| dc.description.abstract | The Moss Au deposit is an orogenic-style gold deposit hosted in felsic to intermediate rocks of
the western Shebandowan Greenstone Belt, close to the terrane boundary between the
Wawa-Abitibi terrane and the Quetico metasedimentary basin, ~120 km west of Thunder Bay.
The deposit has an inferred mineral estimate of 140.07 Mt of ore averaging 1.09 g/t Au, which
yields 4.91 Moz (Goldshore, 2024). The majority of the gold is hosted within diorite and dacite
and is localized by shear zones and an array of quartz-carbonate-pyrite veins. The central-felsic
metavolcanic belt of the Shebandowan Greenstone belt comprises felsic to intermediate units
surrounded by late granitic intrusions, such as the Burchell Lake and Moss Lake stocks. This
study focused on characterizing the alteration and mineralization at the Moss deposit and
investigating any correlation between alteration and gold mineralization. A combination of
petrography, geochronology, geochemistry, and mineral chemistry was used to achieve the
objectives of this study.
Alteration occurs in different styles and intensities but generally comprises albite, biotite,
sericite, chlorite, carbonate, and epidote alteration. Sulfide minerals are dominated by pyrite
with minor chalcopyrite, sphalerite and molybdenite. Sulfide abundance is commonly 2 – 10%
of the samples but can be up to 15% within sulfide-rich veins. Disseminated and vein-hosted
pyrite are the two main textures in which pyrite occurs within the host rocks. A total of 12 vein
types were observed, with quartz and carbonate being the most dominant veins occurring
together in five of the vein types. Using the observed textural and crosscutting relationships of
the alteration, sulfides, and veins, a paragenetic sequence was developed, highlighting the
secondary processes associated with the formation of the Moss Lake deposit. Deformation
textures were observed in early and late alteration phases, suggesting a long deformation
history that was broadly coeval with mineralization.
Quartz-carbonate-pyrite ± sericite ± chlorite ± epidote veins are host to most of the observed
gold occurrences, and are common within or in proximity to shear zones. Gold was rarely
associated with disseminated pyrite away from veins. [...] | en_US |
