Analysis of Fossil Pollen from a Pleistocene Cypress Forest Preserved on the Northern Gulf of Mexico Continental Shelf

<p>This study presents the findings of fossil pollen analysis performed on terrestrial sediments preserved on the northern Gulf of Mexico continental shelf (site hereafter known as the Underwater Forest or DF). This research aims to establish vegetation composition on a continental shelf glacial refuge and provide a better understanding of vegetation response to sea-level rise. Two cores (15DF1 and 15DF3B) located at different locations within the forest were recovered and analyzed. Pollen results from both cores were similar, with high percentages of <em>Taxodium </em>and <em>Nyssa </em>pollen in the lowermost sections reflecting an assemblage typical of contemporary baldcypress swamps. Pollen assemblages then shift in both cores, as Poaeceae becomes dominant in the upper sections. I interpret this as a transition from a baldcypress swamp to more open coastal marsh as marine transgression occurs. During the marsh period in both cores, <em>Alnus</em> becomes a major taxon. This rise in <em>Alnus </em>occurs with high percentages of <em>Taxodium </em>in Core 15DF1, but occurs with high percentages of <em>Poaceae</em> in Core 15DF3B, possibly indicating localized differences. Radiocarbon dates of 15DF1 revealed an age of 45,210 cal a BP placing the core in Marine Isotopic Stage (MIS) 3. An extrapolated optically-stimulated luminescence (OSL) date from a sister core to 15DF3B, revealed an age of 72,000 years (early MIS 4 or 5). However, the pollen results from both cores indicate that the peat sections have recorded the same event in the paleoenvironment, making additional dates necessary to establish more reliable time control.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2022

Author dc:creator

• Garretson, Kathryn Joyce

Contributors dc:contributor

• Dr. Carl Andy Reese
• Dr. David Cochran
• Dr. Thomas Patterson

• Fossil
• Pollen
• Cypress
• Pleistocene
• Forest
• Climate
• Glaciology
• Oceanography
• Paleontology

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/893

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1956