THE EFFECT OF DIAGENETIC PROCESSES ON THE RADIOCHRONOLOGY OF SOFT SEDIMENTS USING PB-210 AND CS-137

Core samples taken from North Lake, a brackish lake located in south L ouisiana, were used to compare radiochronological methods for soft sed iments. The radionuclides Cs-137 and Pb-210 were used to determine the ages of the core segments. The similarities in the vertical profiles of native lead and the radiolead suggested that diagenesis must be con sidered before accurate dares can be obtained. Correcting for the effe cts of diagenesis led to improved correlations with the Cs-137 dates a nd sedimentation rates. Sedimentation rates based on the corrected Pb- 210 dates were 0.234 g/cm(2) year compared to the value for Cs-137 Of 0.210 g/cm(2) year. (C) 1998 Academic Press.