Geological Survey of New South Wales

www.industry.nsw.gov.au/minerals

MINERAL SYSTEMS OF NEW SOUTH WALES VERSION 4 – 2011

Mineralisation source

Magmatic

Magmatic– Hydrothermal

Hydrothermalmetamorphic

+ other

Hydrothermalbasinal fluids

+ other

Hydrothermalinferred

magmaticinput

Sedimentary

Association

increasingfractionation

Intermediate(incl. porphyry)

Alkalineassociation

Magmatic-related

Epithermal

Volcanic-associated

massive sulfide

Fluid/magma type

Alkalic magmas with little or no H2O involved in ore formation.

CommentsDeposit type alternative name in itallics

Kimberlite-hosted diamondLamproite-hosted diamondAlkali basalt-related diamond

Carbonatite-hosted Cu–REE–UCarbonatite-hosted NbCarbonatite-hosted apatite–magnetite (Kiruna-type)

NSW examples

Diamonds (subduction-related)

Fluids from intermediate to felsic magmas with high oxidation potential and low to intermediate fractionation. May include a minor amount of fluids derived from other sources.

For skarns, non-magmatic less oxidised fluids can be important (magmatic vs. non-magatic fluid ratio generally >1:1).

Au porphyryCu–Au porphyryCu porphyryCu–Mo porphyry

Skarns Fe skarn Au–(Bi) skarn Cu–Au–(Fe) skarn Cu–Mo skarn more fractionated

less fractionated

Cargo (Cu–Au)Copper Hill (Cu–Au)Northparkes (Au–Cu)Cadia (Au–Cu)Temora district (Cu–Au) (The Dam, Mandamah, Yiddah)Yeoval (Cu)

Tallawang (Fe) (skarn)Sheahan-Grants (Au) (skarn)Big Cadia (Cu–Au–Fe) (skarn)Browns Creek (Cu–Au) (skarn)

Cu–Mo porphyry deposits generally have a continental association and form in granodioritic to felsic rocks; whereas, Cu–Au porphyry deposits have an island arc and post-collisional or early back-arc association (usually potassic). In addition, for skarn deposits, deposit scale controls include: temperature, initial, magmatic and exotic fluid oxidation state, porosity and host rock composition (i.e. limestone and/or dolomite). These are important controls to the skarn-type (i.e. calcic vs. magnesian skarns, C, Fe, etc).

Fluids from highly fractionated felsic magma, low to high oxidation potential.

Non-magmatic fluids can be important in skarns (magmatic vs. non-mamatic fluid ratio generally >1:1).

Sn–(W) porphyrySn–(W) disseminatedSn–(W) vein

W–Mo–Bi pipes

Mo porphyry

Granite-related gold (GRG)Granite-related polymetallic veinsEpigenetic (Avebury-type) Ni

Skarns Zn–Pb skarn W skarn Sn–(W) skarn Mo skarn U–REE skarn more fractionated

lessoxidised

more oxidised

less fractionated

Ardlethan (Sn)Taronga (Sn)Mole Granite (Sn–W–silexite)Whipstick Mo–Bi–(Au)

Kingsgate (Mo)Mount Pleasant (Mo)Glen Eden (Mo–W–Sn)

Timbarra (Au) (GRG)Dargues Reef (Au) (GRG)Conrad (Ag–Cu–Pb–Zn–Sn–As)

Leadville (Zn–Pb) (skarn)Yetholme (Mo–W) (skarn)Rye Park (W–Sn) (skarn)

Principal controls include oxidation and fractionation state of the intrusion, and depth of emplacement. Level of exhumation is critical. Fluids can have high B, Li and F; be saline or dilute; and be S poor.

Intrusion-related polymetallic veins generally form distal to the causative intrusion.

In Epigenetic (Avebury-type) Ni sulfide systems fluids from fractionated granites remobilises Ni from adjacent mafic–ultramafic sequences.

For skarn deposits, deposit scale controls include: temperature, porosity and host rock composition (i.e. limestone and/or dolomite). These are important controls to the skarn-type (i.e. calcic vs. magnesian skarns, C, Fe, etc).

Oxidised sedimentary-

exhalative systems

Generally low temperature oxidised basin-derived H2S-poor and/or oxidised fluids. Ore deposition is due to sulfate reduction or by the addition of H2S.

Queensland — Mt IsaNT — McArthur RiverParagon Group (within) Broken Hill

Siderite and/or ferroan carbonate alteration haloes are common. Barite, gold and pyrrhotite are generally absent.

basementsources

basinalsources

Reduced sedimentary-

exhalative systems

Moderate temperature (>200°C) basin-derived reduced fluids; mixing of ore-forming fluids with cold sea-water is an important ore-deposition mechanism.

