Assessing volcanism during the PETM based on mercury isotope and abundance data

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was an abrupt hyperthermal event that has been linked to carbon release from volcanism associated with the North Atlantic Igneous Province (NAIP). Anomalously high sedimentary mercury (Hg) concentrations, a proxy for volcanism, have been recorded across the PETM from some locations, supporting this link. Nevertheless, Hg concentration data alone offer little insight into emplacement mechanisms and carbon source(s), and can be influenced by depositional conditions and post-depositional alteration. To help address this issue, and more critically evaluate the efficacy of Hg as a volcanism proxy, Hg-isotope data have been obtained across a thick, deep-marine sedimentary record of the PETM from the North Sea that was deposited in close proximity to active NAIP volcanism. These data are combined with a new global compilation of Hg concertation data across the PETM, which includes new Hg concentration data obtained from five globally distributed sites. Analysis of all the data demonstrates extensive and at least intercontinental Hg enrichments during the onset of the PETM carbon-isotope excursion, and that this was related to a major transient pulse of extrusive volcanism. Hg-isotope data support protracted volcanism through the PETM, but the evidence for sustained Hg enrichment from volcanism through the entirety of the PETM is equivocal. Towards the end of, and after, the PETM, the data suggest an overall waning influence of volcanogenic Hg.