Chlorine 36 fallout in the Summit Greenland ice core project ice core.

Journal of Geophysical Research, Vol. 102, No. C12, p. 26,659-26,662, 1997

S. Baumgartner, J. Beer
Environmental Physics, Swiss Federal Institue for Environmental Science and Technology. Dübendorf, Switzerland
M. Suter, B. Dittrich-Hannen
Institute for Particle Physics, Eidgenössische Technische Hochschule Hönggerberg, Zürich, Switzerland.
H.-A. Synal, P.W. Kubik
Paul Scherrer Institute,Villigen, Switzerland.
C.U. Hammer, H.B. Clausen,
Departement of Geophysics, The Niels Bohr Institute of Astronomy, Physics and Geophysics, University of Copenhagen..

ABSTRACT.
The natural cosmigenic radioisotope ³⁶Cl has been measured in the Greenland Ice Core Project ice core from Summit, Greenland. Generally, a good correlation between ³⁶Cl and δ¹⁸O was found, even in glacial periods with strong δ¹⁸O oscillations. The ³⁶Cl flux is calculated assuming an exponential relationship between accumulation rate and δ¹⁸O. A prominent excursion is detected between 35 and 40 kyr B.P., which coincides with a similar ¹⁰Be peak measured in the same samples. This sheds light on possible causes of the excursion. In the lowest part of the ice core the flux decreses smoothly. This can be interpreted as radioactive decay of ³⁶Cl (T_1/2 = 300 kyr).