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Pallca
Project
Nevado Yerupaja
6617 meters
Traceelementgeochemistry
and distal veins
UBC
MDRU
M i n e r a l D
S. Ebert
April 25 2003
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Outline
1) Trace element dispersion patterns
2) Geology and distal veins
3) Ultraviolet fluorescence of vein calcite
4) Simplified distal vein model
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Trace element dispersion patterns
1) Yauricocha MineMinera Corona
- Reserves of 361,000 tons 7% Zn, 4% Pb, 0.3% Cu 4.9 OPT Ag
- Mineralized zones extend >400m vertically
- District contains CRD-skarn, Carlin-style Au, low-grade
porphyry-Cu, low grade Au, Ag-Cu base metal veins
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SanJuanSan
Antonio
423000E
8640 000N
8638 000N
A
A
B B
N
LakeAcococha
Cu - zone0.3% Cu
Au - zone60 - 264ppb
0 1Km
Quartz monzonite intrusive
Celendine FormationJumasha Formation limestone
Pb-Zn-Ag mineralization
Quartz-sphalerite-pyrite-galena-enargite vein
Purisima Conception
Pass
Cachi-Cachi
421 000E
Lim
ito
fma
rble
Limitofm
arble
Yauricocha District
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Yauricocha, Pass area, looking west
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Prisma Conception area looking east
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Yauricocha Pass - Main Zone traverseWest
East
Simplified geology and sample locations
2800m
2700m
2600m
2500m
CRD mineralization
ConceptionAu zone
Rock sample location
Elevation
(meters)
0 500 1000
? ? ? ?
Quartz Monzonite
Celendin Formation
Jumasha Formation
Bleached marble
Gray marble
Gray limestone
Pb-Zn-Ag orebody
UTM 422385E8639090N
UTM 420600E8638750N
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0
1000
500
0
0
12000
0
500
0
10
Partsp
ermillion
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SanJuanSan
Antonio
423000E
8640 000N
8638 000N
A
A
B B
N
LakeAcococha
Cu - zone0.3% Cu
Au - zone60 - 264ppb
0 1Km
Quartz monzonite intrusive
Celendine FormationJumasha Formation limestone
Pb-Zn-Ag mineralization
Quartz-sphalerite-pyrite-galena-enargite vein
Purisima Conception
Pass
Cachi-Cachi
421 000E
Lim
ito
fma
rble
Limitofm
arble
Yauricocha District
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Cachi-Cachi
Looking west
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Yauricocha Cachi-Cachi traverse
West East
Simplified geology and sample locations
2700m
2600m
2500m
Skarn - CRDmineralization
Rock sample location
Elevation(meters)
Quartz Monzonite
Jumasha Formation
Bleached marble
Gray marblePb-Zn-Ag orebody
0 100 200
Meters
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Trace element dispersion patterns
1) Uchucchacua MineBuenaventura
- South Americas largest Ag producer
- High grade silver hosted in veins
- Roughly 2 million ton reserve at 420 ppm Ag, 2.1% Zn
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km
0 1
Uchucchacua surface map
Cia De Minas Buenaventura
S.A.A.
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NW SE
Upper Jumasha Fm.
Markerhorizon
MiddleJumasha Fm.
Lower Jumasha Fm.
Rosa
Ve
in
Rosa
Ve
in
Rosa2Vein
R o s a
3 V
e i n
4180m
4360m
4450m
4725m
4940m
4400m
4500m
4600m
4700m
4800m
4900m
5000m
4300m
4200m
4100m
Vein, fault
Ag ore zone
0 100
Meters
Uchucchacua simplified
Cross section from Cia De
Minas Buenaventura S.A.A.
