The Svecokarelian anomalous ore lead line

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Abstract
Ore lead isotope ratios from 37 deposits in the Svecokarelian of Fennoscandia are linearly related. Although the anomalous Svecokarelian ore lead line is generally compatible with the Stacey—Kramer two-stage model for the growth of primary lead, closer inspection reveals that the ore lead isotope variations are more consistent with a continuous mixing process. The anomalous lead line is consistent with Hietanen's plate tectonic model for the Fennoscandian Svecokarelinides. The ore lead isotope ratios are spatially related to a trench related to a sub-duction zone in the south-west of the region. This relationship is comparable to that observed in the 1.8-Ga younger Japanese island arc. The Svecokarelian leads are not true primary leads, and the mineralization age given by the Stacey—Kramer model is a minimum age. The apparent source age probably has no simple geological meaning.