Rapid exhumation of ice-covered rocks of the Chugach-St. Elias orogen, Southeast Alaska

Ongoing oblique collision and flat-slab subduction of the Yakutat terrane has produced Earth's highest coastal mountain range, the Chugach-St. Elias orogen in Southeast Alaska. Massive glaciers and ice fields cause extensive erosion, but also limit access to rocks that allow detailed study of the orogen. Fission track and U/Pb dating of detrital zircon from glacial rivers reveal the exhumation history of the Chugach-St. Elias orogen. Orogenic development started ca. 30 Ma and pulses of exhumation occurred 20 +/- 2 Ma and 11 +/- 2 Ma. Differential exhumation occurred across major fault zones and the locus of exhumation shifted southward. The ca. 5 Ma cooling ages of detrital zircon in the Pliocene-Pleistocene Yalkataga Formation reveal that source rock exhumation was likely associated with faulting along the ice-covered Fairweather fault-Contact fault system.