Shallow marine ostracode turnover in response to environmental change during the Paleocene–Eocene thermal maximum in northwest Tunisia

• Published in: Journal of African earth sciences (1994) 2011-02, Vol.59 (2), p.243-268
• Main Authors: Morsi, Abdel-Mohsen M., Speijer, Robert P., Stassen, Peter, Steurbaut, Etienne
• Format: Article
• Language: English
• Subjects: Bairdia; Biostratigraphy; Loxoconcha; Marine; Ostracoda; Paleobiogeography; Paleocene/Eocene boundary; Paleoecology; Paracypris; PETM; Taxonomy; Tunisia
• ISSN: 1464-343X; 1879-1956
• DOI: 10.1016/j.jafrearsci.2010.11.001

► A high resolution ostracode record across the P/E boundary has been investigated. ► The studied record yielded 26 ostracode taxa which have been taxonomically described. ► The recorded fauna reflect deposition in a coastal to inner neritic setting. ► Two different associations characterize the levels below and above the P/E boundary. ► Faunal turnover is attributed to environmental conditions associated with the PETM. Two outcrop sections spanning the Paleocene–early Eocene boundary in the Sidi Nasseur–Wadi Mezaz area in northwest Tunisia provided rich ostracode assemblages, yielding 26 species of which three are newly described: Reymenticosta bassiounii, Reymenticosta nasseurensis and Buntonia? tunisiensis. The recorded ostracode fauna and associated foraminifera reflect deposition in a coastal to inner neritic environment. Many of the recorded taxa have a wide geographic distribution throughout the Middle East and North Africa. A correspondence is also observed with West African faunas, especially in the early Eocene fauna. These taxa seem to have originated in West Africa during the Paleocene and migrated northwards during the late Paleocene to early Eocene. Sea-level change and decrease in oxygenation associated with the Paleocene–Eocene thermal maximum (PETM) caused the local disappearance of the South Tethyan Paleocene fauna represented by Paracosta kefensis (morphotype-A), Paracosta aff. paleomokattamensis, Paracypris sp. B Esker, Loxoconcha saharaensis, Buntonia sp. 3 Donze et al., Protobuntonia nakkadii, and probably Reymenticosta bassiounii and R. nasseurensis. Simultaneously, a new but poorly diverse Afro-Tethyan fauna, mainly represented by Alocopocythere attitogonensis and Buntonia? tunisiensis, settled in the studied part of the basin. After the PETM, diversity increased again as various taxa (e.g. Bairdia aegyptiaca, Reticulina lamellata and Aegyptiana duwiensis) (re)appeared. Although detailed records across the P/E boundary are still sparse, it appears that the PETM exerted significant influence on the paleobiogeography and composition of Tethyan ostracode faunas.