Influence of the Latest Maastrichtian Warming Event on planktic foraminiferal assemblages and ocean carbonate saturation at Caravaca, Spain

A global warming episode in the Late Cretaceous, the Latest Maastrichtian Warming Event (LMWE), has been commonly linked to both the onset of massive Deccan Trap volcanism and the start of a planktic foraminiferal mass extinction prior to the Cretaceous/Paleogene boundary (KPB). The mechanisms that drove the LMWE are still under discussion, but radiometric dating of the onset of the main phase of the Deccan volcanism supports a temporal coincidence and permits a potential mechanistic link. Here we evaluate the planktic foraminiferal record, carbonate content and stable carbon and oxygen isotopes in the Caravaca section, in order to characterize paleoenvironmental change related to the LMWE. We identified negative δ13C and δ18O excursions in bulk carbonate from 66.35 to 66.14 Ma, i.e. ~310 to ~100 kyr before the KPB, which can be stratigraphically correlated to the LMWE and a major pulse of Deccan Traps volcanism. Within this warm interval, we identified high values in the fragmentation index of planktic foraminiferal tests, episodes of very high abundance of the low oxygen tolerant genus Heterohelix, a decrease of thermocline dwellers, dwarfing in Contusotruncana contusa tests, and an increase in the biserial morphotype of Pseudoguembelina hariaensis with elongated terminal chambers. However, the environmental disturbance during the LMWE did not cause changes in the planktic foraminiferal extinction rate. At Caravaca, the warming associated with LMWE was followed by a gradual cooling up to the KPB suggesting no extended interval of perturbed environments before the KPB extinction due to Deccan volcanism. •Evidence of the Latest Maastrichtian Warming Event between 66.35 and 66.14 Ma.•Ocean overheating resulted in a reorganization of planktic foraminiferal assemblages.•Almost null extinction rate suggests low influence of the Deccan volcanism.•Enhanced fragmentation rates on tests could be linked to CO2 Deccan emissions.