Paleoatmospheric pCO2 fluctuations across the Cretaceous–Tertiary boundary recorded from paleosol carbonates in NE China

A dramatic change in atmospheric composition has been postulated because of global carbon cycle disruption during the Cretaceous (K)–Tertiary (T) transition following the Chicxulub impact and Deccan Trap eruptions. Here, pedogenic carbonates were collected from drill core of a borehole (SK-1 (N)) straddling the Late Cretaceous and early Paleocene strata in the Songliao Basin, northeast China, to reconstruct atmospheric CO2 concentrations using a paleosol paleobarometer. Our estimates for atmospheric pCO2 from paleosol carbonates range between 277 ± 115 ppmv and 837 ± 164 ppmv between 67.8 Ma and 63.1 Ma. One large (~ 66–65.5 Ma) and several small CO2 spikes (~ 64.7–~ 64.2 Ma) during the latest Maastrichtian to earliest Danian are reported here and incorporated with previously published pCO2 estimates also estimated from paleosol carbonates. These CO2 spikes are attributed to one-million-year-long emplacement of the large Deccan flood basalts along with the extraterrestrial impact at the K–T boundary.