A 3-D Receiver Function Study of the Western United States
Texas Tech University
P-to-S converted (Pds) phases from teleseismic events recorded throughout the western US, using data from EarthScope Transportable array were used to produce a 3-D image of the mantle from the Pacific coast to the Rocky mountain front. A 3-D surface wave tomography model (NA04 by Van der Lee) was used to compute move-out correction. The image produced has an average depth to the Moho of 39.6 km with ± 14 km of topography. The Moho appears to be deepest beneath the Colorado Plateau and central Montana and shallowest throughout the Basin and Range. The Moho also appears very shallow beneath eastern Washington. There is a band of thick crust along the Yellowstone hot spot track. The 410 km discontinuity appears to have a mean depth of 427 ± 20 km. At this time the images are still very noisy but in a regional sense the 410 appears deepest to the south and shallow to the north. Depths to the 660 km discontinuity appear to average 675 ± 9.8 km. The 660 appears deepest to the Eastern and shallower to the west. This relationship may indicate that the thermal state of the 410 is controlled by high temperatures to the south associated with the Basin and Range and cooler to the north where subduction is present. The 660 may be controlled by the transition from warm oceanic and transitional lithosphere to the west and cooler continental lithosphere to the east.
AAPG Search and Discover Article #90087 © 2008 AAPG/SEG Student Expo, Houston, Texas