Ni-Cu-PGE Deposits in North America - ADIMB
Ni-Cu-PGE Deposits in North America - ADIMB
Ni-Cu-PGE Deposits in North America - ADIMB
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Metallogeny of Chromite, <strong>Ni</strong>,<br />
<strong>Cu</strong> and <strong>PGE</strong> deposits Hosted<br />
<strong>in</strong> Mafic and Ultramafic<br />
Complexes of <strong>North</strong> <strong>America</strong><br />
J.E. Mungall<br />
University of Toronto
Talk outl<strong>in</strong>e<br />
• Overview<br />
• Genesis of <strong>Ni</strong> and Cr deposits<br />
• <strong>Ni</strong> resources <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
– Geological context of major <strong>Ni</strong> camps<br />
• Cr resources <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
– Geological context of Cr deposits
Source – transport –<br />
trap<br />
• Large degrees of<br />
melt<strong>in</strong>g <strong>in</strong> the mantle<br />
• Segregation of sulfide<br />
or chromite from<br />
primitive magmas<br />
• Probable need for<br />
assimilation<br />
• S for <strong>Ni</strong> deposits<br />
• Iron formation for Cr<br />
deposits
Plume magmas
Plume magmas
Mechanisms of sulfide deposition<br />
• Separation of immiscible sulfide liquid droplets<br />
• Collection of base and precious chalcophile<br />
elements by sulfide<br />
• Ra<strong>in</strong> of sulfide droplets <strong>in</strong>to cumulates to<br />
produce dissem<strong>in</strong>ated, net, and massive sulfide at<br />
the base of the liquid zone<br />
• Conduits allow for a large amount of magma to<br />
be processed allow<strong>in</strong>g for mass balance problems<br />
to be circumvented<br />
• Structural traps like depressions, widen<strong>in</strong>gs of<br />
conduits
Chromite precipitation<br />
• Magma mix<strong>in</strong>g<br />
• Assimilation<br />
• Melt-crystalfluid<br />
reactions<br />
• Complex<br />
variations on<br />
these
Assimilation of iron formation<br />
SiO 2<br />
TiO 2<br />
Al 2<br />
O 3<br />
Fe 2<br />
O 3 FeO MnO MgO CaO Na 2<br />
O K 2<br />
O P 2<br />
O 5 TOTAL<br />
picrite 47.07 0.70 10.72 1.70 10.24 0.21 16.83 10.09 0.54 0.71 0.05 99.88<br />
silicate IF 52.93 0.17 5.29 10.57 22.18 0.34 2.40 0.49 0.39 2.31 0.43 99.72<br />
model BIF 50.00 34.48 15.52 100.00<br />
model IF 51.47 0.08 2.65 22.53 18.85 0.17 1.20 0.25 0.19 1.16 0.22 99.86<br />
mix 20 47.95 0.57 9.10 5.87 11.96 0.20 13.70 8.12 0.47 0.80 0.08 99.88<br />
Compositions of picrite and assimilants used <strong>in</strong> the MELTS model<strong>in</strong>g.<br />
Increases modal proportion of chromite <strong>in</strong> cumulates from < 1% to < 5%
Conduits as chemical reactors<br />
• <strong>in</strong>flux of fresh magma<br />
• contam<strong>in</strong>ation, sulfide<br />
saturation<br />
• excess chromite<br />
crystallization<br />
• depleted magma exits<br />
system<br />
• sulfide collects <strong>in</strong><br />
deepest parts of system<br />
• chromite forms layers<br />
9<br />
9
Mechanisms of chromitite<br />
deposition<br />
• Mechanical sort<strong>in</strong>g of chromite and silicate may<br />
be a viable mechanism for the formation of<br />
chromitites<br />
• In turbulent systems such as conduits crystals<br />
may be held <strong>in</strong> suspension until flow slows<br />
• Conduits allow for a large amount of magma to<br />
be processed allow<strong>in</strong>g for mass balance problems<br />
to be circumvented<br />
• Channels and layers <strong>in</strong> conduits<br />
• Stratiform deposition from slurries or turbid<br />
suspensions <strong>in</strong> layered <strong>in</strong>trusions
Physical environments
<strong>Ni</strong>-<strong>Cu</strong>-<strong>PGE</strong> <strong>Deposits</strong> <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
• Mid-Cont<strong>in</strong>ent Rift<br />
• Na<strong>in</strong> Plutonic Suite<br />
