Setting and Evolution of the Archean Synvolcanic Mooshla Intrusive Complex, Doyon-Bousquet-LaRonde Mining Camp, Abitibi Greenstone Belt: Emplacement History, Petrogenesis, and Implications for Au Metallogenesis

2013 ◽  
Vol 109 (1) ◽  
pp. 205-229 ◽  
Author(s):  
A. G. Galley ◽  
B. Lafrance
Keyword(s):  
Greenstone Belt ◽  
Intrusive Complex ◽  
Abitibi Greenstone Belt

The Westwood Deposit, Southern Abitibi Greenstone Belt, Canada: An Archean Au-Rich Polymetallic Magmatic-Hydrothermal System—Part II. Hydrothermal Alteration, Mineralization, and Geologic Model

2021 ◽  
Author(s):  
D. Yergeau ◽  
P. Mercier-Langevin ◽  
B. Dubé ◽  
V. McNicoll ◽  
S. E. Jackson ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Greenstone Belt ◽  
Massive Sulfide ◽  
Alteration Zone ◽  
Intrusive Complex ◽  
Calc Alkaline ◽  
Abitibi Greenstone Belt ◽  
The North ◽  
Vms Deposits ◽  
Ore Zones

Abstract The Westwood deposit, located in the Archean Doyon-Bousquet-LaRonde mining camp in the southern Archean Abitibi greenstone belt, contains 4.5 Moz (140 metric t) of gold. The deposit is hosted in the 2699–2695 Ma submarine, tholeiitic to calc-alkaline volcanic, volcaniclastic, and intrusive rocks of the Bousquet Formation. The deposit is located near the synvolcanic (ca. 2699–2696 Ma) Mooshla Intrusive Complex that hosts the Doyon epizonal intrusion-related Au ± Cu deposit, whereas several Au-rich volcanogenic massive sulfide (VMS) deposits are present east of the Westwood deposit. The Westwood deposit consists of stratigraphically stacked, contrasting, and overprinting mineralization styles that share analogies with both the intrusion-related and VMS deposits of the camp. The ore zones form three distinct, slightly discordant to stratabound corridors that are, from north (base) to south (top), the Zone 2 Extension, the North Corridor, and the Westwood Corridor. Syn- to late-main regional deformation and upper greenschist to lower amphibolite facies regional metamorphism affect the ore zones, alteration assemblages, and host rocks. The Zone 2 Extension consists of Au ± Cu sulfide (pyrite-chalcopyrite)-quartz veins and zones of disseminated to semimassive sulfides. The ore zones are spatially associated with a series of calc-alkaline felsic sills and dikes that crosscut the mafic to intermediate, tholeiitic to transitional, lower Bousquet Formation volcanic rocks. The metamorphosed proximal alteration consists of muscovite-quartz-pyrite ± gypsum-andalusite-kyanite-pyrophyllite argillic to advanced argillic-style tabular envelope that is up to a few tens of meters thick. The North Corridor consists of auriferous semimassive to massive sulfide veins, zones of sulfide stringers, and disseminated sulfides that are hosted in intermediate volcaniclastic rocks at the base of the upper Bousquet Formation. The Westwood Corridor consists of semimassive to massive sulfide lenses, veins, zones of sulfide stringers, and disseminated sulfides that are located higher in the stratigraphic sequence, at or near the contact between calc-alkaline dacite domes and overlying calc-alkaline rhyodacite of the upper Bousquet Formation. A large, semiconformable distal alteration zone that encompasses the North Corridor is present in the footwall and vicinity of the Westwood Corridor. This metamorphosed alteration zone consists of an assemblage of biotite-Mn garnet-chlorite-carbonate ± muscovite-albite. A proximal muscovite-quartz-chlorite-pyrite argillic-style alteration assemblage is associated with both corridors. The Zone 2 Extension ore zones and associated alteration are considered synvolcanic based on crosscutting relationships and U-Pb geochronology and are interpreted as being the distal expression of an epizonal magmatic-hydrothermal system that is centered on the upper part of the synvolcanic Mooshla Intrusive Complex. The North and Westwood corridors consist of bimodal-felsic Au-rich VMS-type mineralization and alteration produced by the convective circulation of modified seawater that included a magmatic contribution from the coeval epizonal Zone 2 Extension magmatic-hydrothermal system. The Westwood Au deposit represents one of the very few documented examples of an Archean magmatic-hydrothermal system—or at least of such systems formed in a subaqueous environment. The study of the Westwood deposit resulted in a better understanding of the critical role of magmatic fluid input toward the formation of Archean epizonal intrusion-related Au ± Cu and seafloor/subseafloor Au-rich VMS-type mineralization.

