C-14 DATING OF TRAPPED GASES IN MASSIVE GROUND ICE, WESTERN CANADIAN ARCTIC

A recently developed technique of gas extraction enables dating of an ice body by measuring the C-14 of the CO2 trapped in gas bubbles withi n the ice. The gaseous component of the ice is extracted by sublimatin g the ice within a vacuum chamber. This enables the total gas volume, CO2 concentration, C-14/C-12 ratio, and delta(13)C values to be determ ined. This technique was applied to dating massive ground-ice bodies i n the western Canadian Arctic. Ground-ice samples from North Point, Pe ninsula Point, and Herschel Island yielded ages of 10,500+/-120 BP, 13 ,860+/-100 sp, and 17,570+/-300 sp, respectively. These ages are young er than previ ously speculated for the massive ground ice in this regi on. The gas and CO2 contents and delta(13)C values indicate the ice bo dies were not formed directly from the compaction of snow.