Baird, Thomas;
(2021)
Dune Sands: Quantifying Celerity, Reactivation Morphometrics, and Provenance.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Criticisms of aeolian geomorphological studies often cite temporal and/or spatial scalability issues along with poor integration of geomatic techniques. This thesis seeks to address these issues while investigating the celerity, reactivation, and geological provenance of sand dunes. Firstly, an automated workflow was devised using COSI-Corr and Landsat L1TP products to produce a map of sand dune movement in the Bodélé Depression, Chad. The automated workflow was found to produce highly variable outputs when applied to the Grand Erg Oriental, Algeria caused by the use of mobile features, such as dune crests, as ‘stable’ ground control points in Landsat orthorectification. Secondly, a combination of structure-from-motion (SfM) optical drone mapping, ground-penetrating radar (GPR), and soil pits were used to investigate dunefield reactivation the Gonghe Basin, China. A mass balance of the scour hollows and lobes varied between sites. Approximately 50% of eroded material was not present in the depositional lobe. Thirdly, the relationship between satellite imagery source and digital image correlation (DIC) method was assessed when measuring dune migration. ASP, MicMac, and COSI-Corr correlation engines were applied to Landsat 5, Landsat 8, PlanetScope, and SPOT-5 imagery of the Gonghe Basin. Overall, no single correlator was found to work well for all satellite imagery, but some were more successful than others. The most appropriate pairings to use when measuring dune migration is dependent on computing power, the timespan being assessed, and the resolution of the data. Penultimately, the provenance of Saharan dune sands was determined by bulk-petrography, heavy-mineral, and detrital zircon U-Pb geochronology analyses of 44 pre-collected samples. Overall, the samples show homogeneity in their composition across the Sahara with only minor differences being identified. Finally, an investigation into the sampling location of detrital zircon found a statistically significant difference between U-Pb age spectra produced from the centre and the edges of the grains, the overall difference in medians and the impact on the provenance of the Sahara were both negligible.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Dune Sands: Quantifying Celerity, Reactivation Morphometrics, and Provenance |
| Event: | UCL |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10139651 |
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