IOCG DEPOSITS DEFINITION, NATURE, TECTONIC SETTING …media.kenanaonline.com/files/0006/6986/Talk 12...
Transcript of IOCG DEPOSITS DEFINITION, NATURE, TECTONIC SETTING …media.kenanaonline.com/files/0006/6986/Talk 12...
IOCG DEPOSITS
DEFINITION, NATURE, TECTONIC
SETTING AND MAGMATIC
HYDROTHERMAL ORIGIN
• Extreme confusion in literature as defined
• Some have no significant Cu nor Au• Vary over several orders of magnitude
WHAT ARE IRON OXIDE COPPER-
GOLD DEPOSITS?
• Vary over several orders of magnitude in Cu and Au grade
• Have non-consistent timing and tectonic setting
• Clearly not a coherent genetic group
Age(Ma)
EARLYPROTEROZOIC
ARCHEAN
Pea Ridge
Malmberget
IRON-OXIDE ASSOCIATED DEPOSITS: SIZE AND AGEFrom Williams et al. (2005)
Kiruna
Olympic Dam
Vergenoeg
Alemao SossegoSalobo
Cristalino
1500
2000
2500
3000
Cu
Maincommodity
Fe
Reported resource (Mt)Candelaria
KorshunovskoeSarbai
ChimiwungoGole Gohar
Kalengwa
Khetri
IronSprings
Ernest HenryBenson Mines
Kacharskoe
Marcona
Sokolovkoe combinedLATE PROTEROZOIC
MIDDLEPROTEROZOIC
PALEOZOIC
MESOZOIC &CENOZOIC
Pea Ridge
200015001000500 2500 30000
500
1000
1500
IOCG deposits:
Geko
IRON-OXIDE ASSOCIATED DEPOSITS: SIZE VS COPPER GRAD EFrom Williams et al. (2005)
StarraSantos
Punta del CobreDistrict
ErnestHenry
Candelaria
%C
u
Cristalino
GrasbergGrasbergGrasbergGrasberg
OlympicDam
BinghamBinghamBinghamBinghamSalobo
Manto Verde (oxide)
1
10
IOCG deposits:main commodity
Porphyry Cu deposits
CuFe
Key depositsCu-(Au-Mo)Calc-alkaline
Cu-Au alkaline
Au-Cu dioritic
Reported resource (Mt)
%
Goroblagadot
Cornwall
Marcona
Kacharoe
10,0001,0001001010.1.01
0.1
0.1 Mt
1 Mt
10 Mt
• Cu + Au as economic metals (NOT simply Fe deposits)
• Hydrothermal characteristics and structural controls: breccias common
DEFINITION OF IOCG SENSU STRICTO
structural controls: breccias common• Abundant low-Ti Fe oxides
(magnetite, hematite) and/or Fe silicates (grunerite, Fe actinolite) and/or Fe carbonates (siderite)
• REE enrichment and low-S sulfides(NOT pyrite deposits as for most other hydrothermal Cu-Au deposits)
• Syn-sulfide quartz veins and SiO2 alteration absent to rare
DEFINITION OF IOCG SENSU STRICTO
alteration absent to rare• Temporal relationship to magmatism
(commonly alkaline to sub-alkaline) but no spatial relationship to causative intrusions
GROUPING OF IRON-OXIDE ASSOCIATED DEPOSITS INTO SUB GROUPS
Age
Cenozoic El Laco Iron SpringsCerro de MercadoCortez, Yerington
Mesozoic Chilean Iron Belt CandelariaManto Verde
MarconaPampa de PongoRaul CondestableHangkowCornwall, GraceKorshunovsk, Tagar
Paleozoic Kachar, Sarbai, SokolovskTeyskoe, AmpalyskoeTashtagolMagnitogorsk
Subgroup 1Iron-oxide (P)
Subgroup 3IOCG
sensu stricto
Subgroup 4Skarn
Subgroup 5High-grade
Au (Cu)
Subgroup 2Iron-oxidelithophileelements
MagnitogorskGoroblagodat, PerschanskChogart
Neoproterozoic Kasempa Jabal IsasMesoproterozoic Benson Mines
Pea RidgeBayan Obo Olympic Dam
AcropolisErnest Henry(Boss-Bixby 70mt)SinghbhumO’okiep
(Dover 26mt)(Osborne 11mt)
StarraTick Hill
Paleoproterozoic KirunaMalmbergetSvappavaara
Vergenoeg Palabora Grangesberg WarregoNobels NobWhite DevilPeko
Neoarchean SaloboCristalinoSossego-SequerinhoAlemao-Igarape Bahia
TONNAGE, GRADE AND AGE OF IOCG SENSU -STRICTO DEPOSITS >100MT
Province
Coastal Cordillera CandelariaManto Verde
