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Theme Magazines and Fact Sheets
Download "Geology and Ore no. 13, January 2009" go13.pdf (~6.9 mb)
IOCG
Iron oxide copper-gold
mineralising systems
in Greenland
No. 13 - January 2009
In the wake of the discovery of the
giant Olympic Dam Cu-U-Au-Ag-REE
deposit in South Australia in 1975, a
conception developed of an important
class of ore deposits not previously
recognised as such. Subsequent reali-
sation of its significance by the dis-
covery of new deposits of this type
attracted keen interest both from aca-
demic institutions and exploration
companies worldwide.
giant Olympic Dam Cu-U-Au-Ag-REE
deposit in South Australia in 1975, a
conception developed of an important
class of ore deposits not previously
recognised as such. Subsequent reali-
sation of its significance by the dis-
covery of new deposits of this type
attracted keen interest both from aca-
demic institutions and exploration
companies worldwide.
Due to its economic importance,
over the last two decades, the so-
called iron oxide copper-gold (IOCG or
FeOx-Cu-Au) class of deposits has
become a prime target for explo-
ration. Since the first definition and
description of the IOCG deposit, new
discoveries, re-classification and
increasing worldwide research have
shown that IOCG deposits encompass
a wide spectrum of hydrothermal ore
deposits.
called iron oxide copper-gold (IOCG or
FeOx-Cu-Au) class of deposits has
become a prime target for explo-
ration. Since the first definition and
description of the IOCG deposit, new
discoveries, re-classification and
increasing worldwide research have
shown that IOCG deposits encompass
a wide spectrum of hydrothermal ore
deposits.
Introduction
It is understood now that the IOCG class
represents a family of related mineral de -
pos its that share a number of distinguishing
features:
represents a family of related mineral de -
pos its that share a number of distinguishing
features:
· low-Ti magnetite and/or hematite
(
<2.0 wt % tio
2
)
· extensive Na-K (-Ca) alteration
· REE, Co, Ag ± U, P
· generally coeval magmatism
· REE, Co, Ag ± U, P
· generally coeval magmatism
The current inadequate state of knowl-
edge about this deposit class is reflected
in the lack of comprehensive genetic mod-
els. Consequently, a genetic classification
appears to be an unnecessary limitation
when identifying new deposits. Therefore,
the classification for the World Minerals
Geoscience's Database Project (Geological
Survey of Canada), defining six types of
IOCG deposits, is used in the fact box. The
characteristics of these IOCG deposit types
can be directly compared to geological fea-
tures recognised in Greenland.
edge about this deposit class is reflected
in the lack of comprehensive genetic mod-
els. Consequently, a genetic classification
appears to be an unnecessary limitation
when identifying new deposits. Therefore,
the classification for the World Minerals
Geoscience's Database Project (Geological
Survey of Canada), defining six types of
IOCG deposits, is used in the fact box. The
characteristics of these IOCG deposit types
can be directly compared to geological fea-
tures recognised in Greenland.
Mineral resources characteristics
IOCG deposits may have enormous re -
sources of a wide spectrum of raw materi-
als. They may comprise Fe, Cu, Au, U, REE,
F, vermiculite and minor resources of Ag,
Nb, P, Bi, Co as well as the less essential
resources of PGE, Ni, Se, Te, Zr, As, B, Ba,
Cl, Co, Mo, Mn and W. The IOCG classes
are generally characterised by high tonnage
and low-grade ore. The giant and famous
Olympic Dam deposit in South Australia is
the world's fourth largest Cu deposit, the
fifth largest Au deposit and the largest U
deposit. It also contains significant quanti-
sources of a wide spectrum of raw materi-
als. They may comprise Fe, Cu, Au, U, REE,
F, vermiculite and minor resources of Ag,
Nb, P, Bi, Co as well as the less essential
resources of PGE, Ni, Se, Te, Zr, As, B, Ba,
Cl, Co, Mo, Mn and W. The IOCG classes
are generally characterised by high tonnage
and low-grade ore. The giant and famous
Olympic Dam deposit in South Australia is
the world's fourth largest Cu deposit, the
fifth largest Au deposit and the largest U
deposit. It also contains significant quanti-
ties of Ag, according to the 2008 status by
the operator BHP Billiton. The Phalaborwa
deposit in South Africa is the world's sec-
ond largest Cu mine and largest vermicu-
lite mine and has by-products of Au, Ag,
PGE, magnetite, P, U, Zr, Se, Te and Bi,
according to the 2008 status by the opera-
tor Rio Tinto Mining and Palabora Mining.
The Bayan Obo deposit in the Mongolia
Autonomous Region, China is the world's
largest rare-earth elements (REE) producer,
where also Nb and Fe are mined. IOCG
deposits, thus, contain major resources
and represent important players on the
global raw-material market.
the operator BHP Billiton. The Phalaborwa
deposit in South Africa is the world's sec-
ond largest Cu mine and largest vermicu-
lite mine and has by-products of Au, Ag,
PGE, magnetite, P, U, Zr, Se, Te and Bi,
according to the 2008 status by the opera-
tor Rio Tinto Mining and Palabora Mining.
The Bayan Obo deposit in the Mongolia
Autonomous Region, China is the world's
largest rare-earth elements (REE) producer,
where also Nb and Fe are mined. IOCG
deposits, thus, contain major resources
and represent important players on the
global raw-material market.
