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RMS-DPI: E2-2011-9-1 http://www.minsoc.ru/E2-2011-9-1

IGEM 15/04/2011 1

Lithocap alteration and sulfidation state evolution of ores over porphyry systems:

IGEM Moscow: April 2011IGEM Moscow: April 2011

Insight from volcanic-hydrothermal systems

Jeffrey W. HedenquistJeffrey W. Hedenquisty qy qOttawa, CanadaOttawa, Canada

Thanks to Kinross Gold CorporationThanks to Kinross Gold Corporation

White Island, New ZealandWhite Island, New Zealand

•• Evolution of hydrothermal alteration and mineralizationEvolution of hydrothermal alteration and mineralization•• Advanced argillic alteration: Condensation of magmatic vaporAdvanced argillic alteration: Condensation of magmatic vapor

•• Mineralization of high & intermediate sulfidation state mineralsMineralization of high & intermediate sulfidation state minerals

•• Evolution of magmaticEvolution of magmatic hydrothermal fluidshydrothermal fluids•• Evolution of magmaticEvolution of magmatic--hydrothermal fluidshydrothermal fluidsHigh-temperature hypogene vapors, ~850 oC (HCl, SO2)


IGEM 15/04/2011 2

H2SO4 HCl Hypogene

Lithocap formed by hypogene condensate

Formation of advanced argillic alteration

H2SO4, HCl HypogenepH <1

HCl, SO2, CO2, H2Shypogene alteration

4 SO2 + 4 H2O => 3 H2SO4 + H2S

H2O, NaCl, SO2, HCl, CO2, H2S, ...


IGEM 15/04/2011 3

Summitville, Colorado

aluminoalumino-- qtzqtz-- residual residual qtzqtz--silicatessilicates alunalun-- qtzqtz alunalun--(kandites)(kandites) pyritepyrite pyritepyrite

residual residual qtzqtz--alunalun--qtzqtz pyritepyrite

( )( ) pypy pypy

Summitville, Colorado

Residual (vuggy) qtz and Residual (vuggy) qtz and qtzqtz--alunite flares upwardalunite flares upward

Residual (vuggy) qtz (ore)Residual (vuggy) qtz (ore)QtzQtz--alunitealunite--pypy

Steven and Ratté, 1960

Steven & Ratté, 1960

pH ~ >6 4 - 6 2 - 4 <2

10 - 100s m


IGEM 15/04/2011 4

Far Southeast Far Southeast –– Lepanto, Phillipines: Lepanto, Phillipines: Linked porphyry and epithermal depositsLinked porphyry and epithermal depositsFar Southeast Far Southeast –– Lepanto, Phillipines: Lepanto, Phillipines: Linked porphyry and epithermal depositsLinked porphyry and epithermal deposits

Mohong Hill quartz-alunite-pyrite lithocapalunite pyrite lithocap

dacite pyroclasticsdacite pyroclastics

volcaniclastic volcaniclastic basementbasement

Lepanto cross section:Lepanto cross section:

Early alteration flares Early alteration flares upward along structure, upward along structure, and outward from feederand outward from feeder

Dacite pyroclastc

and outward from feeder and outward from feeder along unconformityalong unconformity

quartz

LithologyLithology--controlled controlled lithocap lithocap outcropoutcrop

Basement volcaniclastics

Enargite-Au ore in residual qtz host

Quartz-alunite-py ± Al-silicate halo

FreshFresh QtzQtz alunalun VuggyVuggy

Gonzalez, 1956, 1959; Garcia,

Fresh Fresh QtzQtz--alunalun-- Vuggy Vuggy dacite dacite py halopy halo qtz oreqtz ore


IGEM 15/04/2011 5

Satsuma Iwojima, S. Kyushu:Satsuma Iwojima, S. Kyushu:passive degassingpassive degassing 870 870 ooC HC H22O, O,

