An in Situ Gas-Extraction System to Radiocarbon Date Glacier Ice

Abstract

A new down bore-hole instrument to extract atmospheric gases entrapped in glacier ice was designed, developed and tested in a Greenland ice tunnel. Using this ice and a 7.5 kW. source, about 30 hr. are required to melt the approximately 1 metric ton sample, extract the gases, and to separate and collect with molecular sieves the minimum of 100 cm. 3 of CO 2 necessary for the 14 C measurements made later using special low-level counters. Age results using the down bore-hole CO 2 samples agree with results obtained earlier from CO 2 samples collected at the same tunnel location using a vacuum-vessel melting technique. A mean value of 5,120±200 yr. b.p. is obtained for the seven samples measured using both collection systems, making this the oldest natural polar glacier ice measured to date.