Lithocaps and high-sulfidation epithermal deposits - Sociedad ...
Lithocaps and high-sulfidation epithermal deposits - Sociedad ...
Lithocaps and high-sulfidation epithermal deposits - Sociedad ...
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<strong>Lithocaps</strong> <strong>and</strong> <strong>high</strong>-<strong>sulfidation</strong><br />
<strong>epithermal</strong> <strong>deposits</strong><br />
<strong>Sociedad</strong> Geológica de Chile: : July 2011<br />
III<br />
II<br />
I
Formation of advanced argillic alteration: hypogene & steam heated<br />
CO2, H2S<br />
Steam-heated blanket<br />
H2S + 2 O2 = H2SO4<br />
H2SO4, HCl<br />
pH >2<br />
pH <br />
3 H2SO4 + H2S HCl, SO2, CO2, H2S<br />
hypogene alteration<br />
CO2, H2S<br />
steam-heated<br />
alteration<br />
H2O, NaCl,<br />
SO2, HCl, CO2, H2S, ...
Sl<br />
Ya<br />
Wa<br />
RMt<br />
Vi<br />
To<br />
musc<br />
HS IS LS LS(a)<br />
Hedenquist et al., 1996, 2000<br />
LS, shallow (
<strong>Lithocaps</strong> <strong>and</strong> <strong>high</strong> sulf’n: Cu-Au-Ag<br />
Initial leaching: vuggy qtz, qtz-alun<br />
lithocap w/ crs py,
Summitville, Colorado<br />
pH ~ 4-6 2-4 6 4 - 6 2 - 4 10 g/t<br />
Residual quartz, vuggy: Summitville<br />
Quartz-alunite, Summitville
High-temperature hypogene<br />
vapors, !850 C with HCl, SO 2<br />
vadose zone: steam-heated blanket
Arribas et al. (2005) Arribas et al. (2005)<br />
Arribas et al. (2005) Arribas et al. (2005)
Arribas et al., 2000<br />
Steam-heated advanced argillic blanket, La Coipa<br />
Massive supergene<br />
alunite,<br />
Rodalquilar;<br />
post-mineral<br />
weathering<br />
oxidation<br />
Supergene alunite,<br />
Rodalquilar<br />
Supergene oxidation critical to economics!<br />
Supergene alunite,<br />
Riaza<br />
Supergene alunite, Rodalquilar<br />
Rodalquilar, Spain: looking ~east<br />
Rodalquilar,<br />
Spain<br />
Arribas et al., 1995<br />
Drilling beneath<br />
supergene alunite<br />
blanket;<br />
a mistake here....
Nansatsu district, S Kyushu, looking east:<br />
Iwato HS deposit, Maruyama pit<br />
Inset: qtz-alun halo, sharp ctc with vuggy qtz, to r.)<br />
Sonomi<br />
volcano<br />
1 km<br />
Urashima et al., 1981<br />
Iwato,<br />
Arabira rebody:<br />
Structural control<br />
to alteration <strong>and</strong><br />
ore (in feeders)<br />
30 m<br />
Tuff breccia<br />
Nansatsu Group
NB: 27 drill holes on pseudo-section outside mine<br />
MMAJ, 1986<br />
250 m
Exploration <strong>and</strong> discovery histories: Use of models<br />
1991<br />
10 holes, 1869 m, av. 185 m<br />
82 holes, 7656 m, av. 93 m (inclined)<br />
IMG-122 (#40); 71 holes, 23,242 m, av. 330 m<br />
http://www.iamgold.com/presentations2006.asp
Diatreme breccia<br />
w/ porphyry Cu<br />
fragments<br />
2 km<br />
“Stacked” lithocaps!<br />
“Stacked” lithocaps, upper barren...!<br />
Strong lithologic<br />
control to<br />
residual quartz<br />
llithocap: tuffs
http://www.iamgold.com/presentations2006.asp<br />
Longitudinal section, N-S<br />
Pierina, Peru
Volkert et al., 1998<br />
Calipuy volcanic units
Yanacocha<br />
oblique aerial to NE
Cajamarca District<br />
Tantahuatay<br />
Paleozoic-Mesozoic<br />
sedimentary rocks<br />
Cerro<br />
Yanacocha<br />
Perol-Cocanes<br />
Kupfertal<br />
Cretaceous-<br />
Tertiary<br />
intrusive rocks<br />
Tertiary volcanic<br />
