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Reconstitution of dune morphologies and palaeowind regimes in the Proto-Namib since the Miocene

2004; EDP Sciences; Volume: 175; Issue: 6 Linguagem: Inglês

10.2113/175.6.537

1777-5817

Loïc Ségalen, Pierre Rognon, Martín Pickford, Brigitte Sénut, Laurent Emmanuel, Maurice Renard, John Ward,

Aeolian processes and effects

Abstract In the Namib Desert, indurated fossil dunes are found between the active sands. Establishment of a biostratigraphic scale based on associated mammal faunas and ratite eggshells allows the study of palaeowind fluctuations that have controlled these palaeodunes since the Middle Miocene with a temporal resolution of between 1 and 3 Ma. In the southern Namib, the Proto-Namib aeolian systems consist of crescent dunes (barkhan type). In the eastern part of the Namib Desert, the aeolianite cross-bedding corresponds to longitudinal or pyramidal dunes. These aeolian structures are also controlled by local winds, resulting from high relief and the southern trade winds : this regime is identical to that which currently sweeps, through the Namib Desert, and is related to the presence of anticyclonic conditions in the Atlantic Ocean. A regime of seasonal winds from the northeastern sector is also recorded starting in the late Miocene.