Geoelectromagnetic Investigation of the Earth?s Crust and Mantle

Rokityansky, I. I.; Chobotova, N. L. (TRN); Pestryakov, G. M. (TRN); Pristay, M. N. (TRN); Shilman, B. G. (TRN)

ISBN 10: 3642618030 / ISBN 13: 9783642618031

Editore: Springer, 2011

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Codice articolo 18724007-n

Dati bibliografici

• Titolo: Geoelectromagnetic Investigation of the Earth?s Crust and Mantle
• Editore: Springer
• Data di pubblicazione: 2011
• Lingua: Inglese
• ISBN 10: 3642618030
• ISBN 13: 9783642618031
• Rilegatura: Brossura
• Condizione: New

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Riassunto

Electrical conductivity is a parameter which characterizes composition and physical state of the Earth's interior. Studies of the state equations of solids at high temperature and pressure indicate that there is a close relation be­ tween the electrical conductivity of rocks and temperature. Therefore, measurements of deep conductivity can provide knowledge of the present state and temperature of the Earth's crust and upper mantle matter. Infor­ mation about the temperature of the Earth's interior in the remote past is derived from heat flow data. Experimental investigation of water-containing rocks has revealed a pronounced increase of electrical conductivity in the temperature range D from 500 to 700 DC which may be attributed to the beginning of fractional melting. Hence, anomalies of electrical conductivity may be helpful in identitying zones of melting and dehydration. The studies of these zones are perspective in the scientific research of the mobile areas of the Earth's crust and upper mantle where tectonic movements, processes ofthe region­ al metamorphism and of forming mineral deposits are most intensive. Thus, in the whole set of research on physics of the Earth the studies of electrical conductivity of deep-seated rocks appear, beyond doubt, very important.

