Samantha Davies
Pronouns: she/her/hers
Research Mentor(s): Sierra Petersen
Co-Presenter:
Research Mentor School/College/Department: Earth and Environmental Sciences / LSA
Presentation Date: April 20
Presentation Type: Poster
Session: Session 4 – 2:40pm – 3:30 pm
Room: League Ballroom
Authors: Samantha Davies, Sierra Petersen
Presenter: 88
Abstract
Studying past climate can help us understand how past CO2 relates to global warming and how organisms respond to a changing climate. To study mass extinctions, we must know what Earth was like before and after the extinction. We can uncover a baseline climate from before the end-Cretaceous Chicxalub impact and mass extinction by studying the chemistry of fossil shells collected from specific locations that span this boundary. In this project, we aim to determine ocean temperatures from the Cretaceous Gulf Coastal Plain during the Maastrichtian (72.1 to 66 Mya). We collected marine fossils from this time from a new K-Pg boundary site called Ellis Sand Pit (ESP) in Mississippi. We collected shells from 4 layers at ESP and analyzed 1 sample from each horizon for preservation under a scanning electron microscope (SEM). We chose at least 2 samples from each layer and powdered them, then measured the powder for clumped isotopes (?47) and stable oxygen and carbon isotopes (d18O, d13C). We then used the clumped isotope data to calculate ocean temperatures and combined this with shell d18O to determine the oxygen isotopic composition of seawater (d18Osw). Mean ocean temperatures ranged from 17 to 29°C with good agreement between 2 measured samples from each horizon and mean d18Osw was 0.21 ± 0.83‰ (1sd) on average. This new data will be compared to reconstructed temperatures from other K-Pg boundary sites near ESP that have existing clumped isotope data and to modern analog environments.
Environmental Studies, Interdisciplinary, Natural/Life Sciences
