Extended Data Fig. 9: 238U–234U–206Pb ages and concordance of 235U–207Pb ages for Ledyanaya Lenskaya Cave (based on Supplementary Table 1). | Nature

Extended Data Fig. 9: 238U–234U–206Pb ages and concordance of 235U–207Pb ages for Ledyanaya Lenskaya Cave (based on Supplementary Table 1).

From: Palaeoclimate evidence of vulnerable permafrost during times of low sea ice

Extended Data Fig. 9

Ages and age uncertainties are shown in black with the corresponding coloured error bar indicating the degree of concordance (235U–207Pb age as a percentage of the 238U–234U–206Pb age; blue horizontal line indicates perfect concordance) of the 235U–207Pb age. Blue error bars indicate the analysis is concordant within error. Orange error bars denote slightly discordant analyses, where the apparent discordance is likely due to common Pb correction on 207Pb. Red error bars denote analyses that are discordant with markedly low 235U–207Pb ages attributed to overcorrection of the common Pb due to a residual interference on 208Pb. The numbers and bars in red show the percentage bias in the 238U–234 U–206Pb ages if the discordance of these samples is attributed to an interference on 208Pb, based on the relative sensitivity of the 235U–207Pb and 238U–234U–206Pb ages to the common Pb correction (Supplementary Table 1). Grey horizontal lines indicate where ages replicate in two or more speleothems. The biases in the 238U–234U–206Pb ages attributed to the interference on 208Pb do not change these ages outside of error, hence, the tendency of these ages to replicate well in other samples. The discordance arises almost entirely from the 235U–207Pb ages (which are not used), due to their vastly greater sensitivity to over-correction of the common Pb than the 238U–234U–206Pb ages. Errors are 95% confidence. For each speleothem, the stratigraphic age of the dated layers increases from left to right.

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