Ichnological analysis of the Paleocene Eocene thermal maximum

This study investigates the ichnological characteristics of deep-sea cores recovered from site U1580 on the southern Central Agulhas Plateau during International Ocean Discovery Program (IODP) Exp. 392, with a focus on the Paleocene-Eocene Thermal Maximum (PETM) event. By comparing pre-, syn -, and post-PETM intervals, this research applies trace fossil diversity, maximum trace diameter, and bioturbation patterns to assess benthic community responses to extreme climate changes including temperature changes, fluctuating bottom water oxygenation, nutrient availability, as well as changing deep sea circulation patterns. Trace fossil records such as ichnogenera diversity and maximum trace fossil diameters across 10 cm intervals (bins), were extracted from high-resolution photographs of cores U1580A and U1580B. Results reveal a reduction in maximum trace fossil diameters during the PETM, reflecting potential environmental stressors like elevated temperatures and lower oxygen (O 2 ) levels, followed by a post-PETM recovery. Trace fossil diversity increased from the syn - to post-PETM interval, ecological reorganization and potential recolonization of newly available niches. A comparative analysis of the two cores highlights subtle differences, with core U1580B exhibiting larger average maximum trace fossil diameters possibly due to localized variations in seafloor topography, food availability and/or biological factors. The deep-tier trace fossil Zoophycos is both included and excluded from the analysis to explore how its burrow depth – which likely exceeds the 10 cm bin intervals used – impacts ichnological trends. Overall, the ichnological patterns presented here provide new insights into how deep-sea macrobenthic communities responded to PETM environmental stressors, complementing existing paleoenvironmental interpretations based primarily on microfossil data. • Ichnological analysis of deep ocean IODP Site U1580 across the PETM interval. • Trace fossil diameters declined during PETM, indicating environmental stress. • Ichnodiversity increased post-PETM, suggesting ecological resilience and recovery. • Zoophycos exclusion refines ichnological signals and improves inter-core comparison. • Findings imply sustained oxygenation or food availability in deep-sea benthic ecosystems during PETM for this location.