TY - JOUR A1 - Savi, Sara A1 - Schildgen, Taylor F. A1 - Tofelde, Stefanie A1 - Wittmann, Hella A1 - Scherler, Dirk A1 - Mey, Jürgen A1 - Alonso, Ricardo N. A1 - Strecker, Manfred T1 - Climatic controls on debris-flow activity and sediment aggradation: The Del Medio fan, NW Argentina JF - Journal of geophysical research : Earth surface N2 - In the Central Andes, several studies on alluvial terraces and valley fills have linked sediment aggradation to periods of enhanced sediment supply. However, debate continues over whether tectonic or climatic factors are most important in triggering the enhanced supply. The Del Medio catchment in the Humahuaca Basin (Eastern Cordillera, NW Argentina) is located within a transition zone between subhumid and arid climates and hosts the only active debris-flow fan within this intermontane valley. By combining Be-10 analyses of boulder and sediment samples within the Del Medio catchment, with regional morphometric measurements of nearby catchments, we identify the surface processes responsible for aggradation in the Del Medio fan and their likely triggers. We find that the fan surface has been shaped by debris flows and channel avulsions during the last 400 years. Among potential tectonic, climatic, and autogenic factors that might influence deposition, our analyses point to a combination of several favorable factors that drive aggradation. These are in particular the impact of occasional abundant rainfall on steep slopes in rock types prone to failure, located in a region characterized by relatively low rainfall amounts and limited transport capacity. These characteristics are primarily associated with the climatic transition zone between the humid foreland and the arid orogen interior, which creates an imbalance between sediment supply and sediment transfer. The conditions and processes that drive aggradation in the Del Medio catchment today may provide a modern analog for the conditions and processes that drove aggradation in other nearby tributaries in the past. Y1 - 2016 U6 - https://doi.org/10.1002/2016JF003912 SN - 2169-9003 SN - 2169-9011 VL - 121 SP - 2424 EP - 2445 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Schildgen, Taylor F. A1 - Robinson, Ruth A. J. A1 - Savi, Sara A1 - Phillips, William M. A1 - Spencer, Joel Q. G. A1 - Bookhagen, Bodo A1 - Scherler, Dirk A1 - Tofelde, Stefanie A1 - Alonso, Ricardo N. A1 - Kubik, Peter W. A1 - Binnie, Steven A. A1 - Strecker, Manfred T1 - Landscape response to late Pleistocene climate change in NW Argentina: Sediment flux modulated by basin geometry and connectivity JF - Journal of geophysical research : Earth surface N2 - Fluvial fill terraces preserve sedimentary archives of landscape responses to climate change, typically over millennial timescales. In the Humahuaca Basin of NW Argentina (Eastern Cordillera, southern Central Andes), our 29 new optically stimulated luminescence ages of late Pleistocene fill terrace sediments demonstrate that the timing of past river aggradation occurred over different intervals on the western and eastern sides of the valley, despite their similar bedrock lithology, mean slopes, and precipitation. In the west, aggradation coincided with periods of increasing precipitation, while in the east, aggradation coincided with decreasing precipitation or more variable conditions. Erosion rates and grain size dependencies in our cosmogenic Be-10 analyses of modern and fill terrace sediments reveal an increased importance of landsliding compared to today on the west side during aggradation, but of similar importance during aggradation on the east side. Differences in the timing of aggradation and the Be-10 data likely result from differences in valley geometry, which causes sediment to be temporarily stored in perched basins on the east side. It appears as if periods of increasing precipitation triggered landslides throughout the region, which induced aggradation in the west, but blockage of the narrow bedrock gorges downstream from the perched basins in the east. As such, basin geometry and fluvial connectivity appear to strongly influence the timing of sediment movement through the system. For larger basins that integrate subbasins with differing geometries or degrees of connectivity (like Humahuaca), sedimentary responses to climate forcing are likely attenuated. KW - berylium-10 KW - optically stimulated luminescence KW - Humahuaca Basin KW - South American Monsoon System KW - fluvial terraces KW - landscape connectivity Y1 - 2016 U6 - https://doi.org/10.1002/2015JF003607 SN - 2169-9003 SN - 2169-9011 VL - 121 SP - 392 EP - 414 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Schwanghart, Wolfgang A1 - Scherler, Dirk T1 - Bumps in river profiles: uncertainty assessment and smoothing using quantile regression techniques JF - Earth surface dynamics N2 - The analysis of longitudinal river profiles is an important tool for studying landscape evolution. However, characterizing river profiles based on digital elevation models (DEMs) suffers from errors and artifacts that particularly prevail along valley bottoms. The aim of this study is to characterize uncertainties that arise from the analysis of