HCl, SOHCl, SO22

Summit craterSummit craterSampling of 770 C vapor with acidic gases,HCl, SO2


IGEM 15/04/2011 6

Residual (vuggy) qtzResidual (vuggy) qtzSatsuma Iwojima, Japan

pH 1.7 -- 1.1

Hedenquist et al., 1994

dissolved rock pH 1.1pH 1.1


IGEM 15/04/2011 7

Dissociation and increased Dissociation and increased reactivity due to coolingreactivity due to cooling

HCl HCl ⇒⇒ HH++ + Cl+ Cl--HH22SOSO44 ⇒⇒ HH++ + HSO4+ HSO4--

~100 m~100 m

silicicsilicicqtzqtz--alunalun muscovite overprint, muscovite overprint,

transition up to pyrophyllitetransition up to pyrophyllite

150 C 200 C 250 C pH~1.5 ~0.7 ~1

300 CpH~2

W:R <10 W:R >>10

Hypogene acidHypogene acid--leached leached horizon = lithocaphorizon = lithocap

Magmatic condensates more reactive with rock at lower temperature (and high W:R ratio)

350 C350 C

Lepanto Lepanto -- Far Southeast, Philippines:Far Southeast, Philippines:(1 Mt Cu, 4 Moz Au; 5 Mt Cu, 20 Moz Au) (1 Mt Cu, 4 Moz Au; 5 Mt Cu, 20 Moz Au)

Offset of lithocap, and ore, from causative intrusionOffset of lithocap, and ore, from causative intrusion

Hedenquist et al., 1998Hedenquist and Taran 2011

200 C200 C

300 C300 C

Long section along Lepanto faultLong section along Lepanto fault

Hedenquist and Taran, 2011


IGEM 15/04/2011 8

Mankayan Mankayan district, district, Luzon: Luzon:

LepantoLepanto LepantoLepanto Lepanto enargiteenargite--Au, Au, Far Southeast Far Southeast porphyry Cuporphyry Cu--Au, and Au, and Victoria veinsVictoria veins

Lepanto

Far Southeast

Victoria

1 km

Surface projections of Surface projections of Lepanto enargiteLepanto enargite--Au Au deposit, Victoria veins, & deposit, Victoria veins, & Far Southeast porphyryFar Southeast porphyry

X Horn1.45 Ma

Hydro Biot1.40-1.45 Ma

Alunite1.40-1.45 Ma

Ser ~1.35 Ma

Bt 2.2-1.8 Ma

Enargite-AuPorphyry Cu

ArribasArribas et al. (1995); et al. (1995); Cla eriaCla eria (2001)(2001)

Teresaveins

Bulalacao porphyry

X Biot1.18 Ma

X Illite 1.15-1.4 Ma

IS Au-Ag veinsClaveriaClaveria (2001); (2001); Hedenquist et al. (2001)Hedenquist et al. (2001)


IGEM 15/04/2011 9

Einaudi et al., 2003

Sulfidation statesSulfidation states


IGEM 15/04/2011 10

Einaudi et al., 2003

Sulfidation state evolutionSulfidation state evolution Arc Arc magmasmagmasResidual quartz

(secondary quartzite)

Magmas of Magmas of bimodal bimodal

extensionextension

No rock buffer left

e.g., Lepanto, Kochbulak, Bereznyaki

Kovalenker et al., 1997 Hedenquist et al., 1998Plotinskaya et al., 2009

White Island, New Zealand: Quiescent eruption 1988White Island, New Zealand: Quiescent eruption 1988

SulfidationSulfidationand and redoxredoxstatesstates

Vapor condensates Vapor condensates cause acidic leaching.cause acidic leaching.

What more can we learn What more can we learn statesstatesfrom volcanic fluids?from volcanic fluids?


