Lithospheric structure in the Eastern Oregon and Western Idaho across the Western Idaho Shear Zone and Idaho Batholith from teleseismic receiver functions

We present new P-to-S receiver functions at 86 broadband seismic stations that we deployed in Eastern Oregon and Western Idaho as part of the IDOR (IDaho-ORegon) Earthscope project. We obtained a 3D lithospheric image detailing the crustal structure and architecture of the Idaho Batholith and Salmon River suture/Western Idaho Shear Zone (WISZ) at depth. The suture marks the sharp ~110-90 Ma contact between the accreted oceanic terranes (Blue Mountains province) and the North American Craton and is characterized largely by the near vertical dextral transpressional system of the WISZ, which closely follows the Sr 0.706 isopleth. The Idaho Batholith (Atlanta and Bitterroot lobes) is characterized by long-lived magmatism ranging between 108 and 50 Ma occurring during and after the deformation in the WISZ. To understand the evolution of this portion of the western North American plate boundary and the transition from Mesozoic transpressional tectonics west of the Idaho batholith to current basin-and-range-like tectonics to the east, we analyzed more than 350 teleseismic events generated at epicentral distances between 30 and 95 degrees. We constructed receiver functions using a modified version of the Ligorria and Ammon (1999) iterative deconvolution technique, and then applied the H-k stacking procedure of Zhu and Kanamori (2000) for each station to estimate Vp/Vs ratios and depths to different boundary interfaces. In addition we applied the common conversion point stacking method (CCP) of Dueker and Sheehan (1997) for bins of receiver functions. Preliminary results show an important variation of the crustal thickness beneath the IDOR area, with a thicker crust beneath the Atlanta lobe of the Idaho Batholith.