USAP-DC

Intellectual Merit: This project will yield new information on the long term Antarctic climate and landscape evolution from measurements of cosmogenic nuclides in quartz sand from two unique permafrost cores collected in Beacon Valley, Antarctica. The two cores have already been drilled in ice-cemented, sand-rich permafrost at 5.5 and 30.6 meters depth, and are currently in cold storage at the University of Washington. The cores are believed to record the monotonic accumulation of sand that has been blown into lower Beacon Valley and inflated the surface over time. The rate of accumulation and any hiatus in the accumulation are believed to reflect in part the advance and retreat of the Taylor Glacier. Preliminary measurements of cosmogenically-produced beryllium (10Be) and aluminum (26Al) in quartz sand in the 5.5-meter depth core reveal that it has been accreting at a rate of 2.5 meters/Myr for the past million years. Furthermore, prior to that time, lower Beacon Valley was most likely covered (shielded from the atmosphere thereby having no or very low production of cosmogenic nuclides in quartz) by Taylor Glacier from 1 to 3.5 Myr BP. These preliminary measurements also suggest that the 30.6 meter core may provide a record of over 10 million years. The emphasis is the full characterization of the core and analysis of cosmogenic nuclides (including cosmogenic neon) in the 30.6 meter permafrost core to develop a burial history of the sands and potentially a record the waxing and waning of the Taylor Glacier. This will allow new tests of our current understanding of surface dynamics and climate history in the McMurdo Dry Valleys (MDV) based on the dated stratigraphy of eolian sand that has been accumulating and inflating the surface for millions of years. This is a new process of surface inflation whose extent has not been well documented, and holds the potential to develop a continuous history of surface burial and glacial expansion. This project will provide a new proxy for understanding the climatic history of the Dry Valleys and will test models for the evolution of permafrost in Beacon Valley.

Broader impacts:

The landscape history of the McMurdo Dry Valleys is important because geological deposits there comprise the richest terrestrial record available from Antarctica. By testing the current age model for these deposits, we will improve understanding of Antarctica?s role in global climate change. This project will train one graduate and one undergraduate student in geochemistry, geochronology, and glacial and periglacial geology. They will participate substantively in the research and are expected to develop their own original ideas. Results from this work will be incorporated into undergraduate and graduate teaching curricula, will be published in the peer reviewed literature, and the data will be made public.

Person	Role
Sletten, Ronald S.	Investigator and contact
Stone, John	Co-Investigator

Antarctic Earth Sciences	Award # 1341680
Antarctic Instrumentation and Support	Award # 1341680

USAP-1341680_1

Deployment	Type
Ronald S Sletten	field camp

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Chemical and physical characterization of Beacon Valley and Victoria Valley permafrost cores	None	exists

1. Cuozzo, N., R. S. Sletten, Y. Hu, L. Liu, F.-Z. Teng and B. Hagedorn (2019). "Silicate weathering in antarctic ice-rich permafrost: Insights using magnesium isotopes." Geochimica et Cosmochimica Acta. (doi:10.1016/j.gca.2019.07.031)
2. Liu, L., R. S. Sletten, B. Hallet and E. D. Waddington (2018). "Thermal Regime and Properties of Soils and Ice‐Rich Permafrost in Beacon Valley, Antarctica." Journal of Geophysical Research: Earth Surface 123(8): 1797-1810. (doi:10.1029/2017JF004535)
3. Liu, L., R. S. Sletten, B. Hagedorn, B. Hallet, C. P. McKay and J. O. Stone (2015). "An enhanced model of the contemporary and long‐term (200 ka) sublimation of the massive subsurface ice in Beacon Valley, Antarctica." Journal of Geophysical Research: Earth Surface 120(8): 1596-1610. (doi:10.1002/2014JF003415)
4. Liu, L., Sletten, R. S., Hagedorn, B., Hallet, B., McKay, C. P., & Stone, J. O. (2015). An enhanced model of the contemporary and long-term (200 ka) sublimation of the massive subsurface ice in Beacon Valley, Antarctica. Journal of Geophysical Research: Earth Surface, 120(8), 1596–1610. (doi:10.1002/2014jf003415)
5. Liu, L., Sletten, R. S., Hallet, B., & Waddington, E. D. (2018). Thermal Regime and Properties of Soils and Ice‐Rich Permafrost in Beacon Valley, Antarctica. Journal of Geophysical Research: Earth Surface, 123(8), 1797–1810. (doi:10.1029/2017jf004535)