96-Mile Shear Zone view down the Colorado River at the Grand Canyon Supergroup
river mile 98.3 sigmoidal garnet
  • Collaborative research during the first two years of residence at UMass (with Kevin H. Mahan, Michael L. Williams, and Karl E. Karlstrom) in Paleoproterozoic basement of Grand Canyon, Arizona, documented a spectacular near-isobaric level of 0.7 GPa, highly-segmented continental crust coherently exhumed to 0.3-0.4 GPa and stabilized at ca. 1.68 Ga during southward-growth of the Laurentian supercontinent.