Mining Geophysics

Preface Chapter 1. The Role of Geophysics in Ore Prospecting Chapter 2. General Aspects of the Collection and Presentation of Geophysical Data Classification of Geophysical Methods Radioactivity Collection of Preliminary Information Trial Surveys Staking An Area Field Measurements Geophysical Maps Isoanomaly Curves Profile Drawing Interpretation Chapter 3. Magnetic Methods Introduction Recalling Some Fundamental Concepts Induced and Permanent Magnetism General Magnetic Properties of Rocks Susceptibilities of Rocks Permanent Magnetization (Remanence) of Rocks Measurement of Susceptibility and Remanence The Geomagnetic Field Magnetometers Field Work The Zero Level An Orebody As A Magnet Interpretation of Magn Depth,- Strike Length,- Dip and Pitch,- Depth-Extent,- Size and Magnetization A Simple Example of A Magnetic Survey (U-Dal, Central Sweden) Magnetic Survey in the E-O Orefield (Central Sweden) Transverse Magnetization A Simple Geometrical Construction For Determining the Position of An Ore Sheet Magnetic Effects of Broad Zones The Greenstone Area of Loos (Sweden) Vector Measurements Example of Vector Measurements Borehole Measurements Note On Reverse Magnetic Anomalies Chapter 4. The Self-Potential Method Introduction Origin of Self-Potentials Measurement of Self-Potentials Electrodes,- Cable,- Voltmeter Field Procedure Example of SP Surveys The Kimheden Orebody,- The Gransjö Orefield, Central Sweden,- The Copper Deposits of Chalkidiki, Northern Greece,-The Shales of Gautosjö, Northern SwedenChapter 5. Electromagnetic Methods Introduction Geometry of the Electromagnetic Field The Tilt-Angle Method Amplitude and Phase The Phase Angle and the Vector Diagram Real and Imaginary Components Measurement of the Real and Imaginary Components Classification of Electromagnetic Methods Fixed-Source Methods,- Moving Source-Receiver Methods Fixed-Source Methods Tilt-Angle,- Bieler-Watson,- Two-Frame Method,-The Compensator Or Sundberg Method,- The Turam Method Loop Layouts Moving Source-Receiver Methods Coils Horizontal and Coplanar,- Coils Vertical and Coplanar,- Coils Vertical and Coaxial,- Topographic Corrections Examples of Moving Source-Receiver Surveys The Svansele Orebody (Northern Sweden),- The R-Sjö Sulphide Occurrence (Sweden) Use of Two Frequencies in Electromagnetic Prospecting Depth Penetration of Electromagnetic Methods Afmag Chapter 6. Electrical Methods Introduction Resistivity Resistivity of Rocks and Mineral Apparatus Commutation of Current Classification of Electric Methods Equipotential Method Earth-Resistivity Methods Apparent Resistivity Electrode Configurations in Resistivity Methods Electric/Drilling Electric Mapping Mapping By Linear Current Electrodes (Theory) Field Examples of Line-Electrode Mapping The Mise-À-La-Masse Method Potential-Drop Ratio and A.C. Potential Methods Resistivity Measurements in Boreholes Chapter 7. Induced Polarization Methods Introduction Origin of Induced Polarization Electrode Polarization,- Membrane Polarization, The Condenser Model Effect of Alternating Current Time-Domain and Frequency-Domain IP Methods Measures of the IP Effect Time-Domain Measures,-Frequency-Domain Measures Polarizability of Minerals and Rocks Two Examples of IP Surveys Kankberg Orebody, Northern Sweden,- Broken Hill Area, Australia Concluding Remarks Concerning The IP Method Chapter 8. Gravity Methods Introduction Scope of the Gravity Method in Ore Prospecting Some Difficulties Absolute and Relative Gravity Measurements Gravimeters Field Procedure Corrections To Gravimeter Observations Latitude,- Elevation Or Free-Air Correction,- Bouguer Correction,- Terrain Correction The Bouguer Anomaly Density Determination Interpretation of Gravity Anomalies Key Variables of Gravity Interpretation Magnitude,- Sharpness,- Resolution,- Elongation Of Contours,-Shape Gravity Profiles Across Simple Structures Regional and Local Gravity Anomalies Gravity Measurements On The Udden Sulphide Body (Sweden) Effect of Overburden On Gravity Anomalies Mass Estimates A Further Example of A Gravity Survey Underground and Shaft Measurements of Gravity Second Vertical Derivatives of Gravity Anomalies Chapter 9. Seismic Methods Introduction Types of Elastic Waves Scope of Seismic Measurements in Ore Prospecting Generation, Detection and Registration of Seismic Waves The Reflection Method The Refraction Method Illustrations of Seismic Measurements in Ore Prospecting Siderite District of the Siegerland (Germany),- Sulphur Limestone in Sicily (Italy)Chapter 10. Radioactive Methods Introduction Scope of the Method Radioactive Decay and Radioactive Equilibrium Radioactivity of Rocks Instruments and Field Procedure Airborne Radioactive Prospecting Chapter 11. Airborne Magnetic and Electromagnetic Methods Introduction Limitations of Airborne Surveys Magnetic Airborne Work Examples Interpretation of Aeromagnetic Maps Airborne Electromagnetic Methods Classification of Airborne E.M. Systems Fixed-Separation Systems Phase-Measuring Or Quadrature Systems Depth-Penetration and Efficiency of Airborne E.M. Systems Interpretation of Airborne Electromagnetic Anomalies Example of An Airborne Survey Chapter 12. Combination of Geophysical Methods Introduction The Location of Geophysical Indications Examples of the Combination of Geophysical Methods The Västra Maurliden Discovery (Skellefte Ore Field, Sweden),-The Tervaskoski Orebody (Norrbotten County, Sweden)Appendix 1. Simple Method of Determining The Magnetic Susceptibility and Remanence of Approximately Spherical Rock and Ore Samples Appendix 2. Magnetic Anomaly of Pole SystemsAppendix 3. The Magnetic Field of A Large Rectangular Loop Carrying An Electric CurrentAppendix 4. Semi-Absolute Calculation of the Electromagnetic Field Components From Turam Reduced Ratios and Phase DifferencesAppendix 5. Electric Potential Due To A Point and A Line Current Electrode Placed On The Surface of A Homogeneous Ground Appendix 6. Method of Images Appendix 7. Gravity Anomalies Appendix 8. Depth Estimates of Some Simple Mass Shapes Appendix 9. Notes On The Master Curves in Fig. 117 For Total Field Magnetic Anomalies ReferencesIndex