The Cretaceous–Paleogene boundary in the East Carpathians, Romania: evidence from geochemistry, mineralogy and calcareous nannofossils

Abstract

AbstractWe performed detailed geochemical, mineralogical and calcareous nannofossils investigations on two Maastrichtian–Paleocene sections situated in the Eastern Carpathians, Romania. One of the sections is situated in the Carpathian bend area, in the Ialomiţa Valley and is composed of red marine hemipelagic sediments. The other section is located in the northern region of the Eastern Carpathians, along Varniţa Brook and consists mainly of turbidites. In both sections, the Cretaceous–Paleogene (K–Pg) boundary is characterized by nannoplankton mass extinction (over 90%) of the Cretaceous nannofloras, followed by blooms of survivor taxa, such as the calcareous dinoflagellate genus Thoracosphaera and the nannofloral species Braarudosphaera bigelowii. In the Ialomiţa section, the K–Pg boundary is marked by a drop in calcite and TOC content, as well as a negative excursion in the δ13C values of organic material. These trends are only partly present in the Varniţa Brook section, where both calcite and TOC content show a decrease, but no negative excursion is seen in the δ13C values of organic material.