Globally distributed iridium layer preserved within the Chicxulub impact structure

The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The peak in the abundance of ultra-fine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below earliest Danian pelagic limestone. Within years to decades after the impact event, this part of the impact basin returned to a low-energy depositional environment, recording in unprecedented detail the recovery of life after the impact. The iridium layer provides a key temporal horizon precisely linking the Chicxulub cratering processes to K-Pg boundary sections worldwide.