IGEM 15/04/2011 11

Active and extinct volcanic systemsActive and extinct volcanic systemsGiggenbach, 1987Giggenbach, 1987

lfur condensationT ( C)o100 300 500 800

-2

2 arc magmas


-2

2 arc magmas


-2

2 arc magmas


-2

2 arc magmas


-2

2 arc magmas

Einaudi, Hedenquist, Einaudi, Hedenquist, Inan, 2003Inan, 2003

bn

cvdg

Sulfur

poiro

n

tn

mt+qz+po

fayalite

-6

-10

bn

cvdg

Sulfur

poiro

n

tn

mt+qz+po

fayalite

-6

-10

bn

cvdg

Sulfur

poiro

n

tn

mt+qz+po

fayalite

-6

-10

FUMAROLES

MAGMATIC HYDROTHERMAL

bn

cvdg

Sulfur

poiro

n

tn

mt+qz+po

fayalite

-6

-10

FUMAROLES

bn

cvdg

Sulfur

poiro

n

tn

mt+qz+po

fayalite

-6

-10

FUMAROLES

HS

epith

erm

alba

se-m

etal

vei

ns

Porphyry-Cu

py + bn

cp

po

lo+po

hm + py

mt

1000/T (K)3.0 2.0 1.0

-14

-18

py + bn

cp

po

lo+po

hm + py

mt

1000/T (K)3.0 2.0 1.0

-14

-18

py + bn

cp

po

lo+po

hm + py

mt

1000/T (K)3.0 2.0 1.0

-14

-18

py + bn

cp

po

lo+po

hm + py

mt

1000/T (K)3.0 2.0 1.0

-14

-18

py + bn

cp

po

lo+po

hm + py

mt

1000/T (K)3.0 2.0 1.0

-14

-18

T ( C)o100 300 500 800

h

hm

py + bn + hmcp

OXIDIZEDT ( C)o100 300 500 800

h

hm

py + bn + hmcp

T ( C)o100 300 500 800

h

hm

py + bn + hmcp

T ( C)o100 300 500 800

h

hm

py + bn + hmcp

T ( C)o100 300 500 800

h

hm

py + bn + hmcp

T ( C)o100 300 500 800

h

hm

py + bn + hmcp

acid crater-lakesT ( C)o100 300 500 800

h

hm

py + bn + hmcp

acid crater-lakesT ( C)o100 300 500 800

h

hm

py + bn + hmcp

acid crater-lakes

RRH H (log (log ffHH22//ffHH22O) O) -- 1/T “Gigggegram”1/T “Gigggegram”Inan, Einaudi, Inan, Einaudi, Hedenquist, 2002Hedenquist, 2002

oxidizedoxidizedhmmt

mt + Spo

pyhm + Spy

NiO

p

Kspar + mt + qzphlogopite

hmmt

mt + Spo

pyhm + Spy

p


hmmt

mt + Spo

pyhm + Spy

p


hmmt

mt + Spo

pyhm + Spy

p


hmmt

mt + Spo

pyhm + Spy

p


hmmt

mt + Spo

pyhm + Spy

p



hmmt

mt + Spo

pyhm + Spy

p



hmmt

mt + Spo

pyhm + Spy

p


MAGMATIC HYDROTHERMAL f f OO22

reducedreduced

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

REDUCED

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

po

1000/T (K)3.0 1.01.41.82.22.6

mt + qzfayalite

NiONimt + py

poGiggenbachs’‘rock buffer'

FeFe3+3+/Fe/Fe2+2+

reducedreduced


IGEM 15/04/2011 12

Epithermal deposit endmember Epithermal deposit endmember chemical environments: chemical environments:

Sillitoe and Hedenquist, 2003La Coipa

Frutadel

Norte

Evolution affected by composition of magmatic fluid, and interaction with wallrock (many variations)

Norte

Kupol

Hedenquist et al., 2001

Geology of 3 end-member epithermal deposits: high-, intermediate- &

low-sulfidation ores

Geology of 3 end-member epithermal deposits: high-, intermediate- &

low-sulfidation ores

Dr. Glen Masterman, Vice President - Exploration


IGEM 15/04/2011 13

Kinross deposits

Endowment of Endowment of Kinross deposits Kinross deposits that are >10 that are >10 Moz (300 t Au)Moz (300 t Au)

Source: Kinross and Red Back Mining Annual Reports and other sources.Deposit figures are quoted on a100% basis.

