P. Schmoldt, PhD - MTNet - DIAS
P. Schmoldt, PhD - MTNet - DIAS P. Schmoldt, PhD - MTNet - DIAS
List of Figures viii 2.17. Deviation of phase φ and apparent resistivity ρa curves from true values for magnetotelluric and magnetovariational data dependent on the distance between recording point and line electrojet . . . . . . . . . . . . . 28 2.18. Apparent resistivity ρa and phase φ variation curves obtained for electrojets of finite length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.1. Induction depth δs for an MT station over a conductive half-space. . . . . 38 3.2. Change of wave magnitude with depth for the case of a 1D subsurface with n-layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3.3. Apparent resistivity and phase behaviour in the complex plane for a horizontal interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 3.4. Behaviour of TE and TM mode for the same period in the presence of a conductivity contact zone . . . . . . . . . . . . . . . . . . . . . . . . . . 43 3.5. Electric resistivities of rocks and other common Earth materials . . . . . 45 3.6. Electric conductivity profile of the deep Earth . . . . . . . . . . . . . . . 46 3.7. Difference between the impedance calculated with and without neglecting the permittivity term for different frequencies . . . . . . . . . . . . . . . 47 4.1. Model of the potential galvanic and inductive effects in a magnetotelluric survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.2. Orientation-dependent effects of a small-scale 3D body onto the modes of the magnetotelluric measurement . . . . . . . . . . . . . . . . . . . . . . 52 4.3. The galvanic distortion effect . . . . . . . . . . . . . . . . . . . . . . . . 53 4.4. Magnetotelluric responses under the influence of static shift (electric galvanic distortion) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.5. The principle of current channelling . . . . . . . . . . . . . . . . . . . . 55 4.6. Distortion of magnetotelluric responses due to a highly conductive feature at depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.7. The effective area of influence of a dyke for a controlled source survey, and for a natural source survey . . . . . . . . . . . . . . . . . . . . . . . 57 4.8. The inductive effect in a vertical sheet conductor . . . . . . . . . . . . . 58 4.9. Types of electric anisotropy . . . . . . . . . . . . . . . . . . . . . . . . . 60 4.10. Basic anisotropy parameters . . . . . . . . . . . . . . . . . . . . . . . . 60 4.11. Models of (isotropic) subsurface dimensionality . . . . . . . . . . . . . . 62 4.12. Induction area for different period ranges at the same station . . . . . . . 63 4.13. Two subsurface models used to illustrate the effect of frequency-dependent dimensionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 4.14. Responses for a magnetotelluric station on top of a 3D/2D model . . . . . 65 4.15. Responses for a magnetotelluric station over a 2D/2D regional model . . . 66 4.16. Visualisation of Weaver-Agarwal-Lilley (WAL) tensor invariants using Mohr circles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
List of Figures 4.17. Visual representation of the Groom and Bailey concept for decomposition of the magnetotelluric distortion tensor . . . . . . . . . . . . . . . . . . . 74 4.18. Graphical representation of the magnetotelluric phase tensor . . . . . . . 77 5.1. The Preliminary reference Earth model (PREM) . . . . . . . . . . . . . . 82 5.2. Illustration of electrolytic conduction . . . . . . . . . . . . . . . . . . . . 83 5.3. Temperature-dependent conductivity of fluids . . . . . . . . . . . . . . . 85 5.4. Relation between log conductivity and reciprocal of the absolute temperature for charge transport by semiconduction . . . . . . . . . . . . . . . 86 5.5. Typical electric conductivity structures below a continental shield and oceanic lithosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 5.6. Collection of electric conductivity-depth profiles . . . . . . . . . . . . . 89 5.7. Age of the oceanic plates . . . . . . . . . . . . . . . . . . . . . . . . . . 90 5.8. Depth of the lithosphere–asthenosphere boundary (LAB) beneath Europe 92 5.9. Definition of the lithosphere and common proxies used to estimate its thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 5.10. Compilation of resistivity–depth profiles derived by deep-probing electromagnetic induction studies and laboratory experiments on mantle minerals. 94 5.11. Mineral proportions and phase transitions in the Earth’s mantle assuming pyrolitic composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 5.12. Conductivity of hydrogen-iron bearing mantle silicate minerals . . . . . . 98 5.13. Pressure and temperature profiles in the depth range 200 – 2800 km . . . 100 5.14. Conductivity of typical mantle minerals . . . . . . . . . . . . . . . . . . 102 5.15. Electric conductivity of wadsleyite and ringwoodite as a function of reciprocal temperatures in the range 500 – 2500 °C . . . . . . . . . . . . . 104 6.1. Schematic layout of the broadband magnetotelluric recording system used during the PICASSO Phase I fieldwork campaign . . . . . . . . . . . . . 106 6.2. Schematic layout of the long-period magnetotelluric recording system used during the PICASSO Phase I fieldwork campaign . . . . . . . . . . 