Dating of Polar Ice By 32Si

• Published in: Journal of Glaciology
• Main Author: Clausen, Henrik B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1973
• Subjects: Earth-Surface Processes; Greenland; glacier; Ice Sheet; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000031828; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000031828

32 Si dating of glacier ice has hitherto been complicated by the poor knowledge of the half life. Furthermore, fall-out of bomb-produced 32 Si impedes the determination of the specific activity of cosmic-ray produced 32 Si in recent precipitation. Measurements on well-dated pre-bomb samples from the Greenland ice sheet establish a calibration for 32 Si dating of up to 1 000 year old polar ice samples of the magnitude of 1 metric ton. If the technique is used on temperate glaciers, samples of pre-bomb deposits (or from after 1970) must be collected for comparison with samples of old ice, using an apparent half life of 295±25 years. Due to secular cosmic-ray flux variations, the true half life of 32 Si is estimated at the slightly higher value of 330±40 years.