Ichnological and chemostratigraphic analysis from the K-Pg transition in well 1-PO-01-PE, Paraíba Basin, Northeast Brazil

We present an analysis of the ichnofossiliferous content from the Upper Campanian to the Lower Danian, obtained from well 1-PO-01-PE, Paraíba Basin, NE Brazil. The investigation integrated the bioturbation record and lithofaciological changes with δ 13 C and δ 18 O isotopic data to understand how variations in depositional environments and climatic conditions affected the benthic community. The analysis of core samples revealed a low diversity ichnological suite, dominated by the generalist ichnogenera Palaeophycus and Planolites , suggesting an ecosystem under ecological stress. The results suggest an intrinsic relationship between the intensity of bioturbation on the carbonate platform and sea-level changes, which controlled substrate oxygenation and energy levels. Reduced bioturbation is observed in periods associated with shallower waters and increased environmental energy (Danian), and also during the high sea-level period which may have reduced substrate oxygenation. The reduction of bioturbation during the Danian was influenced by marine regressive effects and occurred during colder climatic conditions. • Ichnological suites from a carbonate ramp across the K–Pg boundary. • Integration of ichnology, lithofacies, and isotopic data indicates eustatic control on substrate oxygenation and energy. • Trace-fossil suites enable detection of environmental stress based on limited variation in ichnofossil diversity.