Long-term glacial erosion of active mountain belts: Example of the Chugach- St. Elias Range, Alaska

An emerging paradigm that equates glaciers to "buzz saws" of exceptional erosional efficiency has been strengthened by short-term (<10² yr) sediment yields from southern Alaska. New low-temperature cooling ages from this area, the glaciated Chugach-St. Elias Mountains, constrain long-term (10⁶ yr) exhumation rates. Vertically averaged exhumation rates reach ∼3 mm/yr, but are an order of magnitude lower than rates based on short-term sediment yields. Whereas these exhumation rates are not exceptional for orogenic belts, denudation patterns are strongly correlated with the distribution of glaciers, and erosion appears to keep pace with convergence and uplift. These findings imply a coupling between glacially dominated erosion and tectonics.