Three Short AeroTEM Case Studies

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Three Short AeroTEM Case Studies

• Jonathan Rudd
• Steve Balch
• Aeroquest Limited

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OUTLINE

• Concentric loop Heli-borne TDEM systems
• Capabilities
• Spatial Resolution
• Depth of Exploration
• Source Geometry
• Conductance Discrimination
• Case Studies
• Tli Kwi Cho
• Shabogamo, Labrador
• Expo-Ungava Deposit

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The AeroTEM System

• STRENGTHS
• Spatial Resolution
• Depth of Exploration
• Diagnostic Responses
• Conductance
• Discrimination

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AeroTEM Waveform
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Shabogamo Project

• Geologic Setting
• Geophysics
• 2002 GeoTEM survey
• 2004 AeroTEM survey
• Interpretation and Prioritization
• Drill Testing 5 holes

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Shabogamo Magnetics GEOTEM Bz18
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Shabogamo Magnetics GEOTEM Bz18
SHABOGAMO Evening Lake AeroTEM Survey Magnetic
Gradient
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GEOTEM
Bx
L13601
Bz
AEROTEM
L30
Off - Z
On - Z
Residual
Off - X
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AEROTEM-II 150 Hz NOMOGRAM
RESPONSE (nT/s)
OFF-TIME
CONDUCTANCE (S)
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GEOTEM
Bx
L13701
Bz
AEROTEM
L90
Off - Z
On - Z
Residual
Off - X
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GEOTEM
Bx
L13801
Bz
AEROTEM
L140
Off - Z
On - Z
Residual
Off - X
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GEOTEM
Bx
L13901
Bz
AEROTEM
L190
Off - Z
On - Z
Residual
Off - X
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GEOTEM
Bx
L14001
Bz
AEROTEM
L240
Off - Z
On - Z
Residual
Off - X
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Shabogamo Magnetic Gradient AeroTEM On-time
Residual
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On-time Residual and TAU
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2004 DRILLING
LINE 140
Z off-time
Z on-time
DTM
4
3
2
1
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TLI KWI CHO COMPLEX

• Multiple vents
• DO18 Pipe single vent
• DO27 Pipe two vents
• Hypabyssal Sills

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MAGNETICS
GROUND EM
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GROUND GRAVITY
GRAVITY the only geophysical method to identify
all vents and the sill?
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AEROTEM SURVEY Off-Time Channel 5 (0.150ms)
Tli Kwi Cho
Identifies 2 main pipes and northeastern vent in
DO27
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The AeroTEM system also detects the sill but
from a helicopter
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Reversing Transient Decay
AeroTEM Channel 4
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Reversing DecaysPoints to Ponder

• Possible Remanent Magnetization Association
• Always has an early time conductive response
  near surface conductive layer
• Is this an IP effect driven by the currents in
  the conductive layer? (Hohmann, 1988)
• Is there an exploration significance? Of course
  there is

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1,260 Hz a 300 IP OP
HLEM SURVEY
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AeroTEM TEST
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LINE 320
Z on-time
X off-time
Tau-ON
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Z on-time
LINE 320
X off-time
Tau-ON
Crone PEM In-loop Z-component
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CONCLUSIONS

• Concentric Loop Systems add information
• Decay reversals more work needed
• Detect and resolve large and small sources
• On-time information adds value in high
  conductance environments
• Multi-component HTEM in most situations can
  circumvent the need for ground surveys

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Acknowledgements

• Canadian Royalties Inc.
• Diavik Diamond Mines Inc.
• Novawest Resources Inc.
• Aeroquest Limited

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