Evaluation of the main drivers of environmental and climatic changes of the sea-surface across the Cretaceous-Paleogene transition: A global perspective

The Chicxulub impact and Deccan volcanism have long been considered opposing factors to explain the changes observed across the Cretaceous/Paleogene boundary (KPB). Although the geologically instantaneous effects of the Chicxulub impact better explain the KPB catastrophic mass extinction, refinement of geochemical and micropaleontological proxies contributes to assessing the actual role of the Deccan volcanism in environmental changes across the KPB. Furthermore, cyclostratigraphy is being used to evaluate the role of orbital forcing on climate, and to refine age models. In this paper, we evaluate the climate and environmental changes across the KPB (66.100–65.350 Ma) from a global perspective, exploring several proxies from the Pacific, Atlantic and Tethyan realms: bulk δ¹⁸O and δ¹³C disturbances, mercury enrichments, and blooms of triserial guembelitriids and aberrant planktic foraminifera. The KPB, Dan-C2 and LC29n events, dated at 66.0, 65.8–65.7 and 65.47–65.41 Ma, respectively, have been recognized in all Tethyan and Atlantic localities, but only the KPB in the Pacific. Multiproxy analysis suggests that volcanic activity of the Deccan Traps did not have a relevant role in the aforementioned events, but contributed to environmental stress in the first 10 kyr of the Danian, and between ∼70 and 200 kyr after the KPB.