Ps Reciever Function Analysis of the Crustal Structure Beneath the United States Great Plains

The North American Great Plains, located directly east of the Rocky Mountain deformation front, were initially formed in the Precambrian through a series of island arc accretion events, and they have since been affected by multiple phases of both compression and extension. Understanding both the past and present tectonic deformation occurring throughout the Great Plains region can, therefore, provide valuable information regarding the assembly of southern North America. We use Ps teleseismic receiver functions to investigate the crustal and lithospheric structure throughout this region. Using over 250 M > 6.0 events recorded at ~450 USArray Transportable Array seismic located in the Great Plains, we calculated .5 Hz, 1Hz, and 2 Hz receiver functions. Both CCP stacking and H-k analysis were applied to the dataset in order to determine the crustal thickness structure of the region. The Ps receiver functions indicate an average crustal thickness of ~ 45 km in the central portion of the study region with variations up to +/- 10 km. We observe NE-SW trending zones of increased crustal thickness (up to ~53 km) associated with the NE-SW trending boundaries between accreted Proterozoic terrains. We also observe a sharp increase in crustal thickness from ~35 km just west of the Rio Grande Rift to ~50 km just east of the Rio Grande Rift. Finally, we observe a very complicated crustal structure in the north-central portion of the study region. Here we see a thrust system that appears to affect much of the crust north of 40° latitude between -104° to - 98° longitude. This structure appears to reach Moho depths in some places and is likely associated with the original suturing of the Wyoming and Superior Archean provinces at the Trans Hudson Orogen as well as subsequent Proterozoic accretion events that occurred during continent formation. Similar Moho penetrating features have been observed in the Lithoprobe studies further north (Winardhi et al, 1997; Clowes et al.,2002; Hammer et al., 2010) , and have been attributed to significant crustal shortening that occurred during Proterozoic terrane accretion.