Geochemical anomalies caused by meteorite impact and volcanism at the Cretaceous-Paleogene boundary, Wasserfallgraben (Lattengebirge, Germany)

The Cretaceous-Paleogene (K/Pg) mass extinction is the only major mass extinction event that is known to be related to a major meteorite impact (Chicxulub, Mexico) and also occurred during major flood basalt eruptions (Deccan Traps, India). Here, we present geochemical proxies for impact and volcanism analysed in the same sediment samples from the deep-marine sedimentary record of the Gosau Group spanning the K/Pg boundary at Wasserfallgraben, Germany. We measured major and trace elements, including iridium (Ir), tellurium (Te), mercury (Hg), total organic carbon (TOC), and organic carbon isotopes (d13Corg) on 33 samples from 2 m below to 1.36 m above the K/Pg boundary, a timespan of-260 ka. Results show an undisturbed profile, confirmed by changes in calcareous nannofossils assemblages, with a sharp positive Ir peak (2.3 ppb) at the K/Pg boundary (0e10 cm, 25 cm). Volcanic proxies (Hg/TOC, Te/Th) show three distinct peaks not corresponding to the Ir peak, suggesting a volcanic origin, and higher values in the earliest Danian. Compared to the profile in Bidart the proxies of volcanism are less intense in our profile, indicating that the Deccan Signal is either diluted or not present in some lo-cations worldwide. The time recorded in the sampled sediments is short (-0.26 Ma) compared to Deccan flood basalt eruptions (-1 Ma), but elevated Hg/TOC and Te/Th ratios in the Danian sediments suggests the impact happened prior to the main volcanic outgassing of the Deccan Traps. Our results support the hypothesis that the impact might have triggered the largest, rapidly-erupted Deccan lava formations. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study analyzed geochemical proxies for impact and volcanism at the K/Pg boundary in deep-marine sedimentary record from Germany. The results showed a sharp positive Ir peak at the boundary, while volcanic proxies had higher values in the earliest Danian. This supports the hypothesis that the impact may have triggered the largest, rapidly-erupted Deccan lava formations.