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Rosa VeinThin bedded gray footwall limestone
253254255256257258271272273274275276277278279280
XX
X
X259260
261
262
Verticalcliff
White calcite veinlet Grab sample locationWhite +/- gray and brownishcalcite. Crustiform banding
Late Mn-Fe breccia
Breccia
2 meter chip sample
Crustiform banded white-brown-gray calcite vein
Calcite veinlets with Mnand Fe-oxides
X X X XXX XX
Similar calcite veins andveinlets continue for at leastanother 70 meters
270 269 268 267
266
265
X265
264263
Uchucchacua - Rosa Vein 4940m Sectionvein and footwall geochemical traverse
Average width in cm / number per 2m interval
0.1/6 Calcite veins less than 5cm
Calcite veins greater than 5 cm
Calcite vein density in limestone}00000 0 7/1
0.2/30.2/31/6
15/210/1
2/42/4
10/2
3/50.5/3
25/1
0.7/30.1/1
25/1
2/3
40/2
0.5/60.6/7
5/1
1/5
6/1
1/4
280
UTM 316754E8826157N
0 2 4 6 8 10 12 14 16 18 20
Meters
FaultStr. 110 dip 75 S
0 0SouthNorth
North-south section across the Rosa Vein at surface at 4940m elevation. Face of section trends 020 degrees.
Most veins strike 100 to 1100
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Rosa VeinDark gray limestone withwhite calc ite veins and veinlets
315314313312311
X306307
305
316
304
317
308310
Grab sample locationRosa vein.
2 meter chip sampleCalcite vein
XXX309
X308
Uchucchacua - Rosa Vein 4450m SectionUnderground at 754m (along vein)
Average width in cm / number per 2m interval
1/20 1/20Calcite veins less than 5cm
Calcite veins greater than 5 cm
Calcite vein density in limestone }5/1 7/20 25/1
1/200.5/90.4/25
5/115/2
0.5/20
313
0 2 4 6 8 10 12 14 16 18 20
Meters
SouthNorth
North-south section across the Rosa Vein underground at 4450m elevation.
* Most calcite veins strike 90 to 100 or 010 to 0300 0
X
X
X
X
Not accessable
Limit ofexposure
Adit
Str. 90 dip vertical0
* There are some shallow dipping calcite filledtension gashes
X
(Projected 15 to 20m)
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Distal Veins
1) Quartz-carbonate Ag-Mn base metal veins
2) Geochemistry
3) Link to intrusions
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SanJuanSanAntonio
423000E
A
A
B B
N LakeAcococha
Cu - zone0.3% Cu
Au - zone60 - 264ppb
0 1Km
Quartz monzonite intrusive
Celendine Formation
Jumasha Formation limestone
Pb-Zn-Ag mineralization
Quartz-sphalerite-pyrite-galena-enargite vein
Purisima Conception
Pass
Cachi-Cachi
421 000E
Lim
ito
fmarb
le
Limito
fmarble
Quartz-py-sphal-gal-enargite vein
Ag to 306 ppmCu to 3.3 %Zn to 1.3 %Pb to 0.4 %As to 1.1 %high Sb-Hg
Ag to 66 ppmCu to 0.5 %Zn to 4 %Pb to 3 %
Quartz-py-sphal-enargite
YauricochaDistrict
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Marbl
e
Horn
fels
edlim
estone
X
X245
244XX
X
X
X
X
243242
238
239
240
241
Ag 20 ppmMn 3 %As 623 ppm
Ag 1640 ppmMn 16%As 4090 ppmPb 0.2%Zn 0.6%
Hg >10 ppm
Ag 383 ppmMn 12%As 1910 ppmPb 0.06 %Zn 0.14%Hg 6.3 ppm
0 100 200
Meters
Garnet-pyroxeneSkarn
Intrusive
Limestone
1m veinCalcite-silica with
10% alabandite, 3% pyrite
1m silicified limestonesilica-calcite vein withpyrite-orpiment-realgar
5 to 15 cm vein
Banded carbonate-silica-pyrite
{
{
Calc-silicateveinlets
Silica-carbonateveinlets
AnamaraySkarn
Geology data from
Buenaventura and
a 2002 field visit
Quartz pheric
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0 100 200
Meters
N
65
60
80
65
Geology map of the Contonga Mine area. Simplified andmodified from Bodenlos and Ericksen (1955).
