THE GULF AIRBORNE MAGNETIC GRADIOMETER

Geophysics ◽  
1954 ◽  
Vol 19 (1) ◽  
pp. 116-123 ◽  
Author(s):  
W. E. Wickerham
Keyword(s):  
Qualitative Analysis ◽  
Time Derivative ◽  
Magnetic Intensity ◽  
Magnetic Gradients ◽  
Airborne Magnetic

An instrument capable of measuring magnetic gradients as encountered in airborne magnetometer operations has possible applications as an interpretational aid. Its usefulness, particularly for qualitative analysis, will be discussed briefly. The design of a spatial‐type airborne gradiometer of adequate precision can be shown to be quite impractical. An instrument based on the time derivative of the magnetic intensity variations provides a useful alternative and is described.

Analysis of Noise Coherence in Airborne Magnetic Gradients for UXO Detection

2003 ◽  
Author(s):  
T. Jeffrey Gamey ◽  
William E. Doll ◽  
Les P. Beard ◽  
David T. Bell
Keyword(s):  
Magnetic Gradients ◽  
Airborne Magnetic

scholarly journals Interpretation of high resolution airborne magnetic data (HRAMD) of Ilesha and its environs, Southwest Nigeria, using Euler deconvolution method

2017 ◽  
Vol 64 (4) ◽  
pp. 227-241
Author(s):  
Oluwaseun Tolutope Olurin
Keyword(s):  
High Resolution ◽  
High Amplitude ◽  
Sharp Contrast ◽  
Magnetic Data ◽  
Magnetic Intensity ◽  
Euler Deconvolution ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Low Amplitude ◽  
Airborne Magnetic

AbstractInterpretation of high resolution aeromagnetic data of Ilesha and its environs within the basement complex of the geological setting of Southwestern Nigeria was carried out in the study. The study area is delimited by geographic latitudes 7°30′–8°00′N and longitudes 4°30′–5°00′E. This investigation was carried out using Euler deconvolution on filtered digitised total magnetic data (Sheet Number 243) to delineate geological structures within the area under consideration. The digitised airborne magnetic data acquired in 2009 were obtained from the archives of the Nigeria Geological Survey Agency (NGSA). The airborne magnetic data were filtered, processed and enhanced; the resultant data were subjected to qualitative and quantitative magnetic interpretation, geometry and depth weighting analyses across the study area using Euler deconvolution filter control file in Oasis Montag software. Total magnetic intensity distribution in the field ranged from –77.7 to 139.7 nT. Total magnetic field intensities reveal high-magnitude magnetic intensity values (high-amplitude anomaly) and magnetic low intensities (low-amplitude magnetic anomaly) in the area under consideration. The study area is characterised with high intensity correlated with lithological variation in the basement. The sharp contrast is enhanced due to the sharp contrast in magnetic intensity between the magnetic susceptibilities of the crystalline and sedimentary rocks. The reduced-to-equator (RTE) map is characterised by high frequencies, short wavelengths, small size, weak intensity, sharp low amplitude and nearly irregular shaped anomalies, which may due to near-surface sources, such as shallow geologic units and cultural features. Euler deconvolution solution indicates a generally undulating basement, with a depth ranging from −500 to 1000 m. The Euler deconvolution results show that the basement relief is generally gentle and flat, lying within the basement terrain.

Analysis Of Noise Coherence In Airborne Magnetic Gradients For Uxo Detection

2003 ◽  
Author(s):  
T. Jeffrey Gamey ◽  
William E. Doll ◽  
Les P. Beard ◽  
David T. Bell
Keyword(s):  
Magnetic Gradients ◽  
Airborne Magnetic

MAGNETIC SURVEYING USING HORIZONTAL GRADIENT VECTORS

Geophysics ◽  
1977 ◽  
Vol 42 (6) ◽  
pp. 1262-1264 ◽  
Author(s):  
S. Thyssen‐Bornemisza
Keyword(s):  
Magnetic Field ◽  
Unit Vector ◽  
Magnetic Potential ◽  
Horizontal Gradient ◽  
Magnetic Intensity ◽  
Total Field ◽  
Nonlinear Characteristics ◽  
Normal Magnetic Field ◽  
Vertical Gradients ◽  
Airborne Magnetic

It was pointed out some time ago (Bhattacharyya, 1965) that the total intensity anomaly of a magnetic field ΔT in the direction of the normal magnetic field of earth is expressed by the equation, [Formula: see text]Here ΔV denotes the anomaly of the magnetic potential and t the unit vector in the direction of earth’s undisturbed total field. Horizontal and vertical gradients observed along the tracks of airborne magnetic surveys were discussed by several authors (Wickerham, 1954; Glicken, 1955; Hood, 1965; Langan, 1966). These gradients are obtained from the formulas [Formula: see text] [Formula: see text]where the magnetic intensity differences are observed over horizontal and vertical intervals Δx and Δz between two sensors. However, this approach is only valid when the depth h of the causative body or structure is relatively large compared to Δx and Δz; thus in cases of shallow anomalies, the nonlinear characteristics of the anomalous magnetic field would distort the observed gradients and render interpretation of data very difficult.

Analysis of noise coherence in airborne magnetic gradients for UXO detection

2003 ◽  
Author(s):  
T. J. Gamey ◽  
W. E. Doll ◽  
L. P. Beard ◽  
D. T. Bell
Keyword(s):  
Magnetic Gradients ◽  
Airborne Magnetic
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