ژئومغناطیس: رساله‌ای در ژئوفیزیک

The study of geomagnetism, particularly the study of the Earth's magnetic vield is of increasingly critical importance to geoscientists. Geomagnetism presents various aspects of the magnetic field of Earth. After an overview, topics covered include magnetospheric interactions, secular variation, magnetic induction, archeomagnetism, reversals, excursions, oceanic and continental magnetic anomalies, and long-term behaviors of the magnetic field. The mathematical techniques for treating these phenomena are discussed in detail. The electric and magnetic properties of Earth materials, as well as basic experimental and observational techniques are also described.Self-contained volume starts with an overview of the subject then explores each topic with in depth detailExtensive reference lists and cross references with other volumes to facilitate further researchFull-color figures and tables support the text and aid in understandingContent suited for both the expert and non-expert Cover......Page 1 Editor-in-Chief......Page 2 Volume Editors......Page 3 Preface......Page 4 Early History......Page 7 Early Chinese Compasses......Page 8 Epistola of Petrus Peregrinus......Page 10 European Recognition of Declination......Page 12 De Magnete of William Gilbert......Page 13 Further Developments in Observations......Page 14 Measurement of Intensity......Page 15 Deciphering the Past Using Remanent Magnetization......Page 17 Polarity Reversals......Page 18 Long-Term Behaviors of the Geodynamo......Page 20 Spherical Harmonic Analysis......Page 21 Satellite Measurements......Page 23 Geomagnetic Spectrum......Page 24 Inverse Problem......Page 26 Signal and Noise in Magnetic Field Measurements......Page 28 Magnetic Mapping of Planets......Page 30 Planetary Dynamos: A Comparative study......Page 32 The Magnetic Field of the Sun......Page 33 Discussion and Conclusions......Page 35 References......Page 36 Introduction......Page 38 Magnetic Elements, Coordinates, and Time......Page 40 Dipole coordinates and components......Page 41 Time......Page 42 Ground Data......Page 43 Satellite Data......Page 44 Ørsted......Page 45 Calibration and alignment of satellite magnetometers......Page 46 Dst, an index of magnetospheric ring-current strength......Page 47 Global Models of the Earth’s Magnetic Field......Page 48 Spherical Harmonic Representation of the Field......Page 49 The International Geomagnetic Reference Field......Page 50 More advanced models......Page 51 Models of the Core Field......Page 53 Models of the Crustal (Lithospheric) Field......Page 55 Modelling philosophy......Page 56 Early comprehensive models......Page 58 Recent comprehensive models......Page 59 Predictions from CM4......Page 60 Spatial Power Spectra and Timescales......Page 64 The Field at the Earth’s Surface......Page 68 The Field at the Core Surface......Page 73 References......Page 77 Relevant Websites......Page 80 Introduction......Page 81 Magnetosphere......Page 82 Currents......Page 83 Single-Particle Motion......Page 84 Collisions and Conductivity......Page 86 Convection and Merging......Page 87 Equatorial Electrojet......Page 88 Storms and Sudden Commencements......Page 89 Magnetospheric Convection......Page 90 Auroral Electrojets......Page 91 Substorms......Page 92 Geomagnetic Pulsations......Page 93 Pi2 Pulsations......Page 94 References......Page 95 5.04 Observation and Measurement Techniques......Page 97 nomenclature......Page 98 Instrumentation......Page 99 The induction coil......Page 100 The fluxgate......Page 101 The SQUID......Page 102 Proton precession magnetometers......Page 103 Optically pumped magnetometers......Page 105 Special Magnetic Conditions in an Observatory......Page 107 Absolute measurement of the horizontal component, H, by the Gauss method......Page 108 Absolute measurements with the proton vector magnetometer (PVM)......Page 109 Declinometer......Page 110 DIflux (DIM)......Page 111 Classical magnet-based instruments......Page 112 Calibration of scalar magnetometers......Page 113 Obtaining definitive absolute data......Page 114 The INTERMAGNET Magnetic Observatory Network......Page 115 Fully Automatic Magnetic Observatories......Page 116 Magnetic Surveys for Geological Exploration......Page 117 Mapping Magnetic Anomalies......Page 118 The Origin of Magnetic Anomalies......Page 119 Ground surveys......Page 122 Practical airborne magnetometry......Page 