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Abstract Earth's hydrological cycle was profoundly perturbed by massive carbon emissions during an ancient (56 Ma) global warming event referred to as the Paleocene‐Eocene thermal maximum (PETM). One approach to gaining valuable insight into the response of the hydrological cycle is to construct sea‐surface salinity (SSS) records that can be used to gauge changes in the rates of evaporation and precipitation during the PETM in such climatically sensitive areas as the circum‐Antarctic region. Here, we pair oxygen isotope (δ18O) and magnesium‐calcium (Mg/Ca) measurements to reconstruct PETM sea‐surface temperatures (SSTs) and δ18O composition of seawater (δ18Osw) at austral Site 690 (Weddell Sea). Several discrepancies emerge between the δ18O‐ and Mg/Ca‐based SST records, with the latter indicating that the earliest PETM was punctuated by a short‐lived ~4°C increase in local SSTs. Conversion of the δ18Oswvalues to SSS reveals a ~4 ppt decrease ~50 ka after peak PETM warming at Site 690. This negative SSS (δ18Osw) anomaly coincides with a prominent minimum in the planktic foraminifer δ18O record published for the Site 690 PETM section. Thus, our revised interpretation posits that this δ18O minimum signals a decrease in surface‐ocean δ18Oswfostered by a transient increase in mean annual precipitation in the Weddell Sea region. The results of this study corroborate the view that the poleward flux of atmospheric moisture temporarily increased during a distinctive stage of the PETM.
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Millennial-timescale thermogenic CO2 release preceding the Paleocene-Eocene Thermal Maximum
Abstract Geologic records support a short-lived carbon release, known as the pre-onset excursion (POE), shortly before the Paleocene-Eocene Thermal Maximum (PETM; ~ 56 Ma). However, the source and pace of the POE carbon release and its relationship to the PETM remain unresolved. Here we show a high-temporal-resolution stratigraphic record spanning the POE and PETM from the eastern Tethys Ocean that documents the evolution of surface ocean carbon cycle, redox and eutrophication, confirming the global nature of the POE. Biomarkers extracted from the sedimentary record indicate a smaller environmental perturbation during the POE than that during the PETM in the eastern Tethys Ocean. Earth system modeling constrained by observed δ13C and pH data indicates that the POE was driven by a largely thermogenic CO2source, likely associated with sill intrusions prior to the main eruption phase of the North Atlantic Igneous Province and possibly biogeochemical feedbacks involving the release of biogenic methane.
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- PAR ID:
- 10611267
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 16
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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