L'évolution des Sebkhas du golf de Gabès (Tunisie) à la transition Pléistocène supérieur-Holocène

Abstract

In the north of Africa, in coastal lagoons (sebkhas) like in inland lake environments, changes in andity lead to increased salinities dunng dry penods compared with normal or lower than normal values dunng humid penods. In coastal areas, the effects of changing climatic conditions are seen to interfere with effects due to glacio-eustatic vanations. By adapting to high salinity conditions, certain dinoflagellates form cyst-assemblages of low diversity in which P zoharyi is dominant In lagoons formed at the back of the gulf of Gabes, the salinity attained maximum values at 31 160 ± 2000 years BP and at 18 350 ± 440 ans BP. The increase in humidity between 28 340 ± 660 and 21 240 ± 550 ans BP led to a fall in salinity and the establishment of normal open marine conditions which cannot be considered as a reference to the sea level at that time.