The Complex Gradient Method of Interpreting the Magnetic Anomalies due to Long Horizontal Cylinders

D. Atchuta Rao; H.V. Ram Babu

doi:10.1071/EG980034

ISSN: 0812-3985
E-ISSN: 1834-7533

The Complex Gradient Method of Interpreting the Magnetic Anomalies due to Long Horizontal Cylinders
Authors D. Atchuta Rao^a and H.V. Ram Babu^a
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^a National Geophysical Research Institute, Hyderabad, 500 007, . India, .
Publisher: Australian Society of Exploration Geophysicists
Source: Exploration Geophysics, Volume 11, Issue 1-2, Jun 1980, p. 34 - 37
DOI: https://doi.org/10.1071/EG980034
- Published online: 01 Jun 1980

Abstract

The resultant of the horizontal and the vertical gradients of the magnetic anomaly is a vector quantity and is defined as the complex gradient, the amplitude and phase of the complex gradient are used to evaluate the parameters of the cylinder. The amplitude plot of the complex gradient of the magnetic anomaly due to a long horizontal cylinder, is a bell-shaped symmetric curve and its shape is independent of the magnetic inclination of the area and the strike of the body. The phase plot of the complex gradient is an antisymmetric curve with an offset value equal to the ‘effective inclination’ of the geomagnetic field vector which depends on the magnetic inclination of the area and the strike of the cylinder. A combined analysis of the amplitude and phase plots yields the depth to the centre of the cylinder, the effective inclination of the geomagnetic field vector and the magnetic moment of the cylinder. This method can be applied to the total, vertical or horizontal field components of the magnetic anomaly. Applicability of this method has been tested on a synthetic anomaly.

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1980-06-01

2026-01-16

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References

ATCHUTA, RAO, D., RAM BABU.H. V.,and SANKER NARAYAN P.V., 1980 Relationship of magnetic anomalies due to subsurface features and the interpretation of sloping contacts, Geophysics, 45, 32-36.
BREINER, S, 1973, Applications mannual for portable magnetometers, GeoMetrics publication, 395 Java Drive, Sunnyvale, California, U.S.A.
GAY, S.P. 1965 Standard curves for magnetic anomalies over long Horizontal Cylinders, Geophysics, 30, 818-828.
GREEN, R-, and STANLEY, J.M., 1975 Application of a Hilbert transform method to the interpretation of surface-vehicle magnetic data, Geophys. Prosp. 23,18-27.
HAMMER, S., and ANZOLEAGA, R., 1975 Exploring for strati-graphic traps with gravity gradients. Geophysics, 40, 256-268
MURTHY, I.V.R., and RAO, C.V., 1974 A note on the Sin (X)/X method of continuation. Bullet/no De Geophysics, 16, 223-231
NABHtGHIAN, M.N., 1972, The Analytic signal of two-dimensional magnetic bodies with polygonal cross-section; its properties and use for automated anomaly interpretation. Geophysics, 37, 507-517.
RAO, B.S.R., PRAKASA RAO, T.K.S., and HARNATH BABU, T., 1969 A new technique of interpreting gravity and vertical magnetic anomalies due to infinite horizontal cylindrical ore bodies, Pageoph, 11, 5-10.
RAO, B.S.R., MURTHY, I.V.R., and RAO, C.V., 1973 A direct method of interpreting gravity and magnetic anomalies; the case of a Horizontal Cylinder: Pageoph, 102, 67-72
STANLEY, J.M., 1977 Simplified magnetic interpretation, the geologic contact and thin dyke. Geophysics, 42, 1235-1240.

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Article Type: Research Article

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The Complex Gradient Method of Interpreting the Magnetic Anomalies due to Long Horizontal Cylinders

Abstract

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