LITHOCAPS AND PORPHYRY EXPLORATION

March 2011

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March 2011

WHAT IS A LITHOCAP?WHAT IS A LITHOCAP?

• Hypogene advanced argillic alteration, typically Quartz Alunite (high T) with halos oftypically Quartz-Alunite (high T) with halos of Kaolinite ± Dickite (low T) and roots of Pyrophyllite ± Diaspore (high T).Pyrophyllite ± Diaspore (high T).

• Conditions of formation: pH ~1 – 3, T < 300C• Form above porphyries in the epithermalForm above porphyries in the epithermal

environment from condensates of magmatic vapor that contain SO2 and HCl, all of which p 2 ,exsolved from an underlying intrusive source.

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LITHOCAP & PORPHYRY LINKLITHOCAP & PORPHYRY LINK

From Holiday and Cooke (2007), Sillitoe and Thompson (2006) and Harris (2010)

LITHOCAP EXPRESSIONS IN AN ARID ENVIRONMENT

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Cerro Blanco, Chile

VUGGY SILICA –PRODUCT OF ADVANCED ARGILLIC ALTERATION

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6From “Anatomy of porphyry-related Au-Cu-Ag-Momineralised systems” Greg Corbett, 2009.

THE LEVEL OF EROSION

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Porphyries are ‘Sociable Animals’

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Mankayan Section Philippines (A model to work with)Mankayan Section Philippines (A model to work with)

Lepanto HS 35mt @ 3.5% Cu / 3g/t Au

FSE Porphyry660mt @ 0.65% Cu / 0.94g/t Au

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Bringing the Model to ExplorationBringing the Model to Exploration

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Zonation: The High–Temperature ZoneZonation: The High–Temperature Zone

Coherent zone <300C / pH 1-3

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Zonation: Intermediate–Temperature Zone Zonation: Intermediate–Temperature Zone

Coherent zone 220-270C / pH 5-7characteristic of the phyllic zone.

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13From “Anatomy of porphyry-related Au-Cu-Ag-Momineralised systems” Greg Corbett, 2009.

Zonation: Defining of a PatternZonation: Defining of a Pattern

High-Temp AcidicLower-Temp Neutral pH

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Metal Zonation – Batu HijauMetal Zonation – Batu Hijau

METAL ZONATION – IMPORTANT INDICATIONSMETAL ZONATION – IMPORTANT INDICATIONS

1000 m

Zn in soil (ppm)< 50> 200

6 - 20

> 50

Mo in soil (ppm)

20 - 50

> 200

Fault / fracture trend

Lineament

Drill Hole

Montong Botek:Zn (soil) > 200 ppm

COMBINING METAL ZONATION AND SPECTRAL CLAY DATACOMBINING METAL ZONATION AND SPECTRAL CLAY DATA

1000 m

F lt / f t e t e d

6 - 20

> 50

Mo in soil (ppm)

20 - 50

Fault / fracture trend

Lineament

METHODS OF DETECTION - MAGNETICSMETHODS OF DETECTION - MAGNETICS

At a given location, the airborne magnetometer records the vector sum of the ambient geomagnetic field and the anomalous contribution from (one or more) local sources.The Earth’s dipolar magnetic field

Fi d f “A ti S R 2005

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Figures sourced from “Aeromagnetic Surveys…Reeves, 2005

ALUMBRERA PORPHYRY EXPOSED at SURFACE; Reserve Base: 362Mt @ 0.46% Cu & 0.51 g/t Au.ALUMBRERA PORPHYRY EXPOSED at SURFACE; Reserve Base: 362Mt @ 0.46% Cu & 0.51 g/t Au.

19Terry Hoschke , 2008

FSE Magnetic ResponseFSE Magnetic Response

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Oyu Tolgoi Porphyry DepositsOyu Tolgoi Porphyry Deposits

• Induced Polarisation gradient array chargeability map from the Oyu Tolgoi deposits Mongoliamap from the Oyu Tolgoi deposits, Mongolia.

•Survey details are: current electrode separation 4800m, potential electrode separation 100m on 100m-soaced east-west lines. Data from Ivanhoe Mines Ltd.

• Ore Resource; 36.3 billion lbs Cu & 20.2 Moz Au

•13.87 billion tons @ 1.33% Cu, 0.47g/t Au and 1.63% CuEq as of March 2010

21Image from ‘Advances in Geological Models and Exploration Methodsfor Copper ± Gold Porphyry Deposits’Holliday, J. R. [1], Cooke, D. R. [2]

Batu Hijau; Metal Content vs ChargeabilityBatu Hijau; Metal Content vs Chargeability

22(Arif, 2002). (Terry Hoschke , 2008 )

Batu Hijau Mine. We hope to locate another.

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