orogenic gold deposits in the superior province of …...lake winnipeg northern superior english r....
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Manitoba Mining and Minerals Convention 2008:Orogenic Gold Short Course
Manitoba Mining and Minerals Convention 2008:Orogenic Gold Short Course
Orogenic gold depositsin the Superior Provinceof Manitoba
Orogenic gold depositsin the Superior Provinceof Manitoba
Scott D. AndersonMineral Deposits GeologistManitoba Geological Survey
Scott D. AndersonMineral Deposits GeologistManitoba Geological Survey
Main vein, High Rock Island depositMain vein, High Rock Island deposit
Headframe, Rice Lake mineHeadframe, Rice Lake mine
500
Kilometres
North Caribou Lake
Pickle Lake
Red Lake
Rice Lake
Timmins
HemloCasa Berardi
Kirkland Lake
Chibougamau
Monument Bay
EleonoreBeardmore- Geraldton
Val d’Or
500
Kilometres
North Caribou Lake
Pickle Lake
Red Lake
Rice Lake
Timmins
HemloCasa Berardi
Kirkland Lake
Chibougamau
Monument Bay
EleonoreBeardmore- Geraldton
Val d’Or
• greenstone-granitoiddomains
• domain margins• linear distribution
(crustal-scale faults)
• greenstone-granitoiddomains
• domain margins• linear distribution
(crustal-scale faults)
Regional setting:Superior Province
Regional setting:Superior Province
Manito
baOntar
io
Wabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
200 km
metavolcanic rocks of mainlyoceanic affinity
metavolcanic rocks of mainlycontinental affinity
and isotopic influence> 2.8 Ga continental terranes
Greenstone belts
3.9- 2.81 Ga Northern Superior superterrane 3.0 - 2.87 Ga North Caribou terrane3.4 - 2.8 Ga Winnipeg River terrane
metasedimentary and assoc.granitic rocks
granitoid rocksMan
itoba
Ontario
Wabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
200 km
metavolcanic rocks of mainlyoceanic affinity
metavolcanic rocks of mainlycontinental affinity
and isotopic influence> 2.8 Ga continental terranes
Greenstone belts
3.9- 2.81 Ga Northern Superior superterrane 3.0 - 2.87 Ga North Caribou terrane3.4 - 2.8 Ga Winnipeg River terrane
metasedimentary and assoc.granitic rocks
granitoid rocks
Regional setting:Western Superior Province
Regional setting:Western Superior Province
• collage of continental andoceanic terranes(ca. 3.9-2.7 Ga)
• amalgamated via platetectonic processes
• terminal collisionca. 2.69-2.67 Ga
• collage of continental andoceanic terranes(ca. 3.9-2.7 Ga)
• amalgamated via platetectonic processes
• terminal collisionca. 2.69-2.67 Ga
North Caribou Terrane
North Caribou Terrane
Manito
baOntar
io
Wabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
Manito
baOntar
io
Wabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
North margin of NCT:tectonomagmatic evolution
North margin of NCT:tectonomagmatic evolution
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050
Freq
uenc
y
Age (Ma)
Igneous crystallization ages (north margin NCT)N=113
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050
Freq
uenc
y
Age (Ma)
Igneous crystallization ages (north margin NCT)N=113
• magmatic history spans ~380 my• major additions of crust at ~2.86
and 2.74-2.73 Ga• subduction-accretion complex
• magmatic history spans ~380 my• major additions of crust at ~2.86
and 2.74-2.73 Ga• subduction-accretion complex
riftin
grif
ting
ocean
ic
volca
nism
ocean
ic
volca
nismarc-
volca
nismarc-
volca
nism
MGS, GSC and OGS data,various authors
MGS, GSC and OGS data,various authors
terminal
collis
ion
terminal
collis
ion
~2.69-2.67 Gagranulite
(PGD)
~2.69-2.67 Gagranulite
(PGD)
Manito
baOntar
io
Wabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
Manito
baOntar
io
Wabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050
Freq
uenc
y
Age (Ma)
Igneous crystallization ages (south margin NCT)N=104
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050
Freq
uenc
y
Age (Ma)
Igneous crystallization ages (south margin NCT)N=104
• magmatic history spans ~350 my• major addition of crust at
~2.71-2.75 Ga• subduction-accretion complex
