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Updated: May 12, 2026

Atom Probe Tomography Analysis of Exsolved Mineral Phases
Published on: October 25, 2019
Comment on "Apatite 4He/3He and (U-Th)/He evidence for an ancient Grand Canyon"
Karl E Karlstrom1, John Lee, Shari Kelley
1University of New Mexico, Albuquerque, NM 87131, USA. kek1@unm.edu
Abstract:
Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) propose that the Grand Canyon is 70 million years old. Starkly contrasting models for the age of the Grand Canyon-70 versus 6 million years-can be reconciled by a shallow paleocanyon that was carved in the eastern Grand Canyon 25 to 15 million years ago (Ma), negating the proposed 70 Ma and 55 Ma paleocanyons. Cooling models and geologic data are most consistent with a 5 to 6 Ma age for western Grand Canyon and Marble Canyon.
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