1) 2)Spectral Mapping (SMAM) in Epithermal and Porphyry Copper Systems - Vectors toward the mineralized zone

Ab Scandinavian GeoPool Ltd

1) Epithermal Systems

Many hydrothermal minerals are stable over limited temperature and/or pH ranges. Therefore, by mapping the distribution of alteration minerals in areas of epithermal prospects, it is possible to reconstruct the thermal and geochemical zonation, leading to a model of the hydrology of the extinct hydrothermal system. Alteration minerals are also crucial to distinguish the style of deposit, low sulfidation or high sulfidation.

Common alteration minerals in epithermal systems are e.g. kaolinite, dickite, pyrophyllite, alunite, smectite, illite-smectite, illite and sericite, and these can all be measured with the TerraSpec spectrometer.

Examples of what we can measure with SMAM:

The results can be used to map pH and temperature

variations, which will help to navigate your way in the

epithermal system and locate the mineralized zone.

2) Porphyry Copper Systems

Infrared-active alteration minerals associated with porphyries include sericite/muscovite, biotite, phlogopite, actionolite, chlorite, epidote, calcite, clay minerals (illite, kaolinite, smectite) and tourmaline.

Fig. 1. Illite crystallinity; we can measure the ratio of the depth of the 2200 nm feature to the 1900 nm feature.

© Copyright 2008, Ab Scandinavian GeoPool Ltd

Illite

Muscovite

Kaolinite

Dickite

Pyrophyllite

Alunite +Silica

Kaolinite(Steam-heated)

Increasing Kaolinite crystallinity

Increasing Illite Crystallinity

Increasing Illite abundance

Illite-Smectite

Illite-Smectite

Illite wavelength = 2206nm

Decreasing Mica AlOH wavelength

DH 1 DH 2

Smectite

Illite-Smectite

Illite

Sericite

Kaolinite

Dickite

Pyrophyllite

Alunite

Low Temperature

High Temperature

Low pH Increasing pH

disorderedkaolinite

orderedkaolinite

Low crystallinitymica

High crystallinitymica

Short wavelengthmica

Long wavelengthmica

DH1DH2

Fig. 2. Changing acid mineral phase with increasing temperature.

Wavelength in nm

No

rm.H

ullQ

(Sta

ck

ed

)

1500 1800 2100 2400

Kaolinite

Dickite

Pyrophyllite

Alunite

Wavelength in nm

No

rm.H

ullQ

(Sta

ck

ed

)

1500 1800 2100 2400

Smectite

Illite-Smectite

Illite

Sericite

Inc

rea

sin

g c

rys

tallin

ity

Inc

rea

sin

g t

em

pe

ratu

re

1900 nm2200 nm

Fig. 3. Simplified phase diagram of an epithermal system.

The location of the imaginary drill holes (DH 1 and DH 2) is illustrated in fig. 4.

Fig. 4. Overview of an epithermal system with alteration minerals that can be measured with SMAM. General recommendation; measure 1 spectrum every meter on every exploration drill hole to navigate your way in the system.

Mineral Mapping Pty Ltd

Mineral Mapping Pty Ltd

Vertical zonation from Potassic, (biotite + K feldspar) toPhyllic, (sericite) to Advanced argillic, (pyrophyllite, dickite, quartz Topaz in F-rich systems) orArgillic, (illite-smectite)

Lateral Zonation from Potassic to Propylitic, (actinolite, chlorite, epidote, albite, calcite)

Seedorff et al., 2005

Fe-rich biotiteDistal

Mg-rich biotiteProximal

Muscovite - AcidicAdjacent to Adv. argillic (shallow)

PhengiteAdjacent to potassicor propylitic (deep)

Dickite –Advanced Argillic Topaz

Advanced Argillic(in F-rich systems,eg Porphyry Mo)

Fe Chlorite –Low temp,Acid

Mg Chlorite(overprinting actinolite)High tempneutral

Alteration mineralogy in Porphyry Cu-Mo-Au Systems:

Muscovite

Phengite

Fe-richbiotite

Mg-richbiotite

Potassic alteration

Phyllic alteration

Dickite

Topaz

Advanced argillic alteration

Fe-chlorite

Mg-chlorite

Propylitic alteration

Biotite (potassic alteration): besides the shift in the 2250 nm feature, Mg-chlorite shows a secondary feature at 2390 nm.

White mica (phyllic alteration): the wavelength shifts in this example from 2194 nm in muscovite to 2222 nm in phengite.

Dickite (advanced argillic alteration): major features at 1380, 1415, 2180 and 2208nm; topaz: major features at 1405 and 2080 nm.

Chlorite composition (propylitic alteration): in this example; Mg-chlorite 2324 nm, Fe-chlorite 2350 nm.