Sedimentology and Carbon Isotopes of the Jefferson Formation (Late Devonian), Bridger Mountains, Montana (2025)

The Devonian Period (419.2-358.9Ma) was an interval of significant change in the Earth’s history with the proliferation of land plants and a shift to icehouse conditions. Many of these global changes impacted the carbon cycle. One primary method for identifying perturbations to the global carbon cycle is by using carbon isotopes. However, these records can potentially be influenced by local environmental factors and/or altered by diagenetic processes. The goal of this study is to better understand the relationship between dolomitization, depositional environments, and carbon isotopes in the Jefferson Formation. These results will help us distinguish between primary carbon isotopic trends and those influenced by dolomitization. To accomplish this task, we focused on the Jefferson Formation exposed in the Bridger Mountains of Montana. We measured rock, collected geochemical samples, and identified seven facies associations. By studying trends, we explore the relationship between carbon isotopes, facies associations, and dolomitization.