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The Holloway mine, a mesothermal gold deposit, is located within the western Abitibi subprovince, Ontario. Mineralized zones that contain microscopic gold within pyrite are hosted by a sequence of metakomatiites, mafic to felsic metavolcanic, and metasedimentary rocks. There were two mineralization events, however the early one was the main event in terms of the amount of gold mineralization. This event was associated with albitization, silicification, chloritization, and sericitization in addition to pyritization. The later mineralization is associated with sericitization and pyritization. Carbonate and sericite alterations are associated with both mineralizing events. Results of U/Pb zircon age dating of rocks within the sequence constrains the main mineralization event to ~2672 Ma. Ore lenses of the Holloway deposit are enveloped by 080º-striking, steeply south dipping zones of intense deformation and fabric development within the Porcupine-Destor deformation zone. The shear zones are characterized by a strong foliation and, locally, an associated extension lineation. The ore lenses are interpreted to represent lithons that were formed by boudinage of the more competent mineralized zones, which are pervasively albitized. Analysis of geochemical data demonstrates that the REE, Th, Nb, Hf, Ti, Fe, and Al were largely immobile with respect to the albite, quartz, chlorite, sericite, and hematite alterations. Locally preserved textures such as abundant varioles and spherulites indicate that the host metavolcanics were relatively evolved rocks. Geochemical data show they have an iron enrichment trend typical of tholeiitic mafic to felsic suites and that they were derived through fractional crystallization of parent basalt. Because of their high Fe/Mg ratios the rocks reacted with hydrothermal solutions carrying gold, presumably as thio complexes, to form pyrite, which scavenged the gold.

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The felsic volcanic rocks of the Kidd-Munro assemblage form an important stratigraphic unit that hosts the Kidd Creek volcanogenic massive-sulphide deposit; however, the rocks are poorly understood throughout the assemblage, due to poor exposure. Outcrops in Prosser and Munro townships were mapped in detail to determine volcanic facies and to correlate with the stratigraphy of the Kidd Creek mine. In Prosser Township, the upper part of the assemblage includes aphyric subaqueous coulees formed in a near-vent environment that are interfi ngered and in peperitic contact with massive brown and blockbearing tuff units. The aphyric rhyolite is overlain by a poorly sorted pumice- and spatter-rich tuff in which the fragments lack quenched margins, but have an apparent synvolcanic alteration preserved. The pumice-rich tuff is overlain by a distinctly quartz-phyric rhyolite. Munro Township hosts contrasting rocks including calc-alkaline rhyolite, tholeiitic lapilli tuff, and variolitic rhyolite. The calc-alkaline rhyolite consists of a massive to lobate unit. The lapilli tuff contains a large variety of clasts, including spatter, blocks, jigsaw-fi t breccia clasts, and fractured perlitic clasts, indicating a proximal vent source. The variolitic rhyolite could represent a spherulitic rhyolite, an air-fall bed, a spherulitic pyroclastic fl ow, or be the result of magma mingling. Texturally and geochemically, the rhyolite units of Prosser Township correlate with the mine stratigraphy at the Kidd Creek deposit. The quartz-phyric rhyolite shows a similar fl ow structure, phenocryst population, and geochemical signature. Thus, the stratigraphic sequence equivalent to that of Kidd Creek is found in Prosser Township.