Semester of Graduation
Summer
Degree
Master of Oceanography and Coastal Sciences (SOCS)
Department
Oceanography and Coastal Sciences
Document Type
Thesis
Abstract
The Cretaceous-Paleogene (K/Pg) event caused the extinction of many species in the ocean and on land. Varying rates of plankton survival and puzzling changes in the marine carbon cycle recorded in proxy records are of particular interest to paleoclimatologists, as are the seemingly rapid temperature changes recorded after the extinction event. This thesis uses the Community Earth System Model (CESM) to simulate the Chicxulub asteroid impact, which is thought to be the cause of the K/Pg extinction. The model was used to simulate the Maastrichtian Age ocean, and results were analyzed to understand pre-impact plankton dynamics and their agreement with proxy data. Different sets of impact forcings were used to assess possible changes in ocean productivity, export, and carbon isotope values. Forcings showed that the impact led to significant cooling that increased ocean nutrient availability, leading to a significant spike in net primary productivity. Post-impact changes in particulate organic carbon export were variable, but in simulations where CO2 emissions from impact were highest, export was lowest. Warming oceans associated with high CO2 also caused increases in small phytoplankton (pico- and nanoplankton) productivity and decreases in diatom productivity. Alterations in the δ13C value of atmospheric carbon forced by wildfire emissions drive negative excursions in surface δ13Ccarbonate and δ13Corg consistent with proxy evidence, but questions remain around the how the δ13Corg excursion was resolved while the δ13Ccarbonate excursion continued during the same period.
Date
7-16-2024
Recommended Citation
Tessler, Maya E., "A model-proxy analysis of plankton dynamics across the Cretaceous-Paleogene boundary" (2024). LSU Master's Theses. 6022.
https://repository.lsu.edu/gradschool_theses/6022
Committee Chair
Harrison, Cheryl