• magmatic history spans ~350 my• major addition of crust at
~2.71-2.75 Ga• subduction-accretion complex
riftin
grif
ting
arc-
volca
nismarc-
volca
nism
MGS, GSC and OGS data,various authors
MGS, GSC and OGS data,various authors
terminal
collis
ion
terminal
collis
ion
ocean
ic
volca
nism
ocean
ic
volca
nism
~2.69-2.67 Gagranulite
(ERB)
~2.69-2.67 Gagranulite
(ERB)
South margin of NCT:tectonomagmatic evolution
South margin of NCT:tectonomagmatic evolution
South margin of NCT:tectonic evolution
and regional correlation
South margin of NCT:tectonic evolution
and regional correlationPercival et al., 2006;CJES, v. 43, p. 1085-1117Percival et al., 2006;CJES, v. 43, p. 1085-1117
Continental rifting, plume-magmatismContinental rifting, plume-magmatism
Oceanic and continental-arcmagmatismOceanic and continental-arcmagmatism
Oceanic and continental-arcmagmatismOceanic and continental-arcmagmatism
Orogenic sedimentationOrogenic sedimentationCollisional orogenesisCollisional orogenesis
Western Superior Province:lithospheric structure
Western Superior Province:lithospheric structure
Seismic reflection data and seismic refraction velocity model (Musacchio et al., 2004)
Tectonic interpretation of the seismic data (White et al., 2003)
Percival et al., 2006; CJES, v. 43, p. 1085-1117Percival et al., 2006; CJES, v. 43, p. 1085-1117• Western Superior Lithoprobe transect• Western Superior Lithoprobe transect
• Accretionary orogens on NCT margins• Crustal-scale structures• Favourable geodynamic settings for OGD
• Accretionary orogens on NCT margins• Crustal-scale structures• Favourable geodynamic settings for OGD
Manito
baOntar
ioWabigoon
Uchi
Winnipeg R.
Berens River
Oxford-Stull
LakeWinnipeg
Northern Superior
English R.
Quetico
WawaLake
pSu erior
Island L.
Munro
200 km
metavolcanic rocks of mainlyoceanic affinity
metavolcanic rocks of mainlycontinental affinity
and isotopic influence> 2.8 Ga continental terranes
Greenstone belts
3.9- 2.81 Ga Northern Superior superterrane 3.0 - 2.87 Ga North Caribou terrane3.4 - 2.8 Ga Winnipeg River terrane
metasedimentary and assoc.granitic rocks
granitoid rocks
Western Superior Province:gold deposits
(>50k ounces Au)
Western Superior Province:gold deposits
(>50k ounces Au)
34 deposits>47.6 million ounces Au
34 deposits>47.6 million ounces Au
Gold deposits:>50k oz. Au>1M oz. Au
Gold deposits:>50k oz. Au>1M oz. Au
North Caribou Terrane
North Caribou Terrane
Western Superior Province gold deposits:tonnage vs. grade
Western Superior Province gold deposits:tonnage vs. grade
• relatively high-grade• median grade: 10.0 g Au/T• median tonnage: 836,000 T• two ‘world-class’ deposits
(>100 tonnes Au)
• relatively high-grade• median grade: 10.0 g Au/T• median tonnage: 836,000 T• two ‘world-class’ deposits
(>100 tonnes Au)
Canadian quartz-carbonatevein gold deposits (Robert, 1995)Canadian quartz-carbonatevein gold deposits (Robert, 1995)
Note: Twin Lake resourceexpanded to 1.2M ounces Au
Note: Twin Lake resourceexpanded to 1.2M ounces Au
Western Superior Province gold deposits:contained gold
Western Superior Province gold deposits:contained gold
* From published sources, notnecessarily NI 43-101 compliant • Production +
reserves and resources• Manitoba deposits in red• Large deposits rare, but
account for most of thegold endowment
• Production +reserves and resources
• Manitoba deposits in red• Large deposits rare, but
account for most of thegold endowment
Western Superior Province gold deposits:style of mineralization
Western Superior Province gold deposits:style of mineralization
• 23 quartz-carbonate vein• 6 iron formation-hosted• 2 crustiform vein/sulphidic
replacement• 1 disseminated/stockwork
sulphide• 1 sheeted quartz veins• 1 breccia pipe
• 23 quartz-carbonate vein• 6 iron formation-hosted• 2 crustiform vein/sulphidic
replacement• 1 disseminated/stockwork
sulphide• 1 sheeted quartz veins• 1 breccia pipe
• significant diversity of styles.particularly for larger deposits
