Applied geophysics

Описание

Contents
Problems of
Interpretation / 46
2.7.10. Excess Mass / 47
2.7.11. Overburden Effects / 48
2.7.12. Maximum-Depth Rules/48
2 8. Field Examples / 48
2 9. Problems / 52
References / 60
3. Magnetic Methods / 62
3.1. In troduction / 62
3.1.1. General/62
3.1.2. History of Magnetic
Methods / 62
3.2. Principles and Elementary Theory/ 63
3.2.1. Classical versus Electromagnetic
Concepts / 63
3.2.2. B-H Relations: The Hysteresis
Loop / 64
3.2.3. Magnetostatic Potential for a
Dipole Field / 65
3.2.4. The General Magnetic
Anomaly / 66
3.2.5. Poisson's Relation / 67
3.3. Magnetism of the Earth / 67
3.3.1. Nature of the Geomagnetic
Field / 67
3.3.2. The Main Field / 68
3.3.3. The External Magnetic Field / 72
3.3.4. Local Magnetic Anomalies / 72
3.3.5. Magnetism of Rocks and
Minerals / 72
3.3.6. Remanent Magnetism / 73
3.3.7. Magnetic Susceptibilities of
Rocks and Minerals / 73
3.3.8. Magnetic Susceptibility
Measurements / 73
3.4. Field Instruments for Magnetic
Measurements / 75
3.4.1. General/75
3.4.2. Flux-gate Magnetometer / 75
3.4.3. Proton-Precession
Magnetometer / 77
3.4.4. Optically Pumped
Magnetometer / 78
3.4.5. Gradiometers / 80
3.4.6. Instrument Recording/80
3.4.7. Calibration of
Magnetometers / 80
3.5. Field Operations / 80
3.5.1. General/80
3.5.2. Airborne Magnetic Surveys/81
3.5.3. Shipborne Magnetic Surveys / 83
3.5.4. Ground Magnetic Surveys/83
3.5.5. Gradiometer Surveys / 84
3.6. Magnetic Effects of Simple Shapes / 84
3.6.1. General/84
3.6.2. The Isolated Pole
(Monopole) / 85
3.6.3. The Dipole/87
3.6.4. Two-Dimensional Features/88
3.6.5. Dipping Dike (Prism) / 92
3.6.6. Dipping Sheet / 97
3.6.7. Horizontal Sheet (Plate) / 100
3.6.8. Semiinfinite Horizontal Sheet:
Fault Approximation /100
3.6.9. Contact between Beds
of Different
Susceptibilities /103
3.6.10. Demagnetization /104
3.7. Processing and Interpretation / 106
3.7.1. General/106
3.7.2. Crude Interpretation and
Structural Aspects /106
3.7.3. Data Processing Operations: The
Fourier Transform /107
3.7.4. Derivatives /107
3.7.5. Continuation /107
3.7.6. Spectral Analysis / 108
3.7.7. Reduction to the Pole / 109
3.7.8. Use of Master Curves for Dikes
of Great Depth Extent / 109
3.7.9. Matched Filtering / 112
3.7.10. Werner Deconvolution / 112
3.7.11. Depth Estimates / 113
3.8. Field Examples/ 114
3.8.1. Ground Surveys / 114
3.8.2. Airborne Surveys / 117
3.9. Problems / 124
References / 134

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