river profiles derived from different, near-globally available DEMs. We devised new algorithms quantile carving and the CRS algorithm - that rely on quantile regression to enable hydrological correction and the uncertainty quantification of river profiles. We find that globally available DEMs commonly overestimate river elevations in steep topography. The distributions of elevation errors become increasingly wider and right skewed if adjacent hillslope gradients are steep. Our analysis indicates that the AW3D DEM has the highest precision and lowest bias for the analysis of river profiles in mountainous topography. The new 12m resolution TanDEM-X DEM has a very low precision, most likely due to the combined effect of steep valley walls and the presence of water surfaces in valley bottoms. Compared to the conventional approaches of carving and filling, we find that our new approach is able to reduce the elevation bias and errors in longitudinal river profiles. Y1 - 2017 U6 - https://doi.org/10.5194/esurf-5-821-2017 SN - 2196-6311 SN - 2196-632X VL - 5 SP - 821 EP - 839 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Eugster, Patricia A1 - Thiede, Rasmus Christoph A1 - Scherler, Dirk A1 - Stübner, Konstanze A1 - Sobel, Edward A1 - Strecker, Manfred T1 - Segmentation of the Main Himalayan Thrust Revealed by Low-Temperature Thermochronometry in the Western Indian Himalaya JF - Tectonics N2 - Despite remarkable tectonostratigraphic similarities along the Himalayan arc, pronounced topographic and exhumational variability exists in different morphotectonic segments. The processes responsible for this segmentation are debated. Of particular interest is a 30- to 40-km-wide orogen-parallel belt of rapid exhumation that extends from central Nepal to the western Himalaya and its possible linkage to a midcrustal ramp in the basal decollement, and the related growth of Lesser Himalayan duplex structures. Here we present 26 new apatite fission track cooling ages from the Beas-Lahul region, at the transition from the Central to the Western Himalaya (77 degrees-78 degrees E) to investigate segmentation in the Himalayan arc from a thermochronologic perspective. Together with previously published data from this part of the orogen, we document significant lateral changes in exhumation between the Dhauladar Range to the west, the Beas-Lahul region, and the Sutlej area to the east of the study area. In contrast to the Himalayan front farther east, exhumation in the far western sectors is focused at the frontal parts of the mountain range and associated with the hanging wall of the Main Boundary Thrust fault ramp. Our results allow us to spatially correlate the termination of the rapid exhumation belt with a midcrustal ramp to the west. We suggest that a plunging anticline at the northwestern edge of the Larji-Kullu-Rampur window represents the termination of the Central Himalayan segment, which is related to the evolution of the Lesser Himalayan duplex. Key Points KW - exhumation KW - Himalaya KW - duplex KW - fission track thermochronology KW - MHT Y1 - 2018 U6 - https://doi.org/10.1029/2017TC004752 SN - 0278-7407 SN - 1944-9194 VL - 37 IS - 8 SP - 2710 EP - 2726 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Scherler, Dirk A1 - Schwanghart, Wolfgang T1 - Drainage divide networks BT - Part 2: Response to perturbations JF - Earth surface dynamics N2 - Drainage divides are organized into tree-like networks that may record information about drainage divide mobility. However, views diverge about how to best assess divide mobility. Here, we apply a new approach of automatically extracting and ordering drainage divide networks from digital elevation models to results from landscape evolution model experiments. We compared landscapes perturbed by strike-slip faulting and spatiotemporal variations in erodibility to a reference model to assess which topographic metrics (hillslope relief, flow distance, and chi) are diagnostic of divide mobility. Results show that divide segments that are a minimum distance of similar to 5 km from river confluences strive to attain constant values of hillslope relief and flow distance to the nearest stream. Disruptions of such patterns can be related to mobile divides that are lower than stable divides, closer to streams, and often asymmetric in shape. In general, we observe that drainage divides high up in the network, i.e., at great distances from river confluences, are more susceptible to disruptions than divides closer to these confluences and are thus more likely to record disturbance for a longer time period. We found that across-divide differences in hillslope relief proved more useful for assessing divide migration than other tested metrics. However, even stable drainage divide networks exhibit across-divide differences in any of the studied topographic metrics. Finally, we propose a new metric to quantify the connectivity of divide junctions. KW - dynamics KW - landscape evolution KW - low-relief KW - patterns KW - river KW - scale KW - tectonics Y1 - 2020 U6 - https://doi.org/10.5194/esurf-8-261-2020 SN - 2196-6311 SN - 2196-632X VL - 8 IS - 2 SP - 261 EP - 274 PB - Copernicus CY - Göttingen ER -