2
Soil sampling in a rusty zone of a gneiss sequence in Marshall Bugt, central Inglefield Land.
GEOLOGY AND ORE 13 / 2009
Iron oxide copper-gold (IOCG)
mineralising systems in Greenland
mineralising systems in Greenland
FACT BOX
Classification of IOCG deposits into various types
Type
Olympic
Dam
Dam
Cloncurry
Kiruna
Iron skarn
Phalaborwa
Bayan Obo
Giant ore
deposit
deposit
Olympic Dam,
South Australia
South Australia
Osborne,
Queensland,
Australia
Queensland,
Australia
Kiirunavaara,
Sweden
Sweden
Magnitogorsk,
Urals, Russia
Urals, Russia
Phalaborwa,
South Africa
South Africa
Bayan Obo,
Mongolia
Autonomous
Region, China
Mongolia
Autonomous
Region, China
Mineralisation
magnetite-
hematite-bornite-
chalcopyrite
breccia matrix
hematite-bornite-
chalcopyrite
breccia matrix
magnetite-
hematite-apatite
replaced by Cu-Fe
sulphides, Au, etc.
hematite-apatite
replaced by Cu-Fe
sulphides, Au, etc.
massive
magnetite-apatite-
actinolite
magnetite-apatite-
actinolite
massive
magnetite-garnet-
pyroxene
magnetite-garnet-
pyroxene
magnetite, apatite,
fluorite,
Cu sulphides, etc.
fluorite,
Cu sulphides, etc.
magnetite,
hematite,
bastnaesite, Fe-
Ti-Cr-Nb oxides,
fluorite, monazite,
etc.
hematite,
bastnaesite, Fe-
Ti-Cr-Nb oxides,
fluorite, monazite,
etc.
Alteration
potassic
potassic
sodic
sodic
sodic +
potassic
potassic
sodic +
potassic
potassic
Commodity
Fe, Cu, Au,
Ag, REE, U
Ag, REE, U
Cu, Au, Ag,
Bi, Co, W
Bi, Co, W
Fe ± Cu, Au
Fe ± Cu, Au
Cu, Au, Ag,
REE, PGE,
vermiculite,
magnetite, P,
U, Zr, Se, Te, Bi
REE, PGE,
vermiculite,
magnetite, P,
U, Zr, Se, Te, Bi
Fe, Nb, REE
Ore body
pipe-like and irregular
breccia
breccia
stratabound, vein,
breccia
breccia
tabular, pipe-like,
irregular
irregular
stratabound lensoid,
irregular
irregular
veins, layers,
disseminations
disseminations
stratabound, lenses,
veins, layers,
disseminations
veins, layers,
disseminations
Exploration criteria
IOCG deposits are commonly hosted by
meta morphic terranes that formed during
the entire geologic history, from the Ar chae -
an to recent times, but mostly in the Proter -
o zoic. In spite of large areas of Prot erozoic
rocks in Greenland, about 40% of the ice-
free area, only very few IOCG oc cur rences
were found. Therefore, Green land is regard-
ed as a promising grass roots exploration
target for IOCG deposits. Geo physical, geo -
chemical and remote-sensing techniques
are very useful in this context, and re gional
data available for large parts of Green land.
Due to the commonly large size of the
IOCG-like deposits, such regional explo-
ration methods are well suited in order to
outline potential target areas.
meta morphic terranes that formed during
the entire geologic history, from the Ar chae -
an to recent times, but mostly in the Proter -
o zoic. In spite of large areas of Prot erozoic
rocks in Greenland, about 40% of the ice-
free area, only very few IOCG oc cur rences
were found. Therefore, Green land is regard-
ed as a promising grass roots exploration
target for IOCG deposits. Geo physical, geo -
chemical and remote-sensing techniques
are very useful in this context, and re gional
data available for large parts of Green land.
Due to the commonly large size of the
IOCG-like deposits, such regional explo-
ration methods are well suited in order to
outline potential target areas.
The occurrence of magnetite and/or
hematite (iron oxide) in the mineralisation
is one major unifying feature of IOCG
deposits, which can be picked up by air-
borne as well as ground magnetic and
gravity surveys. High density and magnetic
response result in common coincident
gravity and magnetic anomalies. The min-
eralisation is also characterised by a well-
in duced polarisation and resistivity response,
whereas iron oxide-rich ore bodies show a
good electrical conductivity.
is one major unifying feature of IOCG
deposits, which can be picked up by air-
borne as well as ground magnetic and
gravity surveys. High density and magnetic
response result in common coincident
gravity and magnetic anomalies. The min-
eralisation is also characterised by a well-
in duced polarisation and resistivity response,
whereas iron oxide-rich ore bodies show a
good electrical conductivity.
The frequent regional K-alteration and
U-rich mineralisation result in anomalies
that are detectable by airborne radiomet-
ric surveys. Furthermore, regional geo-
chemical surveys are well suited to identify
the often extensive and multi-element
mineralisation. IOCG deposits are largely
that are detectable by airborne radiomet-
ric surveys. Furthermore, regional geo-
chemical surveys are well suited to identify
the often extensive and multi-element
mineralisation. IOCG deposits are largely
controlled by regional structures and splays
of such structures. These features can eas-
ily be mapped additionally using remote-
sensing techniques. Consequently, there
are a number of well-suited exploration
methods for `greenfields' exploration in re -
mote areas such as Greenland. For many
of Greenland's ice-free areas these
data are already available.
of such structures. These features can eas-
ily be mapped additionally using remote-
sensing techniques. Consequently, there
are a number of well-suited exploration
methods for `greenfields' exploration in re -
mote areas such as Greenland. For many
of Greenland's ice-free areas these
data are already available.
