Abstract

Physical age dates suggest that the sulfides in the Noranda area were deposited 3,250 m.y. ago, the granites were intruded 2,450 m.y. ago and diabase dikes between 1,200 to 1,700 m.y. ago. Five analyses of pre-ore extrusives and seven analyses of post-ore intrusives show that the rocks are near the Qz-Ab join in the granite system, and that the extrusive phases contain more normative quartz than the later intrusives.The delta S 34 sulfur isotope data are presented for 21 pyrite, 9 pyrrhotite, 7 sphalerite, and 6 chalcopyrite samples. Two isotopic effects are noted, one related to the paragenetic sequence, the other a depth effect which is attributed to the melting of the ores by post-ore granite.

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