- Webb Hall 1025
Lauren Simkins will present her PhD defense entitled "Antarctic raised beaches: Insight on geochronology, relative sea level, and coastal processes."
Beaches are preserved above sea level along ice-free portions of the Antarctic coastline due to post-glacial rebound associated with glacial isostatic adjustment since the Last Glacial Maximum. The ages and elevations of these beaches provide relative sea-level constraints for glacial isostatic adjustment models and ice-sheet histories. Due to harsh field conditions and difficulty dating Antarctic materials, a lack of geochronological constraints on raised beaches limits our understanding of relative sea level around Antarctica. The focus of the studies discussed here is on Antarctic raised beaches with goals to improve the methods of dating cobble surfaces from raised beaches using optically stimulated luminescence and use the dated beaches to reconstruct relative sea level and better understand Antarctic coastal processes throughout the Holocene. Through a series of cleaning methods applied to sample carriers used for optically stimulated luminescence measurements of sediment, the contamination of dose-dependent, variable signals from sample carriers previously assumed to have neutral signals is eliminated through a series of cleaning methods. An analysis of optically stimulated luminescence characteristics with sample petrology and cathodoluminescence provides insight on the suitability of Antarctic materials for optically stimulated luminescence dating. A relative sea-level history of Marguerite Bay, Antarctic Peninsula derived from optically stimulated luminescence-dated beach cobble surfaces further constrains post-glacial rebound since the Last Glacial Maximum. The temporal distribution of circum-Antarctic raised beaches throughout the Holocene is utilized to determine the relationship between wave-energy, sea ice, and coastal evolution. The findings of these studies focused on Antarctic raised beaches have implications for understanding sea-level, glacial isostatic adjustment, ice-sheet histories, and coastal processes since the Last Glacial Maximum.