Hydrothermal Alteration Zoning And Gold Concentration At The Kerr-addison Mine, Ontario, Canada
Date of Award
Doctor of Philosophy
Kerr-Addison, a major Archean lode gold deposit of the Abitibi Belt, is located in a zone of talc-carbonate and chlorite-carbonate rocks, immediately south of the Kirkland Lake-Larder Lake Fault Zone. Relict volcanic textures and chemical data indicate that most of the wall rocks of the mine were originally mafic and ultramafic rocks. Petrographic and geochemical studies reveal greenschist facies metamorphism with superposed distinct zonation of hydrothermal alteration, characterized by massive introduction of CO(,2) and variable enrichments of alkali-metals and calcium, which produced a great variety of mineral assemblages. These assemblages are classified into: (a) metamorphic assemblages; (b) an initial stage of alteration; and (c) advanced stage of alteration. The alteration stages are divided into alteration types, based on the presence of certain diagnostic minerals. Alteration types of the initial stage contain chlorite which is replaced by muscovite or albite in the advanced stage of alteration. The proportion of carbonate minerals and quartz increases in this process.;Oxygen isotope data indicate fairly constant temperatures (270(DEGREES)-300(DEGREES)C), and isotopic composition of hydrothermal fluids ((delta)('18)O = 5('o)/oo) across the alteration zoning.;Gold mineralization at the Kerr-Addison mine and its contiguous alteration halo are interpreted as the result of repeated cycles of fracturing, fluid penetration and local reaction with rocks. Fluid-rock interaction produced lateral variations of fluid composition which led to gold concentration, probably due to gradients in pH, in the interface between the carbonate-muscovite and carbonate-albite alteration types.
Kishida, Augusto, "Hydrothermal Alteration Zoning And Gold Concentration At The Kerr-addison Mine, Ontario, Canada" (1984). Digitized Theses. 1372.