123 Elimination of nongeological influences (aircraft, temporal changes)......Page 124 Data Presentation, Enhancement and Interpretation Methods......Page 126 The Link between Magnetic Properties of Rocks and Regional Geology......Page 128 Satellites and Space Probes......Page 130 Introduction......Page 131 Consolidated rocks......Page 132 Unconsolidated (lake and deep sea) sediments......Page 133 Astatic systems......Page 134 Spinner magnetometers......Page 135 Cryogenic magnetometers......Page 136 Introduction......Page 138 Thermal demagnetization......Page 139 Intensity of magnetization against demagnetization level......Page 140 Remagnetization circles......Page 141 Paleomagnetic directions: the Fisher distribution......Page 142 Field tests......Page 143 Baked contact test......Page 144 The GAD hypothesis......Page 146 References......Page 147 Relevant Websites......Page 150 5.05 Geomagnetic Secular Variation and Its Applications to the Core......Page 151 Historical Background......Page 152 Catalogs and Compilations of Data......Page 153 Surveys, Repeat Stations, and Marine Data......Page 154 Observatory Data......Page 156 Satellite Data......Page 159 Time-Dependent Models of the Main Field......Page 160 Methodologies......Page 161 Time-dependent models based on cubic B-splines......Page 163 The ufm1, ufm2, and gufm1 models......Page 164 CHAOS field model of recent satellite data......Page 165 Field Evolution at the Earth’s Surface......Page 166 Axial dipole decay......Page 168 Evolution of integrated rate of change of vertical field at Earth’s surface......Page 170 Geomagnetic jerks......Page 171 Field Evolution at the Core Surface......Page 174 High latitude, approximately stationary flux lobes......Page 176 Low-latitude, westward-drifting field features......Page 177 Interpretation in Terms of Core Processes......Page 180 Maxwell’s Equations and Moving Frames......Page 181 The Induction Equation in a Spherical Earth......Page 183 The Navier-Stokes Equation......Page 185 Application of the frozen flux hypothesis to the generation of secular variation at the core surface......Page 187 Attempts to test the frozen flux approximation using geomagnetic observations......Page 188 Theoretical issues concerning the frozen flux hypothesis......Page 190 Other Invariants......Page 192 References......Page 193 5.06 Crustal Magnetism......Page 198 Glossary......Page 199 Governing Equations......Page 200 Structure of the Remainder of the Chapter......Page 201 Magnetic Petrology......Page 202 Continental and Oceanic Magnetic Anomalies......Page 203 Chicxulub......Page 204 Dike Swarms......Page 205 Heat Flux beneath the Antarctic Ice Sheet......Page 207 Compilations and Models......Page 208 Continental-Scale Compilations......Page 210 Satellite Compilations of Crustal Magnetic Fields......Page 211 Global Magnetization Models......Page 213 Removal of Noncrustal Fields......Page 214 Representations......Page 215 Transformations......Page 220 Pseudogravity......Page 221 Spatial derivatives......Page 222 Euler deconvolution......Page 223 Resolving Interpretational Ambiguity......Page 224 Spectral Overlap with Other Fields......Page 225 Separation of Induced and Remanent Magnetization......Page 228 References......Page 229 5.07 Geomagnetism......Page 239 Historical Beginnings......Page 240 Earth/ionosphere cavity......Page 241 Daily variation and Sq......Page 242 The magnetospheric ring current......Page 243 Introductory Theory......Page 244 The MT Method......Page 245 MT in Practice......Page 246 Magnetic field measurements......Page 247 MT Data Processing......Page 249 Global Response Functions......Page 250 Using magnetic satellites......Page 251 Interpretation of GDS and MT Data......Page 252 Forward Modeling in Higher Dimensions......Page 253 Numerical Inversion of Geomagnetic Data......Page 254 Electrical Conductivity of Earth Materials......Page 256 Conduction in native metals......Page 257 Ionic, or point defect, conduction......Page 258 Binary Mixing Laws......Page 260 Textural anisotropy......Page 261 Laboratory Measurement of Conductivity......Page 262 Thermopower Measurements......Page 264 Conductivity of Mantle Minerals......Page 265 Olivine conductivity......Page 266 The Oceans and Crust......Page 269 The Mantle......Page 271 Water......Page 273 The Core......Page 274 Water in the Mantle......Page 275 References......Page 276 5.08 Magnetizations