Cretaceous-Paleogene boundary impact winter superimposed on long-term climate changes

Abstract:

It has become widely acknowledged that the Cretaceous – Paleogene (K-Pg) boundary mass extinction (~66Ma) is related to the environmental consequences of an impact of a large extraterrestrial body. This impact likely invoked exceptionally rapid and profound global climate change, which occurred superimposed on ongoing, long-term environmental changes. The interplay between impact-related and long-term environmental changes is still poorly documented. In a recent study, we showed that a TEX86 based Sea Surface Temperature (SST) K-Pg record from Brazos River (USA) indeed shows evidence for rapid short-term cooling following the K-Pg impact. This confirmed for the first time the hypothesis of a so-called ‘impact winter’ invoked by dust and aerosols produced by the impact, blocking incoming solar radiation.

This short-lived cold phase has so far not been confirmed by other studies. To verify the record from Brazos River and to reveal ongoing, long-term climate change, we performed a high resolution marine palynological and organic geochemical study on four stratigraphically expanded cores from the New Jersey Shelf, eastern USA, spanning the K-Pg boundary, using the TEX86 sea surface temperature (SST) proxy. Indeed, our new composite record confirms the brief cooler episode immediately following the K-Pg impact. Here we present these impact-related sea surface temperature changes in the context of the long term climate changes across the K-Pg boundary interval.