Localized marble and bleachingproximal to the intrusive contact
Sulfide-quartz-calcite veinletsparallel to bedding in limestone
JumashaLimestone
Silicified Limestone Sample location
Quartz phericrhyolite
Sulfide-skarn ore zone
Sulfide-quartz-calcite veins
337
330331
332333
334, 335, 336
5 to 15 cm wide qtz-cal veinswith 20-40% Gal-sphal-py
Ag 257 to 381 ppmMn 1450 ppmCu 0.2 to 1%Pb 12 to 20%Zn 9 to 16%plus Cd-Se-Te
Pb-Zn-Ag-Cu-Cd-Bi-Se-te
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Calcite-gal-sphal-pyto 361 ppm Ag
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Fortuna
Antamina
Ridge Road
Qtz-gal-py-cal-fluor
Ag-Au-As-Pb-Zn
Calcite gal sphal pyAg-Au-Mn-Pb-Zn-As +/- Cd-Hg-Sb
Peak Nine
to 361 ppm Ag
4.1% Mn
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UV Fluorescence
1) Some hydrothermal calcite
associated with skarn-CRD and
distal veins fluoresces red
2) Upper veins at Uchucchacua
fluoresce red and white-blue
3) Syn-tectonic veins do not
fluoresceUBC
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Contonga Ag-Pb-Zn vein
Yauricocha CRD ore
17.77
11.09
C
D
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Antamina - Fortuna calcite vein
Antamina - Fortuna Ag vein
13.64
14.49
12.34
6.02
A
B
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Uchucchacua 4940 m level
Uchucchacua 4940 m level
16.17
15.94
15.84
B
C
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UV Fluorescence
1) A hand held UV lamp may be useful in distinguishing
calcite related to mineralization vs. syn-tectonic calcite
2) Can UV help distinguish level in the system?
3) What are the compositional variations affecting fluorescence?
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M i n e r a l D
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Simplified distal vein model
1) Geology, geochemistry,
UV fluorescence
(and isotopes) link distalveins and mineralization
2) A model for larger veins
hosted by pure limestone
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MDRU
M i n e r a l D
Surface 0 km
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Limito
fhorn
fels
Limit
ofma
rble
1 km
2 km
Skarn
Graymarble
Bleachedmarble
Fortuna veins
Uchucchacua Ag zone
Barren calcite vein
Surface
Carbonate host rocks
Low-gradeporphyry Cu-Mo
CRD
0 km
Antamina
Milpo
Yauricocha
Dec
reasin
gquartz
inv
eins
Ag-Mn-Pb-Zn-As
Ag-Mn-Pb-Zn-As-Sb-Hg
Cu-Pb-Zn-Ag
(Very weak Mn-Hg-Tl-Ag-Zn)
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Conclusions
1) There are large and variable geochemical anomalies incarbonate rocks around skarn-CRD at Yauricocha, largely
veinlet controlled.
2) Field relationships and geochemistry indicate distal
Ag-Mn-base metal veins are directly related to intrusion/skarn systems.
3) The proposed simplified vein model has important
exploration implications. Additional work to test/improve
the model us ongoing.
4) Combined trace element, oxygen isotopes, and UV
fluorescence may provide exploration guides.
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M i n e r a l D
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Stable Isotopic Studies
225 Analyses Antamina (130)
Chacua (37)
Yauricocha (49)
Milpo (9) Sedimentary protolith:
21 to 25 d18O (VSMOW) 1 to 3 d13C (VPDB)
Mineralized zones and distal halos recorddepletion of d18O +/- d13C
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Overview
Deposits span a continuum within amagmatic hydrothermal system and allowdevelopment of a conceptual model
Distal alteration controlled by stratigraphyand structure
Lateral alteration haloes are narrow whenhosted by steeply dipping strata (Milpo)
Wider haloes are associated with gentlydipping strata
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Vertical Zonation of Targets Shallow: 0.5 km (above Chacua)
No distal alteration
18O and 13C of veins retains magmatic-hydrothermal signature
Intermediate: 1 km (ore zone at Chacua,
Fortuna - top of Antamina)
18O and 13C halo (> 10 m) around veins provideslargest target (larger than trace elements)
Deep: 1.5 to 2 km (Antamina and Yauricocha) Advective bleaching of marble provides largest
target (larger than 18O and 13C)
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MDRU
M i n e r a l D
Surface
0 km
?
