Enrichment of chalcophile elements in seawater accompanying the end-Cretaceous impact event

A new study reveals that chalcophile elements, such as copper (Cu), silver (Ag), and lead (Pb), were significantly enriched in seawater during the end-Cretaceous asteroid impact event. This enrichment is evidenced by their correlation with iridium (Ir) concentrations in Cretaceous–Paleogene (KPg) boundary clays from Stevns Klint, Denmark. Synchrotron X-ray fluorescence imaging showed that Cu and Ag were present as trace elements in pyrite grains or as discrete phases, suggesting different carrier materials transported these elements to the seafloor. The study proposes that iron oxides/hydroxides and organic matter acted as potential carriers for chalcophile elements, which were released during impact heating of target rocks. Intense acid rain following the impact may have further contributed to the enrichment of these elements, particularly those forming acid-soluble sulfides.

Maruoka, T., Nishio, Y., Kogiso, T., Suzuki, K., Osawa, T., Hatsukawa, Y., & Terada, Y. (2020). Enrichment of chalcophile elements in seawater accompanying the end-Cretaceous impact event. GSA Bulletin, 132(9-10), 2055–2066. https://doi.org/10.1130/b35403.1