The Westwood Deposit, Southern Abitibi Greenstone Belt, Canada: An Archean Au-Rich Polymetallic Magmatic-Hydrothermal System—Part I. Volcanic Architecture, Deformation, and Metamorphism

2021 ◽  
Author(s):  
D. Yergeau ◽  
P. Mercier-Langevin ◽  
B. Dubé ◽  
M. Malo ◽  
A. Savoie
Keyword(s):  
Fractional Crystallization ◽  
Greenstone Belt ◽  
Massive Sulfide ◽  
Hydrothermal Systems ◽  
Lava Flows ◽  
Intrusive Complex ◽  
Calc Alkaline ◽  
Abitibi Greenstone Belt ◽  
Intrusive Rocks ◽  
Ore Zones

Abstract The Westwood deposit (4.5 Moz Au) is hosted in the 2699–2695 Ma Bousquet Formation volcanic and intrusive rocks, in the eastern part of the Blake River Group, southern Abitibi greenstone belt. The Bousquet Formation is divided in two geochemically distinct members: a mafic to intermediate, tholeiitic to transitional lower member and an intermediate to felsic, transitional to calc-alkaline upper member. The Bousquet Formation is cut by the synvolcanic (2699–2696 Ma) polyphase Mooshla Intrusive Complex, which is cogenetic with the Bousquet Formation. The deposit contains three strongly deformed (D2 flattening and stretching), steeply S-dipping mineralized corridors that are stacked from north to south: Zone 2 Extension, North Corridor, and Westwood Corridor. The North and Westwood corridors are composed of Au-rich polymetallic sulfide veins and stratabound to stratiform disseminated to massive sulfide ore zones that are spatially and genetically associated with the calcalkaline, intermediate to felsic volcanic rocks of the upper Bousquet Formation. The formation of the disseminated to semimassive ore zones is interpreted as strongly controlled by the replacement of porous volcaniclastic rocks at the contact with more impermeable massive cap rocks that helped confine the upflow of mineralizing fluids. The massive sulfide lenses are spatially associated with dacitic to rhyolitic domes and are interpreted as being formed, at least in part, on the paleoseafloor. The epizonal, sulfide-quartz vein-type ore zones of the Zone 2 Extension are associated with the injection of subvolcanic, calc-alkaline felsic sills and dikes within the lower Bousquet Formation. These subvolcanic intrusive rocks, previously interpreted as lava flows, are cogenetic and coeval with the intermediate to felsic lava flows and domes of the upper Bousquet Formation. The change from fractional crystallization to assimilation- and fractional crystallization-dominated processes and transitional to calc-alkaline magmatism is interpreted to be responsible for the development of the auriferous ore-forming system. The Westwood deposit is similar to some Phanerozoic Au ± base metal-rich magmatic-hydrothermal systems, both in terms of local volcano-plutonic architecture and inferred petrogenetic context. The complex volcanic evolution of the host sequence at Westwood, combined with its proximity to a polyphase synvolcanic intrusive complex, led to the development of one of the few known large Archean subaqueous Au-rich magmatic-hydrothermal systems.

scholarly journals Accessory mineral thermobarometry, trace element chemistry, and stable O isotope systematics, Mooshla Intrusive Complex (MIC), Doyon-Bousquet-LaRonde mining camp, Abitibi greenstone belt, Québec

2021 ◽  
Author(s):  
K Neyedley ◽  
J J Hanley ◽  
Z Zajacz ◽  
M Fayek
Keyword(s):  
Trace Element ◽  
Greenstone Belt ◽  
Analytical Techniques ◽  
Accessory Mineral ◽  
Intrusive Complex ◽  
Magmatic Complex ◽  
Accessory Minerals ◽  
Abitibi Greenstone Belt ◽  
Magmatic Body ◽  
World Class

