TY  - JOUR
A1  - Kober, Florian
A1  - Zeilinger, Gerold
A1  - Hippe, Kristina
A1  - Marc, Odin
A1  - Lendzioch, Theodora
A1  - Grischott, Reto
A1  - Christl, Marcus
A1  - Kubik, Peter W.
A1  - Zola, Ramiro
T1  - Tectonic and lithological controls on denudation rates in the central Bolivian Andes
JF  - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth
N2  - The topographic signature of a mountain belt depends on the interplay of tectonic, climatic and erosional processes, whose relative importance changes over times, while quantifying these processes and their rates at specific times remains a challenge. The eastern Andes of central Bolivia offer a natural laboratory in which such interplay has been debated. Here, we investigate the Rio Grande catchment which crosses orthogonally the eastern Andes orogen from the Eastern Cordillera into the Subandean Zone, exhibiting a catchment relief of up to 5000 m. Despite an enhanced tectonic activity in the Subandes, local relief, mean and modal slopes and channel steepness indices are largely similar compared to the Eastern Cordillera and the intervening Interandean Zone. Nevertheless, a dataset of 57 new cosmogenic 10Be and 26AI catchment wide denudation rates from the Rio Grande catchment reveals up to one order of magnitude higher denudation rates in the Subandean Zone (mean 0.8 mm/yr) compared to the upstream physiographic regions. We infer that tectonic activity in the thrusting dominated Subandean belt causes higher denudation rates based on cumulative rock uplift investigations and due to the absence of a pronounced climate gradient. Furthermore, the lower rock strength of the Subandean sedimentary units correlates with mean slopes similar to the ones of the Eastern Cordillera and Interandean Zone, highlighting the fact, that lithology and rock strength can control high denudation rates at low slopes.
 Low denudation rates measured at the outlet of the Rio Grande catchment (Abapo) are interpreted to be a result of a biased cosmogenic nuclide mixing that is dominated by headwater signals from the Eastern Cordillera and the Interandean zone and limited catchment sediment connectivity in the lower river reaches. Therefore, comparisons of short- (i.e., sediment yield) and millennial denudation rates require caution when postulating tectonic and/or climatic forcing without detailed studies. (C) 2015 The Authors. Published by Elsevier B.V.
KW  - Rio Grande
KW  - seismicity
KW  - uplift
KW  - rock strength
KW  - cosmogenic nuclides
KW  - denudation
Y1  - 2015
U6  - https://doi.org/10.1016/j.tecto.2015.06.037
SN  - 0040-1951
SN  - 1879-3266
VL  - 657
SP  - 230
EP  - 244
PB  - Elsevier
CY  - Amsterdam
ER  -