Terrestrial records of two hyperthermal events in the Cretaceous-Paleogene boundary suggest different control mechanisms

Two hyperthermal events with different carbon cycle perturbations occurred across the Cretaceous-Palaeogene boundary, i.e., the late Maastrichtian Warming Event and the Early Danian Dan-C2 event. However, the roles played by Deccan volcanism and orbital forcing in these two hyperthermal events are still debated. Here we obtain a terrestrial δ¹³C_carb record in the Nanxiong Basin (southeastern China) and compare it with marine records. The results show that both hyperthermal events can be well distinguished and that the Dan-C2 event is characterized by a typical hyperthermal event. In addition, the δ¹³C excursion during the late Maastrichtian Warming Event was more muted and prolonged than that during the Dan-C2 event, and the short-eccentricity cycle disappeared in the marine record during the late Maastrichtian Warming Event, indicating that Deccan volcanism perturbed the carbon cycle during the late Maastrichtian Warming Event, while the Dan-C2 event was less influenced by volcanic perturbation.