Late Quaternary palaeoclimatic oscillations in East Africa recorded by
heavy minerals in the Nile delta
Alain Foucault* & Daniel Jean Stanley†
*Laboratoire de Géologie, Muséum national d'Histoire naturelle, 75005 Paris,
†Mediterranean Basin Program,
Smithsonian Institution, Washington DC 20560, USA
BECAUSE the Nile carries a load derived from markedly different geological terrains and climatic zones, it is expected that minera-logical study of deposits in its delta could help define changes in palaeoclimate affecting East Africa. Here we report measurements on heavy minerals in the Nile delta which can be used as distinct markers of climatic shifts over Africa during the late Pleistocene to Recent. Variations of heavy minerals in radiocarbon-dated cores collected in this delta1, the Nile's major depocentre2, correlate closely with oscillations in African palaeoclimate determined by other independent methods, such as studies of lake levels. These variations are largely a function of the characteristics of the Nile. It flows across nearly 35° of latitude, from south of the Equator to the Mediterranean (Fig. la), and conditions in its drainage basin, which includes central Africa, the Ethiopian plateau and eastern Sahara, range from a tropical, humid to a warm, arid climate. East African climatic belts migrated considerably during the Quaternary3–5, modifying Nile discharge and sediment load. Climatic oscillations have been recorded by changes of sediment yield and grain size along its course6,7 and by well defined depositional cycles8, including sapropels9, in the eastern Mediterranean.
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