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March 2005 1
The Lac des Iles palladium deposit: The Lac des Iles palladium deposit: mineralization within the South mineralization within the South Roby, Twilight, and High Grade Roby, Twilight, and High Grade
Zones.Zones.
A summary of research progressA summary of research progress
John Hinchey & Keiko HattoriJohn Hinchey & Keiko HattoriUniversity of OttawaUniversity of Ottawa
OutlineOutlinePGE mineralization at the Southern Roby PGE mineralization at the Southern Roby and Twilight Zones. and Twilight Zones.
Characteristics of the High Grade Zone. Characteristics of the High Grade Zone.
Current Studies: Current Studies: PetrogenesisPetrogenesis of the SRZ, TZ, and HGZ. of the SRZ, TZ, and HGZ. Base and precious metal Base and precious metal ccnsccns of of sulphidessulphidesfrom each zonefrom each zone
Regional GeologyRegional GeologyProterozoic
Diabase
ArcheanLate Granitoids
Bt-granodiorite/graniteBt-hbl ton./granodiorite
Late Mafic/UltramaficsUltramaficsGab./gabnorHbl gab., hornblenditeHornblende diorite
Early GranitoidsFol./gneissic bt ton.
Supracrustal RocksMafic metavolcanicsMetaseds
FaultPGE occurrence
Modified after Sutcliffe and Smith, 1988
QueticoSubprovince
Lac Des Iles
Tib Gabbro
Dog River Intrusion
Taman LakeIntrusion
Demars LakeIntrusion
Legris LakeIntrusion
Roby Zone
Lac Des IlesComplex
Buck LakeIntrusion
0 5 10Kilometres
Study AreasStudy Areas
Modifed after Sutcliffe and Sweeney, 1986
Hbl. Gabbro
Lac Des Iles
Camp Lake
Roby Zone Twilight
Zone
BakerZone
CreekZone
100 MetresGabbronorite
High Grade Ore
Varitextured gabbroEast GabbroGranitesDiabase
Pyroxenite
March 2005 2
104285N
1051
90E
104080N
1054
10E
Mineralizing melanocratic phases
Mesogabbro
Clinopyroxenite
Dark gabbro
10 m
SouthernRobyZone
Post-mineralizationmelanocratic phases
Medium-grained, medium-green clinopyroxenite
(Hinchey et al., 2003, 2005)
Late melanocratic magma brought PGELate melanocratic magma brought PGE
MgabGab
1.81 g/t Pd
0.042 g/t Pd
ClinopyroxeniteClinopyroxenite
Cpxinite
Gabbro0.19 g/t Pd
5.2 g/t Pd
Late Dark Gabbro is mineralizedLate Dark Gabbro is mineralized
Gabbro
12.5 g/t Pd
9.2 g/t Pd
0.04 g/t Pd
Gabbro
March 2005 3
Twilight ZoneTwilight Zone(Hinchey et al., 2003, 2005)
Granitic DykesPegmatoidsMgab/cpxiniteAnorthositeM.g. Lgab
M.g.gabMicrogabGabnorNorite brecciamnor breccia ***Gab/gabnor breccia~~~ Faults
Mineralized Mineralized MelanonoriteMelanonorite
Mineralizedmelano-norite
Norite
3.0 g/t Pd
0.08 g/t Pd
Sulfide/Silicate at SRZ and TZSulfide/Silicate at SRZ and TZ
Opx
Opx
Opx
Plag
Po,Pn,Cpy
Ser
Po,Pn,Cpy
Ser
Act
Act
Act
Chl
1 mm
1 mm
Hbl
0.5 mm
Pn
Ccp
PoAct
Ccp
0.2 mm
Act
(Hinchey et al., 2005a; Hinchey & Hattori, 2005)
Characteristics of fertile magmaCharacteristics of fertile magma
Fertile magmas are distinctly different from barren magmas
Hinchey et al., 2005a
1
10
Ce Pr Nd Sm Eu Gd Dy Ho Er Yb
Rock
/Cho
ndrit
es
Fertile melanocraticMagmas
Barren clinopyroxenite
March 2005 4
PGE MineralizationPGE Mineralization
Distribution of the PGEDistribution of the PGEIdentify fertile units.Identify fertile units.
Control of mineralizationControl of mineralizationMagmatic Magmatic sulphidesulphide liquid vs. secondary liquid vs. secondary hydrothermal enrichment.hydrothermal enrichment.Proposed model of formation.Proposed model of formation.