Contenuti

1 Geoelectromagnetic Fields.- 1.1 Morphology of the Earth’s Electromagnetic Field.- 1.2 Atmospheric Electricity.- 1.3 Conductivity of the Ionosphere.- 1.4 Formation of the Magnetosphere.- 1.5 Magnetospheric Waves and Their Propagation to the Earth.- 1.6 Conclusions.- 2 Elements of the Theory of Electromagnetic Fields.- 2.1 Fundamental Relations.- 2.2 Electromagnetic Fields in the Spherically Symmetric (and Horizontally Layered) Earth.- 2.3 Impedance and Other Interpretation Parameters (Response Functions).- 2.3.1 The Spectral Impedance.- 2.3.2 Units of Measurement for the Magnetic Field and Impedance.- 2.3.3 The Effective Depth and the Frequency Sounding Condition (FSC).- 2.3.4 Magnetic Ratio, Q, ?a.- 2.3.5 Response Functions of the Layered Earth.- 2.4 Modeling of Geoelectric Fields.- 2.4.1 Horizontally Layered Models (Spherical- and Plane- Layered Media).- 2.4.2 Two- and Three-Dimensional Models.- 2.4.3 Inhomogeneous Surface Thin Layer Model.- 2.5 Conclusions.- 3 The Inverse Problem.- 3.1 Formulation of Inverse Problems.- 3.1.1 Experimental Data.- 3.1.2 The Model of the Sought Object.- 3.1.3 Theoretical Field f of the Model Object.- 3.1.4 Formulation of the Inverse Problem. The Theorem of Uniqueness.- 3.1.5 Properly and Improperly Posed Problems.- 3.1.6 Methods of Solving the Inverse Problem.- 3.2 Solving Procedures of the Trial-and-Error Method.- 3.2.1 The Monte-Carlo and Hedgehog Procedures.- 3.2.2 Linearization of the Inverse Problem. Matrix of Derivatives with Respect to Parameters.- 3.2.3 Generalized Theory for Solving Linearized Inverse Problems.- 3.3 Improperly Posed Problems and Their Regularization.- 3.4 The Information-Statistical Approach.- 3.4.1 Fundamentals.- 3.4.2 Effectiveness of the Solution.- 3.4.3 Illustrative Study on the Interpretation Effectiveness for MTS Curves.- 3.4.4 The Joint Interpretation of the MTS and Global Sounding Data.- 3.5 Direct Inversion. Properties of Response Functions.- 3.5.1 Analytical Properties of the Response Function.- 3.5.2 Dispersion Relations.- 3.5.3 Inequalities Governing the Response Function.- 3.5.4 Correction of the Observation Data into the Domain of Definition of Operator A-1.- 3.6 Approximate Euristic Methods of Inversion.- 3.7 Amplitude-Phase Layer-by-Layer Interpretation.- 3.8 Nonuniqueness of the Inverse Problem and the Resolving Power of Data.- 3.8.1 The Essence of the Nonuniqueness of the Inverse Problem.- 3.8.2 Resolving Power of Accurate Data.- 3.8.3 The Resolving Power of the Data Measured with Errors.- 3.8.4 Calculation of the Fréchet Derivative.- 3.8.5 Resolving Power of Global GDS Data.- 3.9 Conclusions.- 4 Global and Regional Geomagnetic Deep Sounding.- 4.1 General.- 4.2 Geomagnetic Variations Described by Harmonic $$\text{P}_1^0 (\cos \theta ) = \cos \theta$$.- 4.2.1 Aperiodic Dst Variation.- 4.2.2 Harmonic Analysis of the Dst Variation of Individual Storms.- 4.2.3 Continuum.- 4.2.4 Twenty-Seven-Day Variation Harmonics.- 4.2.5 Semi-Annual and Annual Variations.- 4.2.6 Eleven-Year Variation.- 4.3 Daily Variations.- 4.4 Global Sounding Curve.- 4.4.1 Data Estimation and Curve Plotting.- 4.4.2 Differences of Obtained Global GDS Curves from Earlier Ones.- 4.4.3 Error Estimate Problem.- 4.5 Interpretation of Global Sounding Data.- 4.5.1 Interpretation by Schmucker’s and Molochnov’s Methods.- 4.5.2 The Problem of Electrical Conductivity Jump.- 4.5.3 Is the Asthenosphere Global?.- 4.5.4 Models of Most Probable Distribution ? (h).- 4.5.5 Attempt to Describe the Set of Possible Solutions of the Inverse Problem of Global GDS.- 4.6 Geothermic Interpretation of Global GDS.- 4.7 Regional, Local, and Point Geomagnetic Deep Soundings.- 4.7.1 Introduction.- 4.7.2 GDS Using Equatorial and Auroral Electrojet Field.- 4.7.3 Regional GDS’s Using Global Source Field.- 4.7.4 Regional Soundings by the Method of Derivatives.- 4.7.5 Local GDS’s.- 4.7.6 GDS in a Point.- 4.8 Conclusions.- 5 Magnetotelluric Sounding.- 5.1 Introduction.- 5.1.1 MTS Curves over Plane-Layered Structures.- 5.1.2 The Impedance Tensor and the Role of the Source.