MT involves the measurement of naturally occurring magnetic and electric field oscillations'

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Introduction

• MT involves the measurement of naturally
  occurring magnetic and electric field
  oscillations.
• The ratio of E/H (wave impedance) is measured as
  a function of frequency to give resistivity-depth
  information.

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WHAT IS TRANSIENT AMT ?
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Theory
The impedance tensor Z(w) maps magnetic field
oscillations H(w) onto electric field
oscillations E(w) as
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TF Magnetics SW Athabasca Basin
Dr. Michael Leppin
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Dr. Michael Leppin
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VR-01
Stewardson Lake U/C 1135 m
GEOTEM SURVEY 30 Hz Vertical Component Ch12
Objective Map sandstone conductivity
Wide Lake U/C 850 m
Dr. Michael Leppin
VR-18
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2004 TAMT Survey
Stewardson Lake

• Map basement conductors
• Map spatial extent of illite
• anomaly in lower sandstone
• c) Locate Dufferin Lake Fault

Wide Lake
Test AMT response of conductor C and signature of
Dufferin Lake Fault
Calculated Vertical Magnetic Gradient (GSC)
Dr. Michael Leppin
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Disturbed Sandstone
Disturbed Sandstone
680 m
MFa
1135 m
VR-01
Dufferin Lake Fault ?
Fault ?
Felsic Gneiss
Conductor E ?
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MFc
MFa
Felsic Gneiss
C
E
Dufferin Lake Fault
Fault ?
Felsic Gneiss
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Conclusions

• TAMT is a cost effective method for mapping
  basement
• conductors, especially gt 500 m depth. However,
  they need
• to be isolated from other conductive structure
  in order to be
• clearly resolved.
• TAMT can image shallow sandstone structure up
  dip from
• deeper faults.
• Conductive alteration within the sandstone can
  be reliably
• mapped with TAMT.
• TAMT is relatively inexpensive on long regional
  profiles in
• remote areas.
• TAMT will not replace controlled source EM and
  galvanic
• techniques for drill target definition at
  depths lt 500 m.

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Acknowledgements
I would like to thank Cameco Corporation for
making this presentation possible, Dr. Michael
Leppin in particular was the driving force
behind this presentation and study. Also, Dr.
Vladimir Sopuck for initiating the project and
Jamin Kristall and Dr.Leppin for their
assistance during the Wide Lake field work. Dan
Jiricka was also very helpful in framing the
geologic background for this presentation.