14C dating of trapped gases in massive ground ice, western Canadian Arctic

Abstract

A recently developed technique of gas extraction enables dating of an ice body by measuring the 14C of the CO2 trapped in gas bubbles within the ice. The gaseous component of the ice is extracted by sublimating the ice within a vacuum chamber. This enables the total gas volume, CO2 concentration, 14C/12C ratio, and d13C values to be determined. This technique was applied to dating massive ground-ice bodies in the western Canadian Arctic. Ground-ice samples from North Point, Peninsula Point, and Herschel Island yielded ages of 10 500±120 BP, 13 860±100 BP, and 17 570±300BP, respectively. These ages are younger than previously speculated for the massive ground ice in this region. The gas and CO2 contents and d13C values indicate the ice bodies were not formed directly from the compaction of snow.