• significant diversity of styles.particularly for larger deposits
• nature, setting and style ofmineralization indicatedominantly ‘orogenic’ gold
• nature, setting and style ofmineralization indicatedominantly ‘orogenic’ gold
Lake Winnipeg
Thompson
Winnipeg
200 km
Superior Province of Manitoba:gold deposits
Superior Province of Manitoba:gold deposits
• 17 significant deposits(>5000 ounces Au)
• >5.3 million ounces discoveredto date
• four main gold ‘trends’:Oxford-StullIsland LakeRice LakeLake of the Woods
• common affiliations:greenstone terranescrustal-scale faults
• 17 significant deposits(>5000 ounces Au)
• >5.3 million ounces discoveredto date
• four main gold ‘trends’:Oxford-StullIsland LakeRice LakeLake of the Woods
• common affiliations:greenstone terranescrustal-scale faults
Oxford-StullOxford-Stull
IslandLake
IslandLake
Rice LakeRice Lake
Lake of theWoods
Lake of theWoods
South marginSouth margin
North marginNorth margin
North margin NCT:gold deposits
North margin NCT:gold deposits
• six significant deposits
• >1.9M oz. contained Au
• two past-producers
• six significant deposits
• >1.9M oz. contained Au
• two past-producers
North margin NCT:gold deposits
North margin NCT:gold deposits
Stull-Wunnummin Fault• Oxford-Stull terrane (north)
(juvenile oceanic)• Munro Lake domain (south)
(evolved cratonic)Savage Island Fault• Island Lake domain (north)• N.Caribou terrane (south)
(continental arc?)
Stull-Wunnummin Fault• Oxford-Stull terrane (north)
(juvenile oceanic)• Munro Lake domain (south)
(evolved cratonic)Savage Island Fault• Island Lake domain (north)• N.Caribou terrane (south)
(continental arc?)
1) Spatially associated with two crustal-scale faults1) Spatially associated with two crustal-scale faults
Two orogen-scale metallotectsTwo orogen-scale metallotects
SWFSWF
SIFSIF
North margin NCT:gold deposits
North margin NCT:gold deposits
Stull-Wunnummin Fault• Oxford-Stull terrane (north)
(juvenile oceanic)• Molson domain (south)
(evolved cratonic)Savage Island Fault• Molson domain (north)• Island Lake
(intracratonic rift?)
Stull-Wunnummin Fault• Oxford-Stull terrane (north)
(juvenile oceanic)• Molson domain (south)
(evolved cratonic)Savage Island Fault• Molson domain (north)• Island Lake
(intracratonic rift?)
1) Spatially associated with two crustal-scale faults1) Spatially associated with two crustal-scale faults
• two major metallotectsidentified to date
• two major metallotectsidentified to date100 km100 km
SIFSIF
SWFSWF
2) At least two distinct styles of mineralization2) At least two distinct styles of mineralization
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
North margin NCT:gold deposits
North margin NCT:gold deposits
2) At least two distinct styles of mineralization2) At least two distinct styles of mineralization
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
‘Before’‘Before’
‘After’‘After’
‘Feldspar-phyric flow’‘Feldspar-phyric flow’
Twin Lakes shear zoneTwin Lakes shear zone
North margin NCT:gold deposits
North margin NCT:gold deposits
Twin Lakes deposit:mineralization
Twin Lakes deposit:mineralization
Synkinematic crackle-brecciaand stockwork-breccia veinsSynkinematic crackle-brecciaand stockwork-breccia veins
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
• evidence of synkinematicemplacement…
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
• evidence of synkinematicemplacement…
Twin Lakes deposit:timing of mineralization
Twin Lakes deposit:timing of mineralization
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
• evidence of synkinematicemplacement……with significantstructural overprint
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
• evidence of synkinematicemplacement……with significantstructural overprint
Twin Lakes deposit:timing of mineralizationTwin Lakes deposit:timing of mineralization
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
