Reconstruction of a latest Paleocene shallow-marine eutrophic paleoenvironment at Sidi Nasseur (Central Tunisia) based on foraminifera, ostracoda, calcareous nannofossils and stable isotopes (d13C, d18O)
Stassen, P. (K.U.Leuven. Department of Earth and Environmental Sciences)
Dupuis, C. (Faculté Polytechnique de Mons)
Morsi, A. M. (Ain Shams University. Department of Geology)
Steurbaut, E. (Royal Belgian Institute of Natural Sciences. Department of Paleontology)
Speijer, R. P. (K.U.Leuven. Department of Earth and Environmental Sciences)

Data:	2009
Resum:	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 d13C 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.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Stratigraphy ; Benthic foraminifera ; Ostracoda ; Calcareous nannofossils ; Inner neritic ; Coastal ; Stable isotopes
Publicat a:	Geologica acta, Vol. 7, Núm. 1-2 (Març-Juny 2009) , p. 93-112, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/125113
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000000273
DOI: 10.1344/105.000000273

20 p, 2.8 MB

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