470230
1.070.55
0.220.11
ca 115 Maca 115 Ma
Rajasthan KhetriOthers
140140
1.01.3
0.50.4
ca 850 Maca 850 Ma
O’okiep 106 1.71 - ca 1040 MaNamaqualand
Deposit Cu (%) Au(g/t) AgeSize (mt)
Cloncurry Ernest Henry 167 1.1 0.54 ca 1530 Ma
Gawler Craton Olympic DamProminent Hill
3810283
1.00.89l
0.50.81
ca 1590 Maca 1590 Ma
Northern Province Palabora 350 0.52 0.01 ca 2040 Ma
SaloboCristalinoSossegoIgarape Bahia-AlemaoCento et Dezoito
789500355219170
0.961.01.11.41.0
0.520.30.280.860.3
ca 2570 Maca 2570 Maca 2570 Maca 2570 Maca 2570 Ma
Carajas
Tick Hill
50.0
10.0
5.0
1.0
Aug/t
HIGH-GRADE DEPOSITS(Tennant Creek and Cloncurry)
Warrego
PekoStarra
Prominent Hill
Olympic Dam
GOLD VS COPPER GRADES FOR IRON-OXIDE ASSOCIATED DEP OSITS
Ernest Henry
Iron skarns
Iron (P, K)
Nobels NobWhite Devil
0.5
0.1
0.05
0.01
0.01 0.05 0.1 0.5Cu%
1.0 5.0 10.0
Olympic Dam
Rajasthan
Candelaria
Manto Verde PHANEROZOIC IOCG
PRECAMBRIAN IOCG
Carajas Deposits
PalaboraO'okiep MAGMATIC
ENDMEMBERS(?)
80
70
60
40
Benson Mines
PeaRidge Carajas Gp
(Salobo, Khetri
Kiruna,Malberget
TECTONIC/LITHOSPHERIC SETTING OF IRON-OXIDE ASSOCIATED DEPOSITS
Neoproterozoic/Phanerozoic
SkarnsIOCG sensu stricto deposits Iron (P,F,REE) deposits
Paleo-Mesoproterozoic Archean
20
0
-20
-40
-120 -80 -40 0 40 80 120
(Salobo,Cristalino etc)
CandelariaManto Verde
El Romeral
O'okiep
Vergenoeg Palabora
ChimiwungoKasempaTenantCreek
Olympic Dam, Prominent Hill
ErnestHenry,Starra
Khetri
Location of the Carajás Mineral Province: - Margin of both Archean crust (craton margin) & worlds largest A-type granitoid province.
(Santos et al., 2000)
The Itacaiúnas
Belt -Carajás Mineral Mineral Province
IRONIRON--OXIDE CuOXIDE Cu--Au DEPOSITSAu DEPOSITS
Igarape Bahia: Ring Like Breccia Bodies; Others Near-Vertical Pipe or Dyke-Like Bodies
grunerite
magnetite
siderite
chalcopyrite
Typical Fe-Oxide Cu-Au Ore from Cristalino
MODELMODEL –– IOCGIOCG (Fe(Fe--OXIDEOXIDE CuCu--Au)Au)Inferred volc anic se tting & hydro thermal system,Olympic Dam
Inferred volcanic setting & hydrothermal system,Olympic Dam
OLYMPIC DAMMAAR
DEPOSIT MODEL FOR GIANT OLYMPIC DEPOSIT MODEL FOR GIANT OLYMPIC DAM DEPOSITDAM DEPOSIT
WORLDWORLD--CLASS POTENTIALCLASS POTENTIAL
Olympic DamBreccia ComplexOlympic DamBreccia Complex
BasaltBasalt
DykeDyke
Basalt-derivedgroundwaterBasalt-derivedgroundwaterInferred intrusiveInferred intrusive
Roxby Downs GraniteRoxby Downs GraniteDeeply circulated ormagmatic waterDeeply circulated ormagmatic water
CDB1188 7/ 97
ALTERED LAMPROPHYRE DYKES IN IRONALTERED LAMPROPHYRE DYKES IN IRON --OXIDEOXIDE --COPPERCOPPER--GOLD ORE AT OLYMPIC DAMGOLD ORE AT OLYMPIC DAM
EuSm
DEPOSIT SHAPE & SIZE
1 km
Olympic Dam
Palabora
200 m
1 kmN
Volcanic rock
Breccia / oreMafic dykes
Carbonatites
1 kmGranite / gneiss
Breccia
Igarape Bahia
Sedimentary rock
Pyroxenite
N
Pegmatoid
Roc
k / C
hond
rite
10000
1000
100
REE Data: FeREE Data: Fe--Oxide CuOxide Cu--Au Au vsvs PalaboraPalabora((CarbonatiteCarbonatite))
La Pr Pm Eu Tb Ho Tm Lu
Roc
k / C
hond
rite
10
Ce Nd Sm Gd Dy Er Yb1
Olympic Dam hematite breccias
Alemão magnetite-chalcopyrite-bornite Cu-Au oreIgarapé Bahia magnetite breccia Au-Cu ore
Salobo iron-stone Cu-Au orePalabora carbonatite (range)
most REE-
enrichedsamples
VERGENOEGGIANT MAARS:
A FEATURE OF ALKALINE MAGMATIC ACTIVITY?