• Sudbury Impact Structure<br />
• Circum-Superior<br />
• Superior Prov<strong>in</strong>ce greenstone<br />
belts<br />
Raglan<br />
Voisey’s Bay<br />
Eagle’s Nest<br />
Thompson<br />
<strong>Ni</strong>ckel<br />
Duluth<br />
Complex<br />
Eagle<br />
Abitibi<br />
Sudbury <strong>Ni</strong><br />
deposits
Eagle<br />
Eagle’s Nest<br />
After<br />
Naldrett (2003)
<strong>Ni</strong>-<strong>Cu</strong>-<strong>PGE</strong> <strong>in</strong> the Superior Prov<strong>in</strong>ce<br />
R<strong>in</strong>g of Fire<br />
complex<br />
Lac Des Iles<br />
Shebandowan<br />
Montcalm, Shaw Dome etc<br />
14
Eagle’s Nest<br />
up<br />
• Massive sulfide<br />
sheet tight up<br />
aga<strong>in</strong>st NW marg<strong>in</strong><br />
• Net-textured sulfide<br />
forms bulk of<br />
deposit, sitt<strong>in</strong>g on<br />
top (SE) of massive<br />
• Slightly overturned<br />
• Steeply plung<strong>in</strong>g<br />
blade-shaped body
<strong>Ni</strong>-<strong>Cu</strong>-<strong>PGE</strong> <strong>Deposits</strong> <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
• Mid-Cont<strong>in</strong>ent Rift<br />
• Na<strong>in</strong> Plutonic Suite<br />
• Sudbury Impact Structure<br />
• Circum-Superior<br />
• Superior Prov<strong>in</strong>ce greenstone<br />
belts<br />
Raglan<br />
Voisey’s Bay<br />
Eagle’s Nest<br />
Thompson<br />
<strong>Ni</strong>ckel<br />
Duluth<br />
Complex<br />
Eagle<br />
Abitibi<br />
Sudbury <strong>Ni</strong><br />
deposits
Circum-Superior<br />
Raglan deposits
Thompson <strong>Ni</strong> Belt
Raglan horizon<br />
Lesher et al, 2007<br />
• Channelized lava<br />
flows<br />
• Subvolcanic feeder<br />
sills<br />
• Complex<br />
overlapp<strong>in</strong>g<br />
relations<br />
• Thermal erosion of<br />
underly<strong>in</strong>g units.
Cape Smith Belt<br />
Expo Intrusive Suite – feeders to Raglan
Thompson <strong>Ni</strong> Belt Stratigraphic Column
<strong>Ni</strong>-<strong>Cu</strong>-<strong>PGE</strong> <strong>Deposits</strong> <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
• Mid-Cont<strong>in</strong>ent Rift<br />
• Na<strong>in</strong> Plutonic Suite<br />
• Sudbury Impact Structure<br />
• Circum-Superior<br />
• Superior Prov<strong>in</strong>ce greenstone<br />
belts<br />
Raglan<br />
Voisey’s Bay<br />
Eagle’s Nest<br />
Thompson<br />
<strong>Ni</strong>ckel<br />
Duluth<br />
Complex<br />
Eagle<br />
Abitibi<br />
Sudbury <strong>Ni</strong><br />
deposits
Sudbury Structure<br />
Figure 1<br />
B<br />
A<br />
Munster Twp.<br />
D<br />
N<br />
20 km<br />
Legend<br />
Dra<strong>in</strong>age<br />
Town/City<br />
Major highway<br />
Fault<br />
Proterozoic<br />
C<br />
Southern Prov<strong>in</strong>ce<br />
Hess Twp.<br />
Trace of axial surface of<br />
syncl<strong>in</strong>e or anticl<strong>in</strong>e<br />
Vernon Twp.<br />
Hart Twp.<br />
Ermat<strong>in</strong>ger Twp.<br />
Superior<br />
Prov<strong>in</strong>ce<br />
Southern<br />
Prov<strong>in</strong>ce<br />
Sudbury Bas<strong>in</strong><br />
SIC<br />
SRSZ<br />
Sudbury<br />
Onwat<strong>in</strong> Fm<br />
Onap<strong>in</strong>g Fm<br />
Offset dike<br />
Sudbury Igneous Complex<br />
<strong>Ni</strong>piss<strong>in</strong>g diabase (sills, dykes)<br />
Unsubdivided<br />
HURONIAN SUPERGROUP<br />
Cobalt Gp.<br />
Quirke Lake Gp.<br />
Hough Lake Gp<br />
Elliot Lake Gp<br />
Archean<br />
Superior Prov<strong>in</strong>ce<br />
Gneiss, granite<br />
Mafic to <strong>in</strong>termediate<br />
metavolcanic (Benny Belt)<br />
Levack Gneiss Complex
Sulfide liquid<br />
accumulation<br />
<strong>in</strong> embayment<br />
structure<br />
Creighton Embayment<br />
Footwall rocks
Strathcona<br />
Frood-Stobie<br />
Falconbridge<br />
Creighton<br />
Copper Cliff<br />
<strong>Ni</strong> > 0.7% MINERAL<br />
INTERCEPTS<br />
Look<strong>in</strong>g from Southwest<br />