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Limito
fhornfe
ls
L
imitof
marble
1 km
2 km
Skarn
Graymarble
Bleachedmarble
Fortuna Ag-Pb-Zn veins
Uchucchacua Ag zone
Barren calcite vein
d
d
18
13
O 18
C -2
d
18
O depletion inadjacent wall rock
Small O depletionin adjacent wall rock
d18
Strong O depletionin adjacent wall rock
d18
Large zones with variableO depletion halos mostly
within bleached limestoned
18
d
d
18
13
O 16
C -6
d
d
18
13
O 13
C -1 to -3
d
d
18
13
O 10 to 14
C -1 to -9
Background limestone
O 22.5
C +2
d
d
18
13
Carbonate host rocks
Low-gradeporphyry Cu-Mo
Skarn and CRD
CRD
Narrow O depletion halowithin bleached limestone
d18
Antamina
Milpo
Yauricocha
Decreasin
gqua
rtz in
veins
Simplified outline ofdepletion halod
18O
?
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Milpo
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Yauricocha District
Pass transect Variable d18O depletions up to 1400 m Strong d18O depletions within inner 400 m Purisima Conception - meteoric influence?
Depletions in d13C correlate with d18O. Cachi-Cachi transect
Variable d18O depletions coincident withbleached marble (~200 m)
Depletions in d13C correlate with d18O.
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Yauricocha District
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SanJuanSanA
ntonio
423000E
8640 000N
8638 000N
A
A
B B
N
LakeAcococha
Cu - zone0.3% Cu
Au - zone60 - 264ppb
0 1Km
Quartz monzonite intrusive
Celendine FormationJumasha Formation limestone
Pb-Zn-Ag mineralization
Quartz-sphalerite-pyrite-galena-enargite vein
Purisima Conception
Pass
Cachi-Cachi
421 000E
Lim
ito
fm
arble
Limitofm
arble
Yauricocha District
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U h h
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Uchucchacua
Transects sample approx 500 m verticalzonation
Calcite veins have light d18O (14-19 )with lowest values at depth
No lateral alteration halo at highest levels(4950 m)
Lateral d18O depletion halo (> 10 m) atdepth (4450 m)
d13C depletion (values of 0 to -9 )correlates with d18O
Late veins record meteoric influx
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4300
4400
4500
4600
4700
4800
4900
5000
5.00 10.00 15.00 20.00 25.00
Rosa Vein d18O vs depth
d18O
U h h
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Uchucchacua
Transects sample approx 500 m verticalzonation
Calcite veins have light d18O (14-19 )with lowest values at depth
No lateral alteration halo at highest levels(4950 m)
Lateral d18O depletion halo (> 10 m) atdepth (4450 m)
d13C depletion (values of 0 to -9 )correlates with d18O
Late veins record meteoric influx
UBC
MDRU
M i n e r a l D
Rosa vein 4940m surface sectionoxygen and carbon isotopes
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Rosa VeinThin bedded gray footwall limestone
253254255256257258271272273274275276277278279280
XX
X
X259260
261
262
Verticalcliff
X X X XXX XX
Similar calcite veinsandveinlets continue for at leastanother 70 meters
270 269 268 267
266
265 264263
Average width in cm / number per 2m interval
0.1/6 Calcite veins less than 5cm
Calcite veins greater than 5 cm
Calcite vein density in limestone}00000 0 7/10.2/30.2/31/6
15/210/1
2/42/4
10/2
3/50.5/3
25/1
0.7/30.1/1
25/1
2/3
40/2
0.5/60.6/7
5/1
1/5
6/1
1/4
UTM 316754E8826157N
0 2 4 6 8 10 12 14 16 18 20
Meters
SouthNorth
Most veins strike 100 to 1100
20.56, -7.1815.94, -1.9615.84, -1.91
17.67, -1.96
21.15, 2.9319.96, 1.82
18.49, -3.62
21.83, 3.20
18.67, -1.83
Rosa vein 4450m level undergroundoxygen and carbon isotopes
15.84, -1.91
d O per mil C per mil18 13
d
Rosa VeinDark gray limestone withwhite calcite veins and veinlets
315314313312311
X306307
305 304
317
308310XXX
309
0 2 4
Meters
SouthNorth
X
X
X
Not accessable
Limit ofexposure
AditX
Average width in cm / number per 2m interval
Calcite veins less than 5cm
Calcite veins greater than 5 cm
16.60, -5.8815.92, -6.22
15.98, -6.9515.56, -6.86
17.16, 1.23
16.41, -5.73
17.07, 2.37
