Mining Geophysics (eBook)

D. S. Parasnis (Autor)

eBook Download: PDF

2013 | 1. Auflage
372 Seiten
Elsevier Science (Verlag)
978-1-4832-7501-7 (ISBN)

Infos

Methods in Geochemistry and Geophysics, 3: Mining Geophysics focuses on the geophysical methods of ore prospecting, including radioactivity, collection of geophysical data, and field measurements. The manuscript first highlights the role of geophysics in ore prospecting and the general aspects of collection and presentation of geophysical data. Discussions focus on classification of geophysical methods, radioactivity, collection of preliminary information, field measurement, and isoanomaly curves. The text then surveys magnetic and self-potential methods, as well as the general magnetic properties of rocks, geomagnetic field, magnetometers, transverse magnetization, and measurement of self-potentials. The publication ponders on electromagnetic, electrical, and induced polarization methods. Topics include classification of electromagnetic methods; use of two frequencies in electromagnetic prospecting; moving source-receiver methods; electrode configurations in resistivity methods; and resistivity measurements in boreholes. The text also examines gravity, seismic, and airborne magnetic and electromagnetic methods. The manuscript is a valuable source of information for geologists and mining engineers.

Inhalt

Front Cover 1
Mining Geophysics 4
Copyright Page 5
Table of Contents 12
Dedication 7
Preface 8
CHAPTER 1. The Role of Geophysics in Ore Prospecting 18
CHAPTER 2. General Aspects of the Collection and Presentation of Geophysical Data 23
CLASSIFICATION OF GEOPHYSICAL METHODS 23
RADIOACTIVITY 25
COLLECTION OF PRELIMINARY INFORMATION 25
TRIAL SURVEYS 26
STAKING AN AREA 26
FIELD MEASUREMENTS 29
GEOPHYSICAL MAPS 30
ISOANOMALY CURVES 31
INTERPRETATION 33
CHAPTER 3. Magnetic Methods 35
INTRODUCTION 35
RECALLING SOME FUNDAMENTAL CONCEPTS 36
INDUCED AND PERMANENT MAGNETISM 39
GENERAL MAGNETIC PROPERTIES OF ROCKS 40
SUSCEPTIBILITIES OF ROCKS 40
PERMANENT MAGNETIZATION (REMANENCE) OF ROCKS 42
MEASUREMENT OF SUSCEPTIBILITY AND REMANENCE 46
THE GEOMAGNETIC FIELD 46
MAGNETOMETERS 48
THE ZERO LEVEL 52
AN OREBODY AS A MAGNET 54
INTERPRETATION OF MAGNETIC ANOMALIES 57
A SIMPLE EXAMPLE OF A MAGNETIC SURVEY (U-DAL, CENTRAL SWEDEN) 61
MAGNETIC SURVEY IN THE E-O OREFIELD (CENTRAL SWEDEN) 65
TRANSVERSE MAGNETIZATION 69
A SIMPLE GEOMETRICAL CONSTRUCTION FOR DETERMINING THE POSITION OF AN ORE SHEET 72
MAGNETIC EFFECTS OF BROAD ZONES 74
THE GREENSTONE AREA OF LOOS (SWEDEN) 79
VECTOR MEASUREMENTS 80
EXAMPLE OF VECTOR MEASUREMENTS 86
BOREHOLE MEASUREMENTS 88
NOTE ON REVERSE MAGNETIC ANOMALIES 91
CHAPTER 4. The Self-Potential Method 92
INTRODUCTION 92
ORIGIN OF SELF-POTENTIALS 93
MEASUREMENT OF SELF-POTENTIALS 95
FIELD PROCEDURE 99
EXAMPLES OF SP SURVEYS 101
CHAPTER 5. Electromagnetic Methods 111
INTRODUCTION 111
GEOMETRY OF THE ELECTROMAGNETIC FIELD 112
THE TILT-ANGLE METHOD 115
AMPLITUDE AND PHASE 119
THE PHASE ANGLE AND THE VECTOR DIAGRAM 121
REAL AND IMAGINARY COMPONENTS 123
MEASUREMENT OF THE REAL AND IMAGINARY COMPONENTS 124
CLASSIFICATION OF ELECTROMAGNETIC METHODS 125
FIXED-SOURCE METHODS 126
LOOP LAYOUTS 143
MOVING SOURCE-RECEIVER METHODS 144
EXAMPLES OF MOVING SOURCE-RECEIVER SURVEYS 155
USE OF TWO FREQUENCIES IN ELECTROMAGNETIC PROSPECTING 159
DEPTH PENETRATION OF ELECTROMAGNETIC METHODS 160
AFMAG 162
CHAPTER 6. Electrical Methods 164
INTRODUCTION 164
RESISTIVITY 166
RESISTIVITY OF ROCKS AND MINERALS 169
APPARATUS 170
COMMUTATION OF CURRENT 172
