Fig. 3: Geochemistry and sedimentology of the Tanis K-Pg boundary site.
From: Reduced contribution of sulfur to the mass extinction associated with the Chicxulub impact event
Bulk S, Co, Cr, and Ni concentrations; background subtracted Ni/Cr ratios; Ir and Re information values (concentrations close to the detection limit, DL, of the method); and previously published13 median grain-size values of the Tanis K-Pg (Cretaceous-Paleogene) boundary site are presented. Error bars represent the standard deviation for two or more replicates and are often smaller than the symbols. The dashed red line indicates the K-Pg boundary claystone equivalent, based on sedimentological constraints, and the presence of microkrystites and shocked minerals67. Typical Ni/Cr values for the upper continental (UCC) crust69 are shown with a dashed orange line, while the range is marked by an orange interval. The blue region indicates the previously published range for Ni/Cr values from other K-Pg boundary sites and for carbonaceous chondrites68,70,71. The gray region for the median grain size represents the Paleocene coal interval, where data are missing due to insufficient lithogenic fractions for accurate laser-diffraction grain-size analysis after decarbonization13.
