Ichnological analysis of the Paleocene–Eocene Thermal Maximum along a continental–marine transect reveals a protracted recovery at deep marine settings

Abstract

During the Paleocene–Eocene Thermal Maximum (PETM), global temperatures rose, negative carbon isotope excursion (CIE) occurred and widespread oceanic deoxygenation happened, leading to biotic turnover. Moreover, a Pre-Onset Excursion (POE) has been documented globally and claimed to be more similar to ongoing anthropogenic emissions. Understanding how these two events have affected the macrobenthic tracemaker community (e.g., polychaetes, crustaceans, echinodermata, mollusks) provides crucial information for modern and past marine benthic ecology. Here we present an ichnological analysis of both events along a continental–marine transect. The POE had a variable impact at coastal environments while a decrease in trace fossil abundance is observed at platform environments. The PETM onset marked the macrobenthic tracemaker community extinction. However, during the PETM core, abundant root trace fossil beds appeared at coastal areas, probably associated with accelerated hydrological cycles. Then, on the platform, before the CIE recovery starts, the trace fossil assemblage is reestablished, while in the deep-sea, even after the excursion is over, trace fossil abundance only partially recovers. Our study unveils a protracted recovery of the PETM, suggesting that the macrobenthic tracemaker community was under stress for a much longer period in the deep-sea environments of the Pyrenean Basin. Finally, our results indicate that the PETM had a more dramatic impact on the tracemaker community than the POE.