EQUIPOTENTIAL METHOD 174
EARTH-RESISTIVITY METHODS 176
APPARENT RESISTIVITY 178
ELECTRODE CONFIGURATIONS IN RESISTIVITY METHODS 181
ELECTRIC DRILLING 184
ELECTRIC MAPPING 189
MAPPING BY LINEAR CURRENT ELECTRODES (THEORY) 191
FIELD EXAMPLES OF LINE-ELECTRODE MAPPING 194
THE “MISE-À-LA-MASSE” METHOD 199
RESISTIVITY MEASUREMENTS IN BOREHOLES 202
CHAPTER 7. Induced Polarization Methods 204
INTRODUCTION 204
ORIGIN OF INDUCED POLARIZATION 205
THE CONDENSER MODEL 208
EFFECT OF ALTERNATING CURRENT 209
TIME-DOMAIN AND FREQUENCY-DOMAIN IP METHODS 211
MEASURES OF THE IP EFFECT 212
POLARIZABILITY OF MINERALS AND ROCKS 217
TWO EXAMPLES OF IP SURVEYS 219
CHAPTER 8. Gravity Methods 225
INTRODUCTION 225
SCOPE OF THE GRAVITY METHOD IN ORE PROSPECTING 227
SOME DIFFICULTIES 229
ABSOLUTE AND RELATIVE GRAVITY MEASUREMENTS 231
GRAVIMETERS 232
FIELD PROCEDURE 235
CORRECTIONS TO GRAVIMETER OBSERVATIONS 237
THE BOUGUER ANOMALY 244
DENSITY DETERMINATION 245
INTERPRETATION OF GRAVITY ANOMALIES 248
KEY VARIABLES OF GRAVITY INTERPRETATION 250
GRAVITY PROFILES ACROSS SIMPLE STRUCTURES 254
REGIONAL AND LOCAL GRAVITY ANOMALIES 259
GRAVITY MEASUREMENTS ON THE UDDEN SULPHIDE BODY (SWEDEN) 262
EFFECT OF OVERBURDEN ON GRAVITY ANOMALIES 264
MASS ESTIMATES 267
A FURTHER EXAMPLE OF A GRAVITY SURVEY 270
UNDERGROUND AND SHAFT MEASUREMENTS OF GRAVITY 273
SECOND VERTICAL DERIVATIVES OF GRAVITY ANOMALIES 274
CHAPTER 9. Seismic Methods 279
INTRODUCTION 279
TYPES OF ELASTIC WAVES 279
SCOPE OF SEISMIC MEASUREMENTS IN ORE PROSPECTING 281
GENERATION, DETECTION AND REGISTRATION OF SEISMIC WAVES 282
THE REFLECTION METHOD 285
THE REFRACTION METHOD 287
ILLUSTRATIONS OF SEISMIC MEASUREMENTS IN ORE PROSPECTING 289
CHAPTER 10. Radioactive Methods 293
INTRODUCTION 293
SCOPE OF THE METHOD 294
RADIOACTIVE DECAY AND RADIOACTIVE EQUILIBRIUM 295
RADIOACTIVITY OF ROCKS 296
INSTRUMENTS AND FIELD PROCEDURE 298
AIRBORNE RADIOACTIVE PROSPECTING 299
CHAPTER 11. Airborne Magnetic and Electromagnetic Methods 302
INTRODUCTION 302
LIMITATIONS OF AIRBORNE SURVEYS 304
EXAMPLES 306
INTERPRETATION OF AEROMAGNETIC MAPS 308
INTERPRETATION OF AEROMAGNETIC MAPS 308
AIRBORNE ELECTROMAGNETIC METHODS 311
CLASSIFICATION OF AIRBORNE E.M. SYSTEMS 313
FIXED-SEPARATION SYSTEMS 315
PHASE-MEASURING OR QUADRATURE SYSTEMS 316
DEPTH-PENETRATION AND EFFICIENCY OF AIRBORNE E.M. SYSTEMS 318
INTERPRETATION OF AIRBORNE ELECTROMAGNETIC ANOMALIES 323
EXAMPLE OF AN AIRBORNE SURVEY 324
CHAPTER 12. Combination of Geophysical Methods 328
INTRODUCTION 328
THE LOCATION OF GEOPHYSICAL INDICATIONS 329
EXAMPLES OF THE COMBINATION OF GEOPHYSICAL METHODS 334
APPENDIX 1: Simple Method of Determining the Magnetic Susceptibility and Remanence of Approximately Spherical Rock and Ore Samples 343
APPENDIX 2: Magnetic Anomaly of Pole Systems 345
APPENDIX 3: The Magnetic Field of a Large Rectangular Loop Carrying an Electric Current 348
APPENDIX 4: Semi-absolute Calculation of the Electromagnetic Field Components from Turam Reduced Ratios and Phase Differences 349
APPENDIX 5: Electric Potential Due to a Point and a Line Current Electrode Placed on the Surface of a Homogeneous Ground 352
APPENDIX 6: Method of Images 354
APPENDIX 7: Gravity anomalies 356
APPENDIX 8: Depth Estimates of Some Simple Mass Shapes 359
APPENDIX 9: Notes on the Master Curves in Fig.117 for Total Field Magnetic Anomalies 360
References 361
Index 368

Produkt-Details

• Erscheint lt. Verlag: 22.10.2013
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik ► Bergbau
• ISBN-10: 1-4832-7501-9 / 1483275019
• ISBN-13: 978-1-4832-7501-7 / 9781483275017