USAP-DC

Sediments deposited by the Antarctic ice sheet are an archive of its history with time and help geologists to determine how the remote interior of the ice sheet has changed over the past several hundred thousand years. This project will focus on the formation and dynamics of moraines (accumulations of dirt and rocks that are incorporated in the glacier surface or have been pushed along by the glacier as it moves) near the blue ice area of Mt. Achernar in the central Transantarctic Mountains in Antarctica.. The study will improve basic understanding of the formation of these moraines. Fieldwork at the site will focus on imaging the internal structure of the moraine to determine the processes by which it, and others like it, form over time. Additional analyses will include measurements of ice flow and collection of rock samples to determine the timing of debris deposition and the changes in the sources of sediments from deep within the Antarctic continent. The project will provide both graduate and undergraduate students training in paleoclimate studies, geology, and numerical modeling approaches. The broader impacts of the proposed work include hands on training in the Earth Sciences for graduate and undergraduate students, collaboration with colleagues in New Zealand and Sweden to provide an international research experience for students from the US, and three educational modules to be delivered by student researchers regarding Antarctica's role in global environments. The research is societally relevant and multidisciplinary and the topics are ideal for sharing with the public. All research findings will be made publicly available to others via timely publication in high-impact, peer-reviewed journals and all data will be submitted to the National Snow and Ice Data Center, and excess samples will be provided to the U.S. Polar Rock Repository.

Direct observations of ice sheet history from the margins of Antarctica's polar plateau are essential for testing numerical ice sheet models, and the laterally extensive, blue-ice moraines of the Mt. Achernar Moraine complex in the central Transantarctic Mountains contain a unique and nearly untapped direct, quasi-continuous record of ice sheet change over multiple glacial cycles. The project objectives include improved understanding of processes and rates of blue ice moraine formation, as well as identifying the topographic, glaciological, and climatic controls on their evolution. Data to be collected with fieldwork in Antarctica include: imaging of internal ice structure with ground-penetrating radar, measurement of ice flow velocity and direction with a global positioning system (GPS) array, analysis of debris concentration and composition in glacier ice, state-of-the-art cosmogenic multi-nuclide analyses to determine exposure ages of moraine debris, mapping of trimlines and provenance analysis. Numerical model simulations, constrained by field data, will be used to evaluate the factors influencing changes in glacier flow that potentially impact the accumulation of the moraine debris. All together, the new data and modeling efforts will improve conceptual models of blue ice moraine formation, and thereby make them a more valuable proxy for developing a better understanding of the history of the ice sheet.

Person	Role
Kaplan, Michael	Investigator and contact
Schaefer, Joerg	Investigator
Winckler, Gisela	Investigator
Licht, Kathy	Investigator and contact

Antarctic Earth Sciences	Award # 1443433
Antarctic Glaciology	Award # 1443433
Antarctic Earth Sciences	Award # 1443213
Antarctic Glaciology	Award # 1443213

USAP-1443433_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	10Be and 26Al cosmogenic nuclide surface exposure data	None	exists
USAP-DC	3He input data	None	exists

1. M.R. Kaplan, K.J. Licht, G. Winckler, J.M. Schaefer, N. Bader, C. Mathieson, M. Roberts, C.M. Kassab, R. Schwartz, J.A. Graly, 2017. Middle to Late Pleistocene stability of the central East Antarctic Ice Sheet at the head of Law Glacier. Geology (doi:10.1130/G39189.1)
2. Graly, J., Licht,K., Kassab,C., Bird,B., Kaplan, M., 2018. Sediment entrainment mechanisms and ice origin in an Antarctic blue ice moraine assessed through stable isotopes analyses and internal structures of shallow ice cores, Journal of Glaciology, 64, 185-196. (doi:10.1017/jog.2018.4)
3. Kassab, C.M., Licht, K.J., Pettersson, R., Lindback, K., Graly, J., Kaplan, M.R., Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica. Journal of Glaciology. 66, 49-60. (doi:10.1017/jog.2019.83)
4. Graly, J.A., Licht, K.J., Bader, N.A. and Bish, D.L., 2020. Chemical weathering signatures from Mt. Achernar Moraine, Central Transantarctic Mountains I: Subglacial sediments compared with underlying rock. Geochimica et Cosmochimica Acta, 283, pp.149-166. (doi:10.1016/j.gca.2020.06.005)