The Mooshla Intrusive Complex (MIC) is an Archean polyphase magmatic body located in the Doyon-Bousquet-LaRonde (DBL) mining camp of the Abitibi greenstone belt, Québec, that is spatially associated with numerous gold (Au)-rich VMS, epizonal 'intrusion-related' Au-Cu vein systems, and shear zone-hosted (orogenic?) Au deposits. To elucidate the P-T conditions of crystallization, and oxidation state of the MIC magmas, accessory minerals (zircon, rutile, titanite) have been characterized using a variety of analytical techniques (e.g., trace element thermobarometry). The resulting trace element and oxythermobarometric database for accessory minerals in the MIC represents the first examination of such parameters in an Archean magmatic complex in a world-class mineralized district. Mineral thermobarometry yields P-T constraints on accessory mineral crystallization consistent with the expected conditions of tonalite-trondhjemite-granite (TTG) magma genesis, well above peak metamorphic conditions in the DBL camp. Together with textural observations, and mineral trace element data, the P-T estimates reassert that the studied minerals are of magmatic origin and not a product of metamorphism. Oxygen fugacity constraints indicate that while the magmas are relatively oxidizing (as indicated by the presence of magmatic epidote, titanite, and anhydrite), zircon trace element systematics indicate that the magmas were not as oxidized as arc magmas in younger (post-Archean) porphyry environments. The data presented provides first constraints on the depth and other conditions of melt generation and crystallization of the MIC. The P-T estimates and qualitative fO2 constraints have significant implications for the overall model for formation (crystallization, emplacement) of the MIC and potentially related mineral deposits.

Ore mineralogy, pyrite chemistry, and S isotope systematics of magmatic-hydrothermal Au mineralization associated with the Mooshla Intrusive Complex (MIC), Doyon-Bousquet-LaRonde mining camp, Abitibi greenstone belt, Québec

2021 ◽  
Author(s):  
K Neyedley ◽  
J J Hanley ◽  
P Mercier-Langevin ◽  
M Fayek
Keyword(s):  
Trace Element ◽  
Base Metal ◽  
Greenstone Belt ◽  
Analytical Techniques ◽  
Trace Element Distribution ◽  
Intrusive Complex ◽  
Sulphur Isotope ◽  
Distribution Maps ◽  
Abitibi Greenstone Belt ◽  
Base Metal Sulphides

The Mooshla Intrusive Complex (MIC) is an Archean polyphase magmatic body located in the Doyon-Bousquet-LaRonde (DBL) mining camp of the Abitibi greenstone belt, Québec. The MIC is spatially associated with numerous gold (Au)-rich VMS, epizonal 'intrusion-related' Au-Cu vein systems, and shear zone-hosted (orogenic?) Au deposits. To elucidate genetic links between deposits and the MIC, mineralized samples from two of the epizonal 'intrusion-related' Au-Cu vein systems (Doyon and Grand Duc Au-Cu) have been characterized using a variety of analytical techniques. Preliminary results indicate gold (as electrum) from both deposits occurs relatively late in the systems as it is primarily observed along fractures in pyrite and gangue minerals. At Grand Duc gold appears to have formed syn- to post-crystallization relative to base metal sulphides (e.g. chalcopyrite, sphalerite, pyrrhotite), whereas base metal sulphides at Doyon are relatively rare. The accessory ore mineral assemblage at Doyon is relatively simple compared to Grand Duc, consisting of petzite (Ag3AuTe2), calaverite (AuTe2), and hessite (Ag2Te), while accessory ore minerals at Grand Duc are comprised of tellurobismuthite (Bi2Te3), volynskite (AgBiTe2), native Te, tsumoite (BiTe) or tetradymite (Bi2Te2S), altaite (PbTe), petzite, calaverite, and hessite. Pyrite trace element distribution maps from representative pyrite grains from Doyon and Grand Duc were collected and confirm petrographic observations that Au occurs relatively late. Pyrite from Doyon appears to have been initially trace-element poor, then became enriched in As, followed by the ore metal stage consisting of Au-Ag-Te-Bi-Pb-Cu enrichment and lastly a Co-Ni-Se(?) stage enrichment. Grand Duc pyrite is more complex with initial enrichments in Co-Se-As (Stage 1) followed by an increase in As-Co(?) concentrations (Stage 2). The ore metal stage (Stage 3) is indicated by another increase in As coupled with Au-Ag-Bi-Te-Sb-Pb-Ni-Cu-Zn-Sn-Cd-In enrichment. The final stage of pyrite growth (Stage 4) is represented by the same element assemblage as Stage 3 but at lower concentrations. Preliminary sulphur isotope data from Grand Duc indicates pyrite, pyrrhotite, and chalcopyrite all have similar delta-34S values (~1.5 � 1 permille) with no core-to-rim variations. Pyrite from Doyon has slightly higher delta-34S values (~2.5 � 1 permille) compared to Grand Duc but similarly does not show much core-to-rim variation. At Grand Duc, the occurrence of Au concentrating along the rim of pyrite grains and associated with an enrichment in As and other metals (Sb-Ag-Bi-Te) shares similarities with porphyry and epithermal deposits, and the overall metal association of Au with Te and Bi is a hallmark of other intrusion-related gold systems. The occurrence of the ore metal-rich rims on pyrite from Grand Duc could be related to fluid boiling which results in the destabilization of gold-bearing aqueous complexes. Pyrite from Doyon does not show this inferred boiling texture but shares characteristics of dissolution-reprecipitation processes, where metals in the pyrite lattice are dissolved and then reconcentrated into discrete mineral phases that commonly precipitate in voids and fractures created during pyrite dissolution.