• evidence of synkinematicemplacement……with significantstructural overprint
• complex geometry
Main-stage orogenic:(‘Twin Lakes type’)
• hosted by majorshear zones or first-order splays
• evidence of synkinematicemplacement……with significantstructural overprint
• complex geometry
Twin Lakes C-veinTwin Lakes C-vein
Twin Lakes deposit: block model
C-vein long. section(grade x width)
2) At least two distinct styles of mineralization2) At least two distinct styles of mineralization
Late-stage orogenic:(‘High Rock Island type’)• peripheral to major
shear zones or first-order splays
Late-stage orogenic:(‘High Rock Island type’)• peripheral to major
shear zones or first-order splaysSISZ
SISZ
Gabbro
High Rock Island
High Rock Island Gold Deposit
72
70
80
85
80
75
60
80
70
80
0
Foliation (inclined)
Gold deposit
Tonalite and granodioriteMafic volcanic rocksFelsic to intermediate volcanic rocks
94°29'
94°3
4'
53°45'
53°47'
1 km
85
Gabbro
High Rock Island
High Rock Island Gold Deposit
72
70
80
85
80
75
60
80
70
80
0
Foliation (inclined)
Gold deposit
Tonalite and granodioriteMafic volcanic rocksFelsic to intermediate volcanic rocks
94°29'
94°3
4'
53°45'
53°47'
1 km
85
Lin and Corfu, 2002; Econ. Geol., v. 97, p. 43-57.Lin and Corfu, 2002; Econ. Geol., v. 97, p. 43-57.
North margin NCT:gold deposits
North margin NCT:gold deposits
Late-stage orogenic:(‘High Rock Island type’)• peripheral to major
shear zones or first-order splays
• post-date main-phasestructures in wall-rock
Late-stage orogenic:(‘High Rock Island type’)• peripheral to major
shear zones or first-order splays
• post-date main-phasestructures in wall-rock
North margin NCT:gold deposits
North margin NCT:gold deposits
High Rock Island:absolute age of mineralization
High Rock Island:absolute age of mineralization
.
206 Pb
/238 U
207Pb/235U
monazite: ±2687 2 Ma
2630
2650
26702690titanite: ±2658 5 Ma
12.3 12.7 12.9
0.50
0.52
.
206 Pb
/238 U
207Pb/235U
monazite: ±2687 2 Ma
2630
2650
26702690titanite: ±2658 5 Ma
12.3 12.7 12.9
0.50
0.52
• U-Pb geochronology on titanite and monazitefrom vein quartz
• ca. 2687 Ma monazite:emplacement of the ‘main vein’ (± Au)
• ca. 2658 Ma titanite:reactivation, Au mineralization
• U-Pb geochronology on titanite and monazitefrom vein quartz
• ca. 2687 Ma monazite:emplacement of the ‘main vein’ (± Au)
• ca. 2658 Ma titanite:reactivation, Au mineralization
Crack-seal quartz veinCrack-seal quartz vein
3) Recurring stratigraphic affiliation3) Recurring stratigraphic affiliation
Hayes RiverGroup
Oxford LakeGroup
Cross LakeGroup
• significant gold deposits occur at interfacebetween pillowed basalt and orogenicsedimentary rocks
• contact traditionally mapped as contactbetween ca. 2.83 Ga ‘Hayes River Group’and <2.707 Ga ‘Cross Lake Group’
• contact zone occupied by distinctivelithostratigraphic association:
felsic volcanic-volcaniclastic rocks;syn-volcanic felsic dikes;intermediate porphyry flows;iron formation
• locally dated at ca. 2.72 Ga – ‘Oxford LakeGroup’
• significant gold deposits occur at interfacebetween pillowed basalt and orogenicsedimentary rocks
• contact traditionally mapped as contactbetween ca. 2.83 Ga ‘Hayes River Group’and <2.707 Ga ‘Cross Lake Group’
• contact zone occupied by distinctivelithostratigraphic association:
felsic volcanic-volcaniclastic rocks;syn-volcanic felsic dikes;intermediate porphyry flows;iron formation
• locally dated at ca. 2.72 Ga – ‘Oxford LakeGroup’
North margin NCT:gold deposits
North margin NCT:gold deposits
3) Recurring stratigraphic affiliation3) Recurring stratigraphic affiliation
HRG
OLG
HRG
OLG
North margin NCT:gold deposits
North margin NCT:gold deposits
• significant gold deposits occur at interfacebetween pillowed basalt and orogenicsedimentary rocks
• contact traditionally mapped as contactbetween ca. 2.83 Ga ‘Hayes River Group’and <2.707 Ga ‘Cross Lake Group’
• contact zone occupied by distinctivelithostratigraphic association:
felsic volcanic-volcaniclastic rocks;syn-volcanic felsic dikes;intermediate porphyry flows;iron formation
