Reconstruction of a latest Paleocene shallow-marine eutrophic paleoenvironment at Sidi Nasseur (Central Tunisia) based on foraminifera, ostracoda, calcareous nannofossils and stable isotopes (d<sup>13</sup>C, d<sup>18</sup>O)


  • P. STASSEN Department of Earth and Environmental Sciences, K.U.Leuven Celestijnenlaan 200E, B-3001 Leuven, Belgium.
  • C. DUPUIS Faculté Polytechnique de Mons9 rue de Houdain, B-7000 Mons, Belgium.
  • A.M. MORSI Department of Geology, Faculty of Science Ain Shams University, 11566 Cairo, Egypt.
  • E. STERBAUT Department of Paleontology, Royal Belgian Institute of Natural Sciences Vautierstraat 29, B-1000, Brussels, Belgium. Department of Earth and Environmental Sciences, K.U.Leuven Celestijnenlaan 200E, B-3001 Leuven, Belgium.
  • R.P. SPEIJER Department of Earth and Environmental Sciences, K.U.Leuven Celestijnenlaan 200E, B-3001 Leuven, Belgium



Stratigraphy, Benthic foraminifera, Ostracoda, Calcareous nannofossils, Inner neritic, Coastal, Stable isotopes


In order to unravel faunal and paleoenvironmental parameters in shallow marine settings prior to the Paleocene- Eocene thermal maximum, we investigated the Sidi Nasseur section (NAS) in Central Tunisia. This section exposes Paleocene to lower Eocene shales and marls of the El Haria Formation. The uppermost Paleocene part of the Sidi Nasseur section is marked by poor to moderately rich, but fairly diversified nannofossil associations, containing the typical latest Paleocene taxa of the top of NP9a. The ostracode record displays an almost continuous record in the uppermost Paleocene part of the section. Representatives of Aegyptiana, Paracosta, Reticulina and Reymenticosta make up the major part of the ostracode fauna. The benthic foraminiferal assemblage consists of numerous small calcareous benthic foraminifera, like Anomalinoides midwayensis and Lenticulina spp. and many large Frondicularia phosphatica, Pyramidulina spp. These, together with the non-calcareous agglutinated foraminifera and the rare planktic foraminifera, indicate an inner neritic to coastal environment with eutrophic conditions, regularly interrupted by oxygen deficiency. The dominance of non-calcareous benthic foraminifera between intervals with abundant calcareous benthic foraminifera suggests post-mortem dissolution. The foraminiferal d<sup>13</sup>C record (based upon Pyramidulina latejugata) of the latest Paleocene in the Sidi Nasseur area is very similar to these from coeval sediments at Gebel Duwi and Gebel Aweina in Egypt. Oxygen isotopic ratios indicate a marine setting with a water composition affected by evaporation. During the latest Paleocene, the highly productive shallow water environment evolved to shallower water depths with higher salinity and increasing dominance of A. midwayensis.


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