Speaker
Description
Paleoclimate reconstructions from ice core records can be hampered due to the lack of a reliable chronology, especially when the stratigraphy is disturbed and conventional dating methods cannot be readily applied. The noble-gas radioisotopes 81Kr and 39Ar can in these cases provide robust constraints as they yield absolute, radiometric ages. 81Kr (half-life 229 ka) covers the age range of 30 – 1,300 ka, a time span particularly relevant for polar ice cores; 39Ar (half-life 268 a) covers 50 – 1,600 a, and is suitable for alpine glaciers. We have developed the Atom Trap Trace Analysis (ATTA) method to analyze both radio-isotopes in ice core samples [1].
81Kr dating, using 5 – 10 kg of ice for each analysis, was recently applied to samples from the TALDICE ice core [2] and the Larsen Blue ice area [3], Antarctica. 39Ar dating, using 2 - 5 kg of ice for each analysis, was applied to an ice core from the central Tibetan Plateau [4]. These works demonstrate how 81Kr and 39Ar can provide age constraints and complement other methods in developing ice core chronologies.
By implementing new laser-atom techniques, the ATTA method continues to reduce the required sample size, improve the dating precision, and expand the age range coverage. Here, we present our latest advances towards the goal of 81Kr and 39Ar dating with ~ 1 kg of ice.
For more information, please search “ATTA primer” or visit:
http://atta.ustc.edu.cn/en-us/events/attaprimer.html
References:
[1] Z.-T. Lu et al., Tracer applications of noble gas radionuclides in the geosciences. Ear. Sci. Rev. 138, 196-214 (2014).
[2] I. Crotti et al., An extension of the TALDICE ice core age scale reaching back to MIS10.1. Qua. Sci. Rev. 266:107078 (2021).
[3] G. Lee et al., Chronostratigraphy of blue ice at the Larsen Glacier in Northern Victoria Land, East Antarctica. Cryosphere Discuss., under review.
[4] F. Ritterbusch et al., A Tibetan ice core covering the past 1,300 years radiometrically dated with 39Ar, under review.