• locally dated at ca. 2.72 Ga – ‘Oxford LakeGroup’
• significant gold deposits occur at interfacebetween pillowed basalt and orogenicsedimentary rocks
• contact traditionally mapped as contactbetween ca. 2.83 Ga ‘Hayes River Group’and <2.707 Ga ‘Cross Lake Group’
• contact zone occupied by distinctivelithostratigraphic association:
felsic volcanic-volcaniclastic rocks;syn-volcanic felsic dikes;intermediate porphyry flows;iron formation
• locally dated at ca. 2.72 Ga – ‘Oxford LakeGroup’
Possibly reflects strain localization in response topronounced competency contrasts andstrength anisotropy in OLG
Possibly reflects strain localization in response topronounced competency contrasts andstrength anisotropy in OLG
Lake Winnipeg
Thompson
Winnipeg
200 km
Superior Province of Manitoba:gold deposits
Superior Province of Manitoba:gold deposits
Four main gold ‘trends’:Oxford-StullIsland LakeRice LakeLake of the Woods
Four main gold ‘trends’:Oxford-StullIsland LakeRice LakeLake of the Woods
Oxford-StullOxford-Stull
IslandLake
IslandLake
Rice LakeRice Lake
Lake of theWoods
Lake of theWoods
South marginSouth margin
North marginNorth margin
Oxford-Stull and Island LakeSummary:1) Association with SWF and SIF2) Syn- and late-kinematic Au3) Recurring affiliation with OLG
at HRG- CLG interface
Oxford-Stull and Island LakeSummary:1) Association with SWF and SIF2) Syn- and late-kinematic Au3) Recurring affiliation with OLG
at HRG- CLG interface
Gold deposits:Rice Lake belt
Gold deposits:Rice Lake belt
123456789
10
123456789
10
11
33
5577
99
22
4466
88
1010
• 10 deposits• >3.4M ounces
contained Au• two producers:
Rice Lake and SG#1• seven past-producers• uniform characteristics
• 10 deposits• >3.4M ounces
contained Au• two producers:
Rice Lake and SG#1• seven past-producers• uniform characteristics
RLB gold mineralization:general characteristics
RLB gold mineralization:general characteristics
• quartz-carbonate veins• shear zone or fracture control • quartz, subordinate carbonate (ank>cal),
albite, chlorite, sericite• low sulphide content (<5%)• pyrite; other sulphides negligible• free gold, assoc. with pyrite• high Au:Ag (>5:1)• low base metals and pathfinder
elements (e.g., As, Bi, B, Sb, W)• narrow, zoned wall-rock alteration
proximal: ankerite-albite-sericite-pyritedistal: chlorite-calcite
• evidence of wall-rock sulphidation• considerable depth extent (>2 km),
yet negligible variation (RLM)
• quartz-carbonate veins• shear zone or fracture control • quartz, subordinate carbonate (ank>cal),
albite, chlorite, sericite• low sulphide content (<5%)• pyrite; other sulphides negligible• free gold, assoc. with pyrite• high Au:Ag (>5:1)• low base metals and pathfinder
elements (e.g., As, Bi, B, Sb, W)• narrow, zoned wall-rock alteration
proximal: ankerite-albite-sericite-pyritedistal: chlorite-calcite
• evidence of wall-rock sulphidation• considerable depth extent (>2 km),
yet negligible variation (RLM)
Dube et al., 2007Dube et al., 2007
Rice Lake belt• first discovery of gold in Manitoba (1911)• several significant deposits• Rice Lake and SG-1 mines (San Gold Corp.)• Rice Lake deposit >2.3 million ounces Au
(production + reserves, resources)
Rice Lake belt• first discovery of gold in Manitoba (1911)• several significant deposits• Rice Lake and SG-1 mines (San Gold Corp.)• Rice Lake deposit >2.3 million ounces Au
(production + reserves, resources)
‘Mesothermal’‘Shear-hosted’‘Mother-lode’‘Orogenic’
‘Mesothermal’‘Shear-hosted’‘Mother-lode’‘Orogenic’
AKA:AKA:
South margin NCT:Uchi Subprovince
South margin NCT:Uchi Subprovince
TerraneTerrane
NorthCaribou
1) Largest deposits associated with crustal-scaleWanipigow Fault
1) Largest deposits associated with crustal-scaleWanipigow Fault
Gold deposits (>5000 oz. Au)
South margin NCT:Uchi Subprovince
South margin NCT:Uchi Subprovince
2) Largest deposits (Red Lake, Madsen, Rice Lake)exhibit significant diversity….
