Morgan Fries’21 Examines Devonian Black Shales
The diversification of terrestrial plants including the evolution of forests took place during the Devonian. Trees started growing taller, root systems were expanding, and seeds allowed expansion into upland settings. These forests would allow for more nutrients to be transported to the oceans through soil formation and nutrient release. The newly nutrient-rich oceans would stimulate the growth of algal blooms, which when they died and fell to the seafloor would lead to the depletion of oxygen and the creation of an anoxic environment, thus depositing black shales. Using these Devonian black shales, this project will examine how reliable outcrop organic geochemical data is for recording primary geochemical signatures and the potential of modern weathering to alter primary organic geochemical data. Specifically, the hypothesis to be tested is that outcrop data will not have the same geochemical characteristics as the core data due to weathering.
This project compares an organic geochemical dataset from a drill core through the Geneseo Formation from Lansing, New York with three nearby outcrops, two of which are highly weathered. Altogether, there are 80 samples, 70 of which are from the core and 10 of which are from outcrops. Methods utilized in this study include analysis of total organic carbon (TOC), δ13C of organic matter, and biomarker composition.