USAP-DC

Nontechnical Description Glacier ice loss from Antarctica has the potential to lead to a significant rise in global sea level. One line of evidence for accelerated glacier ice loss has been an increase in the rate at which the land has been rising across the Antarctic Peninsula as measured by GPS receivers. However, GPS observations of uplift are limited to the last two decades. One goal of this study is to determine how these newly observed rates of uplift compare to average rates of uplift across the Antarctic Peninsula over a longer time interval. Researchers will reconstruct past sea levels using the age and elevation of ancient beaches now stranded above sea level on the low-lying coastal hills of the Antarctica Peninsula to determine the rate of uplift over the last 5,000 years. The researchers will also analyze the structure of the beaches using ground-penetrating radar and the characteristics of beach sediments to understand how sea-level rise and past climate changes are recorded in beach deposits. The benefits of these new records will be threefold: (1) they will help determine the natural variability of the Antarctic Ice Sheet and relative sea level (2) they will provide new insight about uplift and the structure of the Earth's interior; and 3) they will help researchers refine the methods used to determine the age of geologic deposits. The study results will be shared in outreach events at K-12 schools and with visitors of the Santa Barbara Natural History Museum. Three graduate students will be supported through this project. Technical description Paleo sea-level data is critical for reconstructing the size and extent of past ice sheets, documenting increased uplift following glacial retreat, and correcting gravity-based measurements of ice-mass loss for the impacts of post-glacial rebound. However, there are only 14 sites with relative sea-level data for Antarctica compared to over 500 sites used in a recent study of the North American Ice-Sheet complex. The purpose of this project is to use optically stimulated luminescence to date a series of newly discovered raised beaches along the eastern Antarctic Peninsula and an already known, but only preliminarily dated, series of raised beaches in the South Shetland Islands. Data to be collected at the raised beaches include the age and elevation, ground-penetrating radar profiles, and the roundness of cobbles and the lithology of ice-rafted debris. The study will test three hypotheses: (1) uplift rates have increased in modern times relative to the late Holocene across the Antarctic Peninsula, (2) the sea-level history at the northern tip of the Antarctic Peninsula is distinctly different than that of the South Shetland Islands, and (3) cobble roundness and the source of ice-rafted debris on raised beaches varied systematically through time reflecting the climate history of the northern Antarctic Peninsula.

Person	Role
Simms, Alexander	Investigator and contact
Theilen, Brittany	Researcher
Gernant, Cameron	Researcher
DeWitt, Regina	Co-Investigator

Antarctic Earth Sciences

Award # 1644197

USAP-1644197_1

Deployment	Type
Alexander Simms	field camp

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Granulometry of Joinville and Livingston Island beaches	Not Provided	exists
USAP-DC	Electron Microprobe Analysis of feldspar separates from rock and sediment OSL samples from Joinville and Livingston Island Beaches	Not Provided	exists
USAP-DC	OSL data - Joinville and Livingston Islands - Raw data	Not Provided	exists
USAP-DC	Joinville and Livingston Islands - rock and sediment OSL ages	Not Provided	exists
USAP-DC	Ground Penetrating Radar Profiles from Beaches on Joinville Island, Antarctic Peninsula	None	exists
USAP-DC	Ground-Penetrating Radar data from Livingston Island in the Antarctic Peninsula	None	exists
USAP-DC	Radiocarbon Ages from Beaches on Joinville Island, Antarctic Peninsula	None	exists

1. Zurbuchen, J. and Simms, A.R., 2019. Late Holocene ice-mass changes recorded in a relative sea-level record from Joinville Island, Antarctica. Geology, v. 47, p. 1064-1068. (doi:10.1130/G46649.1)
2. Simms, A.R., Whitehouse, P.L., Simkins, L.M., Nield, G., DeWitt, R., and Bentley, M.J., 2018. Late Holocene relative sea level near Palmer Station, northern Antarctic Peninsula, strongly controlled by late Holocene ice-mass changes. Quaternary Science Reviews, v. 199, p. 49-59 (doi:10.1016/j.quascirev.2018.09.017)
3. Simms, A.R., Bentley, M.J., Simkins, L.M., Zurbuchen, J., Reynolds, L.C., DeWitt, R., and Thomas, E.R., 2021. Evidence for a "Little Ice Age" glacial advance within the Antarctic Peninsula - Examples from glacially-overrun raised beaches. Quaternary Science Reviews, v. 271, p. 107195. (doi:10.1016/j.quascirev.2021.107195)