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New Pb isotopic analyses have been obtained on twenty samples of galena from the Azuaga area. In spite of the overall homogeneity, the results for samples to the North of the Azuaga Fault are perceptible different from those to the South. The observed difference is tentatively related to the nature of the host rocks on both sides of the fault. The new data are consistent with previous values of Pb isotopic composition for galenas from the same region. Yet, these results reveal some incongruity in previous models as regards the origin of Pb in the Azuaga area. We favour a model involving the participation of lower crustal or equivalent rock units rather than a mantle-related source for the Pb

New Pb isotopic analyses have been obtained on twenty samples of galena from the Azuaga area. In spite of the overall homogeneity, the results for samples to the North of the Azuaga Fault are perceptible different from those to the South. The observed difference is tentatively related to the nature of the host rocks on both sides of the fault. The new data are consistent with previous values of Pb isotopic composition for galenas from the same region. Yet, these results reveal some incongruity in previous models as regards the origin of Pb in the Azuaga area. We favour a model involving the participation of lower crustal or equivalent rock units rather than a mantle-related source for the Pb