Delamination-style convective lithospheric downwelling under the Colorado Plateau. This is an ongoing very loosely organized project involving colleagues at a number of institutions: Gene Humphreys, Brandon Schmandt, Meghan Miller, Cin-Ty Lee, Monica Erdman, Mary Reid, Janne Blitchert-Toft,  Karl Karlstrom, and numerous others.

Funding was provided by NSF EarthScope Grant EAR 0844760 to AL and Meghan Miller.

We believe that we have identified an ongoing lithospheric drip/delamination under the west-central Colorado Plateau, the so-called “Escalante Anomaly” observed in western US tomography (Schmandt and Humphreys, 2010, G3;  Levander et al, 2011, Nature). Subsequent work has 1)  determined that the basaltic volcanics around the periphery of the CP are sourced from relatively shallow depths in the asthenosphere (Reid et al, 2012, Geology) suggesting that the lithosphere has been removed, and 2) developed a possible lower crustal instability trigger for the drip/delamination in the form of a dense pyroxenite restite  (Erdman et al, 2016, EPSL).

Seismic images beneath the Colorado Plateau (Levander et al. 2011, Nature)

Seismic images beneath the Colorado Plateau (Levander et al. 2011, Nature)

Bibliography

  1. Levander, A., Schmandt, B., Miller, M.S., Liu, K., Karlstrom, K.E., Crow, R.S., Lee, C.T. and Humphreys, E.D., 2011. Continuing Colorado plateau uplift by delamination-style convective lithospheric downwelling. Nature, 472(7344), pp.461-465.
  2. Liu, K., Levander, A., Niu, F. and Miller, M.S., 2011. Imaging crustal and upper mantle structure beneath the Colorado Plateau using finite frequency Rayleigh wave tomography. Geochemistry, Geophysics, Geosystems, 12(7)
  3. Bailey, I.W., Miller, M.S., Liu, K. and Levander, A., 2012. VS and density structure beneath the Colorado Plateau constrained by gravity anomalies and joint inversions of receiver function and phase velocity data. Journal of Geophysical Research: Solid Earth, 117(B2).
  4. Reid, M.R., Bouchet, R.A., Blichert-Toft, J., Levander, A., Liu, K., Miller, M.S. and Ramos, F.C., 2012. Melting under the Colorado Plateau, USA. Geology, 40(5), pp.387-390.
  5. Levander, A. and Miller, M.S., 2012. Evolutionary aspects of lithosphere discontinuity structure in the western US. Geochemistry, Geophysics, Geosystems, 13(7).
  6. Erdman, M.E., Lee, C.T.A., Levander, A. and Jiang, H., 2016. Role of arc magmatism and lower crustal foundering in controlling elevation history of the Nevadaplano and Colorado Plateau: A case study of pyroxenitic lower crust from central Arizona, USA. Earth and Planetary Science Letters, 439, pp.48-57.