ESR ages and trace elements in a fossil mollusc shell

The distribution of U, Th, and other impurities in a fossil mollusc shell was obtained by laser ablation inductively coupled plasma mass spectrometry (ICP-MS). At the same time the ESR signal was measured for the shell and the values of total dose (TD) were obtained. The A (g = 2.0058) and B (g 2.0033) signal intensities vary greatly in different positions of the shell and have an inverse correlation with the distribution pattern of U concentration. The variation of C (g = 2.0009) and D (g = 1.9976) signals was much smaller however, and had closer correlation with U content. The ESR age of the shell was determined to be 114 ± 16 ka with the correction for the U distribution. (author)