Earth and Planetary Sciences ETDs

Publication Date

Summer 7-15-2019


The Western Interior Seaway (WIS) remains an oceanographic enigma, including its circulation, similarity to the open ocean, and the fidelity of geochemical proxies to reconstruct paleoenvironments. Across the late Campanian and early Maastrichtian I test whether: 1) the WIS had unique δ18OVPDB compared to other marine settings, 2) increasing oceanographic restriction changed the stable isotope composition, and 3) biases, e.g., taxonomy or diagenesis, influenced stable isotope compositions. Results indicate distinct δ18OVPDB in the WIS compared to other marine settings. δ18OVPDB values were stable through time, suggesting insignificant oceanographic restriction and a maintained open-ocean connection despite marine regression. The spread of δ18OVPDB values suggests that mixing of multiple isotopically distinct water bodies in combination with changing evaporation regimes may strongly influence ocean chemistry. Therefore, interpretation of δ18OVPDB in WIS carbonates as a paleotemperature proxy should be done cautiously and the isotopic composition of mixing water bodies must be considered.

Degree Name

Earth and Planetary Sciences

Level of Degree


Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Dr. Corinne Myers

Second Committee Member

Dr. Viorel Atudorei

Third Committee Member

Dr. Jason Moore




Campanian, Maastrichtian, Oxygen Isotopes, Diagenesis, Multiple Linear Regression, Vital Effects, Oceanographic Setting, Restricted Epicontinental Seaway, Carbon Isotopes, Mollusks

Document Type