Turbidite (volcanic) basin-hosted stratiform base metal (Zn–Pb–Ag–Au–barite)(Selwyn (SEDEX)-, Cobar Zn–Pb–Ag- and Broken Hill Ag–Pb–Zn-types)

Turbidite (mafic–igneous) basin-hosted stratiform base metal (Zn–Pb–Ag–Au–barite)

Broken Hill (Broken Hill-type) (Ag–Pb–Zn)The Pinnacles (Broken Hill-type) (Ag–Pb–Zn)Endeavor (Cobar Pb–Zn–Ag-type) (Pb–Zn–Ag)

Metals sourced from basin; transported by reduced fluids and will precipitate a range of metals due to fluid mixing, cooling or increased S content. These deposits are enriched in a wide variety of metals including Pb, Zn, Cu, Ag, Au, Sn. Barite is common in Selwyn-type deposits (deposition in oxidised environment). Cobar-type Pb–Zn–Ag deposits are synchronous with deformation, although formed from basinal fluids, whereas hydrothermal systems for Selwyn-type deposits might be driven by intrusions.

End-member fluids include strongly acidic and oxidised fluids (high sulfidation) and weakly acidic to weakly alkaline reduced fluids (low sulfidation).

High sulfidation (enargite–luzonite–famatinite–covellite) Au–Cu

Intermediate sulfidation (tetrahedrite–tennantite–galena–chalcopyrite–low Fe-sphalerite) Ag–Au–base metal

Low sulfidation (pyrrhotite–arsenopyrite–high Fe-sphalerite) Au–Ag

Peak Hill (Au) (High sulfidation-type)Gidginbung (Au) (High sulfidation-type)

Yerranderie (Ag–Au–base metal) (Intermediate sulfidation-type)Drake (Ag–Au–base metal) (Intermediate sulfidation-type)

Pambula (Au) (Low sulfidation-type)Yalwal (Au) (Low sulfidation-type)

High-sulfidation epithermal deposits have a close association with the causative intrusion and form from oxidised acidic fluids whereas intermediate- and low-sulfidation systems form from near-neutral fluids. Fluid mixing is important in intermediate-sulfidation systems. Boiling is important in low-sulfidation systems.

Term “sulfidation” used to describe the sulfidation state of the observed hypogene sulfide assemblage.

Moderate temperature (<400oC), metal-charged reduced and slightly acidic fluids. Initial ore-forming fluids are often seawater-dominant though a magmatic component can be present. Metals leached from host sequence.

Bimodal mafic-dominated (Noranda-type) Cu–Zn–(Au–Ag–Pb)Mafic setting-hosted (Cyprus-type) Cu–Zn–(Au–Ag)Pelitic–mafic-hosted (Besshi-type) Cu–Ag–(Au–Zn)Bimodal felsic-dominated (Kuroko-type) Pb–Zn–Cu–(Ag–Au)Siliciclastic–felsic-hosted (Iberian-type) Zn–Pb–Cu–(Ag–Au–Sn)/barite

Volcanic-hosted bariteVolcanogenic Mn–Fe

Woodlawn (Pb–Zn–Cu, minor Ag–Au)Captains Flat (Pb–Zn–Cu, minor Ag–Au)Lewis Ponds (Pb–Zn–Cu, minor Ag–Au)Burraga (Cu–Zn–Pb)Gulf Creek (Cu, minor Zn)Kempfield (Ag–barite)Gurrundah (barite)

Massive sulfide deposits that form synchronously with volcanism in a sub-marine setting. Deposits can form at seafloor or sub-seafloor. Some seafloor deposits are brine pool- or Hokuroku-type depending on fluid salinity. Geological settings include mid-oceanic ridges, arc, plate margin, back-arc setting.

Metal budget and hence deposit type largely controlled by the principal volcanic and sedimentary lithological units within the fluid–wallrock reaction zone that was leached to form the deposit.

Mafic(problematic)

Large deposits derived from magmatic aqueous fluids related to mafic intrusions appear to be unlikely although significant alteration systems may be present.

Carbonate- hosted

High salinity epigenetic, low temperature (<150°C) basinal fluids of mixed (often meteoric) origin. The fluids are generally moderately reduced (pyrite-stable).