Possible IOCG occurrences
in Greenland
in Greenland
No IOCG deposit has up till now been re -
cog nised from Greenland. Thus, the poten-
tial IOCG localities mentioned here are
drawn from the literature and their classifi-
cation has to remain vague. How ever, some
occurrences have typical features of IOCG-
cog nised from Greenland. Thus, the poten-
tial IOCG localities mentioned here are
drawn from the literature and their classifi-
cation has to remain vague. How ever, some
occurrences have typical features of IOCG-
3
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
type deposits as listed in the fact box and
show the potential for this kind of minerali-
sation in the areas reported:
show the potential for this kind of minerali-
sation in the areas reported:
Olympic Dam- type deposit
South Greenland with the Proterozoic
Ketilidian orogen represents a known met-
allogenetic province for Cu, Au and U,
locally associated with iron oxides. The
Au-Bi-Ag-As-W-Cu-Mo multi element
mineralisation at Niaqornaarsuk and
Qooromiut occurs in quartz veins with a
quartz-albite-magnetite alteration halo.
The quartz veins are controlled by second-
order shear zones to the regional, NE-SW
trending sinistral, strike-slip shear zones.
The mineralisation is suggested to be
related to mid-crustal, calc-alkaline, arc-
related intrusions (about 1780 Ma) of the
Julianehåb batholith. The mineralised veins
are up to 5 m wide, can be followed
about 200 m along strike and contain
1-5 ppm Au.
South Greenland with the Proterozoic
Ketilidian orogen represents a known met-
allogenetic province for Cu, Au and U,
locally associated with iron oxides. The
Au-Bi-Ag-As-W-Cu-Mo multi element
mineralisation at Niaqornaarsuk and
Qooromiut occurs in quartz veins with a
quartz-albite-magnetite alteration halo.
The quartz veins are controlled by second-
order shear zones to the regional, NE-SW
trending sinistral, strike-slip shear zones.
The mineralisation is suggested to be
related to mid-crustal, calc-alkaline, arc-
related intrusions (about 1780 Ma) of the
Julianehåb batholith. The mineralised veins
are up to 5 m wide, can be followed
about 200 m along strike and contain
1-5 ppm Au.
About 200 km to the northwest of the
above occurrence, copper was mined
between 1905 and 1914 from a minerali-
sation containing up to 5 wt% Cu, 1.5 ppm
Au and 250 ppm Ag in the Kobber mine -
bugt area. The mineralisation, mainly bor-
nite and chalcocite, is hosted in veins and
breccias that are controlled by a higher-
order splay of a regional lineament. The
hydrothermal Cu mineralisation comprises
magnetite, hematite, chalcopyrite, electrum
and native copper. The lineament cuts
through rocks of the Julianehåb batholith
and metavolcanic schist. Near by, south-
west of the hydrothermal mineralisation,
alkaline intrusive rocks of the Gardar suite
occur. The rocks of the Gardar suite
formed during Mesoproterozoic rifting of
the Ketilidian Orogen after its formation.
The IOCG mineralisation at Kobber mine -
bugt is probably related to this extensional
between 1905 and 1914 from a minerali-
sation containing up to 5 wt% Cu, 1.5 ppm
Au and 250 ppm Ag in the Kobber mine -
bugt area. The mineralisation, mainly bor-
nite and chalcocite, is hosted in veins and
breccias that are controlled by a higher-
order splay of a regional lineament. The
hydrothermal Cu mineralisation comprises
magnetite, hematite, chalcopyrite, electrum
and native copper. The lineament cuts
through rocks of the Julianehåb batholith
and metavolcanic schist. Near by, south-
west of the hydrothermal mineralisation,
alkaline intrusive rocks of the Gardar suite
occur. The rocks of the Gardar suite
formed during Mesoproterozoic rifting of
the Ketilidian Orogen after its formation.
The IOCG mineralisation at Kobber mine -
bugt is probably related to this extensional
tectonics as indicated by Pb-isotope char-
acteristics of the hydrothermal bornite.
acteristics of the hydrothermal bornite.
The magnetic expression of the linea-
ment in Kobberminebugt can be followed
beneath the ice from the west coast of
Greenland to the east coast in aeromag-
netic measurements, showing the general
potential for structurally controlled, mag-
matic-hydrothermal mineralisation in the
region.
beneath the ice from the west coast of
Greenland to the east coast in aeromag-
netic measurements, showing the general
potential for structurally controlled, mag-
matic-hydrothermal mineralisation in the
region.
The southern contact zone of the Palae -
o protero zoic Ammassalik mobile belt with
the Archaean Craton in East Green land is
characterised by a series of norite intru-
sions. The roof zones of these intrusions
show breccia zones and up to 30 cm wide
veins with a pronounced hematite miner-
the Archaean Craton in East Green land is
characterised by a series of norite intru-
sions. The roof zones of these intrusions
show breccia zones and up to 30 cm wide
veins with a pronounced hematite miner-
alisation and potassic feldspar alteration.
