Upper Sandbian–lower Katian bio- and chemostratigraphy in the Pajevonys-13 core section, Lithuania

The succession of five formations (Auleliai, Vilučiai, Alvitas, Šakiai, Jakšiai) corresponding to the upper Sandbian and lower Katian in southern Lithuania is dated based on new bio- and chemostratigraphical data from the Pajevonys-13 core section. The dating of the Auleliai and Vilučiai formations is controversial: chitinozoans suggest younger ages (Keila and Oandu) than brachiopods (Haljala and Keila) for this interval. Chemostratigraphical data (δ13Ccarb and δ13Cbrach) agree better with the dating based on brachiopods: the Alvitas and Šakiai formations correspond to the Oandu Stage, the older Vilučiai Formation is of Keila age. The Jakšiai Formation is commonly dated as of Rakvere age, but it is problematic in the studied section. However, its upper boundary is well defined by the appearance of subzonal chitinozoans Armoricochitina reticulifera characteristic of the lowermost Nabala Stage. The Ancyrochitina bornholmensis and Fungochitina spinifera chitinozoan zones, and the upper Amorphognathus tvaerensis, A. superbus and the lowermost A. ordovicicus conodont zones were identified in the studied section.