in Rocks and Minerals......Page 279 Ferromagnetism......Page 280 Antiferromagnetism and Ferrimagnetism......Page 282 Magnetocrystalline Anisotropy......Page 283 Magnetic Quantities, Units, and Conversions......Page 284 Demagnetizing Energy and Domain Structure......Page 285 Domain Wall Width and Energy......Page 287 Equilibrium Domain Structures......Page 288 Observations of Domains......Page 289 Single-Domain Grains......Page 291 Metastable SD Grains......Page 292 Pseudo-Single-Domain Grains......Page 294 Thermomagnetic Curves, Curie Temperatures, and SD Ranges......Page 296 Magnetite......Page 299 Titanomagnetites......Page 300 Maghemite and Titanomaghemites......Page 301 High-Temperature Oxidation......Page 303 Titanohematites (Hemoilmenites)......Page 304 Iron Oxyhydroxides......Page 305 Iron Sulfides......Page 306 Iron Carbonates......Page 307 Iron and Iron-Nickel......Page 308 'Magnetic’ Silicates......Page 309 SD Hysteresis and Susceptibility......Page 310 Temperature Effects: Hopkinson Peak and Koenigsberger Ratio Q......Page 313 AF Demagnetization......Page 315 Thermal Demagnetization of SD Grains......Page 317 Thermal Demagnetization of MD Grains......Page 318 Resolving Multivectorial NRM......Page 319 Thellier Paleointensity Determination......Page 320 Stability and Domain State Tests......Page 321 Thermoremanent Magnetization (TRM)......Page 322 Viscous and Thermoviscous Magnetization......Page 326 Chemical Remanent Magnetization (CRM)......Page 329 Detrital and Post-Depositional Remanent Magnetizations (DRM and PDRM)......Page 330 Summary......Page 332 References......Page 333 Introduction......Page 339 Data Types and Methods......Page 340 Geomagnetic Directional Information......Page 341 Paleointensity Data and Uncertainties......Page 342 Local and Regional Secular Variation Studies......Page 344 The KGCFS Data Compilation......Page 348 The Global Geomagnetic Field and Its Secular Variation on Millennial Timescales......Page 350 The Average Field......Page 353 Jerks, Drifts, and Waves......Page 360 Dipole Moment Variations......Page 361 The Geomagnetic Spectrum......Page 362 Cosmogenic Isotope Production Rates - the Global View Linking Geomagnetic and Climate Studies......Page 364 Surface Exposure Dating and Local Variations......Page 366 Outstanding Problems and Scope for Future Progress......Page 367 Acknowledgment......Page 368 References......Page 369 Relevant Website......Page 374 History of the Polarity Timescale and Excursions......Page 375 Nomenclature for Excursions and Polarity Intervals......Page 377 Introduction......Page 378 The Laschamp Excursion......Page 381 The Mono Lake Excursion......Page 385 The Blake Excursion......Page 387 The Iceland Basin Excursion......Page 389 The Pringle Falls Excursion......Page 391 Excursions in the Early Brunhes Chron......Page 393 Background......Page 395 Gilsa......Page 398 Santa Rosa......Page 399 Geomagnetic Excursions in Pre-Matuyama Time......Page 400 C5n.2n (Late Miocene)......Page 402 Oligocene and Eocene......Page 403 Duration of Geomagnetic Excursions......Page 404 Excursional Field Geometry......Page 406 Concluding Remarks......Page 407 References......Page 409 Introduction......Page 419 Paleosecular Variation......Page 421 The Time-Averaged Field (TAF) - Departures from GAD?......Page 422 Paleomagnetic Observations......Page 424 Comparing data from different locations......Page 425 Measures of PSV and the TAF......Page 426 Global Field Models: Spherical Harmonic Representation......Page 428 Global Database - Paleosecular Variation from Lavas (PSVRL) Database......Page 429 Other Global Lava Flow Data Sets......Page 430 Sedimentary Records......Page 432 Paleosecular Variation......Page 433 Early PSV Models......Page 434 Giant Gaussian Process (GGP) Models......Page 435 The Time-Averaged Field......Page 436 Early Studies......Page 437 The 1990s: Longitudinal Structure in the TAF?......Page 439 Recent Studies: Joint Estimation of PSV and the TAF......Page 440 Data sets: spatial distribution......Page 441 Bias from unit vectors......Page 444 Successes and Limitations of Current TAF and PSV Models......Page 446 Toward New Global Data Sets......Page 449 A New Generation of Paleomagnetic Field Modeling......Page 450 Concluding Remarks......Page 451 References......Page 452 Introduction......Page 456 Polarity Reversals and the Geomagnetic Polarity Timescale......Page 459 Geomagnetic