Ecosystem Disturbance Records During the Uppermost Maastrichtian-Lower Danian in Southern Tethyan Realms (Gafsa Basin, Tamerza Area, Tunisia)

The high-resolution geochemical investigation across the K-T transition of the Tamerza region (Gafsa Basin) allowed to recognize the environmental conditions of the upper Maastrichtian-lower Danian interval. Anoxic conditions were testified by the increase of redox trace elements, Zn, Mo, and V, associated with the decrease of Ca concentrations and the CaCO₃. The marine ecosystem has been hardly disrupted by the environmental changes recorded within this interval. As a result, the anoxic conditions induced noticeable changes in terms of fauna assemblages, test preservation, shape, size, and abundance. The benthic foraminifera were severely influenced by the poor oxygenation and the heavy metal enrichments. The abundance and the diversity of these microfossils sharply decreased and showed bad preservation. Moreover, the benthic foraminifera exhibited fragmented and dissolved shells.