Melanocratic magmas brought PGEMelanocratic magmas brought PGE
Hinchey et al., 2005a0 10 20
0
10
20
Pd (p
pm)
MgO (Wt. %)
0
1
2
Pt (p
pm)
MelanocraticLeucocratic
SRZ melanocratic unitsSRZ early Leucocratic unitsTZ melanonoritic unitsTZ noritic/lnor unitsTZ melanogabbro/cpxinite units
Magmatic mineralization of PGEMagmatic mineralization of PGE
0 1 20
5
10
15
20
25
Pd (p
pm)
S (Wt. %)
r=.895
SRZTZ
PGE ConcentrationsPGE Concentrations
1
102
104
106
Ni Os Ir Ru Rh Pt Pd Au Cu
Roc
k/P
rimiti
ve M
antle
Southern Roby zoneTwilight zoneHigh Grade zone
March 2005 5
Leucocratic magma lost Leucocratic magma lost sulphidessulphides
1 10 102 103 104 10510
102
103
104
Cu/
Pd
Pd (ppb)
Man
tle
J-M
UG
Sud
N
Melanocratic
LeucocraticFPMR
Proposed model of mineralization for the Proposed model of mineralization for the SRZ and TZ.SRZ and TZ.
Bulk of the PGE were introduced by late, fertile, Bulk of the PGE were introduced by late, fertile, melanocratic magmas.melanocratic magmas.Fertile magmas show distinct chemical Fertile magmas show distinct chemical compositionscompositionsCorrelations between S and PGE suggests Correlations between S and PGE suggests magmatic mineralization. magmatic mineralization.
This is supported by This is supported by sulphidesulphide texturestextures
Fractional crystallization resulted in high Fractional crystallization resulted in high PPGE/IPGEPPGE/IPGE
Mineralization process: Part 1Mineralization process: Part 1
sulphides
Mineralization Process: Part 2Mineralization Process: Part 2
incorporation of existing sulphides
March 2005 6
High Grade Ore ZoneHigh Grade Ore Zone
SulphideSulphide and silicate mineralogyand silicate mineralogy
Geochemical characteristicsGeochemical characteristics
Proposed model of formationProposed model of formation
Chlorite + Actinolite
Blue Qtz
High Grade Ore ZoneHigh Grade Ore Zone
Py
QtzQtz
High Grade ZoneHigh Grade Zone
Mi
Sieg
Act
Qtz+Chl+Act+Hbl
Qtz
PoPn
Py
Chl
ActChl+Act+Qtz
Py Chl
Act
Chl
1 mm
Hbl
Hbl
Qtz
Qtz
Mi,Sieg,Cpy
1 mm
Mil
QtzAssemblage 1
milleritesiegenitechalcopyrite
Assemblage 2
pyritechalcopyrite
Palladium, Pt, S were mobilePalladium, Pt, S were mobile
0
20
Se(p
pm)
r=0.815
1 20
1
2
S(W
t.%
)
Pt (ppm)
r=0.759
0
20
Se(p
pm)
r=0.952
0 2000 40000
1
2
S(W
t.%)
Ni (ppm)
r=0.769
~ ~8000
~ ~
SRZ & TZ
SRZ & TZ
SRZ & TZ
SRZ & TZ
High Grade Zone
March 2005 7
Bleached East Gabbro at the Contact with the High Grade Zone
Typical East Gabbro
BleachedEast Gabbrowith moderatePd
HGZ
Pegmatite associated with melanocratic Pegmatite associated with melanocratic magmasmagmas
Pl+CpxPl+Cpx
Coarse grained sulphide (pyrrhotite and chalcopyrite) associated with a pegmatitic vein: main Roby Pit
Summary of the HGZ OreSummary of the HGZ OreIntense alteration and lowIntense alteration and low--temperature temperature sulphidesulphideand silicate assemblages.and silicate assemblages.
Palladium, Pt, Cu, S were mobile.Palladium, Pt, Cu, S were mobile.
The original magmatic mineralization (8The original magmatic mineralization (8--21 21 ppmppmPd) was upgraded during hydrothermal activity.Pd) was upgraded during hydrothermal activity.
Fluids from fertile mafic magmas were Fluids from fertile mafic magmas were responsible for the upgrade.responsible for the upgrade.
March 2005 8
Current StudiesCurrent Studies
The The petrogenesispetrogenesis of the mineralized rocks.of the mineralized rocks.
Possible investigation of PGE contents in Possible investigation of PGE contents in various various sulphidessulphides
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