Lacustrine records of Paleocene-Eocene Thermal Maximum (PETM) triggered by volcanic activity

The Paleocene-Eocene thermal maximum (PETM, ∼ 56 Ma) was driven by global carbon release and temperature increases. Studies of marine strata have indicated that volcanic activity during the PETM led to significant carbon emissions. However, the impact of volcanic activity on terrestrial strata and whether this activity was regional remain unclear. Here, we conducted astrochronological analysis, polycyclic aromatic hydrocarbons (PAHs) analysis, organic petrological identification, and paleo-environmental proxies to identify lacustrine records of PETM from the Miaoxi Depression in the Bohai Bay Basin, eastern China. The analysis of natural gamma-ray (GR) series indicates that PETM occurred at 56.06 Ma and lasted approximately 0.58 Ma within the formation. Significant GR series changes, carbon isotope excursions, and red bed sedimentation were observed during the PETM. Paleo-environmental proxy changes, including decreased paleo-productivity, arid paleo-climate, increased paleo-salinity that promoted strongly reducing conditions, and decreased lake level, were correlated with the GR series and δ¹³C_VPDB excursions. The duration of the PETM event suggests that terrigenous sediments may record climate events in great detail. The PETM corresponds to a peak in 405 kyr eccentricity, but other changes in the astronomical cycle do not align with the paleo-environment data, indicating that astronomical forcing may not be the primary driver of the PETM. Increased PAHs and volcanic proxies suggest enhanced volcanic activity during this period, indicating that the PETM event was associated with regional volcanic activity.