Cosmogenic 36Cl and 10Be in the WAIS Divide ice core from 6-21 kyr BP

Cosmogenic nuclides such as 10Be and 36Cl, produced in the atmosphere by spallation reactions of primary and secondary cosmic ray particles with atoms in the atmosphere, are deposited to the surface with precipitation and stored in glacial ice sheet archives. The final concentration of these nuclides in the ice is dependent upon a number of factors including variations in solar activity, strength of the geomagnetic field, atmospheric transport patterns and snow accumulation rates. Although 10Be is the most commonly measured cosmogenic isotope in ice cores, the measurement of a single isotope may not be sufficient to disentangle these factors. Here we present measurements of 10Be and 36Cl from the West Antarctic Ice Sheet (WAIS) Divide ice core from approximately 6-21 kyr BP. Owing to the differing production rates of 10Be and 36Cl as a function of cosmic ray energy, changes in their ratio may provide information about changes in solar activity in the past. We will also compare this ratio to the accumulation rate at WAIS Divide in order to investigate differences in deposition between the two isotopes. This work was supported by NSF grants ANT-0839042 and 0839137.