wAbstract
@We evaluated the hypothesis that the spatial variation in erosion
in catchment is reflected in the distribution of the cosmogenic
nuclide concentrations in sediments leaving the catchment. Using
published data and four new 10Be measurements in fluvial
sediment collected from the outlets of small river catchments,
we constrained the spatial variability of erosion ratios in the
Gaub River catchment in Namibia. We combined these catchment-averaged
erosion rates, and the mean slope values with which they are associated,
in a digital elevation model (DEM)-based analysis to predict distributions
of cosmogenic 21Ne concentrations in the sediment leaving
the Gaub catchment. We compared these synthetic distributions
with the distribution of concentrations of cosmogenic 21Ne
(21NeC) in 32 quartz fluvial pebbles
(16-21 mm) collected from the catchment outlet. The 21NeC concentrations span nearly two orders of magnitude
(2.6-160~106 atoms/g) and are highly skewed toward
low values. The DEM-based analysis confirms this skew - the measured
21NeC distribution plots within
the envelope of distributions predicted for the catchment. This
match between measured and synthetic 21Ne distributions
implies that the measured distribution is a signature of the spatial
variation in erosion rates.
Keywords: 21Ne; 10Be; cosmogenic nuclides;
denudation rates; slope dependence; landscape evolutionx
Introduction
Field setting
Cosmogenic 10Be and 21Ne data
DEM analysis
Discussion and conclusions
Acknowledgments
References cited