The LaRonde Penna Au-Rich Volcanogenic Massive Sulfide Deposit, Abitibi Greenstone Belt, Quebec: Part I. Geology and Geochronology

2007 ◽  
Vol 102 (4) ◽  
pp. 585-609 ◽  
Author(s):  
P. Mercier-Langevin ◽  
B. Dube ◽  
M. D. Hannington ◽  
D. W. Davis ◽  
B. Lafrance ◽  
...  
Keyword(s):  
Greenstone Belt ◽  
Massive Sulfide ◽  
Sulfide Deposit ◽  
Massive Sulfide Deposit ◽  
Volcanogenic Massive Sulfide ◽  
Abitibi Greenstone Belt ◽  
Volcanogenic Massive Sulfide Deposit

Geologic evolution of the Late Archean Abitibi greenstone belt of Canada

Geology ◽  
1986 ◽  
Vol 14 (8) ◽  
pp. 707 ◽  
Author(s):  
John Ludden ◽  
Claude Hubert
Keyword(s):  
Greenstone Belt ◽  
Abitibi Greenstone Belt

Archean terrane docking: upper crust collision tectonics, Abitibi greenstone belt, Quebec, Canada

1996 ◽  
Vol 265 (1-2) ◽  
pp. 127-150 ◽  
Author(s):  
W.U Mueller ◽  
R Daigneault ◽  
J.K Mortensen ◽  
E.H Chown
Keyword(s):  
Greenstone Belt ◽  
Upper Crust ◽  
Abitibi Greenstone Belt ◽  
Collision Tectonics

2D-3C high-resolution seismic data from the Abitibi Greenstone Belt, Canada

2009 ◽  
Vol 472 (1-4) ◽  
pp. 226-237 ◽  
Author(s):  
David B. Snyder ◽  
Peter Cary ◽  
Matt Salisbury
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Greenstone Belt ◽  
Abitibi Greenstone Belt

Nd and Pb isotope ratios of the Abitibi greenstone belt: new evidence for very early differentiation of the Earth

1994 ◽  
Vol 128 (3-4) ◽  
pp. 215-229 ◽  
Author(s):  
Jeffrey D. Vervoort ◽  
William M. White ◽  
Ralph I. Thorpe
Keyword(s):  
Greenstone Belt ◽  
Isotope Ratios ◽  
Pb Isotope ◽  
Early Differentiation ◽  
Abitibi Greenstone Belt ◽  
The Earth ◽  
New Evidence

Tholeiitic volcanic rocks of the late Archean Blake River Group, southern Abitibi greenstone belt: origin and geodynamic implications

1992 ◽  
Vol 29 (7) ◽  
pp. 1448-1458 ◽  
Author(s):  
M. R. Laflèche ◽  
C. Dupuy ◽  
J. Dostal
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Incompatible Trace Element ◽  
Progressive Change ◽  
Abitibi Greenstone Belt ◽  
Mid Ocean Ridge ◽  
Compositional Variations ◽  
Arc Setting ◽  
Back Arc ◽  
Ocean Ridge

The late Archean Blake River Group volcanic sequence forms the uppermost part of the southern Abitibi greenstone belt in Quebec. The group is mainly composed of mid-ocean-ridge basalt (MORB)-like tholeiites that show a progressive change of several incompatible trace element ratios (e.g., Nb/Th, Nb/Ta, La/Yb, and Zr/Y) during differentiation. The compositional variations are inferred to be the result of fractional crystallization coupled with mixing–contamination of tholeiites by calc-alkaline magma which produced the mafic–intermediate lavas intercalated with the tholeiites in the uppermost part of the sequence. The MORB-like tholeiites were probably emplaced in a back-arc setting.

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