High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Lithocaps and high- to intermediatesulfidation epithermal deposits •
Principal characteristics
•
Origin of features, background
•
Case examples, variations
Exploration implications
Université de Genève : 13 October 2014
Jeffrey W. Hedenquist Ottawa, Canada
Location of Principal Epithermal Gold Deposits Western Pacific Belt
Tethys Belt
Eastern Pacific Belt .
Arribas et al., 2000
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Kochbulak
Sillitoe and Hedenquist, 2003
Epithermal deposit types (end-members!) Arcs andesite
Shallow intrusion source of NaCl
Kupol
Rifts bimodal
Basalt source of H2S?
Hedenquist et al., 2000
Porphyry systems
High-sulfidation Au-Ag-Cu
Lacustrine beds
Intermediate sulfidation Au-Ag
Base of lithocap
Porphyry Cu-Au
Sillitoe, 2010 Economic Geology
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Kawah Ijen, Java: volcanic crater with acidic lake
pH 0.0 Condensation of acid magmatic volatiles, SO2, HCl
Colloidal silica in suspension, and deposited in laminated sediments (also enargite, covellite, stannite in native S)
Photograph: Pierre Delmelle
Volcan Poás, Rica Volcan Costa Poás, Costa Rica
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Volcan Poás, Costa Rica
Acid moat lake around dome, laminated siliceous sediments, paleosurface...
Chaquicocha
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Tony Longo
Yanacocha laminated siliceous lake seds
Formation of advanced argillic alteration: hypogene & steam heated Steam-heated blanket CO2, H2S H2S + 2 O2 = H2SO4 pH >2 pH 3 H2SO4 + H2S HCl, SO2, CO2, H2S hypogene alteration
H2O, NaCl, SO2, HCl, CO2, H2S, ...
J.W. Hedenquist
CO2, H2S steam-heated alteration
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Types of epithermal deposits 3 endmember styles: two in volcanic arcs, 1 in rifts •
Hign sulf’n bodies: Cu-Au-As, sulfide rich, andesite arcs • Hosted by lithocaps: advanced argillic zones over porphyry systems
•
Inter. sulf’n veins: Ag-Au ± Zn-Pb, sulfide rich, andesite arcs • Zoned and/or complex mineralogy (intrusion related, diatreme) • Variable Au:Ag:bms transitional style, deep magma? HS (or lithocap) and IS(Mexican): locally affiliated; also deeper porphyry
•
Low S’n veins: Au-Ag bonanzas, sulfide poor, bimodal setting • LS veins: Au-Ag-Te, sulfide poor, alkalic association
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
III
II I
Three epithermal deposit types to model / target: I. Low-grade, disseminated, oxidized or leachable ore II. Medium-grade, unoxidized and refractory deposit III. Structurally controlled, high-grade veins or lodes
Examples of epithermal deposits (w/ porphyry) •
HS replacements: Goldfield, Summitville; Quimsacocha; Yanacocha, Pierina, Alto Chicama; El Indio, La Coipa, PascuaVeladero; Chelopech, Bor; Chinkuashih; Zijinshan; Lepanto; Mulatos, Sauzal, Orisyvo
• Barren lithocaps: common, W. US, Andes, Asia, etc. (Shuteen) •
IS veins: Many Mexican Ag deposits; Comstock, Creede; Andean (“Cordilleran”), Quirivilca, Arcata; Fruta del Norte; San Jose; Victoria, Baguio; Kelian; Kushikino, Toyoha; Rosia Montana, Tethys belt
•
LS veins: Midas, Sleeper; El Peñón; Esquel; Hishikari; Kupol; Ovacik; (Cienega, Pinos Altos) • LS veins, alkalic: Cripple Creek, Emperor, Porgera, Ladolam
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Geologic setting of HS (and IS) deposits Circum Pacific, 44 deposits
• • • • •
Neutral - mild extension, calc-alkaline andesite-dacite arcs 22 Volcanic domes (single, complex, summit; not host) 12 Central vent volcanoes (including IS) 3 Calderas 4 Diatremes 10 Insufficient information Hosts: A/D flows, bxs, ignimbrites, intrusions, seds LS deposits: Bimodal (rhyolite domes-basalt dikes) in extensional settings: Intra, near, and backarc; postcollision rifts (non porphyry) Arribas, 1995; White et al., 1995, Sillitoe, 1999; pers. obs.
