Lessons learnt from three massive sulphides test sites

Li Zhen Cheng, Denis Bois, UQATMichel Chouteau, Ecole PolytechniqueMichel Allard, Noranda (now is Xstrata)

David Fountain, Richard S. Smith, Jean Lemieux, Marc A. Vallee, Fugro Airborne Surveys

Pierre Keating, GSC

Geological provinces in Québec

Abitibi greenstone Belt

700 nT/s (off time)

IsoNew Insco

ZnCuPy

semi- massivesulphide

800 m

600 m

Gallen deposit

pH = 2.3

Aldermac

Summary

• Iso-New Insco : simple geometry in a resistive host Test the performance of MEGATEM system.

• Gallen: Main body mined out and residual massive sulphides are submerged in acidic water with surrounded metal fence.

Look at the impact from these unfavourable conditions to AEM surveys.

• Aldermac: small and deep pods under tailing dump in a hydrographic basin - conductive overburden. Challenge for MEGATEM system?

What have been done?

Field tests

• Two base frequencies of 90 Hz and 30 Hz

• Height attenuation tests

• Reverse flight direction tests

• Transmitter off

Research

• Data processing & visualization

• Anomalies classification

• Modeling and interpretation

What we have learnt?

L301 L501

copper rich zone

IsoN30 Hz 90 Hz

30 Hz 90 Hz

MEGATEM flights over Iso deposit at different altitudes (line 100501)

250 m

500 m

750 m

1000 m

250 m

500 m

750 m

1000 m

35000 fT

35000

35000

100000

300000

35000 fT

35000

35000

100000

300000

Bx Bz461 m

371 m

274 m

187 m

122 m

461 m

371 m

274 m

187 m

122 m

overburden conductance = 1.2 S

channel 6

channel 20

350 450

channel 6

channel 20

Basalt

Diorite

Rhyolite

Dacite

Andesite

Basalt

Massive sulphide

Diorite250

500

750

(m)

0

700 nT/s

700 nT/s

700 nT/s

0

0

0

0

0

0

700 nT/s

700 nT/s

700 nT/s

Basalt

Diorite

Rhyolite

Dacite

Andesite

Basalt

Massive sulphide

Diorite250

500

750

0

(m)

In the down-dip direction In the up-dip direction

Bx Bx

By By

Bz Bz

30 o 60 o 30 o60 o

Plate model: 600 m in width, 800 m in deep extension

at 50 m depth

W E

X

Z

down - dip up - dip

a b c d

X old X new Z old Z new

• Maxwell

• Plate

• LeroiAir

• Emigma

• MacroAir

• ArjunaAir

• EmQ

• LokiAir

Thin sheet

Prism

Sphere

2.5 D

3 D

(EMIT_Au)

(U_Toronto)

(PetRos_EiKon)

(CSIRO_Au)

(GSS_Au)

3D modeling tools for EM data interpretation

Polyhedron

20 S

40 S

55 S

30 S

Gallen deposit

Gallen deposit

Aldermac deposit

10000 pT/s

10000 pT/s

0

0

dBx/dt dBx/dt

dBz/dt dBz/dt

30 Hz 30 Hz

10000 pT/s

10000 pT/s

0

0

0 03 km 3 km

dBx/dt dBx/dt

dBz/dt dBz/dt

Line 401 Line 501

measured measured

measured measured

Thick prism Thick prism

Thick prism Thick prism

Aldermac deposit

Conclusion

The present project to enhance the MEGATEM technology has been a successful collaboration between universities and industry.

New objective

Develop new interpretation tools for geophysical exploration methods