Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The Redstone Archean volcanic-hosted nickel sulphide deposit is located on the southern flank of the Shaw dome, near Timmins, Ontario, and is hosted within steeply dipping, southwest-facing dacitic ash flows and tuff of the Deloro or Lower volcanic Supergroup, and overlain by komatiitic flows with spinifex tops of the Tisdale or Upper volcanic Supergroup. A stratabound massive layer of Fe-Ni-Cu sulphides is spatially enclosed by a sequence of metasomatically-derived rocks at the komatiitic/dacitic tuff contact, is flanked by sulphide iron formation, and is locally underlain by Mn-garnet-stilpnomelane rock.;Contact metasomatic rocks consisting of talc, calcicamphibole, chloritite and biotite are developed along komatiitic/dacitic tuff contacts and represent progressive stages of contact metasomatism of both dacitic and komatiitic volcanic rocks by extensive, probably deuteric seafloor, hydrothermal processes. Chloritite caps the nickel sulphide layer along altered contacts between komatiitic flows and dacitic tuff, and was derived by metasomatic assimilation, involving leaching of SiO(,2) and introduction of MgO and FeO, assuming relative immobility of Al, Ti, Zr and Y, during serpentinization and talc-carbonate alteration of the adjacent komatiitic rock.;Mn garnet-stilpnomelane rock represents a mixture of volcaniclastic tuff plus chemical precipitate. The Al-Ti-Zr-V-P had a volcaniclastic origin, most of the Fe-Mn-Mg-Ca-Co-Y-Rb were chemically precipitated, whereas Cr, Ni, Sr, Na, Nb, Ba and K have been leached from the dacitic tuff precursor. Y appears to have been a highly mobile constituent here, perhaps due to its preferential partitioning into Mn garnet.;The juxtaposition of the chloritite member overlying the stratabound nickel sulphide lens implies that the sulphides were emplaced prior to the overlapping komatiitic rocks, probably as a chemical sedimentary layer. The spatial association of sulphide and silicate-facies iron formation with the deposit, mineral and metal zoning within the nickel sulphide layer, and carbonate-enveloped nickel sulphide blebs disseminated in dacitic tuff are all indicative of a volcanic-exhalative origin for the Redstone deposit.



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