rocks<br />
Gustafson et al., 2004<br />
40 km<br />
Yanacocha<br />
cluster<br />
Giuliana<br />
Antonio<br />
Maqui Maqui; 3<br />
Perol, Cocañez: 8 km<br />
Cerro Yanacocha; 25<br />
Norte, Oeste, Sur, Encajon<br />
(Verde - sulfide)<br />
Norte<br />
Leach pad<br />
Oeste<br />
Sur<br />
Kupfertal<br />
Cerro Negro; 1<br />
Encajon<br />
Tapado-<br />
Corimayo; 4<br />
La Quinua; 9<br />
Carachugo-<br />
Chaquicocha; 6<br />
5 km<br />
Quilish; 4<br />
Kupfertal<br />
porphyry:<br />
KUP-3<br />
San Jose; 4<br />
5 km<br />
Longo <strong>and</strong><br />
Teal, 2005
8.2 – 9.2 Ma (Yanacocha Complex)<br />
10 – 10.5 Ma (San Jose)<br />
From Longo, 2005, et al. 2010; Perol <strong>and</strong><br />
Cocañez dates from Gustafson et al., 2004<br />
Alunites<br />
Bell et al., 2005<br />
Longo <strong>and</strong> Teal, 2005<br />
Longo et al., 2010<br />
10.7 Ma (Kupfertal<br />
porph)<br />
Late dacite<br />
10.7 – 11.1 Ma (Corimayo-Carachugo-Tapado)<br />
11.5 – 13.5 Ma (Cerro Negro, Quilish)<br />
15.8-16.1 Ma (Perol<br />
porph, Cocañez litho)<br />
From Longo, 2005; Perol <strong>and</strong> Coca<br />
Longo,<br />
2005;<br />
et al.,<br />
2010<br />
Km 3<br />
San Jose<br />
Tapado<br />
Corimayo<br />
Carachugo<br />
Maqui Maqui<br />
Moz<br />
Yanacocha<br />
Complex<br />
Cerro Negro<br />
Quilish<br />
(7 Moz) (20 Moz) (25 Moz)<br />
Longo et al., 2010
Hydrothermal breccia body<br />
Lithologic horizon (70% of ore in<br />
welded pyroclastics)<br />
2 km<br />
Margin of dome intrusion<br />
pH ~ >6 4 - 6 2 - 4
Dome moat, laminated<br />
siliceous sediments,<br />
paleosurface...<br />
Chaquicocha<br />
Carachugo
Low Au-Ag-Hg-As<br />
Hg<br />
Bi-Ba-As-Sb<br />
CHAQUICOCHA<br />
oxide<br />
Au-Ag-As-Sb<br />
~100 m<br />
sulfide<br />
Zn-Pb<br />
Cu-Au-As-Ag<br />
Patchy<br />
Wormy<br />
KUPFERTAL PORPHYRY<br />
Fault contact between <strong>epithermal</strong> <strong>and</strong> porphyry<br />
alteration at Kupfertal<br />
Epithermal<br />
Porphyry<br />
Porphyry-style<br />
quartz veins<br />
with phyllic<br />
alteration<br />
2. Cooling<br />
2<br />
185.3m: pyrophyllite,<br />
minor alunite<br />
205.6m: pyrophyllite,<br />
alunite<br />
210.6m:<br />
pyrophyllite,<br />
kaolinite<br />
215.3m:<br />
Muscovite<br />
1<br />
1. Vapor<br />
condensation<br />
Breccia: from 181.5m<br />
Pyrophyllite, alunite,<br />
kaolinite<br />
Fault<br />
contact<br />
DDH KUP-3
Milagros porphyry prospect,<br />
Alto Chicama, Peru<br />
0 500 m<br />
Patchy texture outcrop<br />
Garia, 2009<br />
Residual quartz (silicic) <strong>and</strong> advanged argillic size matters...<br />
El Indio 8 Moz<br />
...much of the time, cf. El Indio<br />
Arribas et al., Gold in 2000
100 m<br />
Qtz-alunite<br />
Pyrophyllitek<strong>and</strong>ite<br />
White mica<br />
Jannas et al., 1990<br />
Jannas et al., 1990
NB: Mixing will not<br />
cause amorphous<br />
silica saturation<br />
<strong>and</strong> colloform gels
Relation of porphyry, lithocap, HS ore, <strong>and</strong> marginal IS ore<br />
Erosion level?<br />
Co. Cocañez<br />
(barren)<br />
Lepanto,<br />
Victoria<br />
Perol<br />
FSE<br />
Chimu qtzites<br />
Calipuy volcanics<br />
Alto Chicama, Peru<br />
10.5 Moz resource, 2003<br />
Lagunas Norte, 1.24 g/t Au, 14 Moz
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