On the age of the Cretaceous−Paleogene boundary event and millennial-scale climate variability during its aftermath at Elles, Tunisia

The Cretaceous−Paleogene boundary (KPB) marks one of the most abrupt environmental crises of the Phanerozoic, driven primarily by the Chicxulub asteroid impact, yet the pace of climate variability in its aftermath remains poorly constrained at millennial resolution, and its age is still debated. Here, we present a high-resolution coarse-fraction (>32 µm) record from the expanded shallow-marine Elles I section, Tunisia, revealing a clear precession signal and its modulation by short eccentricity across the boundary. Our results place the KPB close to a short-eccentricity minimum, with a preferred astrochronological age of 65.967 ± 0.011 Ma and a sensitivity range across all tested solutions of 66.065−65.956 Ma. The earliest Danian shows robust millennial-scale climate variability with periodicities at ;#8764;4.0 k.y. and ;#8764;2.5 k.y. The ;#8764;4.0 k.y. band exhibits amplitude modulation by precession and obliquity, indicating that astronomical forcing continued to structure climate variability down to suborbital time scales after the impact. These results provide a new benchmark for the KPB age and reveal pervasive rapid climate variability during the earliest postimpact recovery.