Intensity Fluctuations......Page 463 Anomaly Skewness and Nondipole Field......Page 470 Magnetic Source Regions......Page 471 Initial grain size and composition......Page 473 Low-temperature alteration......Page 475 Magnetization of Dikes......Page 482 Magnetization of Gabbros......Page 485 Mantle-Derived Peridotites......Page 489 Crustal Accretion and Structure of the Magnetic Source......Page 490 Nonvertical Magnetic Boundaries......Page 491 Rotations of the Magnetic Source Layer......Page 494 Future Directions......Page 496 Acknowledgments......Page 500 References......Page 501 Relevant Website......Page 508 5.13 Paleointensities......Page 509 Theory of Paleointensity......Page 510 Paleointensity with Thermal Remanence......Page 511 Linearity Assumption......Page 513 Alteration during Heating......Page 514 KTT family of experiments......Page 515 Shaw family of experiments......Page 518 Reduced number of heating steps......Page 520 Use of controlled atmospheres to reduce alteration......Page 521 Use of microwaves for thermal excitation......Page 522 Paleointensity with Depositional Remanences......Page 523 Physical Alignment of Magnetic Moments in Viscous Fluids......Page 524 Nonflocculating environments......Page 525 Flocculating environments......Page 526 PostDepositional Processes......Page 529 Normalization......Page 530 Chemical Alteration......Page 531 Depositional Remanences......Page 532 Paleomagnetic Databases......Page 533 Absolute paleointensity data......Page 534 Relative paleointensity data......Page 538 Selection Criteria from the PINT06 Database......Page 539 What is the Average Strength of the Geomagnetic Field?......Page 540 Source of scatter in the CNS......Page 542 The oldest paleointensity records......Page 543 The paleointensity 'saw-tooth’......Page 544 Sediments......Page 546 Atmospheric Interaction......Page 549 Frequecy of Intensity Fluctuations and the Climatic Connection......Page 552 Conclusions......Page 554 References......Page 555 Relevant Websites......Page 563 Planetary Moment of Inertia and the Spin-Axis......Page 564 Different Information in Different Reference Frames......Page 565 Type I TPW: Slow/Prolonged TPW......Page 566 Hypothesized Rapid or Prolonged TPW: Late Paleozoic-Mesozoic......Page 568 Hypothesized Rapid or Prolonged TPW: 'Cryogenian’-Ediacaran-Cambrian-Early Paleozoic......Page 570 Precision of TPW Magnitude and Rate Estimation......Page 571 Physical Oceanographic Effects: Sea Level and Circulation......Page 573 Chemical Oceanographic Effects: Carbon Oxidation and Burial......Page 575 Ediacaran-Cambrian TPW: 'Spinner Diagrams’ in the TPW Reference Frame......Page 578 Proof of Concept: Independent Reconstruction of Gondwanaland Using Spinner Diagrams......Page 580 Summary: Major Unresolved Issues and Future Work......Page 584 References......Page 585 Treatise on Geophysics: Geomagnetism, Volume 5, provides an overview of the most important aspects of geomagnetism. The book begins by tracing the history of the study of geomagnetism. It then reviews global models of the Earth's magnetic field; the main sources of external magnetic field contributions; and the instruments and practices used to observe and measure the full range of features of the geomagnetic field. It discusses the origins of current knowledge of the secular variation of the Earth's magnetic field; crustal magnetism; geomagnetic excursions; the study of geophysical electromagnetic induction; the magnetization process; and the status of recent magnetic field data and their applications. The remaining chapters cover the geometry of the geomagnetic field and its temporal variability as recorded in volcanic and sedimentary rocks over the past few million years; the ocean crust as a recorder of geomagnetic field variations; and the theoretical basis for paleointensity experiments in igneous and sedimentary environments. The final chapter explains the concept of true polar wander (TPW), defined as shifts in the geographic location of Earth's daily rotation axis and/or by fluctuations in the spin rate (length of day anomalies). Self-contained volume starts with an overview of the subject then explores each topic with in depth detail Extensive reference lists and cross references with other volumes to facilitate further research Full-color figures and tables support the text and aid in understanding Content suited for both the expert and non-expert