2 km
A
B
ARGYLELAMPROITEPIPE
Ore body: F for A. Diamonds for B. Cu-Au for C.
Breccia
Associated rocks:
Ignimbrite for A. Tuff for B. Granite breccia for C.
Sedimentary or volcaniclastic rocks
500 m
C OLYMPIC DAM
2 km
80
70
60
40
Benson Mines
PeaRidge Carajas Gp
(Salobo, Khetri
Kiruna,Malberget
TECTONIC/LITHOSPHERIC SETTING OF IRON-OXIDE ASSOCIATED DEPOSITS
Neoproterozoic/Phanerozoic
SkarnsIOCG sensu stricto deposits Iron (P,F,REE) deposits
Paleo-Mesoproterozoic Archean
20
0
-20
-40
-120 -80 -40 0 40 80 120
(Salobo,Cristalino etc)
CandelariaManto Verde
El Romeral
O'okiep
Vergenoeg Palabora
ChimiwungoKasempaTenantCreek
Olympic Dam, Prominent Hill
ErnestHenry,Starra
Khetri
Longevity of Kaapvaal Craton Surrounded by Proterozoic Mobile Belts
LONGEVITY OF ARCHAEAN CRATON LONGEVITY OF ARCHAEAN CRATON MARGINSMARGINS
O’R
eilly
(200
3)
Buoyant Archaean Sub-Continental Lithosphere
TECTONIC SETTING OF IOCG DEPOSITSTECTONIC SETTING OF IOCG DEPOSITS
IOCGS : MAGMATISM FROM METASOMATISED IOCGS : MAGMATISM FROM METASOMATISED SCLMSCLM
TEMPORAL DISTRIBUTIONS: RESOLUTION OF TEMPORAL DISTRIBUTIONS: RESOLUTION OF PROPOSED GENETIC CONNECTIONPROPOSED GENETIC CONNECTION
• No > 100mt IOCG deposits known from this period• NICO in Great Bear Magmatic Zone, Canada has
42mt of 0.5%Au, 0.1%Co, 0.12%Bi adjacent to 1500mt of 35%Fe
• Sue Diane in same Zone has 17mt at 0.72%Cu,
IOCG-LIKE DEPOSITS ASSOCIATED WITH
GIANT IRON-OXIDE AT CA. 1.9 – 1.8GA
• Sue Diane in same Zone has 17mt at 0.72%Cu, 2.7glt Au
• Kolari District, Finland, including Hannukainen, is developing district in a province dominated by giant to world-class Fe-oxide deposits
• Tennant Creek Cu ± Au ± Bi deposits in same period
DEPOSIT STYLES IN CARAJAS PROVINCE
• Iron-oxide Cu-Au Deposits Include Igarape-Bahia/Ale mao, Salobo, Cr Cristalino and Sossego-Sequeirinho. − Size: 170-1000 Mt of 0.95-1.4% Cu and 0.3-0.85 g/t Au. − Features: Extreme Fe and LREE Enrichment; Anomalous U and
Co; Quartz- and Sulfur- Deficient; Pipe or Ring-Like Ore Bodies; Hosted in Range of Lithologies (Mostly Lower Volcani c Sequences and Gneisses) at Varying Metamorphic Grad es.
• Copper-Au ± Sn ± W ± Bi Deposits Include Breves, AquasClaras and Gameleira . Claras and Gameleira . − Size: <50 Mt at < 1% Cu and < 1 g/t Au in Hypogene O re. − Features: Quartz-Bearing; More Sulfur-Rich Fe-Cu Sul phides;
Greisen to Ring-Like Bodies; Hosted Mainly by Upper Sedimentary Sequences.
• Gold-PGE Deposits at Serra Pelada. − Estimated Size………. − Features: Mainly Supergene Mineralogy; Fold Hinge i n
Carbonaceous Shales; Magnetite-Rich Breccias and Ma ssive Hematite; Anomalous U, Co and LREE.
• Minor Au-Cu at Formiga Garimpo in Breccias Rich in Fe -Oxides.
