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Mantle structure beneath the western edge of the Colorado Plateau
Author(s) -
Sine C. R.,
Wilson D.,
Gao W.,
Grand S. P.,
Aster R.,
Ni J.,
Baldridge W. S.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl033391
Subject(s) - geology , mantle (geology) , lithosphere , transition zone , subduction , crust , seismology , basin and range topography , proterozoic , continental crust , geophysics , tectonics
Teleseismic traveltime data are inverted for mantle Vp and Vs variations beneath a 1400 km long line of broadband seismometers extending from eastern New Mexico to western Utah. The model spans 600 km beneath the moho with resolution of ∼50 km. Inversions show a sharp, large‐magnitude velocity contrast across the Colorado Plateau‐Great Basin transition extending ∼200 km below the crust. Also imaged is a fast anomaly 300 to 600 km beneath the NW portion of the array. Very slow velocities beneath the Great Basin imply partial melting and/or anomalously wet mantle. We propose that the sharp contrast in mantle velocities across the western edge of the Plateau corresponds to differential lithospheric modification, during and following Farallon subduction, across a boundary defining the western extent of unmodified Proterozoic mantle lithosphere. The deep fast anomaly corresponds to thickened Farallon plate or detached continental lithosphere at transition zone depths.