GETMAG – a new magnetic tensor gradiometer for exploration

Getmag Team

doi:10.1071/ASEG2004ab047

ISSN: 2202-0586
E-ISSN:

oa GETMAG – a new magnetic tensor gradiometer for exploration
Authors Getmag Team^a
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^a CSIRO Telecommunications & Industrial Physics,, Australia, [email protected]
Publisher: Australian Society of Exploration Geophysicists
Source: ASEG Extended Abstracts, Volume 2004, Issue ASEG2004 - 17th Geophysical Conference, Dec 2004, p. 1 - 4
DOI: https://doi.org/10.1071/ASEG2004ab047
- Published online: 01 Dec 2004

Abstract

CSIRO and Australian exploration companies have developed a new instrument for mineral exploration.

The GETMAG (Glass Earth Tensor Magnetic Airborne Gradiometer) instrument measures the magnetic gradient tensor and the components of the magnetic field. The sensors are high temperature superconducting (HTS) quantum interference devices (SQUIDs) operating at liquid nitrogen temperature. A superconducting transformer coupled to a SQUID magnetometer is rotated to detect all gradients perpendicular to the rotation axis. Three SQUID-loop assemblies are required to measure the full tensor.

Field trials demonstrate that the inversion of a few tensor measurements yields as much information as a high-resolution total magnetic intensity (TMI) survey. Direction to individual sources and their magnetic moments (reduced according to distance) can be determined directly from the tensor. GETMAG has applications in mineral exploration, environmental studies, ordnance detection, ship degaussing, submarine tracking and monitoring of marine currents.

The project was funded by CSIRO, BHP, De Beers, MM, Newmont and WMC.

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2026-01-19

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References

Bick, M, Leslie, K.E., Binks, R.A, Tilbrook, D.L., Lam, S.K.H., Gnanarajan, R., Du, J., and Foley, C.P., (2004) Axial high-Tc superconducting gradiometer with a flexible flux transformer, submitted to Appl.Phys.Letters.
Christensen, A. and Rajagopalan, Shanti, (2000) The magnetic vector and gradient tensor in mineral and oil exploration, Preview, 84, 77.
Heath, P., Heinson, G. and Greenhalgh, S., (2003) Some comments on potential field tensor data, Exploration Geophysics, 34, 57-62.
Schmidt, P.W. and Clark, D.A., (2000) Advantages of measuring the magnetic gradient tensor, Preview, 85, 26-30.
Tilbrook, D.L. (2002) Design and development of a SQUID tensor gradiometer, presented at the Applied Superconductivity Conference in Houston, Texas, USA, August 2002, http://www.tip.csiro.au/IMP/SmartMeasure/ASC2002_GETMAG_Presentation.pdf
Vrba, J. (1996) in SQUID Sensors: Fundamentals and Applications, edited by H. Weinstock (Kluwer Academic Publishers, Dordrecht) p.l 17.
Wilson, H., (1985) Analysis of the magnetic gradient tensor. Defence Research Establishment Pacific, Canada Technical Memorandum, 85-13, 47.
Zhang, Changyou, Mushayandevu, M.F., Reid, A.B., Fairhead, J.D. and Odegard, M.E., (2000) Euler deconvolution of gravity tensor gradient data, Geophysics, 65, 512-520.

/content/journals/10.1071/ASEG2004ab047

Article Type: Research Article

Keyword(s): Eigenvalue; Eigenvector; Euler; gradiometer; SQUID; tensor

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