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Transient sediment supply in a high‐altitude Alpine environment evidenced through a 10 Be budget of the Etages catchment (French Western Alps)
Author(s) -
Delunel Romain,
Beek Peter A.,
Bourlès Didier L.,
Carcaillet Julien,
Schlunegger Fritz
Publication year - 2013
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.3494
Subject(s) - geology , drainage basin , denudation , glacial period , massif , hydrology (agriculture) , sedimentary budget , geomorphology , landform , sediment , streams , earth science , physical geography , geochemistry , sediment transport , paleontology , geography , tectonics , cartography , geotechnical engineering , computer network , computer science
Although beryllium‐10 ( 10 Be) concentrations in stream sediments provide useful synoptic views of catchment‐wide erosion rates, little is known on the relative contributions of different sediment supply mechanisms to the acquisition of their initial signature in the headwaters. Here we address this issue by conducting a 10 Be‐budget of detrital materials that characterize the morphogenetic domains representative of high‐altitude environments of the European Alps. We focus on the Etages catchment, located in the Ecrins‐Pelvoux massif (southeast France), and illustrate how in situ 10 Be concentrations can be used for tracing the origin of the sand fraction from the bedload in the trunk stream. The landscape of the Etages catchment is characterized by a geomorphic transient state, high topographic gradients, and a large variety of modern geomorphic domains ranging from glacial environments to scarcely vegetated alluvial plains. Beryllium‐10 concentrations measured in the Etages catchment vary from ~1 × 10 4 to 4.5 × 10 5 atoms per gram quartz, while displaying consistent 10 Be signatures within each representative morphogenetic unit. We show that the basic requirements for inferring catchment‐wide denudation from 10 Be concentration measurements are not satisfied in this small, dynamic catchment. However, the distinct 10 Be signature observed for the geomorphic domains can be used as a tracer. We suggest that a terrestrial cosmogenic nuclide (TCN) budget approach provides a valuable tool for the tracing of material origin in basins where the ‘let nature do the averaging’ principles may be violated. Copyright © 2013 John Wiley & Sons, Ltd.