….a cautionary tale for model-driven exploration
2) Largest deposits (Red Lake, Madsen, Rice Lake)exhibit significant diversity….
….a cautionary tale for model-driven exploration
NORTH CARIBOUNORTH CARIBOU
UCHIUCHI
ENGLISH RIVERENGLISH RIVER
South margin NCT:Uchi Subprovince
South margin NCT:Uchi Subprovince
3) Rice Lake belt deposits cluster around marginsof the Ross River Pluton…
…but proximity does not indicate genesis
3) Rice Lake belt deposits cluster around marginsof the Ross River Pluton…
…but proximity does not indicate genesis
Several authors haveproposed geneticlink between RRPand Au
(e.g., Cooke, 1922; Reid, 1931; Wright,1932; Stockwell, 1940)
Several authors haveproposed geneticlink between RRPand Au
(e.g., Cooke, 1922; Reid, 1931; Wright,1932; Stockwell, 1940)
At odds with fieldrelationships, style ofmineralization, andstructural timing
At odds with fieldrelationships, style ofmineralization, andstructural timing
But…But…
• brittle-ductile shear zones• shear and tensile fracture arrays• competent rock types, with
strength anisotropies• shear-hosted veins – massive,
laminated and brecciated• evidence of ‘fault-valve’ (Sibson et al.,
1988) behaviour• extension-vein stockworks –
intensify into hydraulic breccia• subhorizontal extension veins
• brittle-ductile shear zones• shear and tensile fracture arrays• competent rock types, with
strength anisotropies• shear-hosted veins – massive,
laminated and brecciated• evidence of ‘fault-valve’ (Sibson et al.,
1988) behaviour• extension-vein stockworks –
intensify into hydraulic breccia• subhorizontal extension veins
• high degree of structural control• synkinematic vein emplacement• brittle-ductile (mid-crustal) conditions• high fluid pressure
(transiently supralithostatic)
• high degree of structural control• synkinematic vein emplacement• brittle-ductile (mid-crustal) conditions• high fluid pressure
(transiently supralithostatic)
RLB gold mineralization:style
RLB gold mineralization:style
RLM; 3096ERLM; 3096E
SG-1; L6ESG-1; L6ERLM; 4670 (A-vein)RLM; 4670 (A-vein)
RLM; 3096ERLM; 3096ERLM; 2998WRLM; 2998W
RLM; 3096ERLM; 3096E
Rice Lake mine:styles of mineralization
Rice Lake mine:styles of mineralization
• Gold mineralization hosted by two distincttypes of vein within the differentiated ‘SAM’ sill
• High degree of structural control• Brittle-ductile conditions, with high-fluid pressures• Alteration overprints regional g.schist assemblage
(Ames, 1988; Ames et al., 1991)
• Gold mineralization hosted by two distincttypes of vein within the differentiated ‘SAM’ sill
• High degree of structural control• Brittle-ductile conditions, with high-fluid pressures• Alteration overprints regional g.schist assemblage
(Ames, 1988; Ames et al., 1991)
Fault-fill vein3096EFault-fill vein3096E
Stockwork-breccia vein3098WStockwork-breccia vein3098W
Local geology:Rice Lake area
Local geology:Rice Lake area
Au depositAu deposit
Rice Lake deposit
Emplacement2724±2Ma
Age of detritus2724 Ma
RRPRRP
Deposit genesisconstrained by fieldrelationships and U-Pbzircon geochronology
Deposit genesisconstrained by fieldrelationships and U-Pbzircon geochronology
Erosional contact
Rice Lake belt:summary of deformation
Rice Lake belt:summary of deformation
D4D4
D5D5
• structures indicatecomplex sequenceof deformation
• belt geometry mainlyreflects regionalD4 and D5
• structures indicatecomplex sequenceof deformation
• belt geometry mainlyreflects regionalD4 and D5
4) Orogenic model provides best explanation for Au deposition in the Rice Lake belt
4) Orogenic model provides best explanation for Au deposition in the Rice Lake belt
D4 deformationsinistral transpression
(ca. 2.69-2.68 Ga?)