U h h
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Uchucchacua
Transects sample approx 500 m verticalzonation
Calcite veins have light d18O (14-19 )with lowest values at depth
No lateral alteration halo at highest levels(4950 m)
Lateral d18O depletion halo (> 10 m) atdepth (4450 m)
d13C depletion (values of 0 to -9 )correlates with d18O
Late veins record meteoric influx
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Synthesis
Skarn, CRD deposits have d18O of 11 to 14, indicative of magmatic fluid (~ 11)
Uchucchacua veins formed at 175 to 275 C
(based on fluid inclusions, Bussell et al1990)
Vertical zonation in vein d18O consistent withprecipitation from magmatic fluids at 200-
250 C
UBC
MDRU
M i n e r a l D
LimestoneMagmatic-
hydrothermalMeteoricinfluence?
Ave 22.5 (8 samples)A
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d18O
0 5 10 15 20 25
Contonga
Yauricocha
Antamina (Fortuna)
Anamary
Milpo
Uchucchacua
yue ce
Distal vein calcite
Skarn-CRD calciteor proximal vein
Late calcite vein
400 Co
300 Co
200 Co
(F.I. Temps. Mainly 175 to 275 C, ave. 250 C)o o
A t i
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Antamina
Exposures allow sampling of vertical zonationover 500 m
Highest levels (Fortuna, ~ 1km) probably slightlydeeper than Ag zone at Chacua
Isotope alteration style is similar to Chacua Agzone
Distal alteration target is stable isotope depletionhalo
Deepest levels (1.5 to 2 km) have similarities to
Yauricocha
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M i n e r a l D
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Gray Marble and Limestone
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Gray Marble and Limestone
Gray Marble (G) reflects protolithcomposition
Cryptic distal alteration recorded in somesamples
Gray marble from vicinity of browncarbonate veins (GVB) are depleted to aslow as 11
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Grey marble and limestone
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00
d 18O (VSMOW)
d
G
GL
GVB
Bleached Marble
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Bleached Marble
Diffusional Bleaching (BS) Planar harline sulfide veins with cm wide
bleaching haloes
Isotopically unaltered
Massive Bleaching (BM) Stratigraphically and structurally controlled
Massive, homogeneous d18O depletion to as lowas 13
Pervasive homogeneous percolation of magmatic-hydrothermal fluids
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M i n e r a l D
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Antamina UBC
MDRU
M i n e r a l D
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UBC
MDRU
M i n e r a l D
Antamina
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Antamina UBC
MDRU
M i n e r a l D
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UBC
MDRU
M i n e r a l D
Antamina
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Bleached Marble
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00
d 18O (VSMOW)
d
BS
BL
BM
Veins
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Veins
Early (syntectonic) veins (VE) are similar toprotolith isotopically
Syn-mineralization veins (VM) and browncarbonate mineralized veins (VMB) are low in d18O(11 to 14 )
VM, VMB also depleted in d13C with lighter valuesat depth
Late white and clear calcite (VL) veins locally havemeteoric signature
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Veins
-12.00
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
0.00 5.00 10.00 15.00 20.00 25.00
d 18O (VSMOW)
d
VE
VM
VMB
VL
O i
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Overview
Deposits span a continuum within amagmatic hydrothermal system and allowdevelopment of a conceptual model
Distal alteration controlled by stratigraphy
and structure Lateral alteration haloes are narrow when
hosted by steeply dipping strata (Milpo)
Wider haloes are associated with gentlydipping strata
UBC
MDRU
M i n e r a l D
Surface
Carbonate host rocks
0 km
?