107 6.3. Illustration of a staggered grid . . . . . . . . . . . . . . . . . . . . . . . 117 6.4. Finite element mesh parameterising the model of a mid-oceanic ridge . . 118 6.5. Types of minima types . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 6.6. The non-uniqueness problem of magnetotelluric inversion . . . . . . . . . 121 6.7. L-curve: magnetotelluric data misfit versus Model Roughness . . . . . . 122 7.1. Main tectonic features and geological units of the Iberian Peninsula . . . 134 7.2. Location of magnetotelluric recording sites in the Betic Cordillera . . . . 136 7.3. Dimensionality analysis results for magnetotelluric data from the Betic Cordillera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 7.4. Subsurface model of the electric conductivity distribution beneath the Betic Cordillera by Pous et al. [1999] . . . . . . . . . . . . . . . . . . . 138 ix
- Page 1: Multidimensional isotropic and anis
- Page 4 and 5: Contents 2.3. Deviation from plane
- Page 6 and 7: Contents 8.3. Inversion of 3D model
- Page 9: List of Figures 2.1. Amplitude of t
- Page 13 and 14: List of Figures 8.2. Ambient noise
- Page 15 and 16: List of Figures 10.10.RMS misfit va
- Page 17: List of Figures A.15.Result of anis
- Page 20 and 21: List of Tables xviii 5.5. Parameter
- Page 22 and 23: List of Acronyms FE finite element
- Page 25 and 26: List of Symbols Below is a list of
- Page 27 and 28: Symbol SI unit Denotation φ · pha
- Page 29: Abstract The Tajo Basin and Betic C
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- Page 34 and 35: Acknowledgements Team, namely Colin
- Page 37 and 38: Introduction 1 The Iberian Peninsul
- Page 39 and 40: ections from enhanced one-dimension
- Page 41: Part I Theoretical background of ma
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List of Figures<br />
4.17. Visual representation of the Groom and Bailey concept for decomposition<br />
of the magnetotelluric distortion tensor . . . . . . . . . . . . . . . . . . . 74<br />
4.18. Graphical representation of the magnetotelluric phase tensor . . . . . . . 77<br />
5.1. The Preliminary reference Earth model (PREM) . . . . . . . . . . . . . . 82<br />
5.2. Illustration of electrolytic conduction . . . . . . . . . . . . . . . . . . . . 83<br />
5.3. Temperature-dependent conductivity of fluids . . . . . . . . . . . . . . . 85<br />
5.4. Relation between log conductivity and reciprocal of the absolute temperature<br />
for charge transport by semiconduction . . . . . . . . . . . . . . . 86<br />
5.5. Typical electric conductivity structures below a continental shield and<br />
oceanic lithosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88<br />
5.6. Collection of electric conductivity-depth profiles . . . . . . . . . . . . . 89<br />
5.7. Age of the oceanic plates . . . . . . . . . . . . . . . . . . . . . . . . . . 90<br />
5.8. Depth of the lithosphere–asthenosphere boundary (LAB) beneath Europe 92<br />
5.9. Definition of the lithosphere and common proxies used to estimate its<br />
thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93<br />
5.10. Compilation of resistivity–depth profiles derived by deep-probing electromagnetic<br />
induction studies and laboratory experiments on mantle minerals. 94<br />
5.11. Mineral proportions and phase transitions in the Earth’s mantle assuming<br />
pyrolitic composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95<br />
5.12. Conductivity of hydrogen-iron bearing mantle silicate minerals . . . . . . 98<br />
5.13. Pressure and temperature profiles in the depth range 200 – 2800 km . . . 100<br />
5.14. Conductivity of typical mantle minerals . . . . . . . . . . . . . . . . . . 102<br />
5.15. Electric conductivity of wadsleyite and ringwoodite as a function of reciprocal<br />
temperatures in the range 500 – 2500 °C . . . . . . . . . . . . . 104<br />
6.1. Schematic layout of the broadband magnetotelluric recording system used<br />
during the PICASSO Phase I fieldwork campaign . . . . . . . . . . . . . 106<br />
6.2. Schematic layout of the long-period magnetotelluric recording system<br />
used during the PICASSO Phase I fieldwork campaign . . . . . . . . . . 107<br />
6.3. Illustration of a staggered grid . . . . . . . . . . . . . . . . . . . . . . . 117<br />
6.4. Finite element mesh parameterising the model of a mid-oceanic ridge . . 118<br />
6.5. Types of minima types . . . . . . . . . . . . . . . . . . . . . . . . . . . 120<br />
6.6. The non-uniqueness problem of magnetotelluric inversion . . . . . . . . . 121<br />
6.7. L-curve: magnetotelluric data misfit versus Model Roughness . . . . . . 122<br />
7.1. Main tectonic features and geological units of the Iberian Peninsula . . . 134<br />
7.2. Location of magnetotelluric recording sites in the Betic Cordillera . . . . 136<br />
7.3. Dimensionality analysis results for magnetotelluric data from the Betic<br />
Cordillera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137<br />
7.4. Subsurface model of the electric conductivity distribution beneath the<br />
Betic Cordillera by Pous et al. [1999] . . . . . . . . . . . . . . . . . . . 138<br />
ix
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