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Tectonic and Climatic Controls on the Spatial Distribution of Denudation Rates in Northern Chile (18°S to 23°S) Determined From Cosmogenic Nuclides
Author(s) -
Starke J.,
Ehlers T. A.,
Schaller M.
Publication year - 2017
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1002/2016jf004153
Subject(s) - denudation , cosmogenic nuclide , geology , drainage basin , tectonics , geomorphology , physical geography , paleontology , geography , physics , cosmic ray , cartography , astrophysics
In the arid region of northern Chile the environmental conditions are favorable for measuring tectonic and climatic influences on catchment denudation rates in the absence of vegetation. Previous studies of denudation rates from cosmogenic 10 Be and 26 Al concentrations are limited to single drainages. In this study, we examine catchment‐ to orogen‐scale spatial variation in denudation rates between 18 and 23°S in the Coastal and Western Cordilleras of northern Chile. 10 Be and 26 Al data were obtained from 33 catchments to examine the relative roles of tectonics and climate on catchment‐averaged denudation rates. At broader scales, we examine whether denudation rates and orogen topography reflect the 3‐D plate geometry of the region. Cosmogenic nuclide‐derived denudation rates range from 0.4 ± 0.5 to 20.6 ± 1.5 m/Myr in the Coastal Cordillera and from 1.4 ± 0.7 to 168.0 ± 19.8 m/Myr in the Western Cordillera. The controls on the denudation rates are evaluated using a statistical factor analysis of 10 selected catchment parameters. Denudation rates indicate a strong linear relationship with channel steepness indices but insignificant correlations and covariation with mean annual precipitation rates, drainage area, stream order, mean elevation, mean local relief, mean basin slope, and grain size of the sampled sediments. Moreover, denudation rates are better correlated with tectonic controls at catchment scale than orogen‐scale plate tectonics in the Western and Coastal Cordillera.