Target-definition of Kuroko-type deposits in Abitibi by discriminant analysis of geochemical data

CIM Bulletin, Vol. 74, No. 828, 1981

D. MARCOTTE University of Montreal, M. DAVID Managing Director, Mineral Exploration Research Institute Montreal, Quebec

A new exploration procedure is proposed for volcanogenic massive sulphide deposits of the Abitibi belt. "Samples" of acidic volcanic rocks (SiO2 > 60%) were compiled from the literature. From the 574 samples collected, 322 were used in each of a number of experiments. Forward inclusion linear discriminant analysis performed on the untransformed geochemical data shows a general depletion in Na2O and CaO along with an enrichment in MgO for a "proximal" group of samples relative to a "distal" one. The percentage of misclassifled samples reaches 20% to 30%, but test sets shows good stability.The exploration procedure was applied to the Normetal deposit, where the authors took 160 samples during the summer of 1977. It quickly leads to the definition of targets for more detailed exploration together with a good recognition of the old known deposit.

Mots Clés: Exploration, Target definition, Kuroko deposits, Abitibi district, Discriminant analysis, Geochemical data, Massive sulphides, Normetal deposit.