Radio-carbon age and oxygen 18 content of Greenland icebergs

Abstract

The main objective of the Arctic Institute Greenland Expedition 1958 was (a) to determine the composition and age of ancient atmosphere trapped in glacier ice, and (b) to seek information regarding age and origin of the icebergs. All operations were performed on board a Norwegian sealing vessel equipped with deck laboratory, machine shop, and vacuum boilers for processing large quantities of ice. By melting 6 to 16 tons of the iceberg ice, sufficient CO2 from the gas enclosures was vacuum extracted and collected for one radio-carbon dating. Melt water was sampled at the same time for oxygen-18 determinations. Ice with perfectly homogeneous composition was never encountered, however, so some process, like melting and possibly organic contamination, must have slightly changed the entrapped air. The age of the ice ranged from recent to over 3000 years, with the oldest ice having the least oxygen-18; i. e., it was formed at the lowest temperatures, thus highest up and furthest inland.

Most samples had originated relatively near the coast, and only three out of our eleven samples were formed 200 km or more inland. The overall rate of movement of the ice, calculated from age and distance, ranged between 110 and 270 m/year, which is in reasonable agreement with estimates by other authors in regard to icebergs formed not too far from the coast. Our data from separate flow systems indicate that simultaneous carbon-14 and oxygen-18 determinations may yield valuable flow information, especially so if applied to single drainage systems.