oa Palaeoenviromental Changes Inferred by Biomarkers at the Cretaceous Paleogene Boundary Distal Section

The Cretaceous/Paleogene boundary (K-Pg) represents the latest of the five major mass extinctions in Earth´s history. Determining the nature of the associated rapid environmental change and biotic recovery is critical for understanding the cause and effects of this event, a key event in the history of life on our planet and potentially relevant for future biotic events. Here, we present a continuous cm-scale resolution and multiproxy analysis across ∼300 cm-thick K-Pg boundary interval at the Caravaca distal section (SE Spain) that spans the ∼75 kyr following and ∼100 kyr previously to the K-Pg event. We compared changes in organic matter input using a range of apolar (n-alkanes, steranes and hopanes) biomarkers, major and continuous trace element profiles (Ca/Al, K/Al, Ba/Ti, Ti/Al, Ir/Al ratios), % of Ca CO3, and stable carbon isotopes variations (bulk, organic and compound specific in n-alkanes). These results indicate that an erosive event associated with a change in lithology and mobilization of ancient sedimentary carbon happened right after the Chicxulub impact event. Crucially, similar biomarker distributions, sterane assemblages occur pre- and post-K-Pg boundary which suggest a rapid recovery of non-fossilizing algal communities in distal sites following this major extinction event.