VERY-LOW OXYGEN CONCENTRATION IN BASAL ICE FROM SUMMIT, CENTRAL GREENLAND

Oxygen concentration as low as 3% has been detected in the basal silty ice of the GRIP core. Such values were never observed in ice from ice sheets. They are most probably the consequence of organic matter oxid ation in ice developed in a peaty deposit when the Greenland Ice Sheet was not present at the site. Flow-induced mixing has further incorpor ated this ice into glacier ice during the ice sheet build up. The part of the local ice component in the mixing process diminishes with the distance from the bed. This is the process which explains the oxygen p rofile.