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Title: Single grain detrital cosmogenic ²¹Ne analysis : a new tool to study long-term landscape evolution
Author: Codilean, Alexandru Tiberiu
ISNI:       0000 0004 2674 6572
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 2008
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Cosmogenic nuclide concentrations in alluvial sediment are now routinely used to estimate time and space-averaged catchment-wide denudation rates, but have the potential to offer considerably more. This is because each grain leaving a catchment has a potentially unique history of erosion, transport and storage, and so the frequency distribution of cosmogenic nuclide concentrations in large numbers of grains can provide an integrated signature of the catchment's geomorphic history. This thesis evaluates the extent to which aspects of source area geomorphology and geomorphological processes can be inferred from frequency distributions of single grain detrital cosmogenic nuclide concentrations through the use of a combination of cosmogenic Be-10 and Ne-21 analyses and numerical modelling. The Gaub River study catchment is a tributary of the ~15,500 square km Kuiseb, one of the major ephemeral river systems draining western Namibia. The geomorphology of the upper Gaub is that of a high elevation passive margin and is characterised by an extensive low relief upland region and a highly dissected, high-relief zone marking the Great Escarpment. Denudation rates in the steeper escarpment sub-catchments of the upper Gaub, based on analysis of Be-10 concentrations in 6 amalgamated sediment samples, range from 12.5±0.8 to 14.1±0.9 m/Myr. These rates are twice those obtained for 5 upland plateau sub-catchments: 3.4±0.2 to 8.0±0.5 m/Myr. The Be-10 analyses show that there is a very strong linear relationship between measured denudation rate and mean slope of a sediment sample's source catchment. The analysis of Be-10 in a sample from the outlet of the Gaub and in the 11 sub-catchment samples confirms that, despite the strong geomorphic asymmetry that characterises this catchment, sediment leaving the upper Gaub is well mixed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available