Spatial pattern of denudation in a lithologically controlled sub-tropical flat landscape: insights from the Kimberley region, NW Australia
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Date
2016-01-01
Authors
Journal Title
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Publisher
European Geophysical Union
Abstract
The Kimberley region, northwest Australia, is well known for its expansive and diverse collection of prehistorical
aboriginal rock art that potentially dates back to 40,000 years ago. The region is characterized by a tropical, semiarid
climate with a monsoonal rainfall distribution and a flat landscape interrupted by massive sandstone mesas and
deeply incised bedrock river gorges. In order to constrain the chronology of the rock art it is necessary to quantify
the spatial and temporal dimensions of landscape evolution.
We report cosmogenic 10Be and 26Al concentrations in modern fluvial sediment collected from 27 catchments with
areas spanning several orders of magnitude (13.6 – 13,900 km2
). All catchments are characterized by a very low
topographic gradient (average basin slopes < 3◦
) and subdued local relief of at most 200m. Assuming negligible
sediment storage times and rapid sediment transport driven by the annual monsoonal washout, we calculate 10Be
based catchment-wide denudation rates ranging between 1.87 ± 0.23 and 9.48 ± 1.05 m.Myr−1
. These low rates
are among the slowest recorded in the world, despite the strong climatic seasonality of the region. Our measured
denudation rates exhibit a strong correlation with topographic gradient, which in the overall flat landscapes of the
Kimberley, is controlled by the prevailing sandstone bedrock lithology and the presence of numerous escarpments
adjacent to the river channels. We present a modelling approach that makes use of the 26Al/10Be ratio in the fluvial
sediments as a source tracer (ie escarpment cliffs, river channels, plateau bedrocks), and use this to explore the
control and retreat rate of the eroding escarpment cliffs in order to provide information on the spatial distribution
of denudation in the landscape. © Author(s) 2016. CC Attribution 3.0 License.
Description
Keywords
Spatial distribution, Lithology, Australia, Rock beds, Landscaping, Rivers
Citation
Cazes, G. , Fink, D., Codilean, A. T., & Fülöp, R.-H. (2016). Spatial pattern of denudation in a lithologically controlled sub-tropical flat landscape: insights from the Kimberley region, NW Australia. Paper presented at the European Geosciences Union General Assembly 2016, Vienna, Austria, 17-22 April 2016.