Latest Campanian and Maastrichtian palaeoenvironmental changes: Implications from an epicontinental sea (SE Poland and western Ukraine)

The Maastrichtian was a time of a high variability in the climate/ocean system. Most studies on Maastrichtian palaeoenvironment fluxes have been based on evidence from the open ocean realm or from outcrops in the Tethyan realm. We have investigated epicontinental carbonate-rich sediments of Maastrichtian age of the Lublin-Lviv Syncline (SE Poland and western Ukraine). Our study is focused on the population changes of planktonic foraminifers from 21 Maastrichtian outcrop successions and one borehole section. Quantitative and qualitative studies of planktonic foraminifers show long-term foraminiferal changes that make it possible to reconstruct climatic changes and a sea-level curve for the latest Campanian and Maastrichtian from the high-latitude epicontinental sea. A significant regression is inferred for the latest Campanian and earliest Maastrichtian. The highest sea level is noted in the earliest Late Maastrichtian. It coincides with a migration of the benthic and planktonic foraminiferal fauna that was probably triggered by a cooling episode. The cooler episodes correlated with a eustatic sea-level highstand during that time, suggesting that sea level was the most likely mechanism causing a change of global circulation; this temperature drop could be the cause of the mid-Maastrichtian event.