It is concluded that British leads typify generation from normal marine sediments to which they correspond broadly in age. Deposition probably was due to igneous influence in some cases and not in others, and metamorphism is lacking. Norwegian leads are similar, but mild contamination, presumably from the Precambrian, was added by Caledonian metamorphism. Swedish Phanerozoic leads are highly contaminated by radiogenic lead selectively extracted from the Precambrian basement.

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