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Barry

Quebec, Canada

Main commodities: Au
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The Barry Gold deposit is located approximately 100 km east of the town of Lebel-sur-Quévillon, and 200 km northeast of the Val d'Or gold district in Quebec, Canada. It lies within the central part of the narrow east-west trending volcano-sedimentary Urban-Barry volcanic belt in the Abitibi greenstone belt of the Archaean Superior province.

The Urban-Barry volcanic belt is predominantly composed of 2791 to 2707 Ma mafic volcanic rocks and isolated felsic volcanic rocks interbedded with, or overlain by, volcanoclastic sedimentary rocks. It lies within the broader Lac aux Loutres region of the Abitibi greenstone belt, which comprises mafic volcanic flows, comagmatic gabbro sills, local felsic flows, lapilli and welded tuffs, and sedimentary rocks intruded by tonalite to granodiorite plutons, diorite dykes, and feldspar and/or quartz porphyry dykes. The volcanic rocks are basaltic to andesitic and are massive, pillowed and breccia flows that are commonly vesicular or porphyritic with phenocrysts of plagioclase. Comagmatic gabbro sills vary from 100 to 600 m in width and 400 to 3000 m in length. Felsic flows are dacitic to rhyolitic in composition, equigranular and locally porphyritic, forming thin bands that vary from 50 to 200 m in width and 300 to 1000 m in length and have been dated at 2716.9±2 Ma. Sedimentary rocks in the region include conglomerates composed of volcanic and intrusive clasts with minor siltstone, argillite and wacke. These rocks are cut by major intrusive rock bodies of tonalite, diorite and granodiorites of the Archean Father, Hébert, and Souart plutons and the Barry complex, which are in turn locally cut by Proterozoic dolerite dykes.

These rocks were deformed during the 2.71 to 2.66 Ga Kenoran orogeny, with a foliation that trends NE to ENE and dip at 30 to 85° SE, reflecting regional, generally isoclinal folding with steeply plunging axes, although shallowly plunging open folds are also present at the Barry deposit. Three main fault sets are present in the region, oriented: (i) NE-SW, characterised by an intense, and locally mylonitic, foliation with associated minor brecciated and silicified wall rocks, with subvertical stretching lineations; (ii) east-west-trending shear zones; and (iii) NNE-SSW brittle, sinistral structures with offsets of several cm to metres, and lineations plunging 45° NE, that crosscut the other two fault sets and are interpreted as late features. Greenschist facies metamorphism predominates, but locally reached the amphibolite facies in zones of intense deformation or adjacent to intrusions.

Three main stratigraphic units are found in the Urban-Barry volcanic belt, namely the:
(i) Urban Formation - the lowest unit, composed of glomeroporphyritic basalt with comagatic gabbro, overlain by minor felsic volcanic rocks;
(ii) Macho Formation - which hosts the Barry deposit and comprises: a lower Rouleau Member of felsic volcanic rocks and tuffs, overlain by the Windfall Member which has a lower andesite-basalt-trachyandesite unit, overlain by felsic volcanic rocks, rhyolite tuffs and flows, quartz and/or feldspar porphyritic rocks and capped by a porphyritic andesite and tuff band. This member is overlain by a series of aphyric basalts (which dominate the formation and hosts the Barry deposit), gabbros, felsic volcanic rocks, wackes, mudstones, and conglomerates and tuffs;
(iii) Romeo Formation - which is composed of wackes and mudstone.

Gold mineralisation at the Barry deposit is spatially associated with NE-trending ductile shear zones with moderate SE dips. It occurs within albite-carbonate-quartz veins and in altered mafic volcanic rocks, mostly of the Macho Formation, which have locally been pervasively altered to carbonate, and strikes at 60° with a dip of 45° SE. The main ore zone is bounded by a NE-striking (55 to 60°), 58° SE-dipping shear zone to the north, and by a quartz monzonite intrusion to the south, and is truncated and offset by various late brittle faults. The main monzonitic intrusion outcrops ~50 to 75 m to the south of the main ore zone but cuts across the main zone at depth.

The mineralised albite-carbonate-quartz veins may be either straight structures, trending at 60° and dipping at 65° SE, or folded and oriented on average at 20° with a dip of 60°SE. The auriferous veins comprise 5 to 15 vol.% of the mafic volcanic rocks, are 1 to 5 cm wide, and are locally boudinaged. They are surrounded by carbonate-quartz-pyrite, and locally within biotite-carbonate alteration zones within the host mafic volcanic rocks. Gold generally occurs as micro-inclusions in pyrite but is also present as free gold in albite-carbonate-quartz veins, syn-mineralization altered host rocks, and locally within quartz veins cutting early QFP dykes.

Zircons from both the pre-mineralisation diorite and post-mineralisation QFP yielded indistinguishable U-Pb dates averaging 2697±0.6 Ma. This age and the field relationships indicate that lode gold mineralisation was coeval with regional deformation and magmatism, similar to that documented at the Kiena, Norlartic and Siscoe (Main zone) deposits of the Val d'Or district.

The deposit has resources of (Kitney et al., 2011):
    indicated - 7.701 Mt @ 1.25 g/t Au for 9.63 t (0.3095 MOz) Au, plus,
    inferred - 10.411 Mt @t 1.41 g/t Au for 14.68 t (0.4719 MOz) Au.

The most recent source geological information used to prepare this summary was dated: 2011.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


  References & Additional Information
   Selected References:
Kitney K E, Olivo G R, Davis D W, Desrochers J-P and Tessier A,  2011 - The Barry Gold Deposit, Abitibi Subprovince, Canada: A Greenstone Belt-Hosted Gold Deposit Coeval with Late Archean Deformation and Magmatism: in    Econ. Geol.   v.106 pp. 11291154


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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