This occurrence has only been little ex -
plored, so it cannot be said with confidence
that this is actually an IOCG deposit.
This occurrence has only been little ex -
plored, so it cannot be said with confidence
that this is actually an IOCG deposit.
The Palaeoproterozoic Nagssugtoqidian
orogen in West Greenland represents the
western extension of the Ammassalik mo -
bile belt to the east. The Arfersiorfik quartz-
diorite intruded a crustal-scale shear zone
of the orogen and is known to be magne -
tite-rich in places. A mineralised amphibo-
lite containing 786 ppb Au, 1.7 wt % Cu
and 520 ppm Co is known from a find near
the southern extension of the Arfersiorfik
quartz-diorite. The close relationship
between crustal-scale sequences and calc-
alkaline intrusions with magnetite and
western extension of the Ammassalik mo -
bile belt to the east. The Arfersiorfik quartz-
diorite intruded a crustal-scale shear zone
of the orogen and is known to be magne -
tite-rich in places. A mineralised amphibo-
lite containing 786 ppb Au, 1.7 wt % Cu
and 520 ppm Co is known from a find near
the southern extension of the Arfersiorfik
quartz-diorite. The close relationship
between crustal-scale sequences and calc-
alkaline intrusions with magnetite and
4
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
Breccia zone with copper mineralisation in
Kobberminebugt near the Josva mine in South-
West Greenland
Kobberminebugt near the Josva mine in South-
West Greenland
GEOLOGY AND ORE 13 / 2009
albite alteration as well as a Cu-Au-Co
occurrence is characteristic of IOCG miner-
alising systems.
occurrence is characteristic of IOCG miner-
alising systems.
Cloncurry-type deposit
Southern West Greenland is underlain by
the North Atlantic craton with several
known occurrences of orogenic or lode
gold mineralisation (e.g., Storø, Paamiut,
Taartoq). In the Paamiut area an amphibo-
lite-hosted breccia contains an iron oxide-
Cu-Au mineralisation with a hydrothermal
carbonate alteration halo at the Nigerleq
Mountain. Further to the south similar
occurrences are reported from north of the
fjord Sermilik. However, the dimension of
these mineralisations is rather small.
Southern West Greenland is underlain by
the North Atlantic craton with several
known occurrences of orogenic or lode
gold mineralisation (e.g., Storø, Paamiut,
Taartoq). In the Paamiut area an amphibo-
lite-hosted breccia contains an iron oxide-
Cu-Au mineralisation with a hydrothermal
carbonate alteration halo at the Nigerleq
Mountain. Further to the south similar
occurrences are reported from north of the
fjord Sermilik. However, the dimension of
these mineralisations is rather small.
In North West Greenland, the Palaeo -
proterozoic Inglefield mobile belt hosts
IOCG-like mineralisation in the so-called
`North Inglefield Land gold belt', however,
only known from reconnaissance explo-
ration. Gold contents between 0.2 and
12.5 ppm Au and up to 1.28% Cu are
reported from a bornite, chalcopyrite,
chalcocite, covellite, magnetite, hematite
IOCG-like mineralisation in the so-called
`North Inglefield Land gold belt', however,
only known from reconnaissance explo-
ration. Gold contents between 0.2 and
12.5 ppm Au and up to 1.28% Cu are
reported from a bornite, chalcopyrite,
chalcocite, covellite, magnetite, hematite
and gold accumulation. Regional eastwest-
trending fault zones host breccias cement-
ed by hematite that are enriched in Cu
and Au as well as a hydrothermal pyrite-
barite-hematite alteration within a 4 km
by 70 km northeast-striking corridor.
trending fault zones host breccias cement-
ed by hematite that are enriched in Cu
and Au as well as a hydrothermal pyrite-
barite-hematite alteration within a 4 km
by 70 km northeast-striking corridor.
Bayan Obo-type deposit
The Neoproterozoic Sarfartoq carbonatite
complex is located at the northern margin
of the West Greenland Archaean craton. It
forms a conical body of carbonatite and
sodic fenite in the core and a marginal
potassic hydrothermal alteration zone (75
km
The Neoproterozoic Sarfartoq carbonatite
complex is located at the northern margin
of the West Greenland Archaean craton. It
forms a conical body of carbonatite and
sodic fenite in the core and a marginal
potassic hydrothermal alteration zone (75
km
2
) with hematite and carbonatite dykes.
The hydrothermal Nb, Ta, U and REE min-
eralisation occurs within this marginal
zone in breccia veins associated with the
alteration. The mineralisation comprises
up to 40 wt % Nb
eralisation occurs within this marginal
zone in breccia veins associated with the
alteration. The mineralisation comprises
up to 40 wt % Nb
2
O
5
, 1 wt % Ta
2
O
5
and
1 wt% U.
The Mesozoic Qaqqaarsuk carbonatite
complex forms a ring-dyke structure with
dimensions at the surface of about 15 km
dimensions at the surface of about 15 km
2
.
It hosts a Nb, U, REE, Ta and P mineralisa-
tion with 3.5 to 6 wt % P
tion with 3.5 to 6 wt % P
2
O
5
and up to
0.5 wt % Nb
2
O
5
and
<1 wt % ta
2
O
5
.