1600
2000
24002800
0.4
0.6
206 P
b / 23
8 U
27800.55
0.60
Hydrothermal Monazites
2575±12Ma (MSWD = 1.19)
AGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSITAGE OF IGARAPE BAHIA DEPOSIT
800
1200
0.0
0.2
0 5 10 15207Pb / 235U
206
25002540
25802620
26602700
27402780
0.40
0.45
0.50
0.55
10 11 12 13 14
Strong Agreement With Re-Os Age of Salobo Early Mol ybenite at 2576±8 Ma, Pb-Pb Age of Cu-Fe Sulphides at 2579±71 Ma and U-Pb Zircon Age of 2573±2 Ma for Old Salobo granite (Reqvia et al., 2003).
AGE OF BREVES DEPOSITAGE OF BREVES DEPOSITAGE OF BREVES DEPOSITAGE OF BREVES DEPOSITAGE OF BREVES DEPOSITAGE OF BREVES DEPOSITAGE OF BREVES DEPOSITAGE OF BREVES DEPOSIT
1980
19401900
1800
1760
0.28
0.32
0.36
0.40
4.5 5.0 5.5 6.0207Pb / 235U
206
Pb
/ 238
U
2000
0.4
Xenotime
19601940
1900
1800
0.34
0.36
0.38
206P
b / 23
8U
Monazite
1600
1200
800
400
00.0
0.1
0.2
0.3
0 2 4 6207Pb / 235U
206P
b / 23
8U
Xenotime1800
1760
0.30
0.32
4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0207Pb / 235U
206
Weighted Mean Age of 1872±7 Ma (MSWD = 1.2) is in E rror of Weighted Mean SHRIMP U-Pb Zircon Age of Breves Gran ite at 1878±8 Ma (MSWD = 1.1) and of Breves Episyenite at 1882±7 Ma.
AGE OF SERRA PELADA AuAGE OF SERRA PELADA AuAGE OF SERRA PELADA AuAGE OF SERRA PELADA AuAGE OF SERRA PELADA AuAGE OF SERRA PELADA AuAGE OF SERRA PELADA AuAGE OF SERRA PELADA Au--------PGE PGE PGE PGE PGE PGE PGE PGE
DEPOSITDEPOSITDEPOSITDEPOSITDEPOSITDEPOSITDEPOSITDEPOSIT
• 17 Hydrothermal Monazite Grains Analyzed• Only 8 Grains Have Common-Pb Corrected Values <3%• These Yield Imprecise Age of • 1861±45 Ma (MSWD = 2.3)• Hydrothermal Biotite Occurs in• Hydrothermal Biotite Occurs in
Distal Alteration Zone• Presumed Related to Au-PGE
Ore• 40Ar/ 39Ar Age of Five Biotites is
1882±3 Ma• Cigano Granite has U-Pb Zircon Age of 1883 ±2 Ma
(Machado et al., 1991)
AGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITEAGE OF FORMIGA GRANITE
Archean and Proterozoic Xenocrystic Zircons Reset at Ca 550Ma
IMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDYIMPLICATIONS OF CARAJAS STUDY
• Two Major and One Minor Periods of Au-Cu Mineraliza tion in Carajas Mineral Province: Suggest Inheritance in Sou rce.
• All Have Strong REE Enrichment and Enhanced LREE.
• Trend From Low-SiO 2, Low-S to Quartz-Bearing and More S-Rich Systems with Time.
• Cannot be Significant Connate/Basinal Fluid Involved : All Hosts Metamorphosed Before Mineralization: Some Amphibolite .Metamorphosed Before Mineralization: Some Amphibolite .
• Mineralization Events Correspond to Three Periods o f Alkaline/Subalkaline magmatism at ca 2.57 Ga, ca 1.88 Ga and ca 0.55 Ga. Magmatic Association is Compelling.
• Largest Fe-Oxide Cu-Au Deposits Show Least Obvious Spatial Relationships to Intrusions (Deep Alkaline Intrusio ns?): Compare With Other Fe-Oxide Cu-Au Deposits.
• Suggest That Magmas and Ore Fluids Derived From Lon g-Lived Metasomatised Sub-Continental Lithosphere Beneath Am azon Craton Margin: Compare With Other Precambrian Fe-Oxi de Cu-Au Deposits.
• IOCG has become a garbage-can term for a variety of deposits
• True IOCG deposits mostly have Cu-Au grades with <1% Cu and < 1gltAu and high tonnages
• They have low-Ti iron-oxides, silicates or carbonates, low-SiO2, low-S sulfides and REE enrichment (LREE –rich)
• Precambrian examples occur within 100km of older craton
SUMMARY
• Precambrian examples occur within 100km of older cratonmargins: Phanerozoic examples have less-clear tectonic setting
• There is a close temporal but not spatial relationship to magmatism in intracratonic settings
• The most likely genetic model is association with alkaline magmatism derived from metasomatised lithosphericmantle