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Differences in 10Be concentrations between river sand, gravel and pebbles along the western side of the central Andes

Fecha de publicación:
2015
Unidad:
NO UDA
Datos de publicación:
Quaternary Geochinology Volume 27, April 2015, Pages 33-51
Enlace:
https://doi.org/10.1016/j.quageo.2014.12.002
Palabras Claves:
Base de datos:
Science Direct
Descripción:
Cosmogenic nuclides in river sediment have been used to quantify catchment-mean erosion rates. Nevertheless, variable differences in 10Be concentrations according to grain size have been reported. We analyzed these differences in eleven catchments on the western side of the Andes, covering contrasting climates and slopes. The data include eight sand (0.5–1 mm) and gravel (1–3 cm) pairs and twelve sand (0.5–1 mm) and pebble (5–10 cm) pairs. The difference observed in three pairs can be explained by a difference in the provenance of the sand and coarser sediment. The other sand–pebble pairs show a lower 10Be concentration in the pebbles, except for one pair that shows similar concentrations. Two sand–gravel pairs show a lower 10Be concentration in the gravel and the other five pairs show a higher 10Be concentration in the gravel. Differences in climate do not reveal a particular influence on the 10Be concentration between pairs. The analysis supports a model where pebbles and gravel are mainly derived from catchment areas that are eroding at a faster rate. The five gravel samples with high 10Be concentrations probably contain gravel that were derived from the abrasion of cobbles exhumed at high elevations. In order to validate this model, further work should test if pebbles are preferentially exhumed from high erosion rate areas, and if the difference between pebbles with high 10Be concentrations and sand decreases when the erosion rate tends to be homogeneous within a catchment.

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Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

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