The main Nb mineralisation is hosted by
pyrochlore that is associated with sodic
alteration and massive magnetite.
pyrochlore that is associated with sodic
alteration and massive magnetite.
The recently discovered Tikiusaaq car-
bonatite complex is of Mesozoic age and
anomalous contents of P, U and REE are
reported. The appearance of this complex
as a ring complex is very similar to the
Qaqqaarsuk complex.
anomalous contents of P, U and REE are
reported. The appearance of this complex
as a ring complex is very similar to the
Qaqqaarsuk complex.
IOCG potential in Greenland
the `greenfields' approach
the `greenfields' approach
In the description above, some of the
IOCG deposit types listed in the fact box
are not discussed. These include the iron
skarn-type and the Kiruna-type both char-
acterised by large-scale, massive magne -
tite bodies, which are easily recognised by
geophysical surveys. Such massive magne -
tite bodies are not known from Greenland
and, therefore, the potential for finding
such a deposit is regarded as being low
and restricted to the poorly studied areas
in East Greenland.
IOCG deposit types listed in the fact box
are not discussed. These include the iron
skarn-type and the Kiruna-type both char-
acterised by large-scale, massive magne -
tite bodies, which are easily recognised by
geophysical surveys. Such massive magne -
tite bodies are not known from Greenland
and, therefore, the potential for finding
such a deposit is regarded as being low
and restricted to the poorly studied areas
in East Greenland.
5
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
Proposed Genetic Models for IOCG Mineralisation
Magmatic
Type: Phalaborwa / Olympic Dam
Metamorphic
Type: Cloncurry
Connate
Type: Cloncurry / Olympic Dam / Kiruna
meteoric / connate
fluids
Fe-oxide
± Cu(Au)
± local magmatic
K-silicate alteration
regional
Na(Ca)
alteration
Cu(-Au)-
Fe-oxide
early Fe-oxide
(barren)
connate
fluids
meteoric brines
± magmatic
fluids
magmatic
fluids
meteoric
fluids
connate
fluids
Cu(-Au)±
Fe-oxide
Cu(-Au) mineralisation
Fe-oxide mineralisation
Acidic alteration
Na(Ca) alteration
Biotite K-feldspar alteration
K-feldspar alteration
metamorphic fluids
Several carbonatite complexes are
known from southern West Greenland,
but they all lack the distinct Cu mineralisa-
tion of the Phalaborwa-type deposits.
Therefore the potential for Phalaborwa-
type IOCG deposits in Greenland is evalu-
ated as being very low. However, three of
the carbonatites are spatially associated
with a distal Nb, REE, U, Ta and P mineral-
isation typified by the Bayan Obo type.
but they all lack the distinct Cu mineralisa-
tion of the Phalaborwa-type deposits.
Therefore the potential for Phalaborwa-
type IOCG deposits in Greenland is evalu-
ated as being very low. However, three of
the carbonatites are spatially associated
with a distal Nb, REE, U, Ta and P mineral-
isation typified by the Bayan Obo type.
The major characteristics of the Olympic
Dam-type IOCG deposits are:
· craton margin setting
· associated with A-type and/or I-type
· associated with A-type and/or I-type
magmatism
· two stages of mineralisation, early
high-temperature iron oxide, late Cu-Au
· large-scale potassic alteration
Examples of this type in Greenland are
occurrences in the numerous Proteroaoic
orogens and mobile belts surrounding the
Archaean craton, namely the Ketilidian
orogen and the Ammassalik mobile belt.
occurrences in the numerous Proteroaoic
orogens and mobile belts surrounding the
Archaean craton, namely the Ketilidian
orogen and the Ammassalik mobile belt.
These areas represent at the same time a
craton margin setting. Furthermore, there
is a large overlap with areas favourable for
hydrothermal Cloncurry-type IOCG miner-
alisation.
craton margin setting. Furthermore, there
is a large overlap with areas favourable for
hydrothermal Cloncurry-type IOCG miner-
alisation.
The major characteristics of the
Cloncurry-type IOCG deposits are:
· synchronous with regional metamor-
phism
· associated with I-type magmatism
· formed mainly between 1.8 1.4 Ga
· Cu-Au mineralisation overprints a BIF
· formed mainly between 1.8 1.4 Ga
· Cu-Au mineralisation overprints a BIF
or an earlier hydrothermal iron oxide
mineralisation
mineralisation
Small occurrences within the North Atlantic
craton and the Cu-Au corridor in the Ingle -
field mobile belt are examples of this type
in Greenland. Favourable areas in Green -
land that fulfil the geological characteris-
tics listed above are located within the
numerous Proter ozoic orogens and mobile
belts surrounding the craton nucleus. One
distinguishing feature is that Cu-Au miner-
craton and the Cu-Au corridor in the Ingle -
field mobile belt are examples of this type
in Greenland. Favourable areas in Green -
land that fulfil the geological characteris-
tics listed above are located within the
numerous Proter ozoic orogens and mobile
belts surrounding the craton nucleus. One
distinguishing feature is that Cu-Au miner-
alisation overprints earlier iron oxides.
Therefore, areas with known BIF and/or
hydrothermal iron oxide mineralisation are
fertile for IOCG mineralising systems.