Carbonate-hosted stratabound Zn–Pb(Mississippi Valley-, Irish- and Carbonate base-metal-types — excludes skarn)

Sandstone-hosted stratabound Pb

Wonawinta (MVT)Endeavor (part) (carbonate base metal)

Characterised by Pb>Zn>>Cu, presence of high-evaporitic sabkha setting and regional fluid flow. The dominant ore controls are dissolution collapse breccias and/or lithological boundaries. Deposit modelling indicates a high meteoric fluid flow (common in low latitudes).

Continental rift Cu

Low temperature (100–150°C) saline (to 20%), relatively oxidised fluids that are pH neutral. Fluid chemistry constrained by carbonate +/ silicates. The sulfur species is generally SO4

2-.

Stratabound siliciclastic-hosted Cu–Co–Ag–U–PGE(Stratabound sediment-hosted Cu-, Continental red bed- and Kupferschiefer-types)

Stratabound clastic-hosted U–Pb–Cu

Sydney Basin (minor)Hervey Group (minor)

Deposited in intercontinental rift-related sequences typically containing oxidised (red-bed) aeolian to sabkha environment that are frequently capped by shallow marine reduced assemblages.

Carlin-type

Low salinity, moderate temperature (150–200°C), moderately acidic (pH ~5) reduced H2O–CO2-rich fluids. Fluids have characteristics indicating inputs of deep metamorphic and/or magmatic origin.

Carbonate-hosted disseminated (Carlin-type) Au Potential in the Cobar Basin and Hill End Trough

Features of Carlin-type deposits mirror orogenic Au deposits, with mineralisation being linked to orogenic activity. They form at the start of extensional activity following earlier subduction. Precipitation of gold is probably linked to carbonate dissolution.

Hydrothermal:metamorphic

Au

Moderate temperature, low salinity, generally reduced CO2-bearing fluids that are mostly metamorphic in origin.

Structurally controlled low sulfide Au(Orogenic Au-type)

Structurally controlled Sb–Au (Orogenic Sb–Au-type)

Hill End (Au)Adelong (Au)Wyoming (Au)London–Victoria (Au)Hillgrove (Au–Sb)

Mineralisation synchronous with deformation; gold transported as a bisulfide complex. Sulfidation reactions are the major ore deposition mechanism. Ore localisation is generally controlled by 'void creation' (e.g. competency contrast, intersection of structures etc.).

Felsic association Felsic magmas with little or no H2O

involved in ore formation.

Peraluminous-related (Rossing-type) UPeralkaline-related (Bokan Mountain-type) ULi–Cs–Ta–(B) pegmatite with SnTa–Sn–Li–(B) pegmatiteNb–Y–F pegmatite‘rare metal granites’

Triple Chance (feldspar–mica–beryl)WA Greenbushes (Nb–Sn)

Toongi (ZrO2, HfO2, Y2O3, Nb2O5, Ta2O5)

Pegmatites and 'rare metal granites' comprise extremely fractionated melts resulting in crystallisation of ore elements at the magmatic stage (cf. hydrothermal dominated systems).

Mafic–ultramaficassociation

Mafic magmas with little or no H2O involved in ore formation.

Gabbronorite–troctolite-related deposits Intrusive-related basal Ni–Cu–(PGE) Intrusive-related stratiform Cr–PGE Intrusive-related stratiform Fe–Ti–V Flood-basalt-related Ni–PGE–CuUltramafic-related deposits Komatiite-related Ni–Cu–(PGE) Picrite-related Ni–Cu–(PGE) Intrusive-related podiform (Alaskan- and Alpine-type) Cr, PGE

Fifield (PGE Alaskan)Coolac (podiform Cr)Gordonbrook (podiform Cr)

Siderophile/chalcophile/PGE elements mainly associated with magmas of mafic to ultramafic composition.

Basin-related U systems

Fluids are acidic to extremely acidic and/or oxidised, salinity is high,fluid temp is generally low to moderate.

Beverley (U) (South Australia) Ranger (U) (Northern Territory)

U transported as a carbonate complex in saline oxidised fluid at pH <5, precipitation occurs about a redox front when the fluid reacts with either reduced basement rocks or a reduced fluid to precipitate uraninite and related minerals. Additionally changes to ligand activity and/or pH increases can trigger U-mineral deposition.

Surficialprocesses

Residual

Deposits formed by regolith- and/or supergene-related processes: e.g. lateritisation, silicification etc. (producing gossans and leached caps).

Ni–Co lateritesSupergene AuSupergene CuSupergene Fe, MnBauxiteKaoliniteLimonite pisolites Magnesite

Syerston (Ni–Co)Young (Ni–Co) magnesite)Inverell (bauxite)Gulgong (kaolin)Inverell bauxite district

Tertiary weathering surfaces are present throughout New South Wales.

