Major-element geochemistry of the Noranda volcanic belt, Quebec-Ontario
The results of detailed mapping and sampling of two sections of Blake River Group volcanic rocks in the Noranda, Quebec region are presented and discussed. The Duparquet section, west of Lac Duparquet, crosses the north limb of a regional synclinorium where the assemblage is more than 40 000 ft thick. Continuity in upper levels of the succession is disrupted by folds, and the relative stratigraphic position of a sequence south of the folds near the synclinorium axis is uncertain but is interpreted as younger. The base of the section is the Porcupine-Destor fault. A subordinate section 40 miles to the east comprises a 12 500-ft thick assemblage overlying Kewagama sediments. Both sections were sampled at 400–500 ft stratigraphic intervals. The samples were analyzed for major elements by X-ray fluorescence and rapid chemical methods and the results checked by classical chemical analyses.Basalts and andesites are predominant rock types. Acidic volcanic rocks, prominent in assemblages a few miles east of the D...