Therefore, areas with known BIF and/or
hydrothermal iron oxide mineralisation are
fertile for IOCG mineralising systems.
Small BIFs occur in the numerous supra -
crustal belts of the craton, with a world
class deposit at Isukasia. Sulphide-rich,
hydro thermal mineralisation is, e.g., recog-
nised at Isukasia and Taartoq. The genetic
association of these occurrences within the
IOCG class is, however, unclear. Similarly,
numerous sulphide occurrences are identi-
fied in North-West Greenland around
Melville Bugt, where the entire coastal strip
is to a variable extent underlain by BIF
horizons. These areas represent, therefore,
promising targets for IOCG exploration.
class deposit at Isukasia. Sulphide-rich,
hydro thermal mineralisation is, e.g., recog-
nised at Isukasia and Taartoq. The genetic
association of these occurrences within the
IOCG class is, however, unclear. Similarly,
numerous sulphide occurrences are identi-
fied in North-West Greenland around
Melville Bugt, where the entire coastal strip
is to a variable extent underlain by BIF
horizons. These areas represent, therefore,
promising targets for IOCG exploration.
In particular, the Ketilidian orogen in
South Greenland is regarded as being fertile
for IOCG mineralisation, because it com-
bines several of the important characteristics:
for IOCG mineralisation, because it com-
bines several of the important characteristics:
· craton margin setting
· associated with A-type and/or I-type
· associated with A-type and/or I-type
magmatism: the Julianehåb batholith
6
GEOLOGY AND ORE 13 / 2009
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
View at the possible IOCG mineralisation in Pariser Bugt, Inglefield Land, North-West Greenland
7
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
500 km
Ice caps / Lakes
Quaternary rock
Phanerozoic basins ( <400ma)
Phanerozoic basins ( <400ma)
Lower Palaeozoic and Neoproterozoic basins
Mesoproterozoic basin
Palaeoproterozoic supracrustal rock
Archaean supracrustal rock
Palaeogene magmatic province
Proterozoic magmatic province
Caledonian magmatic province
Proterozoic basement
Reworked Archaean basement
Archaean basement
Fault, thrust
Potential IOCG occurrence
s
s
s
s
Ammassalik (Tasiilaq)
Arfersiorfik
Inglefield Land
Julianehåb
(Qaqortoq)
Kobberminebugt
Paamiut
Taartoq
Nigerleq/
Sermilik
Sermilik
Niaqornaarsuk
Qoorormiut
Melville Bugt
Isukasia
Tikiusaaq
Qaqarssuk
Storø
Nuuk
Sarfartoq
Inland Ice
Ketilidian
mobile belt
mobile belt
Ammassalik
mobile belt
mobile belt
North
Atlantic
craton
Atlantic
craton
Nagssugtoqidian
Nagssugtoqidian
mobile belt
mobile belt
mobile belt
Nagssugtoqidian
mobile belt
mobile belt
· formation between 1.85-1.65 Ga
· numerous crustal-scale structures
· regional extension: the Gardar suite
· numerous crustal-scale structures
· regional extension: the Gardar suite
(ca. 1.35-1.15 Ga) with alkaline intru-
sions and sediment basins
sions and sediment basins
Also the Nagssugtoqidian, Rinkian,
Ammassalik and Inglefield orogenic sys-
tems are prospective for IOCG deposits.
Crustal-scale structures, associated with
alkaline, I-type intrusive rocks, host
hydrothermal albite and iron oxide alter-
ation as well as localised, small Cu-Au
occurrences.
Ammassalik and Inglefield orogenic sys-
tems are prospective for IOCG deposits.
Crustal-scale structures, associated with
alkaline, I-type intrusive rocks, host
hydrothermal albite and iron oxide alter-
ation as well as localised, small Cu-Au
occurrences.
Concluding remarks
Greenland represents an area for grass-
roots exploration posing a challenge to
material and logistics and, therefore, also
has a large potential for successful `green-
fields' exploration. Greenland has a long
tradition of geological exploration and
research and its south-western area is
widely covered by measurements from
geochemical and geophysical programmes,
but in the north and the east only local
areas are covered.
roots exploration posing a challenge to
material and logistics and, therefore, also
has a large potential for successful `green-
fields' exploration. Greenland has a long
tradition of geological exploration and
research and its south-western area is
widely covered by measurements from
geochemical and geophysical programmes,
but in the north and the east only local
areas are covered.
Although no definite IOCG deposit are
recognised in Greenland to this date,
some IOCG-like occurrences are suggested
and favourable geological environments
are observed. This indicates that the ice-
free area in Greenland is generally fertile
for IOCG deposits and that target-orient-
ed `greenfields' exploration has a good
potential to locate IOCG occurrences or
even deposits.
some IOCG-like occurrences are suggested
and favourable geological environments
are observed. This indicates that the ice-
free area in Greenland is generally fertile
for IOCG deposits and that target-orient-
ed `greenfields' exploration has a good
potential to locate IOCG occurrences or
even deposits.
8
GEOLOGY AND ORE 13 / 2009
Fe-Cu sulphides with Au,
magnetite
magnetite
Cu sulphides with Au,
magnetite, hematite
magnetite, hematite
Iron oxide, sulphides ?
Iron oxide, sulphides ?