Bauxite deposits are associated with deeply weathered Tertiary basalts.

Chemicalprecipitates

Deposits formed by the precipitation of minerals of economic interest at low temperature, mainly associated with weathering-related processes, with many deposits forming a marine environment.

Amagmatic banded iron formation (Hamersley-type)Volcanic-related banded iron formation (Algoma-type)

Iron oxide precipitates (Bog iron ore)LimestoneMagnesiteManganese oxide-rich sedimentsPhosphatesOpalEvaporites

Hawsons (Fe)

Crookwell (Fe)Thuddungra (magnesite)Lightning Ridge (opal)Kandos (limestone)

Dissolution and precipitation of metals within the zone of weathering.

A number of processes have been proposed for upgrading the iron content of Banded Iron Formation (BIF). These include supergene, metamorphic and hydrothermal processes.

Bog iron ores were important sources of iron in the past.

Hydrothermal:metamorphic

base metal

Reduced to relatively oxidised (pyrrhotite–pyrite-stable) NaCl-rich fluids at temperatures 250–340°C.

Structurally controlled high sulfide base metal (+/- Au)(Orogenic base metal-, Mt Isa Cu-, Metamorphic Cu- and Cobar Cu–Au-types)

Kangiara (Cu–Pb–Zn)Frogmore (Cu)

CSA (Cobar Cu–Au-type)The Peak (Cobar Cu–Au-type)

Hera (Cu–Pb–Zn–Au–Ag)Nymagee (Cu)

Tritton (Cu)

Orogenic base metal and related deposits form from low- to moderate-salinity, reduced fluids containing CO2, CH4, C2H6, H2S, CH4 with mineralisation being synchronous to post-peak deformation. Fluids transport base metals as chloride complexes, whereas gold is likely to be transported as bisulfide complexes. Sulfides are precipitated by reduction, pH increase and fluid mixing.Cobar-type Cu–Au deposits include metals sourced from both basement and basinal sources.

MechanicalConcentration by mechanical or gravitational processes including mass movement, wind and water.

Au–Ag eluvial/alluvial/deep leadSn eluvial/alluvial/deep leadPt/Pd/Au alluvial/deep leadSapphire/diamond eluvial/alluvial/deep leadMineral sand depositsChannel iron depositsDiatomiteAeolian

Macquarie River (Au)Araluen Valley (Au)Vegetable Creek deep lead (Sn)Fifield deep lead (PGE)Ginkgo (Murray Basin mineral sand)Kyooma (diatomite)

Tertiary weathering surfaces are present throughout New South Wales.

Channel iron deposits are extensively developed in Cobar peneplain district.

Cu–Au–Fe–REEIOCG deposits

Post orogenic U-rich magmatic fluids mixed with surface waters.

Hematite-group (Olympic Dam-type) Cu–Au–REE–U

Magnetite-group (Ernest Henry- and Candelaria-types) Cu–AuCopper Blow (Cu–Fe–(U))

Associated with potassic oxidised, intermediate to felsic granites emplaced at depths from ~2 to 15km. Unmixing of magmatic H2O–CO2–saline-rich fluids may be important in generating sodic/feldspathic alteration.

Sandstone-hosted UUnconformity-related U

Stratabound siliciclastic basin-hosted Zn–Pb–Ag (Mt Isa-type)

Granite

by Peter M. Downes, Phil L. Blevin, David B. Forster, John Whitehouse, Peter Lewis and Robert G. Barnes

Cadia (Au–Cu)

Hera (Cu–Pb–Zn–Au–Ag)

Tritton (Cu)

Browns Creek (Cu–Au) (skarn)

Broken Hill (Ag–Pb–Zn)

Gundaroo (Sandstone-hosted stratabound Pb–Zn–Ag)

Peak Hill (Au) (High sulfi dation-type)

Conrad (Ag–Cu–Pb–Zn–Sn–As)

Big Bygoo (Ardlethan) (Sn)

Northparkes (Au–Cu)

Adelong (Au)

Mineral Hill (Ag–Au–base metal)(Intermediate sulfi dation-type)

Hillgrove (Au–Sb)

CSA (Cobar Cu–Au-type)

Adelong (Au)

Eaglehawke (Windeyer) (Orogenic Au)

Bodangora (Orogenic Au)

Conrad (Ag–Cu–Pb–Zn–Sn–As)

Ardlethan (Sn)

Ardlethan (Sn)

Halls Peak (Siliciclastic–felsic-hostedZn–Pb–Cu–Ag)

GS2010/0917