Depositos epitermals_ejemplos

8/19/2019 Depositos epitermals_ejemplos

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Epithermal Systems

Low and high sulphidation deposits


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Submarine Epithermal Systems


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The significance of Epithermal

Deposits as a Gold Resource


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Distribution of Epithermal Deposits

High Sulphidation

Low Sulphidation


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Surface expression of a

low sulphidation

epithermal deposit


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Low Sulphidation Deposits

Ore Styles and Alteration Assemblages


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luid !nclusion Temperatures and Salinities


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Oxygen and "ydrogen !sotopic Data


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Temperature#p" $onditions

%&&

'&&

(&&

)&&* ) ( ' % +

o$

Log m,-

.m"-

/usco0ite ,#feldspar

,aolinite

Andalusite

( ,AlSi(O1 - ) "- 2 ,Al(Si(O*&3O"4) - + SiO) - ) ,

-


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The Low Sulphidation Epithermal 5The Low Sulphidation Epithermal 5

Geothermal Lin6Geothermal Lin6

$hampagne 7ool8 9ew :ealand

;p to aira6ei Geothermal

7ower 7lant8 9ew :ealand


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The Low Sulphidation Epithermal 5The Low Sulphidation Epithermal 5

Geothermal Lin6Geothermal Lin6


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Geothermal >ell ScalingsGeothermal >ell Scalings

from $erro 7rieto8 /exicofrom $erro 7rieto8 /exico

Electrum

$halcopyriteSphalerite

$lar68 ?@R@ >illiams#?ones8 A@E@8 3*


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$ontrols on the Solubility of Gold

Au3"S4)# -"- - &@% ")O

2 Au - )")S -&@)%O)

Au$l)# - &@%")O

2 Au - )$l# - "- -&@)%O)

>illiams#?ones et al@ )&&<

Au3"S4o - &@% ")O

2 Au - ")S -&@)%O)


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A model for the formation of low

sulphidation epithermal deposits

*4 /agmatic 0apour condenses in meteoric water

)4 Gold transported as Au 3"S4)#

(4 >ater rises and boils8 releasing ")S and destabiliCing Au3"S4)#

'4 Gold deposits as the nati0e metal

Au3"S4)# - "- - &@% ")O

2

Au - &@)%O) - )")S

Removed by boiling


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Epithermal Systems"igh sulphidation deposits


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"igh Sulphidation Deposits

Ore Style and Alteration Assemblages


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Acid#Sulphate Alteration

uggy silica Ad0anced argillic alteration

All components of the roc6

leached lea0ing behind 0uggy

silica 3p" *4

Alunite 3,Al(3SO'4)3O"4+,aolinite 3Al)Si)O%3O"4'FuartC and 7yrite

7yrite


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$onditions of Acid#Sulphate Alteration

,ing et al@8 )&*'


20/39$houinard et al@8 )&&%

The high sulphidation 7ascua epithermal

deposit8 $hile


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/ineraliCation at 7ascua


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Oxygen and "ydrogen !sotopic Data


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luid !nclusion Temperatures and Salinities


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A /odel for the ormation of "igh A /odel for the ormation of "igh

Sulphidation DepositsSulphidation Deposits

$oo6e and Simmons8 )&&&


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$ontrols on the Solubility of Gold

Au3"S4)# -"- - &@% ")O

2 Au - )")S -&@)%O)

Au$l)# - &@%")O

2 Au - )$l# - "- -&@)%O)

>illiams#?ones et al@ )&&<

Au3"S4o - &@% ")O

2 Au - ")S -&@)%O)


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Sangihe

Lessons from !ndonesia


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The Sangihe Au#Ag Deposits

Py I Au 1.1 ppm Ag 33 pp

Py II Au 1 ppm Ag 81 pp


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Copper mapfor Py II atSangihe

Gold map for

pyrite atPasua

Cu !green" As

!#lue" maps for pyrite atPasua

/etal Coning in pyrite


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The Lycurgus $up 5 dichroic glass and nanogold

A possible explanation for in0isible goldH in pyrite 5 electrostatic attraction

of negati0ely charged nanogold particles to the surfaces of positi0ely charged

pyrite >illiams#?ones et al@ )&&<


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The Sangihe /odel

King et al.(2014)

$awah I%en High Sulphidation 'pithermal


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$awah I%en & High Sulphidation 'pithermal(eposit in the )a*ing+

(aite (ome

Alunite,pyrite

Aid la*e pH -.

)ining sulphur


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/H0 !gas" 2 /S0!gas" 0S !solid" 2 0H0S/ !gas"

H0S/!a4" 0H2 2 S/0&

Sulphur condensation

and acidity creation

+&& o$

p" #O@+


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Sampling the gases

Giggenbach bottle

Gas condenser

9ew dome

Alunite.pyrtite AuI


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Acid Sulphate Alteration at ,awah !Jen

$ristobalite#alunite spineResidual silica in andesite

pillow

Alunite#pyrite alteration Alunite#pyrite 0ein


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Distribution of Alteration at ,awah !Jen

Scher et al@ 3)&*(4


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Gold Sil0er mineralisation at ,awah !Jen

Sangihe

Sangihe

,awah !Jen

,awah !Jen


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Solubility of Sil0er in "$l#")O apour

Sil0er solubility increases with hydration

Migdisov and Williams-Jones (2013)


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Epithermal Au Ore Formation

apour#dominated hydrothermal plume rises from magma transporting

Au and depositing it as temperature drops below '&&°$

Hurtig and Williams-Jones (2014)


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References

>illiams#?ones8 A@E@ and "einrich8 $@"@8 )&&%8 apor transport of metals and

the formation of magmatic#hydrothermal ore depositsB Econ@ Geol@8*&&8 p@*)1K#*(*)@

,ing8 ?@8 >illiams#?ones8 A@E@8 0an "insberg8 @8 and >illiams#?ones8 G@

"igh sulfidation epithermal pyriote#hosted Au 3Ag#$u4 ore

formation by condensed magmatic 0apors on Sangihe !sland8

! d i E i G l *&< *K&% *K((

$oo6e8 D@R8 Simmons8 S@@8 )&&&@ $haracteristics and genesis of

epithermal gold deposits@ !nB "agemann8 S@G@8 rown8 7@E@ 3Eds@48

Gold in )&&&8 Re0iews in Econ@ Geol@ 0ol@ *(@ Society of Economic

Geology8 oulder8 $O8 pp@ ))*5)''@

$lar68 ?@R@ and >illiams#?ones8 A@E@8 3*illiams#?ones8 A@E@8 Leonardson8 R@>@8 "odgson8 $@?@8

Sil0a87@8 TMlleC8 $8 ega8 ?@8 and RoJas8 @8 )&&%a8 Geology and

genesis of the multistage high#sulfidation epithermal 7ascua Au#Ag#

$u deposit8 $hile and ArgentinaB Econ@ Geol@8 0@ *&&8 p@ '+(5'

Documents

Depositos epitermals_ejemplos