Lacustrine littoral landforms in drylands: diversity and significance with examples from Quaternary megalakes of Africa and Australia

Schuster Mathieu1, May Jan-Hendrik2,3, Nutz Alexis4

1CNRS & University of Strasbourg, Strasbourg, France, 2School of Geography, University of Melbourne, Melbourne, Australia, 3GeoQUest, University of Wollongong, Wollongong, Australia, 4Aix-Marseille University, Aix-en-Provence, France

Due to the scarcity of water that defines dryland continental systems, the superficial processes (erosion, transport and deposition) are there dominantly controlled by wind and intermittently by water. As such, sedimentologists and geomorphologists working in drylands expect to find there a great diversity of landforms, bedforms and surfaces related to aeolian and alluvial-fluvial environments. However, it is not rare to also identify abandoned landforms which are quite exotic for drylands, such as beach ridges-and-swales, spits, cuspate forelands, barrier islands, wave-ravinement surfaces, or lobate-cuspate deltas. These typical shore-related morpho-sedimentary structures evidence past more humid events or periods that have culminated in the development of large lakes. As for their marine counterparts, these littoral landforms provide key geomarkers to restore the trajectory of the shorelines through time, and to understand the cross-shore and alongshore redistribution of clastics by waves and currents.

To illustrate the diversity of the lacustrine littoral landforms that can be preserved in drylands and to explain their significance for climate, environments and hydrodynamics, we focus here on a selected number of remarkable very large paleolakes which developed over Quaternary times in continental deserts from both hemispheres. These are Megalakes Chad, Eyre Kati-Thanda and Frome (Cohen et al. 2012; May et al. 2015; Schuster et al. 2005).

According to both the physiography of the lake basins and the importance of the associated littoral landforms marking their shorelines, these megalakes can be considered as wind-driven waterbodies (Nutz et al. 2018), a category of lakes for which sedimentation is dominated by wind-wave-related processes and basin-scale wind-induced hydrodynamics.

References cited

Cohen et al. 2012. https://doi.org/10.1016/j.palaeo.2011.06.023

May et al. 2015 https://doi.org/10.1016/j.yqres.2014.11.002

Nutz et al. 2018. https://doi.org/10.1007/s10933-016-9894-2

Schuster et al. 2005. https://doi.org/10.1016/j.quascirev.2005.02.001


Biography

I received my PhD in sedimentary geology from the University of Strasbourg in 2002. I then worked at the universities of Cologne, Brest and Poitiers, and at the French geological survey. My deals with continental paleoenvironments, with a focus on clastic littoral lacustrine systems.

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