OCEAN, ATMOSPHERE, LAND: ASSESSING THE SOURCE(S) OF MERCURY TO SEDIMENTS ACROSS THE PALEOCENE-EOCENE THERMAL MAXIMUM

The Paleocene-Eocene Thermal Maximum (PETM) is an extreme global warming event that occurred ~56 Ma. It is indicated by a negative carbon isotope excursion due to the release of ¹³C-depleted carbon into the ocean-atmosphere system. A plethora of ideas regarding the source(s) of these carbon emission continues to be debated. The coincident emplacement of a large igneous province (LIP), the North Atlantic Igneous Province (NAIP), however, has placed massive volcanism at the forefront of this debate. Recently, sedimentary mercury (Hg) contents have been used as a novel tool to track ancient volcanic activity during the PETM. It is suggested that the PETM sedimentary Hg anomalies were a function of direct volcanogenic outgassing or proximity to the NAIP. Mercury is transported to oceans through a variety of processes (weathering, soil loss, biomass burning), and these other delivery mechanisms must be considered when determining controls on Hg anomalies. Furthermore, Hg is redox-sensitive and local redox conditions should also be determined in order to provide context during interpretation. Here, we assess the morphology of Hg chemostratigraphic trends from a basin transect of sites in the New Jersey Coastal Plain. We also provide for the first time a high-resolution Hg analysis of paleosols from the Bighorn Basin in Wyoming.

In New Jersey, the PETM is represented by the Malboro Formation, a silty to clayey unit that contrasts greatly with the lithology of the underlying and overlying formations. From this basin transect we will provide Hg data from proximal environments to more distal deep-water environments. This will help determine any relationship between sedimentary Hg concentrations and distance from land. In Wyoming, the PETM is recorded in vertically stacked mudstone paleosols of the Willwood Formation. Rapid deposition in this fluvial setting provides and expanded stratigraphic record of changing Hg concentration, much of which may have been deposited directly from the atmosphere. This study aims to produce high-resolution Hg datasets from different sedimentary environments in order to better understand the controls on Hg cycling across the PETM with the eventual goal of constraining the mechanism(s) of carbon release.