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Limito
fhornfe
ls
Limito
fmarb
le
1 km
2 km
Skarn
Graymarble
Bleachedmarble
Fortuna Ag-Pb-Zn veins
Uchucchacua Ag zone
Barren calcite vein
d
d
18
13
O 18
C -2
d18
O depletion inadjacent wall rock
Small O depletionin adjacent wall rock
d18
Strong O depletionin adjacent wall rock
d18
Large zones with variableO depletion halos mostlywithin bleached limestoned
18
d
d
18
13
O 16
C -6
d
d
18
13
O 13
C -1 to -3
d
d
18
13
O 10 to 14
C -1 to -9
Background limestone
O 22.5
C +2
d
d
18
13
Carbonate host rocks
Low-gradeporphyry Cu-Mo
Skarn and CRD
CRD
Narrow O depletion halowithin bleached limestone
d18
Antamina
Milpo
Yauricocha
Decreasin
gqua
rtz in
veins
Simplified outline ofdepletion halod
18O
Vertical Zonation of Targets
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76/81
Vertical Zonation of Targets Shallow: 0.5 km (above Chacua)
No distal alteration
18O and 13C of veins retains magmatic-hydrothermal signature
Intermediate: 1 km (ore zone at Chacua,
Fortuna - top of Antamina)
18O and 13C halo (> 10 m) around veins provideslargest target (larger than trace elements)
Deep: 1.5 to 2 km (Antamina and Yauricocha) Advective bleaching of marble provides largest
target (larger than 18O and 13C)
UBC
MDRU
M i n e r a l D
Uchucchacua
8/3/2019 Distal Alteration
77/81
0.1
1
10
100
1000
0 2 4 6 8 10 12
distance from Rosa vein (m)
10
12
14
16
18
20
22
24
d18O(permil)
Ag
18O
Surface
Carbonate host rocks
0 km
?
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Limito
fhornfe
ls
Limito
fmarb
le
1 km
2 km
Skarn
Graymarble
Bleachedmarble
Fortuna Ag-Pb-Zn veins
Uchucchacua Ag zone
Barren calcite vein
d
d
18
13
O 18
C -2
d18
O depletion inadjacent wall rock
Small O depletionin adjacent wall rock
d18
Strong O depletionin adjacent wall rock
d18
Large zones with variable
O depletion halos mostlywithin bleached limestoned
18
d
d
18
13
O 16
C -6
d
d
18
13
O 13
C -1 to -3
d
d
18
13
O 10 to 14
C -1 to -9
Background limestone
O 22.5
C +2
d
d
18
13
Carbonate host rocks
Low-gradeporphyry Cu-Mo
Skarn and CRD
CRD
Narrow O depletion halowithin bleached limestone
d18
Antamina
Milpo
Yauricocha
Decreasin
gqua
rtz in
veins
Simplified outline ofdepletion halod
18O
8/3/2019 Distal Alteration
79/81
Pit West Wall
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Pit West Wall
Massive bleaching over 20 m immediatelyoutboard of skarn
Oxygen isotope depletion is limited to ~ 2 m
Limited lateral percolation of magmatic fluids
Marble cap was an effective seal to the system
UBC
MDRU
M i n e r a l D
MDRU
8/3/2019 Distal Alteration
81/81
UBC
M i n e r a l D