Download - Porphyry Transitions Anti Ago
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Sakurajima, Kyushu: ionized gases Bingham Canyon, Utah: >31 Mt Cu!
Sociedad Geolgica de Chile: July 2011
Adv. argillic?
Bingham porphyry, Utah
Redmond et al., 2004
80% 20%
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Diorite intrusion: if X magmatic fluid advected,
intrusion heat convects ~19X meteoric water
Extreme hydrolytic = advanced argillic
Na-Ca basinbrines
F - feldspar stable (potassic)
H - hydrolytic (attack by H+)
(phyllic and advanced argillic)
E - caused by external fluids
(propylitic and sodic-calcic)
propylitic
Lowell and Guilbert, 1970
Giggenbach,
1984, GCA
Potassic or phyllic
Sodic-calcic
(propylitic)
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Dilles et al., 2000
Ann Mason MacArthur
porphyry Cu-Mo porphyry Cu
~3 km
~3 km
Seedorff et al., 2005
Adv argillic
Seedorffet al., 2005
potassic
sericitic
potassic
sericitic
argillic
argillicT
emperature
Low
H
igh
adv. arg.
Time >
Depthkm2
4
2
4
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80% 20%
Redmond etal., 2004
Cathodo-
luminscence
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Grade: Cu equiv
Vein density ~40%
Vein density ~5%
Modifiedfrom LCMC,1994
-100 m elev. plan
Far Southeast porphyry, Philippines:
Cu equiv. grade and quartz vein density
Changet al.,
2011
Seedorff et al., 2005, fromHemley and Montoyo, 1964, etc.
White mica KAl3Si3O10(OH)2
PyrophylliteAl2Si4O10(OH)2
Andalusite
Al2SiO5
Dickite / kaoliniteAl2Si2O5(OH)4
(Na,Ca)1/3(Al,Mg)2(Si4O10)(OH)2!nH2O
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Mineral stabilities vsfluid compositions
150
Watanabe and Hedenquist, 2001,
after Hemley et al., 1980
El Salvador, Chile: Watanabe and
Hedenquist, 2001, after Hemley et al., 1969
pyrophyllite
muscovite
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Watanabe and
Hedenquist, 2001
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Watanabe andHedenquist, 2001
El Salvador, Chile: Watanabe and Hedenquist, 2001
pyrophyllite alunite lithocap (late)
El Salvador, looking ~SE
Watanabe andHedenquist, 2001
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Pebble
dikes
Muscoviteoverprint
(andal)trans
ition
pyroph
Watanabe and Hedenquist, 2001
Fluids from alteration at present-day level of exposure
Deep biotitedickite
Watanabe andHedenquist, 2001
2M1 musc
late Q-A
early qtz-alun
lithocap??
retrograde
pyroph
Damiana exotic
paleosurface?
encapsulated
potassic, sulfides
Lithocap with metals present??
Erosion at El Salvador
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Magma mine, Arizona:1875~1990s; 2nd Ag, cc
cc-en-bn vn,
ser (dk-zy)hm-py-cp-bn
(gn-spl) mantos
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E
H
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1998 resource:
455 Mt at 1.2%
Cu, 0.02% Mo;
1250-1550 m
below surface,
1050 x 365 x305 m
http://riotinto.msgfocus.com/q/1cRLO25OxfDl/wv
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Sericite halos to py-
qtz veins; ccp, bn,cv, cc, en, tn, spl
Chuquicamata, Chile
Rusk et al. (2008)
potassic centers
3 km
3 km
Seedorff et al., 2008
1 km Main Stage
QSP
pyrophkaol-dick
ser-
kaol
ser-
kaol
R. Sales, C. Meyer, J. Proffett, compiled by M. Einaudi
Rusk et al. (2008)
m
pre-Main Stage
(potassic)
pre-Main
Stage
(potassic)
ZnCu
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Sulfide zoning
in porphyries:Greys=potassic
Lined=sericiticoverprint
Marco
Einaudi,2002,
unpub.
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Bingham
Chuquicamata
Potrerillos
El Salvador
Gibraltar
Sungun
Ann Mason
Silver Bell
Sierrita-Esperanza
Butte
py-en,py-bn
py-hm-(cp)
Early, higher temp Late, lower temp
bn + cp, cp + pyss
dominant assemblageore
no pyrite pyrite
(bn-cp) dg-bn-cp
bn-cp
(dg-bn)-cp
(bn)-cpcp-py
py-cp-(tn)
mt-cp
cp-py
py-cp-bn,py-bn
py, cv, dg,en, cp
py-cp-tn
py-cp
bn-cp
(mt)-bn-cp
mt-bn-cpmt-cp-py
bn-cp
(mt-bn-cp)
py, tn, en
cp-py
dg-bn-(cp)
(bn)-cpcp-py
cp-py
cp bn-cpbn-cp,
cp-py (SC)
cp cp-py py
cp-py cp-py (C) py-cp
mt-cp-py(EDM)
mt-cp-py (SC)py-cp (S)
py, cv, dg,bn, cp, en
Early to intermediate (potassic to phyllic), high to lowT, progressively higher sulfd state in porphyry; --
metals introduced early or intermediate
Einaudi, Hedenquist,
Inan, 2003
alunite host
phyllic
potassic
illite
Einaudi et al., 2003, modifiedby Seedorff et al., 2005
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Marte Au-rich porphyry,
Maricunga, Chile
Sillitoe, 1994Sillitoe, 1990
?
Singer et al., 2008J. Muntean unpub.
epithermal
Au
?
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Muntean andEinaudi, 2000
1 km
Maricunga
(Refugio):
Geology
Muntean and
Einaudi, 2000Maricunga (Refugio): Verde West
Qtz diorite
porphyry
Muntean andEinaudi, 2000
Maricunga:Pancho
Maricunga porphyry Au:
banded silica gel +mt, recrystallized
low-grade to barren
Muntean andEinaudi, 2000
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Highstrain
rate
3
2
1
0
40
Early BarrenQ uartz-Alunite Ledges
MeteoricWater
MagmaticVapor
?
MagmaticBrine
SupercriticalMagmaticFluid
BandedQuartzVeinlets
Magma
D Veins
Ore-BearingQuartz-Alunite
Ledges
Sector Collapse?
Faulting
Early Mineral ization Late Mineral ization
Approximate Time Range (m.y.)
? ? ??
1
Evolution of porphyry systems
Sillitoe, 2010 Varying depths and
intervals between base of
lithocap and top of
porphyry
Only some (few)lithocaps are mineralized
IF rapid syn-hydrothermaluplift...
lithocap collapse; HS ore, if present,
overprints porphyry
Petelovo
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Wafi, Papua New GuineaTelescoped porphyry Cu-Au
Sillitoe, 1999
M. Herve, 2010
Pampa Escondida
M. Herve, 2010
37.5 Ma 37.7 Ma
36.1 Ma
Pampa Escondida
Lepanto,
FSE
Victoria
Cerro Casale
Co. Catedral
(barren)
El Salvador
Preservation of lithocap, or erosion to transitional levels
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Porphyry systems
Sillitoe, 2010Economic Geology
Hedenquist et al., 1998; Chang et al., 2011
500 m
Residual (vuggy) qtz
Qtz-alun (py), dick-kaol
Porphyry systems: asymmetric (shallow) alteration
Porphyry systems: steep tilting
Sillitoe, 2010Economic Geology
Porphyry systems: deeply eroded