Receiver Function Analysis Beneath the CD-Yellowstone Array

The existence of a mantle plume beneath Yellowstone National Park is controversial, and the study of mantle discontinuities beneath this region will provide insight into the thermal structure of the mantle. The Continental Dynamics Yellowstone (CD-Yell) broadband PASSCAL Array consisted of 78 broadband seismometers deployed within a 250 km radius of Yellowstone Park. Receiver function analysis using a common conversion point stacking technique is being used to examine the shear wave velocity discontinuities of the upper mantle and crust beneath these arrays. Corrections for lateral velocity heterogeneity, that may create false mantle discontinuity topography, are applied using the local P and S-wave upper mantle velocity models produced from the array travel-time data. A primary scientific question is to constrain the thermal structure of the transition zone via correlation of transition zone topography with tomographic velocity models. Preliminary results show 30 km of variation in the transition zone thickness indicative of substantial transition zone thermal heterogeneity. The region of thinnest transition zone (220 km) is located 100 km east of the Yellowstone Caldera. In addition, a potential discontinuity northwest of the park exists around ~800 km depth. More detailed results will be presented at conference.