary (LAB). Water-level (i.e. prewhitening) deconvolution in the frequency domain was used to filter out the bad stations. The good stations were further improved by cross-correlating and stacking the vertical component of nearby stations (i.e. beamforming) and simultaneously deconvolved to reduce the need for prewhitening and improve the signal-to-noise ratio in the receiver functions. These stacked move-out corrected receiver functions (SMOCRF) were used to interpret depth and Vp/Vs ratios of features in the lithosphere including the Moho, Hales discontinuity, and the LAB, and related these to the geology of the Rocky Mountain Front and Great Plains. The Moho depth across the Rocky Mountain Front and Great Plains correlates well with the previous geological and geophysical work done from the literature with deep signatures along the Rocky Mountain Front, southern granite-rhyolite belt, and Black Hills area, and shallow signature along the southern portion of the Rio Grande Rift. Crustal Vp/Vs ratios are mostly uniform throughout the study area at 1.73 to 1.76, which is average for continental crust. The Hales discontinuity is 80 to 90 km for most of the study area. This correlates well with the original discovery made by A.L. Hales in 1969. Deeper regions on the Hales may be related to orogenic events from the past. It appears that Precambrian features are preserved in the mantle between the Moho and Hales discontinuity. The lithosphere-asthenosphere boundary can be divided into a shallow northern half and deep southern half in the study area. Vp/Vs ratios for each interval do not vary much throughout the entire study area. However, Vp/Vs ratios mapped for the Hales discontinuity show higher values above the Yavapai-Mazatzal transition zone, which is interpreted to be the boundary of this accreted Proterozoic province. Skeptical of the lithosphere-asthenosphere boundary results due to crustal reverberations affecting the quality of data that can occur with P-to-S imaging. Recommend following up with S-to-P receiver functions.