An outcrop with non-marine ostracodes in the Early Eocene of Djebel Amour, central Saharian Atlas, Algeria: taxonomy, palaeoecology and palaeobiogeography

作者：Mebrouk Fateh; Colin Jean Paul^*; Hennache Fatima

来源：Carnets de Geologie, 2011, CG2011_A04.

• Ostracodes
• brackish environment
• Early Eocene
• Algeria
• Saharan Atlas
• taxonomy
• palaeoecology
• palaeobiogeography

An outcrop with non-marine ostracodes in the Early Eocene of Djebel Amour, central Saharian Atlas, Algeria: taxonomy, palaeoecology and palaeobiogeography.- An outcrop with non-marine ostracods in the Early Eocene of Djebel Amour, an outcrop well dated by a rich charophyta microflora characterizing the Peckichara disermas Zone of the Early Eocene (Lower Ypresian = Ilerdian), has yielded an interesting non-marine ostracode fauna in the Djebel Amour, Western Saharian Atlas, in Algeria. This fauna is characterized by the dominance of the genus Neocyprideis with the new species Neocyprideis meguerchiensis nov. sp., and the occasional occurrence of the genera Hemicyprideis, Perissocytheridea (P. algeriensis nov. sp.) and Limnocythere. It is the second discovery of the genus Neocyprideis in the Palaeogene of the African continent, the first one being in the Early Eocene of Senegal. The Neocyprideis are represented by 75 % of smooth and normally calcified carapaces, 20 % by reticulate-noded specimens and 5 % of only reticulate forms. This polymorphism suggests a marked seasonality with fluctuating salinity. The dominance of smooth and well calcified morphs indicates an environment with an equilibrium Ca(++) /Mg(++), the reticulate morphs characterizing waters richer in Mg(++). The presence of noded-reticulate forms suggests seasonal influxes of organo-siliceous material from the continent and a salinity which could temporarily reach values lower or equal to 5 psu.

• 出版日期2011-7-5