CHLORINE-36 FALLOUT IN THE SUMMIT GREENLAND ICE CORE PROJECT ICE CORE

The natural cosmogenic radioisotope Cl-36 has been measured in the Gre enland Ice Core Project ice core from Summit, Greenland. Generally, a good correlation between Cl-36 and delta(18)O was found, even in glaci al periods with strong delta(18)O oscillations. The Cl-36 flux is calc ulated assuming an exponential relationship between accumulation rate and delta(18)O. A prominent excursion is detected between 35 and 40 ky r B.P., which coincides with a similar Be-10 peak measured in the same samples. This sheds light on possible causes of this excursion. In th e lowest part of the ice core the flux decreases smoothly. This can be interpreted as radioactive decay of Cl-36 (T-1/2 = 300 kyr).