Sl Ya RMt
Wa Vi
To
Waldemar Lindgren, 1922: “epithermal” = over, above; ~1 km deep
Arcs HS
IS
Rifts alkalic LS
LS(a)
Hedenquist et al., 1996, 2000
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Temperature-dependent alteration mineralogy Hedenquist et al. (1996) from Henley and Ellis (1983), Reyes (1990)
HS replacements: silicic host, quartz-alunite halo (kaolinite, dickite, pyrophyllite, diaspore, topaz); alunite, barite, anhydrite • Barren lithocaps: silicic core, quartz-alunite halo, other adv. arg. minerals
musc
IS veins: muscovite (“sericite”); quartz, rhodochrosite, barite, anhydrite; local (early?) hi-T advanced argillic structures (e.g., LS, shallow (2
qtz-alun
qtzalun
10 - 100s m
4-6
2 - 4 10 g/t
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Residual quartz, vuggy : Tucari
Advanced argillic slides: 11
(if scanned can be reduced to 5)
Residual quartz, vuggy: Pierina
1) Hypogene acidic vapor condensates (pH~1 leaching, residual quartz)
Hypogene alunite, El Tambo Arribas et al., 2000
Quartz-alunite, Summitville
Residual quartz, vuggy: Summitville
White Island, New Zealand: High to low T fumaroles Steam-heated acid sulfate waters: can also occur over hypogene acidic fluids
~110 C
High-temperature hypogene vapors, ≤800 C with HCl, SO2
Steam-heated zone, ~100 C (CO2, H2S)
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Domes 16.2, 24.8 Ma
Geneva, 13 October 2014
Alunite: 15.5, 17.3, 20.2 Ma
20 km
Falda Esperanza
La Coipa, to NW
1 km
Puren La Coipa
Arribas et al., 2005
Coipa Norte: Steam-heated cristobalite-aluniteKaolinite blanket over residual quartz zone
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Puren, Chile
H2S + 2 O2 = H2SO4 Steam-heated alunite-kaolinite Puren Norte: 1.5 Moz
SiO2, Fe+++
chalcedony blanket
Puren Norte IS veins, 1.5 Moz Au eq. (Ag, Zn, Cu) vadose zone: steam-heated blanket Shallow geochemical anomalies (Ag…)
South central Peru
Chalcedony horizon at paleowater table, below steam-heated blanket of alunite-kaolinite (now eroded) Kaolinite, alunite…
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Arribas et al., 2000
2) Steam-heated advanced argillic blanket, La Coipa
3) Supergene alunite, Rodalquilar
Massive supergene alunite, Rodalquilar; post-mineral weathering oxidation
Supergene oxidation critical to economics!
Supergene alunite, Riaza
Supergene alunite, Rodalquilar
Rodalquilar, Spain: looking ~east
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Rodalquilar, Spain Arribas et al., 1995
Drilling beneath supergene alunite blanket; a mistake here....
Sonomi volcano
1 km
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Nansatsu district, S Kyushu, looking east: Iwato HS deposit, Maruyama pit Inset: qtz-alun halo, sharp ctc with vuggy qtz, to r.)
Urashima et al., 1981
Tuff breccia Nansatsu Group
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Iwato, Arabira rebody: Structural control to alteration and ore (in feeders)
30 m
Mulatos, Mexico: “Residual quartz is steep”, and must be sampled
J.W. Hedenquist
Sauzal, Mexico
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Cajamarca district, Peru Yanacocha district: supergene oxidized high-sulfidation Au (51.9 Moz Au, PR) Minas Conga, Perol: porphyry Au-Cu (641 Mt @ 0.3% Cu, 0.69 g/t Au) Co. Corona: porphyry Au-Cu (~300 Mt @ 0.3% Cu, 0.5 g/t Au) Michiquillay: porphyry Cu-Au (737 Mt @ 0.65% Cu, 0.16 g/t Au) Galeno: porphyry (445 Mt, 0.38% Cu, 0.11 g/t Au) Gustafson et al., 2004
Paleozoic-Mesozoic sedimentary rocks Co. Corona Perol-Cocanes Cerro Yanacocha
16-21 Ma Galeno
8-12 Ma CretaceousTertiary intrusive rocks
Tertiary volcanic rocks
Kupfertal
Michiquillay
40 km
Yanacocha
Kupfertal
oblique aerial to NE
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Perol, Cocañez: 8 km
Kupfertal
5 km
Longo and Teal, 2005
Maqui Maqui; 3
Cerro Yanacocha; 25 Norte, Oeste, Sur, Encajon (Verde - sulfide)
Cerro Negro; 1
TapadoCorimayo; 4
La Quinua; 9 Kupfertal porphyry: KUP-3
J.W. Hedenquist
CarachugoCarachugoChaquicocha;10 6 Chaquicocha; San Jose; 4
2 km
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Gold deposited in leached core of deposits
Yanacocha Norte pH ~
>6
4-6
2-4
0.9 Mt Cu & 102 t Au
Buaki porphyry
FSE porphyry: 891 Mt @ 0.5% Cu & 0.7 g/t Au
Victoria veins, 11 Mt @ 7.3 g/t Au + AgCu-Pb-Zn
Guinaoang porphyry, 500 Mt @ 0.4% Cu & 0.4 g/t Au
Teresa veins, 0.8 Mt @ 5.74 g/t Au Nayak veins
1 km
Mankayan district, Luzon: geologic map
Mohong Hill porphyry + HS Chang et al., 2011
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Lepanto high-sulfidation deposit, Far Southeast porphyry, and Victoria/Teresa intermediate sulfidation veins, Luzon, Philippines
Lepanto
FSE lithocap
From Palidan slide to north Unconformity and silicic-alunite (~1.4 Ma) lithocap – cliffs
Surface projections of Victoria-Teresa IS vein & Lepanto HS enargite, over Far Southeast porphyry Arribas et al. (1995); Claveria (2001); Hedenquist et al. (2001)
Alunite 1.40-1.45 Ma Enargite-Au
Porphyry Cu Hydro Bt 1.40-1.45 Ma Ser ~1.35 Ma X Horn 1.45 Ma
IS Au-Ag veins X Bt 1.18 Ma
Teresa veins
J.W. Hedenquist
Bt 2.2-1.8 Ma
Bulalacao ?
