Advances in the application of audiomagnetotellurics (AMT) for mineral exploration

6/4/2001


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Table of Contents

Advances in the application of audiomagnetotellurics (AMT) for mineral exploration

Overview

AMT Acquisition

AMT Acquisition System

AMT - Acquisition

Physical Phenomenon: EM Skin Depth

AMT 1D response: 2-layers

2D Earth response

Why use AMT?

AMT - Source Field

AMT advantages over CS EM

Commercial AMT in Canada

AMT �dead band�

AMT dead band problems

Diurnal and annual variations at VLF frequencies

Variation in the AMT frequency range

Processing AMT data

Techniques used

Maximum power spectrum of the magnetic field

3D galvanic decomposition or � Should we decompose the data?

3D galvanic decomposition model

Decomposition tests

Okak Bay: another Voisey�s Bay?

Aeromag anomaly

AMT site locations

ra,av map

Preliminary inversion model

Drilling program

Borehole intersections

Strike & distortion analysis

Incompatible response:

1D inversion of site GAL004 data

2D inversion of Line 6

2D inversions of all lines

Pseudo-3D model space: body volume

Preliminary interpretation

Non-inductive response: Why?

Regional 3D currents - local charges?

EMIGMA modelling: phases

Conclusions-1

Conclusions-2

Conclusions-3

Future work ...

Acknowledgements

Author: Xavier Garcia

Email: [email protected]

Home Page: http://www.cg.nrcan.gc.ca/staff/jones