Geometry of sedimentary deposits and evolution of the landforms in the Chobe Enclave, Northern Botswana

Détails

Ressource 1Télécharger: GEOMOR_Mokatse 2022.pdf (7750.55 [Ko])
Etat: Public
Version: Final published version
Licence: CC BY 4.0
ID Serval
serval:BIB_6EE2017DCC98
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Geometry of sedimentary deposits and evolution of the landforms in the Chobe Enclave, Northern Botswana
Périodique
Geomorphology
Auteur⸱e⸱s
Mokatse Thuto, Vainer Shlomy, Irving James, Schmidt Christoph, Kgosidintsi Boniface, Shemang Elisha, Verrecchia Eric P.
ISSN
0169-555X
Statut éditorial
Publié
Date de publication
10/2022
Peer-reviewed
Oui
Volume
415
Pages
108406
Langue
anglais
Résumé
The imprint of neotectonics is frequently obscured in low-relief environments by the sedimentary cover. This is the case in the Chobe Enclave, part of a pristine region of the Middle Kalahari Basin in northern Botswana, where numerous fossil landforms, such as sand dunes, pans, sand ridges, and carbonate islands, can be observed but whose detailed origins are unclear. In this study, a combination of near-surface geophysical surveys, sedimentological analysis, and optically-stimulated luminescence (OSL) dating were used to study the relationship between landscape development and neotectonic activity in one region of the Chobe Enclave. Specifically, electrical resistivity tomography (ERT) and ground penetrating radar (GPR) surveys were used to define the lateral and vertical distribution of sedimentary deposits associated with a prominent sand ridge and its margins. Sedimentological analysis and OSL dating of soil samples from pits taken along the survey lines were then used to calibrate the geophysical results and establish a chronostratigraphical framework. Our results lead to the following hypotheses regarding the evolution of this part of the Chobe landscape: (i) during the Late Pleistocene (>~25 ka), fluvial channels were buried due to epeirogenic movements, resulting in paleo-channels; (ii) between ~25 ka and ~6 ka, a paleo-lake shoreline formed, which resulted in the linear eastern margin observed on the considered sand ridge. Erosional bounding surfaces suggest the syndepositional uplift of the sand ridge morphologies during this time; (iii) a neotectonic influence on the evolution of the landscape is revealed by the incision of the sand ridge forming fluvial watergaps since ~6 ka ago; and (iv) due to continuous aeolian and fluvial reworking, the western-most ridge became gradually isolated from the floodplain resulting in an inherited relief. In conclusion, this investigation allowed the deformation caused by epeirogenic movements acting on a low relief landscape to be characterized in terms of landforms and sedimentary body properties.
Mots-clé
Sand ridges, Neotectonics, Watergaps, Grain-size distributions, Middle Kalahari
Open Access
Oui
Financement(s)
Fonds national suisse / 200021_172944
Création de la notice
01/09/2022 11:04
Dernière modification de la notice
21/11/2022 8:09
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