Date of Award
M.S. in Engineering Science
Brian F. Platt
Jennifer N. Gifford
Inoka H. Widanagamage
University of Mississippi
Hyperthermals are periods of extremely rapid global warming. In order to understand the magnitude of hyperthermals, a more complete understanding of background conditions must be established. My goal is to study the paleoclimatic conditions that existed prior to the onset of Paleocene- Eocene hyperthermal events in order to establish background conditions. Relatively thick Paleocene and Eocene sedimentary units ideal for this study are present in the Mississippi Embayment (MSE), a major southwest- dipping sedimentary basin in the Gulf of Mexico coastal region of North America. The MSE contains an extensive record of Paleocene strata that were deposited prior to the onset of the Paleocene Carbon Isotope Maximum (PCIM), a gradual global warming event upon which various hyperthermals were superimposed upon. In order to evaluate pre-warming conditions, a core from the Paleocene age Naheola Formation (Fm) was selected. A suite of core description methods was performed including logging of visual observations, magnetic susceptibility, smear slide analysis, Scanning Electron Microscopy and Electron Dispersive x-ray Spectroscopy (SEM-EDS), and stable isotope analysis. Results indicate a >8-m-thick interval of 5 stacked paleosols associated with 4 lignite seams. Paleosols are hydric, representing waterlogged wetland soils. These paleosols alternate with lignites that represent variability in proximity to shore and cyclicity in relative sea level as a result of delta lobe switching. Stable isotope results indicate a temperature of ~20°C. The chemical index of alteration minus potassium (CIA-K) yields preliminary mean annual paleoprecipitation values of 1200-1300 mm/yr. X-ray Fluorescence (XRF) completed shows variability in physical vs. chemical weathering. XRF weathering proxies compared with their standard deviations indicate climate during this paleosol interval was stable and thus is suitable for describing prehyperthermal conditions.
Rathbun, Savannah Reese, "Determining Background Deep-Time Critical Zone Conditions in Mississippi Preceding the Onset of Paleocene-Eocene Hyperthermals" (2023). Electronic Theses and Dissertations. 2565.
Available for download on Saturday, September 13, 2025