Prolonged 187Os/188Os excursion implies hydrothermal influence after the Chicxulub impact in the Gulf of Mexico

Abstract

The Cretaceous/Paleogene boundary asteroid impact is recorded globally as a negative 187Os/188Os excursion, including in sediments recovered from the IODP-ICDP drilling within the peak ring of the Chicxulub structure in the Gulf of Mexico. The reconstructed marine 187Os/188Os curves can be used for global age correlations on the ~10 kyr scale. However, the versatility of Os isotope clock between the proximal and distal sites remains unclear. This paper presents 187Os/188Os records from early Paleocene sediments deposited in the Chicxulub impact basin and Mexican sites with biochronological scales. The results for these proximal sites show a recovery timescale of ~700 kyr, which is significantly longer than that of the distal sites (~200 kyr). The interval showing the 187Os/188Os decline coincides with the enrichment of hydrothermally-derived Mn, implying that hydrothermal venting at the Chicxulub structure may have played a role in the marine chemistry and ecosystem of the Gulf of Mexico.