Globally distributed iridium layer preserved within the Chicxulub impact structure

Area of Science:

• Geoscience
• Paleontology
• Planetary Science

Background:

• The Cretaceous-Paleogene (K-Pg) mass extinction event is globally recognized by elevated iridium concentrations.
• This iridium layer is attributed to a hypervelocity asteroid impact approximately 66 million years ago.

Purpose of the Study:

• To analyze iridium concentrations within the Chicxulub impact structure's peak-ring sequence.
• To establish a precise temporal link between the Chicxulub impact and global K-Pg boundary sections.

Main Methods:

• Analysis of drill core samples from IODP-ICDP Expedition 364.
• High-precision iridium concentration measurements conducted by four independent laboratories.

Main Results:

• A distinct positive iridium anomaly was detected within the peak-ring sequence of the Chicxulub impact structure.
• The highest concentration of meteoritic matter was found in post-impact sediments just below the Danian limestone.
• This layer serves as a precise temporal marker correlating Chicxulub with worldwide K-Pg boundary sites.

Conclusions:

• The iridium anomaly confirms the Chicxulub impact's role in the K-Pg mass extinction.
• The studied sediments offer detailed insights into the post-impact recovery of life.
• This research solidifies the Chicxulub impact structure as a key reference point for understanding the K-Pg boundary event.