- 1Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- 2CAS Center for Excellence in Quantum Information and Quantum Physics, School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- 3Department of Geosciences, Princeton University, Princeton, NJ, USA
- 4School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China
- 5College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
- 6Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- 7School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
- 8Scripps Institution of Oceanography (SIO), University of California, San Diego, La Jolla, CA 92037, USA
- 9School of Nuclear Science and Technology, Chinese Academy of Sciences, Lanzhou 730000, China
81Kr (t1/2=229 ka) is a valuable isotope for radiometric dating of water and ice with a dating range from thirty thousand to over one million years. It is produced by cosmic rays in the stratosphere, and uniformly distributed in the atmosphere with an isotopic abundance of 81Kr/Kr ~ 1 ×10-12. Based on laser cooling and trapping, the detection method Atom Trap Trace Analysis (ATTA) has enabled 81Kr analysis at the extremely low isotopic abundance levels in the environment. However, it has been a challenge to apply 81Kr dating on ice cores where sample size is limited. Here, we present the realization of an all-optical ATTA system, reducing cross-sample contamination during 81Kr analysis by two orders of magnitude. As a consequence, the sample size requirement reduces to 1 kg of ice and the upper dating limit is extended to 1.5 million years. Using the all-optical ATTA system, we demonstrate 81Kr dating of 1-kg ice core samples from Taylor Glacier, Antarctica, whose gas ages are precisely known from their stratigraphic alignment. Moreover, we have performed 81Kr analysis on basal ice samples of the GISP2 core, providing constraints on when Greenland Summit was most recently ice-free. The achieved sample size reduction facilitates 81Kr dating of ice-core sections to address open questions in paleoclimatology such as the evolution of glaciers on the Tibetan Plateau or the stability of the West-Antarctic ice sheet.
How to cite: Wang, J., Ritterbusch, F., Feng, X., Shackleton, S., Bender, M., Brook, E., Higgins, J., Jia, Z., Jiang, W., Lu, Z., Severinghaus, J., Sun, L., Yang, G., and Zhao, L.: 81Kr dating of 1 kg polar ice, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2317, https://doi.org/10.5194/egusphere-egu25-2317, 2025.
