@article{KoberZeilingerHippeetal.2015, author = {Kober, Florian and Zeilinger, Gerold and Hippe, Kristina and Marc, Odin and Lendzioch, Theodora and Grischott, Reto and Christl, Marcus and Kubik, Peter W. and Zola, Ramiro}, title = {Tectonic and lithological controls on denudation rates in the central Bolivian Andes}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {657}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2015.06.037}, pages = {230 -- 244}, year = {2015}, abstract = {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.}, language = {en} } @article{HaghipourBurgKoberetal.2012, author = {Haghipour, Negar and Burg, Jean-Pierre and Kober, Florian and Zeilinger, Gerold and Ivy-Ochs, Susan and Kubik, Peter W. and Faridi, Mohammad}, title = {Rate of crustal shortening and non-Coulomb behaviour of an active accretionary wedge - the folded fluvial terraces in Makran (SE, Iran)}, series = {Earth \& planetary science letters}, volume = {355}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2012.09.001}, pages = {187 -- 198}, year = {2012}, abstract = {We surveyed fluvial terraces to decipher the Quaternary increment of crustal shortening and shortening rate in the on-shore Makran Accretionary Wedge. We focused on three major catchment basins and associated fold systems. Terrace profiles reconstructed from differential GPS measurements combined with DEM revealed two regional dominant wavelengths, about 5 km in the northern part of the study area and about 15 km to the south. These two wavelengths suggest the existence of two active decollement layers at two rooting depths. The average shortening rate due to folding is estimated at 0.8-1.2 mm/a over the last 130 ka. This accounts for 10-15\% of the shortening rate (similar to 8 mm/a) given by kinematic GPS measurements between Chabahar and Bazman and 3\% of the convergence between Arabia and Eurasia, across the Makran subduction zone. Despite active deformation and a relatively high shortening rate, the geophysical record shows nearly absent seismic activity in Makran. We propose that strain accumulated in folds over intermediate decollement levels within a thick, incompletely lithified sedimentary cover explains the essentially aseismic, recent tectonics in this region. The importance of folds points to imperfect Coulomb behaviour of the wedge. (C) 2012 Elsevier B.V. All rights reserved.}, language = {en} } @article{HippeKoberZeilingeretal.2012, author = {Hippe, Kristina and Kober, Florian and Zeilinger, Gerold and Ivy-Ochs, Susan and Maden, Colin and Wacker, Lukas and Kubik, Peter W. and Wieler, Rainer}, title = {Quantifying denudation rates and sediment storage on the eastern Altiplano, Bolivia, using cosmogenic Be-10, Al-26, and in situ C-14}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {179}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, number = {22}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2012.07.031}, pages = {58 -- 70}, year = {2012}, abstract = {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.}, language = {en} } @article{KoberZeilingerIvyOchsetal.2013, author = {Kober, Florian and Zeilinger, Gerald and Ivy-Ochs, Susan and Dolati, A. and Smit, J. and Kubik, Peter W.}, title = {Climatic and tectonic control on fluvial and alluvial fan sequence formation in the Central Makran Range, SE-Iran}, series = {Global and planetary change}, volume = {111}, journal = {Global and planetary change}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0921-8181}, doi = {10.1016/j.gloplacha.2013.09.003}, pages = {133 -- 149}, year = {2013}, abstract = {The geomorphic evolution of the Makran Range of SE-Iran and SW-Pakistan has been controlled by the prevailing SW-Asian monsoon and Mediterranean winter rainfall climate and the surface uplift processes resulting from the Arabia-Eurasia collision. The impact of climate on Quaternary fluvial and alluvial sequence formation and their regional correlation has been little investigated due to limited age control of these sequences. Using Be-10 cosmogenic nuclide exposure ages we established a Middle to Late Pleistocene terrace chronology. Our record tentatively indicates that terrace levels were abandoned towards the transition to or during warmer/pluvial periods (interglacials and/or interstadials) back to Marine Isotope Stage (MIS) 7, but abandoned ages show a large spread. It is hypothesized that pluvial phases correspond with times of enhanced SW-monsoons and a northward shift of the Intertropical Convergence Zone (ITCZ). Furthermore, orbital periodidties can be deduced on frequencies related to obliquity and precession cycles. Overall, caution has to be placed in sampling and interpreting alluvial deposits, which may have complex inheritance patterns and spatially and temporarily variable catchment erosion histories and terrace-channel dynamics. Beside the dominant climate control on terrace formation, elevated channel steepness indices around major thrusts and numerous knickpoints indicate an additionally tectonic influence on terrace formation. Local incision rates (mean similar to 0.6-0.8 min.a(-1)) are variable in space and time but are similar to uplift rates obtained from coastal terraces and thus suggest a regional surface uplift. (C) 2013 Elsevier B.V. All rights reserved.}, language = {en} } @article{KoberIvyOchsZeilingeretal.2009, author = {Kober, Florian and Ivy-Ochs, Susan and Zeilinger, Gerald and Schlunegger, Fritz and Kubik, Peter W. and Baur, Heinrich and Wieler, Rainer}, title = {Complex multiple cosmogenic nuclide concentration and histories in the arid Rio Lluta catchment, northern Chile}, issn = {0197-9337}, doi = {10.1002/Esp.1748}, year = {2009}, abstract = {Terrestrial cosmogenic nuclide (TCN) concentrations measured in river sediments can be used to estimate catchment-wide denudation rates. By investigating multiple TCN the steadiness of sediment generation, transport and depositional processes can be tested. Measurements of Be-10, Ne-21 and Al-26 from the hyper- to semi-arid Rio Lluta catchment, northern Chile, yield average single denudation rates ranging from 12 to 75 m Myr(-1) throughout the catchment. Paired nuclide analysis reveals complex exposure histories for most of the samples and thus the single nuclide estimates do not exclusively represent catchment-wide denudation rates. The lower range of single nuclide denudation rates (12-17 m Myr(-1)), established with the noble gas Ne-21, is in accordance with palaeodenudation rates derived from Ne-21/Be-10 and Al-26/Be-10 ratio analysis. Since this denudation rate range is measured throughout the system, it is suggested that a headwater signal is transported downstream but modulated by a complex admixture of sediment that has been stored and buried at proximal hillslope or terrace deposits, which are released during high discharge events. That is best evidenced by the stable nuclide Ne-21, which preserves the nuclide concentration even during storage intervals. The catchment-wide single Ne-21 denudation rates and the palaeodenuation rates contrast with previous TCN-derived erosion rates from bedrock exposures at hillslope interfluves by being at least one order of magnitude higher, especially in the lower river course. These results support earlier studies that identified a coupling of erosional processes in the Western Cordillera contrasting with decoupled processes in the Western Escarpment and in the Coastal Cordillera.}, language = {en} } @article{HippeKoberZeilingeretal.2009, author = {Hippe, Kristina and Kober, Florian and Zeilinger, Gerald and Ivy-Ochs, Susan and Kubik, Peter W. and Wieler, Rainer}, title = {Short and long-term denudation rates at the Altiplano margin, La Paz region, Bolivia}, issn = {0016-7037}, doi = {10.1016/j.gca.2009.05.006}, year = {2009}, language = {en} }