Fe-Cu sulphides with Au,
magnetite
magnetite
Fe-Cu sulphides with Au,
magnetite, hematite
magnetite, hematite
Hematite, magnetite,
apatite
apatite
Magnetite, apatite
Magnetite, apatite
Olympic Dam
Olympic Dam
Olympic Dam
Olympic Dam
Cloncurry
Cloncurry
Bayan Obo
Bayan Obo
Bayan Obo
Niaqornaarsuk/
Qoorormiut
Qoorormiut
Kobberminebugt
Ammassalik
Arfersiorfik
Paamiut/Nigerleq
Inglefield Land
Sarfartoq
Qaqarssuk
Tikiusaaq
Sodic
Epidote, fluorite,
potassic
potassic
Potassic
Carbonate
Carbonate
Sodic, barite
Potassic (proximal);
sodic (distal)
sodic (distal)
Sodic
Sodic
Au, Bi, Ag, As, W, Cu,
Mo
Mo
Cu, Au, Ag
Cu ?
Cu, Au, Co
Cu, Au
Cu, Au
Nb, U, Ta, REE, P
Nb, U, REE, P
REE, P
Veins, shear zones
Veins, breccias
Breccias
?
Veins, breccias
Veins, breccias, shear
zones
zones
Veins, layers
Veins, layers
Veins, layers
Locality Type Mineralisation
Alteration
Commodity
Ore
body
POTENTIAL IOCG OCCURRENCES IN GREENLAND
Gully with potassic / iron oxide alteration in the
radioactive shear zone located marginally to the
Sarfartoq carbonatite complex, southern West
Greenland
radioactive shear zone located marginally to the
Sarfartoq carbonatite complex, southern West
Greenland
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
9
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
10
GEOLOGY AND ORE 13 / 2009
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
A.
Total magnetic intensity field from regional
aeromagnetic data for the Ketilidian orogen.
The different segments of the orogen are clearly
distinguishable from the magnetics, with the
Julianehåb batholith reflected as high magnetic
anomaly.
aeromagnetic data for the Ketilidian orogen.
The different segments of the orogen are clearly
distinguishable from the magnetics, with the
Julianehåb batholith reflected as high magnetic
anomaly.
B.
Total magnetic intensity field from regional
aeromagnetic data covering the Arfersiorfik
fjord. The central magnetite-bearing part of the
Arfersiorfik quartz diorite shows up a highly
magnetic anomaly that can be followed to the
east. A Cu-Co-Au-bearing rock sample has been
collected just south of the diorite near the
Inland Ice. North and south of the diorite is the
Nordre Strømfjord shear zone and Nordre
Isortoq steep belt located; both crustal-scale
structures of the Nagssugtoqidian orogen.
aeromagnetic data covering the Arfersiorfik
fjord. The central magnetite-bearing part of the
Arfersiorfik quartz diorite shows up a highly
magnetic anomaly that can be followed to the
east. A Cu-Co-Au-bearing rock sample has been
collected just south of the diorite near the
Inland Ice. North and south of the diorite is the
Nordre Strømfjord shear zone and Nordre
Isortoq steep belt located; both crustal-scale
structures of the Nagssugtoqidian orogen.
6
0
°
6
1
°
6
2
°
6
0
°
6
1
°
6
2
°
-48°
-45°
-42°
-48°
-45°
-42°
TMI
[nT]
0
25
50
km
Pelite
Zone
Psammite
Zone
Julianehåb
batholith
Kobberminebugt
Archaean
Foreland
Border
Zone
-745
-307
-253
-225
-202
-188
-179
-169
-160
-151
-141
-130
-120
-109
-97
-84
-71
-58
-44
-31
-18
-2
15
36
56
79
100
124
146
168
192
216
243
271
305
345
394
460
565
2220
Niaqornarsuk
Nordre
Isortoq
steep belt
Arfersiorfik
Quartz Diorite
Arfe
rsior
fik fjo
rd
A.
6
7
°
3
3
0
'
6
8
°
6
7
°
3
3
0
'
6
8
°
-51°
-50°
-51°
-50°
TMI
[nT]
0
10
20
km
6
-517
-327
-287
-260
-236
-216
-197
-179
-165
-151
-138
-127
-117
-107
-97
-87
-78
-69
-61
-53
-45
-37
-28
-20
-11
-3
17
28
40
52
64
77
94
113
139
177
236
359
1337
Inland
Ice
Nordre
Nordre
Isortoq
Isortoq
steep belt
steep belt
Nordre
Isortoq
steep belt
Nordre
Strømfjord
shear zone
Arfersiorfik
Arfersiorfik
Quartz Diorite
Quartz Diorite
Arfersiorfik
Quartz Diorite
Arfe
rsiorfik fj
ord
Arfe
rsior
fik fjo
rd
Arfersiorfik fj
ord
B.
A.
B.
11
I O C G MINERAL I S I N G S Y S T E M S I N GREENLAND
Brecciation near the Cu-Fe mineralisation at the
coast north of Rødtop mountain, Kobbermine -
bugt, South Greenland
coast north of Rødtop mountain, Kobbermine -
bugt, South Greenland
Fault zone in paragneiss south of Arfersiorfik
with malachite staining. Lenses with iron and
copper-sulphides occur within the fault zones in
this area, southern West Greenland.
with malachite staining. Lenses with iron and
copper-sulphides occur within the fault zones in
this area, southern West Greenland.
