Mercury isotope evidence for protracted North Atlantic magmatism during the Paleocene-Eocene Thermal Maximum

Abstract

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was a major hyperthermal event that has been linked to CO2 release from the North Atlantic Igneous Province (NAIP). Anomalously high sedimentary mercury (Hg) concentrations, a proxy for volcanism, have been recorded across the PETM, but the precise mechanistic links between NAIP emplacement and the event are unclear. Here, we present Hg abundance and Hg-isotope data across a thick, deep-marine sedimentary record deposited in close proximity to active NAIP volcanism. A marked transient shift of Δ199Hg towards higher values occurs within the PETM onset, indicating a causal link to extrusive volcanic activity from the NAIP. Increasing Δ199Hg values through the body of the PETM indicate a protracted interval of magmatism. Towards the end of, and after, the PETM the data suggest an overall waning influence of direct volcanogenic Hg outgassing. Our data can explain both the triggering mechanism and long duration of the PETM.