Holocene palaeoclimate in the northern Sahara margin (Jefara Plain, northwestern Libya)

摘要

The palaeoclimatic evolution of northwestern Libya has been deduced from the study of the palustrine and aeolian sediments. The Holocene environmental variations have been recognized through geological and stratigraphic surveys and by pollen analysis and malacofauna content of the sediments. Some organic-rich horizons have been dated using the radiocarbon method. The data show that in general, the presence of marshes is linked with the period of higher humidity, which began around 9.4 ka BP and ended around 5.0 ka BP. From c. 5.0 ka BP up to about 4.4 ka BP, there was a simultaneous presence of marshes and vegetation of arid climate as a consequence of rainfall in the mountains and/or a decrease in temperatures. The Holocene wet period was interrupted by two arid spells dated about 8.2 and 5.5-5.4 ka BP. The end of the wet phase must have been gradual. The climatic events that occurred in the Jefara plain seem to be well correlated with those identified in Saharan Africa even if the Mediterranean is only 100 km away.