Spatiotemporal distribution of global mercury enrichments through the Paleocene-Eocene Thermal Maximum and links to volcanism

Mercury (Hg) concentrations and Hg isotopes have been widely used to fingerprint geological volcanism. Mercury content, as a more accessible proxy, is more frequently used than mercury isotopes. With the deepening of research, however, it has been found that the Hg content of sediments can be strongly heterogeneous. The Paleocene–Eocene Thermal Maximum (PETM) was likely at least in part driven by magmatic activity based on multiple proxies, but existing PETM Hg records can be complex and sometimes ambiguous. To gain a global overview of the temporal and spatial distribution of Hg enrichment during the PETM, a compilation of new and existing mercury and associated data across this event from 19 globally distributed sites has been analyzed. Our findings indicate intercontinental Hg enrichment in the late Paleocene (∼120 kyr prior to the PETM). Hg further increased ∼30 kyr before, and within the onset of, the PETM carbon isotope excursion (CIE), supporting significantly increased volcanic Hg release and/or thermogenic Hg release via hydrothermal vent complexes (HTVCs) as the key trigger of the PETM. Evidence for magmatic activity during the CIE body is more complex and equivocal, and there is a general decline in Hg enrichment in the latter part of CIE body. This decline may indicate a decrease in volcanism, in-line with the general lack of tephra deposits close to the NAIP, and implies a decrease in highly explosive events capable of dispersing ash (and Hg) significant distances. Toward the end of and after the CIE, abundant tephras in the area proximal to the NAIP are contemporaneous with low Hg, suggesting a likely change in magmatic style and Hg flux, and emphasizing complexity in the expression of magmatism in sedimentary Hg data.