- 5.1.3 Some Properties of the Impedance Tensor.- 5.2 Data Processing for the Impedance Tensor Determination.- 5.2.1 Spectral Analysis of Time Series.- 5.2.2 Estimating the Impedance Tensor Elements.- 5.2.3 Noise and Ways of Its Removal.- 5.3 Interpretation of the Deep Magnetotelluric Sounding Curves at the Distorting Effect of Surface Lateral Inhomogeneities.- 5.3.1 Fundamentals.- 5.3.2 MTS Modeling on a Layered Model with Circular Inhomogeneities in the Upper Layer. An Example.- 5.3.3 Interpretation of Distorted MTS Curves.- 5.4 Deep MTS Study on Two-Dimensional Structures.- 5.4.1 Principles of Classification of Distortions of MTS Curves.- 5.4.2 B-Polarization.- 5.4.3 E-Polarization.- 5.4.4 Comparison of Transverse and Longitudinal Curves.- 5.5 Distorting Effects on Three-Dimensional Structures.- 5.5.1 Concentration and Rarefaction (Deconcentration) of Currents. Channeling and Flow-Around of Inhomogeneities.- 5.5.2 Induction Distortions.- 5.5.3 Superchanneling.- 5.6 The MTS in Elongated Depressions.- 5.6.1 The MTS in the Rhine Graben.- 5.6.2 MTS in the Dnieper-Donets Depression (DDD).- 5.6.3 MTS in Foredeeps.- 5.7 MTS in Shields and Basement Escarpments.- 5.7.1 Review of MTS in Different Crystalline Massives. The Possibility of Normal Curve Determination.- 5.7.2 MTS in the Ukrainian Shield.- 5.8 The Conducting Layers as Derived by MTS.- 5.8.1 The MTS Grouping in the Peri-Baikal Region.- 5.8.2 The Asthenosphere.- 5.9 Conclusions.- 6 Magnetic Variation Profiling (MVP).- 6.1 Formation of Anomalous MVP Field.- 6.1.1 The Field of a Sphere and a Cylinder.- 6.1.2 Conductive Type Anomalies.- 6.1.3 Eddy-Type Anomalies.- 6.1.4 Comparison of Conductive and Eddy Anomalies.- 6.2 Anomalous Fields over Two-Dimensional Inhomogeneities.- 6.2.1 Surface Anomaly. Insertion.- 6.2.2 Graben.- 6.2.3 Deep Anomaly. Elliptical Cylinder.- 6.2.4 Comparison of Deep and Surface Anomalies.- 6.3 Anomalous Fields on Three-Dimensional Inhomogeneities.- 6.3.1 Physical Modeling.- 6.3.2 Effect of Body Length on the Anomalous Field.- 6.4 Integral Relations Between the Components of the Anomalous Field.- 6.5 Observation Data Processing.- 6.5.1 Anomalous Field Determination Using a Reference Station.- 6.5.2 Profile (Array) Data Processing.- 6.5.3 Processing of the Point Observation.- 6.5.4 Interpretation of the Induction Vector Pair at a Point.- 6.5.5 New Processing Techniques.- 6.6 Methods of MVP Data Interpretation.- 6.6.1 Two-Dimensionality.- 6.6.2 Surface Anomalies.- 6.6.3 Moments.- 6.6.4 Estimation Techniques for Longitudinal Conductivity G of a Cross-Section of an Anomalous Body.- 6.7 Principles of MVP Data Interpretation.- 6.7.1 Uniqueness Theorem.- 6.7.2 A Practical Example of an Ambiguous MVP Inverse Problem.- 6.7.3 Potentialities of MVP.- 6.8 Joint MVP and MTS Studies of Conductivity Anomalies.- 6.8.1 The MTS-Estimation of G of the Anomaly.- 6.8.2 Analysis of Three-Dimensionality of a Body.- 6.9 Conclusions.- 7 Electrical Conductivity Anomalies.- 7.1 Coast Effect.- 7.2 Anomalies in Western North America.- 7.2.1 Coastal Anomalies.- 7.2.2 Rio-Grande Anomaly.- 7.2.3 South-Western Canada.- 7.2.4 Magnetometer Array Study.- 7.2.5 MTS Results.- 7.2.6 Geophysical Correlations.- 7.3 Crustal Anomalies of the East-European Platform.- 7.3.1 Kirovograd Anomaly.- 7.3.2 Near-Moscow Anomaly.- 7.4 Carpathian Anomaly.- 7.4.1 Geoelectrical Data.- 7.4.2 Geological Interpretation of the Carpathian Electric Conductivity Anomaly Based on the Ideas Developed by Hyndman and Hyndman (1968).- 7.5 Classification of Electrical Conductivity Anomalies.- 7.5.1 Anomalies Classification According to Geologic Environment.- 7.5.2 Anomalies Classification by Depth with Allowance for Possible Nature.- 7.5.3 Anomalies Classification by Scale.- 8 Conclusions.- 8.1 Geoelectric Model for the Earth’s Crust and Mantle Based on the Results of Chapters 3–7.- 8.2 Geoelectric Methods (Fanselau Approach).- 8.3 Comparison Between the Three Methods.- 8.4 Strategy of Electromagnetic Data Interpretation.- Appendix Geomagnetic Observatories of World-wide Network.- References.