Morrison, 1999
<strong>Ni</strong>-<strong>Cu</strong>-<strong>PGE</strong> <strong>Deposits</strong> <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
• Mid-Cont<strong>in</strong>ent Rift<br />
• Na<strong>in</strong> Plutonic Suite<br />
• Sudbury Impact Structure<br />
• Circum-Superior<br />
• Superior Prov<strong>in</strong>ce greenstone<br />
belts<br />
Raglan<br />
Voisey’s Bay<br />
Eagle’s Nest<br />
Thompson<br />
<strong>Ni</strong>ckel<br />
Duluth<br />
Complex<br />
Eagle<br />
Abitibi<br />
Sudbury <strong>Ni</strong><br />
deposits
Voisey’s Bay<br />
After Kerr and<br />
Ryan<br />
2000
After Li and Naldrett (1999)
<strong>Ni</strong>-<strong>Cu</strong>-<strong>PGE</strong> <strong>Deposits</strong> <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
• Mid-Cont<strong>in</strong>ent Rift<br />
• Na<strong>in</strong> Plutonic Suite<br />
• Sudbury Impact Structure<br />
• Circum-Superior<br />
• Superior Prov<strong>in</strong>ce greenstone<br />
belts<br />
Raglan<br />
Voisey’s Bay<br />
Eagle’s Nest<br />
Thompson<br />
<strong>Ni</strong>ckel<br />
Duluth<br />
Complex<br />
Eagle<br />
Abitibi<br />
Sudbury <strong>Ni</strong><br />
deposits
Mid-Cont<strong>in</strong>ent Rift<br />
Duluth<br />
Complex
Mid-Cont<strong>in</strong>ent Rift – Eagle Deposit<br />
4.05 million tonnes with an average grade of<br />
3.57% <strong>Ni</strong>, 2.91% <strong>Cu</strong>
Global Chromite Resources (Mt)<br />
213 179<br />
161<br />
70<br />
40 31<br />
South Africa (Bushveld)<br />
640<br />
Zimbabwe (Great Dyke)<br />
1140<br />
Kazakhstan (Donskoye)<br />
Canada (ROF)<br />
India (Suk<strong>in</strong>da)<br />
F<strong>in</strong>land (Kemi)<br />
8600<br />
Turkey (various podiform)<br />
Philipp<strong>in</strong>es (podiform)<br />
Brazil (various stratiform)
Chromite occurences <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
Muskox Intrusion<br />
Oregon<br />
Resources<br />
Corp<br />
Big Trout<br />
Lake<br />
Double Eagle<br />
complex<br />
Mouatt M<strong>in</strong>e<br />
Stillwater Complex<br />
Bird River Belt<br />
36
Chromite <strong>in</strong> the Superior Prov<strong>in</strong>ce<br />
Big Trout Lake<br />
<strong>in</strong>trusion<br />
Double Eagle<br />
complex<br />
Bird River<br />
greenstone belt<br />
37
Double Eagle Complex – 2735 Ma<br />
38<br />
38
Blackbird Deposit<br />
GROUND GRAVITY<br />
SURVEY:<br />
0.5 milligal<br />
• High Bouguer<br />
anomaly over<br />
peridotite<br />
• Sharp local<br />
<strong>in</strong>crease over<br />
chromitite<br />
• Use of high pass<br />
filter successfully<br />
picks out<br />
chromitite beds<br />
39<br />
39
NOT 08 1G31<br />
70 m chromitite <strong>in</strong>tersection<br />
40<br />
40
Intercalated beds<br />
J Mungall 2008
Bird River<br />
belt<br />
• 2745 Ma<br />
• 3.6 Mt 21%<br />
Cr 2 O 3<br />
• 20 to 30% Cr 2 O 3<br />
• 40 to 44% Cr 2 O 3<br />
<strong>in</strong> chromite,<br />
Cr/Fe between<br />
1 and 1.36<br />
(Bateman,<br />
1945)<br />
42
Big Trout Lake<br />
• 140 Mt 8.4%<br />
Cr 2 O 3 (Plat<strong>in</strong>ex)<br />
• 28.5% Cr 2 O 3 over<br />
3.3 m<br />
43
Stillwater Complex 2705 Ma<br />
Ze<strong>in</strong>tek, 2005<br />
44
Mouat Cr M<strong>in</strong>e (1940’s to 1962)<br />
• Total Stillwater reserves 50 Mt ~ 22% Cr 2 O 3 (Nevoro Inc)<br />
• Only historic Cr production <strong>in</strong> <strong>North</strong> <strong>America</strong><br />
45
Conclusions<br />
• Known giant deposits mostly m<strong>in</strong>ed out<br />
• New deposits cont<strong>in</strong>ue to be discovered<br />
• R<strong>in</strong>g of Fire deposit group cont<strong>in</strong>ues to grow<br />
• > 200 Mt chromitite, 20 Mt <strong>Ni</strong> ore added to<br />
resources s<strong>in</strong>ce 2008<br />
• Are there any giant deposits left to discover<br />
Yes!
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