View Of La Coipa MineView Of La Coipa MineView over La Coipa Mine, Chile: to NW

Production: 1989-now, 108 t Au, 6030 t Ag; Resource: 57 t Au, 1770 t Ag


IGEM 15/04/2011 14

- Alteration Steam heated, residual qtz,

advanced argillic (alunite), argillic

La Coipa, Chile: Geological characteristics of a high-sulfidation deposit

Domes

- Mineralization Styles Disseminated, breccia, veins, mantos

- Structural & lithological controls

- Hypogene mineralizationNative gold and silver, argentite, electrum, proustyte, pyrargyrite, pyrite, enargite, tetrahedrite, tennantite, chalcopyrite, bornite, galena, sphalerite: high sulfidation

- Supergene overprintNative gold and silver, cerargyrite, embolyte, iodargyrite, argento-jarosite

Domes

La Coipa: Ladera Farellón Cross Section

Qtz-alunite with roots of pyrophyllite ± zunyite, diaspore, APS (mica)

Pyrite-enargite (luzonite)-tennantite, pyrite-covellite/digenite, chalcocite/chalcopyritechalcocite/chalcopyrite, (+chalcopyrite, bornite, covellite, galena, sphalerite, tennantite)

(supergene overprint)


IGEM 15/04/2011 15

Di (2006) f thDiscovery (2006) of theFruta del Norte epithermal Au/Ag deposit, Ecuador

LOCAL CRUSTAL STRUCTURESuarez pull-apart basin

SuarezFormation

Peñas FaultZone

Misahuallí Formation(main vein host)

FDN Juxtaposed

Suarez Fm


IGEM 15/04/2011 16

Setting of Fruta del Norte

Cretaceous 119-110 Ma CretaceousCretaceous

Jurassic 170-190 Ma

Fruta del Norte 158-156 Ma

FRUTA DEL NORTE – BLIND TARGET – PATH-FINDER GEOCHEMISTRY

Suarez Fm: silicified - As, Sb, Hg, marcasite, BM


IGEM 15/04/2011 17

THE DISCOVERY

Fruta del Norte MINERAL ZONESIntermediate Sulfidation Epithermal System:

R 204 t A (8 1 /t) AReserves: 204 t Au (8.1 g/t) Au


IGEM 15/04/2011 18

LAMINATED SILICA SINTER/MUD POOL DEPOSITS

FDN-1 Mn-carbonate/rhodochrosite stockworks + BM7.43 g/t Au, 7.54 M oz (55% of orebody)

TEXTURES:- Crustiform-colloform-cockade-ginguroDiatreme breccia (dacite)


IGEM 15/04/2011 19

FDN-2 Chalcedony marcasite + base metal sulphide7.31 g/t Au, 3.64 M oz (22% of orebody)

FEATURES:- >1% SULPHIDE (marcasite) – blackened fine matrix

FDN-3 Upper silica low sulphide carapace12.36 g/t Au, 0.4 M oz (2% of orebody)

FEATURES:- Depleted in sulphide, enriched in celadonite, locally vuggy


IGEM 15/04/2011 20

FDN-4 Northern quartz vein zone6 g/t Au, 2.1 M oz (18% of orebody)

FEATURES:- Bladed carbonate (replaced) , adularia – intense stockworks - electrum

THE GOLD

FDN1…. 2447 g/t Au


IGEM 15/04/2011 21

OkhotskOkhotsk--Chukotka metallogenyChukotka metallogeny


IGEM 15/04/2011 22

Kupol regional geologyKupol regional geology

• Text• Text

Initial Occurrence Discovered in 1966 during Initial Occurrence Discovered in 1966 during 1:200,000 Regional Mapping Program1:200,000 Regional Mapping Program


IGEM 15/04/2011 23

Kupol deposit discovered in 1995 Kupol deposit discovered in 1995 on last prospecting traverse of the seasonon last prospecting traverse of the season

Kupol DiscoveryKupol Discovery

Very little Very little outcrop of outcrop of ppKupol Vein. Kupol Vein. Big Bend Big Bend was buried was buried under talus under talus and tundra.and tundra.Vein float Vein float present in present in

th dth dnorth and north and south.south.


