Table 1 Estimation of the contribution in lead from the two end-members identified in the present study: (1) basement-derived lead and (2) “organic lead”.

From: Petroleum as source and carrier of metals in epigenetic sediment-hosted mineralization

Average isotopic composition 206Pb/204Pb 207Pb/204Pb   
End-member Pb source 1 (n = 25) 24.1513 0.0023 16.3337 0.0016   
End-member Pb source 2 (n = 5) 18.9976 0.0018 15.7135 0.0015   
“Extreme” ore samples on the “Laisvall line” (n = 47) 206 Pb/ 204 Pb 207 Pb/ 204 Pb %Pb contributed by end-member Pb source 2 (“organic lead”) %Pb contributed by end-member Pb source 1 (“basement lead”)
Aliquot in bottom left-hand corner 21.0369 0.0020 15.9777 0.0015 60% 40%
Aliquot in top right-hand corner 21.8592 0.0021 16.0710 0.0015 44% 56%
  1. The estimation is based on the average lead isotopic composition (206Pb/204Pb and 207Pb/204Pb ratios) of each source, and the isotopic composition of the two extreme sulphide ore samples from the Laisvall mixing line.