Laura Hughson ’22 Compares Patterns of Marine Black Shale Organic Matter Composition

Laura Hughson ’22 is an Environmental Geology major working with thesis advisor Jay Zambito. She focuses on comparing local and regional patterns of marine black shale organic matter composition in the Devonian Appalachian Basin.

The evolution of forests during the Mid to Late Devonian (~375mya) drastically altered atmospheric composition, the Earth’s climate system and disrupted the carbon cycle. The newly evolved forests, it has been proposed from previous studies, increased nutrient and organic material runoff which led to ocean eutrophication. These anoxic conditions resulted in increased black shale deposition, global-scale climate change, and related extinctions. In order to better understand this process, the following hypotheses are being tested based on organic geochemical data collected from the two closely positioned cores from the western Appalachian Basin:1) the stratigraphic patterns observed in the two cores used for this study should closely reflect one another, and, 2) the stratigraphic patterns observed in the two cores will be similar to those observed in previous studies of correlative Appalachian Basin black shale.

The core samples used for this thesis come from the western side of the Appalachian Basin (Powell and Estill counties, Kentucky). X-ray fluorescence and loss-on-ignition will be used to determine elemental composition and organic matter content, respectively; this will provide a deeper understanding of lithology, conditions present during deposition, and aid in chemostratigraphy. Organic carbon isotopic analysis will be used to differentiate marine and terrestrial organic matter and therefore constrain organic matter fluxes into the depositional environment and reconstruct any changes in organic matter composition through time. The data from this study will contribute to a deeper understanding of previous anoxic conditions and also serve as a reference for understanding future anthropogenic disruptions to the carbon cycle.

By: Laura Hughson'22
July 20, 2022

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