Physics of the Earth

Transcription

1 Physics of the Earth Fourth edition Frank D Stacey CSIRO Exploration and Mining, Brisbane, Australia Paul M Davis Department of Earth and Space Sciences, University of California, Los Angeles, USA CAMBRIDGE UNIVERSITY PRESS

2 Contents deface pa^xiil I Origin and history of the Solar System i 1.1 Preamble! 1.2 Planetary orbits: the Titius-Bode law Axial rotations Distribution of angular momentum Satellites Asteroids Meteorites: falls, finds and orbits Cosmic ray exposures of meteorites and the evidence of asteroidal collisions io 1.9 The Poynting-Robertson and Yarkovsky effects Parent bodies of meteorites and their cooling rates Magnetism in meteorites Tektites The Kuiper belt, comets, meteors and interplanetary dust The terrestrial planets: some comparisons Early history of the Moon 23 2 Composition of the Earth Preamble Meteorites as indicators of planetary compositions Irons and stony-irons Ordinary and carbonaceous chondrites Achondrites The solar atmosphere The mantle The core The crust The oceans Water in the Earth The atmosphere: a comparison with the other terrestrial planets 45 3 Radioactivity, isotopes and dating Preamble Radioactive decay A decay clock: 14 C dating Accumulation clocks: K-Ar and U-He dating Fission tracks 52

3 3.6 The use of isochrons: Rb-Sr dating U-Pb and Pb-Pb methods Sm- 143 Nd and other decays Isotopic fractionation 57 4 Isotopic clues to the age and origin of the Solar System 4.1 Preamble The pre-nuclear age problem Meteorite isochrons and the age of the Earth Dating the heavy elements: orphaned decay products Isotopic variations of pre-solar System origin Sequence of events in Solar System formation 70 5 Evidence of the Earth's evolutionary history Preamble Argon and helium outgassing and the Earth's potassium content Evolution of the crust Separation of the core The fossil record: crises and extinctions 79 6 Rotation, figure of the Earth and gravity Preamble Gravitational potential of a nearly spherical body Rotation, ellipticity and gravity The approach to equilibrium ellipticity 87 6i 7 Precession, wobble and rotational irregularities Preamble Precession of the equinoxes The Chandler wobble Length-of-day (LOD) variations Coupling of the core to rotational variations 99 8 Tides and the evolution of the lunar orbit Preamble Tidal deformation of the Earth Tidal friction Evolution of the lunar orbit The Roche limit for tidal stability of a satellite ill 8.6 The multiple moons hypothesis 114

4 9 The satellite geoid, isostasy, post-glacial rebound and mantle viscosity Preamble The satellite geoid The principle of isostasy Gravity anomalies and the inference of internal structure Post-glacial isostatic adjustment Rebound and the variation in ellipticity Elastic and inelastic properties Preamble Elastic moduli of an isotropic solid Crystals and elastic anisotropy Relaxed and unrelaxed moduli of a composite material Anelasticity and the damping of elastic waves Inelasticity, creep and flow Frequency dependent elasticity and the dispersion of body waves Deformation of the crust: rock mechanics Preamble The tensor representation of stress and strain Hooke's law in three dimensions Tractions, principal stresses and rotation of axes Crustal stress and faulting Crustal stress: measurement and analysis Tectonics Preamble Wadati-Benioff zones and subduction Spreading centres and magnetic lineations Plate motions and hot spot traces The pattern of mantle convection Tectonic history and mantle heterogeneity Convective and tectonic stresses Preamble Convective energy, stress and mantle viscosity Buoyancy forces in deep mantle plumes Topographic stress Stress regimes of continents and ocean floors Coulombic thrust wedges 193

5 14 Kinematics of the earthquake process Preamble Earthquakes as dislocations Generalized seismic moment First motion studies Rupture models and the spectra of seismic waves Earthquake magnitude and energy The distribution of earthquake sizes Tsunamis Microseisms Earthquake dynamics Preamble Stress fields of earthquakes Fault friction and earthquake nucleation: the quasi-static regime The dynamic regime Omori's aftershock law Stress drop and radiated energy Foreshocks and prediction ideas Seismic wave propagation Preamble Body waves Attenuation and scattering Reflection and transmission coefficients at a plane boundary Surface waves Free oscillations The moment tensor and synthetic seismograms Seismological determination of Earth structure Preamble Refraction in a plane layered Earth Refraction in a spherically layered Earth Travel times and the velocity distribution Earth models: density variation in a homogeneous layer Internal structure of the Earth: the broad picture Boundaries and discontinuities Lateral heterogeneity: seismic tomography Seismic anisotropy Finite strain and high-pressure equations of state Preamble High-pressure experiments and their interpretation 296

6 18.3 The appeal to atomic potentials Finite strain approaches Derivative equations Thermodynamic constraints Finite strain of a composite material Rigidity modulus at high pressure A comment on application to the Earth's deep interior Thermal properties Preamble Specific heat Thermal expansion and the Griineisen parameter Melting Adiabatic and melting point gradients Thermal conduction Temperature dependences of elastic moduli: thermal interpretation of tomography Anharmonicity The surface heat flux Preamble The ocean floor heat flux The continental heat flux Lithospheric thickness Climatic effects The global energy budget Preamble Radiogenic heat Thermal contraction, gravitational energy and the heat capacity Energy balance of the core Minor components of the energy budget Thermodynamics of convection Preamble 22.2 Thermodynamic efficiency, buoyancy forces and convective power Convection through phase transitions Thermodynamic efficiency of mantle convection and tectonic power Why are mantle phase boundaries sharp? Compositional convection in the core Thermodynamic efficiency of core convection and dynamo power Refrigerator action in the core

7 23 Thermal history Preamble The rate of heat transfer to the oceans The heat balance equation and mantle rheology Thermal history of the mantle Cooling history of the core The geomagnetic field Preamble The pattern of the field The secular variation and the electrical conductivity of the mantle Electrical conductivity of the core The dynamo mechanism The westward drift and inner core rotation Dynamo energy and the toroidal field Magnetic fields of other planets Rock magnetism and paleomagnetism Preamble Magnetic properties of minerals and rocks Secular variation and the axial dipole hypothesis Geomagnetic reversals Paleointensity - the strength of the ancient field Polar wander and continental drift 'Alternative' energy sources and natural climate variations: some geophysical background Preamble Natural energy dissipations 'Alternative' energy sources: possibilities and consequences Orbital modulation of insolation and solar variability A concluding comment regarding 'alternative' energies 447 Appendix A General reference data 448 Appendix B Orbital dynamics (Kepler's laws) 454 Appendix C Spherical harmonic functions 457 Appendix D Relationships between elastic moduli of an isotropic solid 462

8 Appendix E Thermodynamic parameters and derivative relationships 464 Appendix F An Earth model: mechanical properties 469 Appendix G A thermal model of the Earth 472 Appendix H Radioactive isotopes 474 Appendix I A geologic time scale 476 Appendix J Problems 477 References 496 Name index 514 Subject index 521