Table 1 Lead and Sr isotopic ratios of Archaean limestones with the low 87Sr/86Sr of coeval seawater.

From: Marine Carbonates in the Mantle Source of Oceanic Basalts: Pb Isotopic Constraints

Sample

206Pb/204Pb

207Pb/204Pb

208Pb/204Pb

87Sr/86Sr

87Sr/86Sr*

184bulk

24.864

16.107

39.335

0.710224

 

184carb f

27.208

16.206

39.551

0.702060

0.70217

185bulk

23.670

16.061

40.012

0.710354

 

185carb f

24.404

16.094

40.354

0.701980

0.70209

187bulk

16.437

15.253

34.113

0.701541

 

187carb f

18.202

15.441

33.762

0.701510

0.70162

1977/7bulk

18.689

15.592

36.173

0.702607

 

1977/7carb f

19.157

15.714

35.978

0.702220

0.70233

1977/43bulk

24.034

16.704

39.664

0.701920

 

1977/43carb f

26.002

17.098

39.804

0.701760

0.70187

  1. *Carbonate fraction data from refs22,23, normalized to NBS987 87Sr/86Sr = 0.710254. Analytical errors are ±0.000018 for 87Sr/86Sr, ±0.002 for 206Pb/204Pb, ±0.003 for 207Pb/204Pb and ±0.010 for 208Pb/204Pb; 2σ precisions for individual Sr and Pb measurements are better than these.
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