CALIBRATION AND APPLICATION OF THE MERCURY GEOCHEMICAL PROXY IN LONGNOSE GAR SCALES: RESOLVING THE DRIVER OF THE PALEOCENE-EOCENE THERMAL MAXIMUM

The Paleocene-Eocene Thermal Maximum (PETM) is an interval associated with a geologically sudden release of carbon to the ocean-atmosphere around 56 million years ago. The carbon release caused a host of changes to marine and continental ecosystems. As a result, the PETM is widely considered the closest geological analog for climate change, which makes understanding its causes and consequences an important area of study. Recent research suggests that much of the carbon that caused the PETM was derived from the emplacement of the North Atlantic Igneous Province (NAIP), evidenced by high concentrations of mercury (Hg) in PETM sediments. The biogeochemical cycling of Hg is, however, complex; it is cycled through Earth’s surface environments from volcanoes, wildfires, and changes in floral communities, all of which varied during the PETM. Further, enhanced Hg loading also has toxic effects on floral and faunal communities. To better understand the cause of the PETM and the potential effects of Hg on PETM ecosystems, we will present Hg concentration data from modern gar tissues and scales, fossilized gar scales from the garfish Lepisosteouscollected from the Bighorn Basin CAB-10 section, as well as paleosols from the CAB-10 section. This study will allow us to 1) quantify if any relationship exists between Hg concentrations in gar scales and tissue, 2) determine if environmental loading of Hg occurred during the PETM, and 3) what the potential sources of Hg were to the Bighorn Basin.