Using in situ 14C to unravel complex exposure histories along the David Glacier, Antarctica

Understanding the past Antarctic Ice Sheet (AIS) is critical to forecast the impacts of future of the AIS and its contribution to sea level rise. Ice sheet models constrained by geological data provide improved confidence in future projections. Both marine and terrestrial geologic data are required for a robust reconstruction of both the extent and thickness of the AIS. On land, cosmogenic nuclides have transformed the ability to constrain reconstructions of the past AIS through time. Highresolution, low-inheritance chronologies focused on large outlet glaciers provide enhanced understanding on the timing, rate and potential mechanisms driving past ice sheet change. Using the ‘glacial dip stick’ approach at each site, we sample glacial debris and bedrock from the local peak down to the modern ice surface. While field sampling strategies and analytical capability continues to improve, ‘complex’ exposure histories remain a common occurrence in practice. Inheritance, or a signal of cumulative exposure, can arise due to burial by cold-based, non-crosive nature of the AIS. At Mt. Kring along the upper David Glacier, previous studies show a distinct mid-Holocene signal of glacier thinning as well as at least two populations of apparent older glacial thinning events. Here, we use 14C measurements on samples suspected of having an inherited signal. We show that samples with >30 ka 10Be exposure ages indeed carry a mid-Holocene 14C exposure age and improve the existing thinning history. This multi-nuclide comparison approach provides a preliminary data set to bolster previous and emerging studies where complex exposure histories occur around Antarctica. © The Authors

Keywords

Carbon 14, Antarctica, Glaciers, Ice, Isotopes, Rocks, Quaternary period

Citation

Stutz, J., Fülopm R., Norton, K., Mackintosh, A., Whitemore, R., Yang, B., & Smith, A. (2021). Using in situ 14C to unravel complex exposure histories along the David Glacier, Antarctica. Paper presented to the 15th International Conference on Accelerator Mass Spectrometry. ANSTO Sydney, Australia. November 15th – 19th, 2021, (pp. 59). Retrieved from: https://ams15sydney.com/wp-content/uploads/2021/11/AMS-15-Full-Program-and-Abstract-Book-R-1.pdf

URI

https://ams15sydney.com/wp-content/uploads/2021/11/AMS-15-Full-Program-and-Abstract-Book-R-1.pdf
https://apo.ansto.gov.au/dspace/handle/10238/14414

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