The Paleocene-Eocene transition in the southern Tethys (Tunisia): Climatic and environmental fluctuations

This study, based on a multidisciplinary approach including micropaleontology, sedimentology, mineralogy and geochemistry, evaluates the Paleocene-Eocene transition in Tunisia. At Foum Selja, sediment deposition occurred in the shallow, restricted Gafsa Basin influenced by the adjacent Saharan Platform. During the early Paleocene this area experienced a warm and humid climate that changed to warm but arid climatic conditions during the Paleocene-Eocene transition. At Elles the sediment deposition in the El Kef Basin occurred in an open marine environment connected to the Tethys. During the late Paleocene, the Tethyan region was submitted to a seasonal warm climate changing to a warm and humid climate across the P/E transition and becoming seasonal/arid in the early Eocene. From Africa to northern Europe, kaolinite, a strong marker of warmth and humidity disappeared diachronously suggesting a latitudinal shift in the source area of this mineral and consequently in the climatic zones, from lower to higher latitudes. The P/E transition observed at Elles corresponds to a 2.7 m thick clay layer and is marked by a drastic decrease in carbonate sedimentation, a negative δ¹³C excursion of 1.3‰ and increased detrital input. The presence of a condensed interval, the accumulation of phosphate deposits after the P/E event, which obliterate the original isotopic signal and strong dissolution of the planktic fauna and flora in these phosphatic layers, all are criteria that prevent the Elles section to be a potential GSSP candidate for the P/E boundary.