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  - 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  -