AbstractsEarth & Environmental Science

The petrology of a complex syenite porphyry stock, occurring on the property of the Aldermac Copper Corporation, west of Noranda, Quebec, is described. The stock is a plexus of dykes of diverse, though related composition, belonging to a soda-rich, alkali-calcic suite. Diversity in composition of the dykes is thought to be due to differentiation at depth, antecedent to injection, rather than to differentiation in place. The economie geology of the Aldermac mine is not discussed although the ore-bodies, which occur to the south of the stock, are possibly genetically related to it.