Publication Date

Spring 5-8-2023

Document Type

Dissertation/Thesis

First Advisor

Scherer, Reed

Degree Name

B.S. (Bachelor of Science)

Department

Department of Geology and Environmental Geosciences

Abstract

Because of ever rising temperatures driven by anthropogenic climate change, much attention has been given to the West Antarctic Ice Sheet (WAIS) by the scientific community. This is due to its sensitivity to global climate change and vulnerability for collapse as evidenced by Pleistocene interglacial events. Paleotemperature estimates from the Amundsen Sea are crucial for understanding how global temperature changes impacted WAIS throughout the Pleistocene. Marine Isotope Stage 5 (MIS 5) is of particular interest as it contains different substages and intervals of fluctuating temperatures. This period also is estimated to have had temperatures equal to, or slightly higher than the modern averages.

Paleotemperature estimates can be derived from diatom morphometrics. The two dominant morphotypes of the diatom Fragilariopsis kerguelensis that exist in the Amundsen Sea and Southern Ocean can be utilized to indicate Sea Surface Temperatures (SSTs). This is based on whether high rectangularity or low rectangularity morphotypes are the dominate F. kerguelensis valves present in the interval assemblages. In this study, F. kerguelensis specimen

from MIS 5 were used to calculate paleotemperatures by processing images through SHERPA (Shape Recognition, Processing, and Analysis) which analyzed the rectangularity of diatom frustules. These temperatures estimates were compared to other previous work and proxies. There is some variability between the results of this study and previous work, nonetheless temperature fluctuations throughout the stage are evident and substages are apparent through this method.

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