Cosmogenic 10Be denudation rates and geomorphometric analysis in the Ambato range (28°-29°S), Sierras Pampeanas, Argentina

Abstract

Quantifying denudation rates along orogenic systems is crucial to understand how tectonics and climate interact with each other to create topography. Long-term mean denudation rates estimated from geologic data in the Ambato range (Sierras Pampeanas) is 0.34 mm/yr. When compared with short-term denudation rates from other studies northward and southward along the Argentine South Central Andes foreland, our results are similar to those found in regions with higher mean annual precipitation. Here we utilize concentrations of 10Be cosmogenic radionuclide (CRN) in river sediments from catchments along the eastern slope of the Ambato range to understand the relationship among short-term (102–104 yrs) catchment-wide denudation rates and long-term denudation rates estimated from geologic data. CRN denudation rates range between ∼0.038 and ∼0.12 mm/yr. The relationship between geomorphometric parameters (local relief, slope, hypsometric integral, and catchment mean channel steepness index, Ksn) and CRN denudation rates shows linear behavior. The best correlation concerned Ksn indicating a strong connection in the Ambato range between tectonics and denudation. When analyzed together with denudation rates from other studies northward and southward along the South Central Andes foreland, our results are similar to those found in more arid regions and suggest that bedrock strength variations should be contemplated in a regional analysis as well as climate.