12
GEOLOGY AND ORE 13 / 2009
Key literature
Erfurt, P. & Lind, M. 1990:
Reconnaissance for
noble and base metals in the IvigtutKobber -
mine bugt area, South Greenland: analytical
results. Open File Series Grønlands Geologiske
Under søgelse
90/7
, 14 pp.
Gandhi, S.S. 2003:
An overview of the Fe oxide-
Cu-Au deposits and related deposit types. CIM
Montreal 2003 Mining Industry Conference and
Exhibition, Canadian Institute of Mining, Technical
Paper, CD- ROM.
Gandhi, S.S. 2004:
Magmatic-hydrothermal Fe
oxide±Cu±Au deposits: classification for a digi-
tal database and an overview of selected dis-
tricts. IAVCEI General Assembly, Pucón, Chile
2004, CD-ROM.
Garde, A.A., Hamilton M.A., Chadwick B.,
Grocott J. & McCaffrey K.J.W. 2002:
The
Ketilidian orogen of South Greenland: geo -
chronology, tectonics, magmatism, and fore-arc
accretion during Palaeoproterozoic oblique con-
vergence. Canadian Journal of Earth Sciences
39
, 765793.
Henriksen, N., Higgins, A.K., Kalsbeek, F. &
Pulvertaft, T.C.R. 2000:
Greenland from
Archaean to Quaternary. Descriptive text to the
Geological map of Greenland 1:2 500 000.
Geology of Greenland Survey Bulletin
185
, 93 pp.
Hitzman, M.W., Oreskes, N. & Einaudi, M.T.
1992:
Geological characteristics and tectonic set-
ting of Proterozoic iron oxide (Cu-U-Au-REE)
deposits. Precambrian Research
58
, 241287.
Kalsbeek, F. (ed.) 1989:
Geology of the Ammas -
salik region, South-East Greenland. Rapport
Grønlands Geologiske Undersøgelse
146
, 106 pp.
Kolb, J., Sakellaris, G.A. & Meyer, F.M. 2006:
Controls on hydrothermal Fe oxide-Cu-Au-Co
mineralisation at the Guelb Moghrein deposit,
Akjoujt area, Mauritania. Mineralium Deposita
41
,
6881.
Porter, T.M. 2000:
Hydrothermal iron oxide cop-
per-gold & related deposits: a global perspective
1
, 349 pp. Linden Park: Porter Geoconsulting
Publishing.
Porter, T.M. 2002:
Hydrothermal iron oxide cop-
per-gold & related deposits: a global perspective
2
, 377 pp. Linden Park: Porter Geoconsulting
Publishing.
Secher, K. & Kalvig, P. 1987:
Reconnaissance for
noble and base metal mineralisation within the
Precambrian supracrustal sequences in the
IvigtutKobberminebugt region, South-West
Greenland. Rapport Grønlands Geologiske Under -
søgelse
135
, 5259.
Secher, K. & Larsen L.M. 1980:
Geology and min-
eralogy of the Sarfartôq carbonatite complex,
southern West Greenland. Lithos
13
, 199212.
Steenfelt, A. 2001:
Geochemical atlas of Green -
land West and South Greenland. Danmarks og
Grønlands Geologiske Undersøgelse Rapport
2001/46
, 39 pp., 1 CD-ROM.
Stendal, H. & Frei, R. 2000:
Gold occurrences
and lead isotopes in Ketilidian Mobile Belt, South
Greenland. Transactions Institution of Mining
and Metallurgy
109
, B6B13.
Thomassen, B., Pirajno, F., Iannelli, T. R., Dawes,
P. & Jensen, S. M. (2000):
Economic geology
investigations in Inglefield Land, North-West
Greenland: part of the project Kane Basin 1999.
Danmarks og Grønlands Geologiske Undersøgelse
Rapport,
2000/100
, 98 pp.
van Gool, J.A.M., Connelly, J.N., Marker, M. &
Mengel, F. 2002:
The Nagssugtoqidian Orogen
of West Greenland: tectonic evolution and
regional correlations from a West Greenland per-
spective. Canadian Journal of Earth Sciences
39
,
665686.
Front cover photograph
Gossan zone, anomalous in Au, As, Cu
and Zn, hosted by Palaeoproterozoic
paragneiss, 10 km south of Marshall
Bugt, central Inglefield Land.
Bureau of Minerals and Petroleum
(BMP)
Government of Greenland
P.O. Box 930
DK-3900 Nuuk
Greenland
Tel: (+299) 34 68 00
Fax.: (+299) 32 43 02
E-mail: bmp@gh.gl
Internet: www.bmp.gl
Geological Survey of Denmark
and Greenland (GEUS)
Øster Voldgade 10
DK-1350 Copenhagen K
Denmark
Tel: (+45) 38 14 20 00
Fax.: (+45) 38 14 20 50
E-mail: geus@geus.dk
Internet: www.geus.dk
Authors
J. Kolb & B.M. Stensgaard, GEUS
Editor
Karsten Secher, GEUS
Graphic Production
Carsten E. Thuesen, GEUS
Photographs
GEUS unless otherwise stated
Printed
January 2009 © GEUS
Printers
Schultz Grafisk
ISSN
1602-818x
View to the core area of the Sarfartoq carbonatite complex.
Last modified: January 25, 2009
|
