TY - JOUR A1 - Hippe, Kristina A1 - Kober, Florian A1 - Zeilinger, Gerald A1 - Ivy-Ochs, Susan A1 - Kubik, Peter W. A1 - Wieler, Rainer T1 - Short and long-term denudation rates at the Altiplano margin, La Paz region, Bolivia Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00167037 U6 - https://doi.org/10.1016/j.gca.2009.05.006 SN - 0016-7037 ER - 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 - TY - JOUR A1 - Hippe, Kristina A1 - Kober, Florian A1 - Zeilinger, Gerold A1 - Ivy-Ochs, Susan A1 - Maden, Colin A1 - Wacker, Lukas A1 - Kubik, Peter W. A1 - Wieler, Rainer T1 - Quantifying denudation rates and sediment storage on the eastern Altiplano, Bolivia, using cosmogenic Be-10, Al-26, and in situ C-14 JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Denudation processes and sediment transfer are investigated in a high-elevation, low-relief environment (eastern Altiplano, Bolivia) using Be-10, Al-26, and in situ C-14 analysis in fluvial sediments. Concentrations of the long-lived nuclides Be-10 and Al-26 yield consistently low catchment-wide denudation rates of similar to 3-29 mm ky(-1) (integrating over 21-194 ky), which reflect the low geomorphic gradients and the discontinuity of fluvial transport along the eastern Altiplano margin. No significant correlation is recorded between denudation rates of individual catchments and morphological basin parameters (slope, area, elevation). This is attributed to the overall little variability in morphology. The agreement between the denudation rates and published modern sediment discharge data suggests steady landscape evolution of the eastern Altiplano from the latest Pleistocene until today. While Be-10 and Al-26 provide long-term estimates on sediment production, in situ cosmogenic C-14 is used to trace short-term sediment storage. In situ C-14 concentrations are comparatively low indicating that C-14 decayed during alluvial storage over at least the past similar to 11-20 ky. We assume storage at shallow depth (2 m) and consider the influence of soil-mantled hillslopes on the in situ C-14 concentration. Our results illustrate the importance of sediment storage even over short distances and demonstrate the potential of in situ C-14 to study sediment routing and transfer times within drainage systems. However, this study also demonstrates that the long-lived Be-10 and Al-26 nuclides can provide adequate estimates on long-term denudation rates even if sediment transport is not fast but interrupted by several thousands of years of storage. KW - Cosmogenic nuclides KW - Denudation KW - Sediment storage KW - In situ C-14 KW - Altiplano Y1 - 2012 U6 - https://doi.org/10.1016/j.geomorph.2012.07.031 SN - 0169-555X VL - 179 IS - 22 SP - 58 EP - 70 PB - Elsevier CY - Amsterdam ER -