Extended Data Fig. 8: Standard reproducibility for Pb isotopes.
From: Sampling the volatile-rich transition zone beneath Bermuda
Recommended USGS standard values (BHVO-2, AGV-2 and BCR-2) compared with standards run during this study for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb. Recommended standard values are from refs 63,82 and the most recent GEOREM preferred values. We did not leach any of our standards. It is important to note that ref. 63 reports that all the USGS standards are variably contaminated during processing, and therefore we plot the residues and leachate data for these USGS standards. a, b, Pb isotopes for BHVO-2 showing that our 206Pb/204Pb ratios are within error of the other values, but our 207Pb/204Pb ratios are lower than those in refs 63,82, yet within error of the GEOREM recommended values and the residues of leaching from ref. 63. In ref. 63 it was noted that the BHVO-2 and BHVO-1 are contaminated and that, upon leaching, their residues converge. c, d, Pb isotopes for AGV-2 showing that our data are within error of those in ref. 63 and the GEOREM recommended values. On the basis of AGV-2, our Pb isotope data are both accurate and highly precise (the duplicates overlap on the symbol size). e, f, Pb isotopes for BCR-2 showing that our 207Pb/204Pb values are identical to those of refs 63,82. As in the BHVO-2, our data are closer to the residues of leaching reported in ref. 63. Ours and literature data plot on a mixing line with the residues of leaching for BCR-2 being highly variable, pointing to heterogeneity in these standards.
