CONTINENTAL DELAMINATION AND THE COLORADO PLATEAU

Continental lithosphere is in unstable mechanical equilibrium because its mantle layer is denser than the asthenosphere. If any process such as cracking, slumping, or plume erosion initially provided an elongated conduit connecting the underlying asthenosphere with the base of the continental crust, the dense lithospheric boundary layer could peel away from the crust and sink. The geologic and geophysical data from the Colorado Plateau are shown to be consistent with the hypothesis that it was uplifted by a delamination event 30 Myr ago and perhaps a second event about 5 Myr ago. -from Author