D4 deformationsinistral transpression
(ca. 2.69-2.68 Ga?)
S0-S2S0-S2
S3S3
L3L3
CC
SS
C’C’
Crustal thickeningCrustal thickening
• first ‘regional’ deformation• greenschist-facies regional
metamorphism • NE-SW shortening strongly
partitioned in three distinctmacroscopic domains
• first ‘regional’ deformation• greenschist-facies regional
metamorphism • NE-SW shortening strongly
partitioned in three distinctmacroscopic domains
Sinistral-reversenon-coaxial shearSinistral-reversenon-coaxial shear
Bulk flattening and stretchingBulk flattening and stretchingUpright subhorizontal foldingUpright subhorizontal folding
WingoldWingold
RLM; 3098ERLM; 3098E
Big FourBig Four
RLM; 3096WRLM; 3096W
• subhorizontal σ1• subvertical σ3• supralithostatic Pf
• subhorizontal σ1• subvertical σ3• supralithostatic Pf
• far-field NE-SW, subhorizontal shortening(see also Davies, 1953; Lau, 1988; Lau and
Brisbin, 1996; Brommecker, 1991)
• far-field NE-SW, subhorizontal shortening(see also Davies, 1953; Lau, 1988; Lau and
Brisbin, 1996; Brommecker, 1991)
RLB gold mineralization:kinematic framework
RLB gold mineralization:kinematic framework
Section view (looking east)Section view (looking east)
Plan viewPlan view
Pencils point northPencils point north
• near-field σ1 roughlyNNE-SSW
• near-field σ1 roughlyNNE-SSW
RLB gold mineralization:late D4 structural timing
RLB gold mineralization:late D4 structural timing
S3-L3S3-L3
S3S3
S3S3
• post-dates at least initialincrements of regional D4
• post dates arc magmatism by>10 million years
• precludes syngenetic Au
• post-dates at least initialincrements of regional D4
• post dates arc magmatism by>10 million years
• precludes syngenetic Au
S3S3
3096E; 1st sublevel3096E; 1st sublevel
South margin of NCT:metallogenic model
South margin of NCT:metallogenic model
• ca. 2.69-2.67 Ga collisional orogenesis• crustal thickening• prograde metamorphism• dehydration reactions at depth• high fluid pressures• regional NE-SW compression• structural anisotropy (RRP)• domains of low mean stress• shear and hydraulic fracturing of
competent rock-types• enhanced permeability• channeling of auriferous
metamorphic fluids• decompression-induced Au precipitation
• ca. 2.69-2.67 Ga collisional orogenesis• crustal thickening• prograde metamorphism• dehydration reactions at depth• high fluid pressures• regional NE-SW compression• structural anisotropy (RRP)• domains of low mean stress• shear and hydraulic fracturing of
competent rock-types• enhanced permeability• channeling of auriferous
metamorphic fluids• decompression-induced Au precipitation
4) Orogenic model provides best explanation for Au deposition in the Rice Lake belt
4) Orogenic model provides best explanation for Au deposition in the Rice Lake belt
Lake Winnipeg
Thompson
Winnipeg
200 km
Superior Province of Manitoba:gold deposits
Superior Province of Manitoba:gold deposits
Oxford-StullOxford-Stull
IslandLake
IslandLake
Rice LakeRice Lake
Lake of theWoods
Lake of theWoods
South marginSouth margin
North marginNorth marginOxford-Stull and Island LakeSummary:1) Association with SWF and SIF2) Syn- and late-kinematic Au3) Recurring affiliation with OLG
at HRG- CLG interface
Oxford-Stull and Island LakeSummary:1) Association with SWF and SIF2) Syn- and late-kinematic Au3) Recurring affiliation with OLG
at HRG- CLG interface
Rice LakeSummary:1) Association with WF and MF2) Regional diversity of styles 3) Syn-kinematic Au (not syngenetic!)4) Regional NE-SW compression
Rice LakeSummary:1) Association with WF and MF2) Regional diversity of styles 3) Syn-kinematic Au (not syngenetic!)4) Regional NE-SW compression
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