The mass extinction marking the Cretaceous/Palaeogene boundary (KPgB), 66.02 million years ago. It was one of the most devastating events in the history of life, as well as the most recent and best studied of the ‘big five’ mass extinctions that occurred during the Phanerozoic. After decades of research, one of the most critical lines of inquiry is understanding the short- to long-term effects of this impact on the global environmental system, including the re-establishment of pre-impact environmental conditions and marine biological productivity. After characterizing how the recovery of palaeoenvironmental conditions were by the analysis of inorganic geochemical proxies, critical questions were raised about the nature of and recovery after the event. how did primary productivity and the biological pump change and how did that impact the source and character of organic matter reaching the seafloor? And crucially, how did these interlinked processes recover after the impact event? The Caravaca section is amongst the most continuous, well-preserved, and well-studied KPgB distal sections in the world. This allows these questions to be explored using molecular fossils (or biomarkers) – for the first time in this section and consequently at unprecedented stratigraphic resolution. The approach will broadly encompass several methods, all of which will be carried out in the OGU (Organic Geochemistry Unit) at Bristol University. These will include but are not limited to, the determination of total organic carbon (TOC) contents; the extract and analysis of the biomarkers from ground samples; the determination of key biomarker abundances and distributions by GC and GC-MS in order to ascertain changes in organic matter (OM) source, algal assemblages, terrestrial biomarkers, redox state (pristane/phytane ratio; homohopane index) and microbial inputs (hopanes); and finally, to explore changes in ‘apparent thermal maturity’ which could reflect changes in reoworked OM input.
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