Results of alternate tuning experiments using (1) the original sapropel midpoints only, (2) sapropel mid-points and Pb isotope 'peaks' based on the 206Pb/204Pb record, and (3) based on only the 206Pb/204Pb 'peaks.'

Empty age column means there are no new tuning point data. Comment parameter meaning: Star - samples not run for Pb isotopes, used here for age-depth comparison; MP - sapropel mid-point: Contact - contact between two lithologies, used in time series figures to draw lithological boundaries.