Attenuation Tomography Beneath the Rocky Mountain Front: Implications for the Physical State of the Upper Mantle

摘要: Utilizing the Rocky Mountain Front (RMF) broadband seismic dataset acquired in 1992, this study has derived attenuation structure underlying part of Southern Mountains and surrounding areas through measurements differential t* S-phase waveforms. Previous studies area include P, S surface wave travel time tomography, all indicate low upper mantle velocities below region. Calculations intrinsic coupled with current velocity models aid determination temperature, partial melt distributions, compositional variation. A N-S zone high shear (Q s 30) is found beneath lies east region lowest velocity. Relationships between are consistent both thermal variability. Along eastern Colorado Rockies due north Rio Grande Rift, relationships an interpretation elevated temperatures by up to 50 K at 125 km depth. West suggest either unusual composition or very temperatures. The density material addition increased crustal thickness intrusions provides a contrast sufficient support its overburden.