Millennial-timescale thermogenic CO₂ release preceding the Paleocene-Eocene Thermal Maximum

Area of Science:

• Paleoclimatology
• Geochemistry
• Oceanography

Background:

• Geologic records indicate a short carbon release, the pre-onset excursion (POE), preceding the Paleocene-Eocene Thermal Maximum (PETM) around 56 million years ago.
• The origin, timing, and connection of the POE to the PETM remain unclear, necessitating further investigation into early Cenozoic climate events.

Purpose of the Study:

• To investigate the source and pace of the POE carbon release.
• To clarify the relationship between the POE and the PETM.
• To confirm the global extent of the POE and its environmental impact.

Main Methods:

• High-temporal-resolution stratigraphic analysis of sedimentary records from the eastern Tethys Ocean spanning the POE and PETM.
• Biomarker extraction and analysis to assess environmental changes.
• Earth system modeling constrained by paleoclimatic data (δ13C and pH).

Main Results:

• The study confirms the global nature of the POE through stratigraphic records from the eastern Tethys Ocean.
• Biomarker data reveal a less severe environmental perturbation during the POE compared to the PETM in the studied region.
• Earth system modeling indicates a thermogenic CO2 source, likely from sill intrusions preceding North Atlantic Igneous Province volcanism, drove the POE, potentially amplified by methane release.

Conclusions:

• The POE was a global event driven by thermogenic CO2, likely linked to early magmatic activity.
• The environmental impact of the POE was less pronounced than the PETM.
• Biogeochemical feedbacks, including methane release, may have influenced the POE's carbon cycle dynamics.