The Registration of the Mid-Paleocene Biotic Event (MPBE) in Tunisia

In Tunisia, the Paleocene biomarkers are identified within the El Haria Formation shales. The Selandian is absent in most of the Paleocene outcrops and the Thanetian is unconformable to different stages of the Cretaceous. In the middle of Selandian, with the beginning of the Globanomalina pseudomenardii (P4) zone, we note that the assemblage of planktonic foraminifera becomes very poorly preserved and much less abundant than at the base. It is represented by rare species and there has been a start of the microfauna dissolution tests and an enrichment in iron oxides, silica, and gypsum crystals. The dissolution process is increasing more and more and a drop in the content of carbonates is clearly recorded at the top of Selandian. However, we note that some small benthic foraminifera belonging to the genera Lenticulina and Anomalina escape the dissolution and very few planktonic foraminifera belonging to the genera Subbotina are preserved. This dramatic and abnormal dissolution extends over a considerable thickness. These features could be an expression of the mid-Paleocene biotic event (MPBE), registered for the first time in Tunisia. This intense dissolution is caused probably by the change in the solubility of carbonates, which may be related to the changes in the deep-water circulation or to the change in the productivity of the surface waters. 1. Introduction The mid-Paleocene biotic event (MPBE) has been described at the beginning, offshore in some studies of deep-sea sections, at Shatsky Rise (Ocean Drilling Program, central Pacific) and Walvis Ridge (south Atlantic) (e.g., [1–5]). In 2007, this event was first recognized onshore, in the Zumaia section (western Pyrenees) (e.g., [6]). This event is characterized by the existence of a remarkable dissolution level in the carbonate sediments and it was short lived and probably related to hyperthermal events (e.g., [1–3, 7]). The aim of this paper is to show the micropaleontologic and geochemical analysis of the middle Paleocene series in the northwest of Tunisia (Tejerouine section), the evidence of the mid-Paleocene biotic event (MPBE) similar to the one described previously. We want to demonstrate that this event is also recorded in Tunisia and, therefore, is a worldwide event. It needs intensive work to get more information and to find far more interpretations. 2. Material and Methods The Paleocene series are complete, well exposed, and easily accessible, in the Tejerouine section. In the field, the sampling was done particularly in marls and was tighter at the boundaries. In the laboratory, samples