X Illite porphyry Wallrock, ~1.4 Ma Vein, ~1.3-1.15 Ma
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Targeting IS veins Present surface above Victoria veins, to south
Victoria-Teresa veins
Surface alteration (projection of veins)
Weak montmorillonite+pyrite; illite-montmorillonite+pyrite at lower elevation
DNK: dickite, nacrite, kaolinite, or any combinations
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
iX: illite crystallinity
Geneva, 13 October 2014
DNK: dickite, nacrite, kaolinite, or any combinations
Mankayan: Linked porphyry and epithermal deposits (1.4 to 1.2 Ma), both lithocap-hosted high- sulfidation deposit, and intermediatesulfidation veins
Lepanto FSE porphyry
Victoria veins Lepanto
500 m FSE
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Y. Watanabe (2004)
Gold provinces in Kyushu
Kushikino: Mt Kamuridake to east capped by silicic zones, adv. argillic halos Kushikino IS veins: qtz-calcite-Au
Kushikino IS veins 2 km west
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Volcanic setting of Kushikino IS deposit, Kyushu Volcanism: 3.6-3.9 Ma Muscovite (halo to pyrophyllite): 3.4-3.8 Ma Adularia-Au: 3.4-3.7 Ma (Izawa and Zeng, 2001)
55 t Au production
100200 m
500 m
0m
Arcata, Perú: IS Ag-Au vein: >3,000 t Ag, 30 t Au advanced argillic halo to veins at surface Candiotti et al. (1990)
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Arcata, Perú: IS Ag vein: qtzrhodochrosite
Selene dome and IS Ag-vein system, Peru
Dietrich et al., 2007
1 km
Barren 14.714.1 Ma
13.7 Ma
13.5 Ma
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Porphyry systems
Residual quartz (vuggy)
± enargite, Au (HS) Quartz-alunite
IS veins
Base of lithocap
Sillitoe, 2010
Porphyry Cu (Au)
Miocene volcanic arc, Peru:
Intermediate: Lower T magmatic, 100 Moz gold in high-sulfidation lithocap-hosted deposits, discovered in ~16 years
1996 (1998)
1997, 2000 (2002, 2004) ARUNTANI discovery (production) 2008: CHUCAPACA
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Late Miocene high-sulfidation epithermal gold deposits of the Aruntani district, southern Peru
Recent discovery of a new ore type in an abandoned mining district
Dante Loayza, Jorge Barreda, Alvaro Crósta, Jeffrey Hedenquist and Wolfgang Morche: SEG Perth 2004
Tucari south: colluvial scree deposit of 5 MT @ 1.5 g/t gold (approx. 300,000 oz gold)
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Discovery of Santa Rosa (1997/2002, 0.4 Moz Au) led to Tucari (2000/2004, 2+ Moz) Reawakened interest in region...
Tucari, 2002: 5000 m
Lago Titicaca
Chucapaca
Aruntani
J.W. Hedenquist
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Chucapaca: Dacite dome, lithocap alteration, low grades
Canahuire pseudogossan 2.5 km NE, diatreme host (intermediate sulf’dn assemblage)
Discovery Sept 2008: Buenaventura • Resource, mid 2011: 7.6 Moz Au eq.
•
Canahuire resource model & pit shell: Chucapaca JV W
E
1.3 km
350 m 100E 300W
g/t Au
700W
Looking North
• IS
mineralization related to plunging diatreme
• Think
J.W. Hedenquist
laterally (figuratively and literally)
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High- and intermediate-sulfidation deposits
Geneva, 13 October 2014
Erosion level?
Exploration for epithermal and porphyry deposits •
Large variations between deposit types, styles and districts
•
Understand possibilities in the porphyry system
•
Model the prospect, do not fit prospect to a (“the”) model
•
Beware generalizations
•
Observations: • Lithology: effect on permeability • Structure: relation to lithology; feeders, veins • Alteration mineralogy, and zonation • Paleosurface, erosion level: topography, paleohydrology
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