IGEM 15/04/2011 24

Aerial View of Big Bend Aerial View of Big Bend ((40% of all gold at Kupol)40% of all gold at Kupol)

Kupol area geologyKupol area geology

Gently eastward dipping andesitic flows and pyroclastics, intruded by rhyolite dikes and flow dome complex

1 km


IGEM 15/04/2011 25

Kupol Longitudinal Section, 2007Kupol Longitudinal Section, 2007(magnenta = 100 g*m Au )(magnenta = 100 g*m Au )

400 m

2003 to 2006, >150,000 m in 700 ddh define >180 t Au

Production, May 2008; development cost, $407 M

End 2010: 69 t Au equil.; Reserves, 75 t Au (10.7 g/t), 948 t Ag

Big BendBig Bend

• Single large vein• Single large vein• Steepening toward surface• Bisected by rhyolite dikes


IGEM 15/04/2011 26

North ZoneNorth Zone

North and South Zones display near vertical multiple anastomosinganastomosing veins

Kupol mineralization stagesKupol mineralization stages

Early phase of quartz adularia (stained yellow) with minor goldyellow) with minor gold and silver

Second phase of sulfosalt-Second phase of sulfosaltrich quartz + adularia. Principal Au and Ag rich phase.


IGEM 15/04/2011 27

Kupol “Bonanza” styles of mineralizationKupol “Bonanza” styles of mineralization

289 g/t Au, 3336 g/t Ag

Examples of high Examples of high grade sulfosaltgrade sulfosalt--rich rich colloform & colloform & crustiform banded crustiform banded veins and brecciasveins and breccias

237 g/t Au, 4291 g/t Ag

Main Ore MineralogyMain Ore Mineralogy•• Electrum, Native Gold, Native SilverElectrum, Native Gold, Native Silver•• Sulfosalts: Sulfosalts:

• Stephanite (Ag5SbS4) • Pyrargyrite (Ag3SbS3) • Tetrahedrite (Cu12Sb4S13) • Freibergite(Ag,Cu,Fe)12(Sb,As)4S13

• Perceite (Ag, Cu)16As2S11

•• Sulphides:Sulphides:A hi (A S)• Acanthite (Ag2S)

• Pyrite • Marcasite • Chalcopyrite • Sphalerite


IGEM 15/04/2011 28

Low sulfidation deposit indicators: Vein formation at neutral pHLow sulfidation deposit indicators: Vein formation at neutral pH

Amorphous silica Amorphous silica depositiondepositionC liC li tiftifCyclic Cyclic crustiformcrustiformand and colloformcolloformbandingbanding

Sulfosalt rich Sulfosalt rich (ginguro) bands (ginguro) bands abundantabundant

HishikariHishikariKyushu, Japan:Kyushu, Japan:330 t Au, 40 g/t330 t Au, 40 g/t

10001000--4000 g/t Au4000 g/t Au~20 g/t Au~20 g/t Au

<1 g/t Au<1 g/t Au


IGEM 15/04/2011 29

Kyushu tectonic evolutionKyushu tectonic evolution

Y. Watanabe, 2004Y. Watanabe, 2004

S Kyushu, looking south

• Tectonics influence type ypof epithermal Au deposit (early HS, IS, or later LS)

• Variable features, no single deposit type

Hishikari Hishikari (LS) 0.7 Ma(LS) 0.7 MaKushikino Kushikino

(IS) 3.7 Ma(IS) 3.7 Mamigration of volcanism

Epithermal deposit stylesEpithermal deposit styles

• Endmember styles can have a wide• Endmember styles can have a wide range of characteristics

• Variations caused by:• Tectonic setting• Magmatic affiliationg• Depth of formation and structural control• Degree of wallrock influence on paths of

fluid evolution


IGEM 15/04/2011 30

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