lessons learnt from three massive sulphides test sites li zhen cheng, denis bois, uqat
DESCRIPTION
Lessons learnt from three massive sulphides test sites Li Zhen Cheng, Denis Bois, UQAT Michel Chouteau, Ecole Polytechnique Michel Allard, Noranda (now is Xstrata ) David Fountain, Richard S. Smith, Jean Lemieux, Marc A. Vallee, Fugro Airborne Surveys Pierre Keating, GSC. - PowerPoint PPT PresentationTRANSCRIPT
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