Petrography, geochemistry and petrogenesis of alkaline dyke rocks from the Coldwell Alkaline Complex, Northwestern Ontario

Abstract

Dyke rocks occurring in the Coldwell alkaline instrusive complex, N. W. Ontario, were studied by various petrographic and geochemical means. The resulting observations indicate that 5 types of mafic alkaline lamprophyres, distinguished on the basis of chemistry and mineralogy according to the scheme of Rock (1977), and 1 type of felsic tinguaite occur in the complex (in approximate order of abundance): a) ocellar camptonites b) analcite tinguaites c) quartz-bearing camptonites e) amphibole camptonites f) monchiquites Lamprophyres are characterized mineralogically by phenocrysts of clinopyroxene and brown amphibole, and remnant phenocrysts of olivine...(see document for full abstract)