Source and timing of gold and other mineralization in the Red Lake area, northwestern Ontario, based on lead-isotope investigations

The problems of the timing and source of gold mineralization and the sulfidation mechanism in the Red Lake area, northwestern Ontario, have been addressed using more than 300 Pb-isotope analyses of more than 250 samples of sulfides, oxides, gold, and potential source rocks. Base metals and some gold from the Campbell and Dickenson mines are interpreted to have been mainly derived from the mafic-intermediate and felsic volcanic rocks of the lower sequence of ca. 2865 Ma, the model age calculated for samples of gold, chalcopyrite, pyrite, and galena. Other samples of gold are considered to have formed at younger ages, perhaps at ca. 2700 Ma. Differences in isotopic patterns for deposits in possibly different deformation zones but hosted by rocks of the same age and composition are interpreted to mean that some of the deposits formed at different times or from different sources or both. -from Authors