Some new insights into palaeoenvironmental dynamics and Holocene landscape evolution in the Nigrian Central Sahara (Ténéré, Erg of Ténéré, Erg of Fachi- Bilma)
published: Dec 10, 2014
palaeoecological studies of terminal Pleistocene and Holocene deposits in the Central Sahara allow some new insights of the palaeoenvironmental development of the vast Ténéré sand plain, Erg of Fachi-Bilma and Erg of Ténéré region of Central Sahara, NE-Niger. The environmental changes are deduced from geomorphological, sedimentological and biological remains as well as from palaeolimnological and prehistoric evidence. Comparing the lacustrine sediments, three stages of water bodies with different conditions can be distinguished. Topographical factors, geomorphological evidence and biological remains (e. g. Lates niloticus) suggest that from 11. 5 ka cal BP onwards a widespread lacustrine landscape existed with perennial deep-water lakes changing in size, water level and water balance. Following a change between 7. 5 ka cal BP and 6. 8 ka cal BP in the northern and central parts of Ténéré, and 6. 5 ka cal BP in the southern part of the region studied, desiccation of the by now shallow permanent freshwater lakes began, coinciding with the establishment of seasonal ponds characterized by low water level and high pH. From 6. 0 ka cal BP onwards in the north and 5 ka cal BP onwards in the south a more swampy environment developed finally. Concerning the Early Holocene, and towards the Mid-Holocene, the findings suggest an increasingly steep precipitation gradient from SW to NE as well as a more pronounced seasonality, indicating a weakening contact between the summer monsoon front and the westerlies.