Lecture Schedule

  1. Plate Tectonics (Week 1-2)
    1. Organization meeting and course overview
    2. Introduction of the plate tectonics theory
      The theory: rigid plates, three types of plate boundaries
      A brief history: continental drift, seafloor spreading, the development in 60s
    3. Elements of plate tectonics on Earth
      • Lithosphere (plates)
        rheological definition, rigid, no-significant deformation on geological time scale (~1 Ga)
        thermal definition: 1600K isotherm
        seismic lithosphere, LID and LVZ, different time scale.
        oceanic and continental lithosphere.
        thickness of lithosphere: ~100 km thick under ocean basins, ~200 km under continents.
      • Accretional plate boundaries: mid-ocean ridges
        topographic feature, relationship to spreading rate, sea-level change
        forming of new oceanic crust, ophiolites
        pressure-release melting of mantle rocks
        fractionation and depleted mantle, "pyrolite" mantle model
      • Subduction
        cooling of oceanic lithosphere, gravitational unstable, slab pull
        max. age of ocean floor
        Wadati-Benioff zone, bending of slab
        island arc, arc radius vs.. subduction angle
        phase change at 410 and 660 discontinuities, fate of slab, whole mantle convection?
        volcanisms associated with subducting slab, mechanisms? melting in the mantle wedge
        back-arc spreading
      • Transform fault
        discovery of transform fault, topo relief, fracture zone
      • Hotspots and mantle plume
        volcanism not directly associated with plate tectonic processes
        hotspot track, age progression
        nearly fixed, ~mm/yr
        topography swell, mantle plume
        volcanic rocks same as those in MOR
        flood basalts
    4. Geomagnetism
      Earth's magnetic field, inclination, declination, and intensity (20 to 60 mT)
      dipole field, magnetic potential; fit to the actual field
      palaeomagnetism, TRM, CRM, and DRM, Curie temperature
      apparent location of palaeomagnetism pole, APW
      palaeomagnetism reversal, geodynamo theory
      marine magnetic anomalies, palaeomagnetic time scale
    5. Plate motion
      Euler theory, rotation pole
      calculate plate velocity using its rotation pole and rotation rate, PA-NA example
      triple junction, types of triple junction, examples (RRR, TTT, RTF)
      velocity diagram, determine relative velocity of TJ, stability of triple junction
    6. Quiz 1; HW1: 1,3,5,7,9,15,22-25 in Chapter 1, due Wednesday, 9/17.
    7. The Wilson cycle and plate reconstruction
      rifting, three-armed pattern, failed arm, aulacogen (Red sea-Gulf of Aden-E. African rift)
      seafloor spreading and forming of new ocean (Red sea)
      subduction
      ridge subduction of close of a ocean basin
      plate reconstruction back to 170 Ma
    8. Continental collision
      mountain building (orogeny)
      suture zone
      delamination and subduction of the lower crust
      India-Eurasia collision, broad deformation, strength of continental lithosphere
  2. Stress and Strain in Solids (Week 3-4)
    1. stress
      normal stress and shear stress; sign convention
      stresses in lithosphere, lithostatic stress; isostasy; crustal stretching model of sedimentary basin
      deviatoric stress in continents associated with height
      shear stress in thrust sheet
    2. stress in 2D and 3D, coordinates, principal axis of stress, pressure and invariant
    3. strain, normal strain in 1-D and 3-D, displacement field in solid, dilatation
    4. shear strain, solid-body rotation, pure shear and simple shear
    5. strain in different coordinates, principal axes of strain, principal strain
    6. strain measurement, triangulation, electro-optical technique, VLBI, GPS, InSAR
    7. examples, 1906 SF Earthquake, SAF relative velocity, SAF shear, Perth to Maui
    8. Q2; HW2: 2-6, 2-8, 2-11, 2-14, 2-16, 2-21, 2-25, 2-27, 2-29, 2-31 , due Friday, 9/27
  3. Elasticity and Flexure (Week 5)
    1. elastic, plastic, and viscous deformations
    2. linear elasticity, isotropic; Young's modulus and Poisson's ratio; rigidity, simple shear and pure shear; Lame constant; Bulk sound modulus
    3. uniaxial strain, stresses caused by sedimentation and erosion
    4. HW3: 3-1, 3-4, 3-5, 3-7, 3-10, 3-11, 3-13, 3-15, 3-17, 3-19, due Friday, 10/18
    5. plane stress, application to lithosphere
    6. 2D beding of plates, radius of local curvature R, flexure rigidity D
    7. lithosphere response to periodic loading
    8. bending of lithosphere under the loads of island chains, structure of foreland basins
    9. bending of lithosphere at an ocean trench
    10. buckling of a plate under horizontal load, stability of lithosphere
    11. Q3
  4. Heat Transfer (Week 6-7)
    1. three mechanisms:
      conduction: by molecular collision, random walk, diffusive; within lithosphere.
      convection: by motion of medium, efficient; in mantle and core.
      radiation: photon emission (EM waves); for small scale in side earth, important in the atm.
    2. The Fourier law of conduction: q=-k dT/dy, thermal conductivity
    3. Earth's surface heat flow
      continents: 65 +/- 1.6 mW/m^2; correlates with concentration of radioactive isotopoes (U,Th,K); decrease with ages.
      ocean: 101 +/- 2.2 mW/m^2; dependence on sea floor age, cooling of oceanic lithosphere
      global average 87 mW/ms^2, corresponds to 4.43*e+13 W loss in total from the solid earth.
    4. Heat generation by the decay of radioactive elements
      mainly from (235,238)U, 232Th, and 40K
      currently provides 80% of the heat loss (mantle: 3e+13 W, continental crust 7.4e+12 W,
      the radioactive elements concentration in oceanic crust is one order of magnitude smaller).
      was more significant in early stage of the Earth (twice at 3 Ga ago).
      the rest 20% heat loss is from secular cooling of the Earth, 5e-7 deg/yr.
      For comparison, earth intercepts 1.3e+17 W from the sun (it also radiates heat to out space).
    5. 1-D steady heat conduction with H
      equation
      case for half space with constant T0 and q0: application to mantle, solidus line, T too high.
      surface heat flow of a plate with thermally isolated bottom;
      too low for oceanic crust, => heat generation is a minor contribution
      too high for continental crust => H decrease with depth
      continental crust with H exponentially decreasing with depth, q0 linear proportional to H0
    6. Time-dependent heat conduction
      thermal capacity, diffusion equation, thermal diffusivity k, characteristic time and length.
      seasonal changes in subsurface temperature, skin depth, phase difference.
      cooling of half-space and plate
      similarity variable eta=y/2*sqrt(kt), error function, solution
      thermal boundary layer = 2.32 sqrt(kt)
      surface heat flow decreases with sqrt(t), Kelvin's age of earth.
      application of oceanic lithosphere: thickness, heat flow, mean heat flow.
      application to the reduced heat flow of continents (Fig 28), constant mantle heat flow.
      cooling of a plate
      ocean floor topography, sea level change
      Heating a half-space by surface heat flux, island arc volcanism
      Stefan problem, latent heat, solidificatin of lava lake, dike and sill.
      Thermal stress, thermal expansion coef and compressibility, modification to the linear elasticity
      Mantle geotherms and adiabats
      Thermal structure of the subducted slab, Clapeyron curve
    7. HW4: 4-1, 4-3, 4-6, 4-9, 4-15, 4-20, 4-23, 4-28, 4-33, 4-39, due Monday, 11/4
  5. Mid-term exam on 10/15
  6. Gravity (Week 9-10)
    1. introduction, gravitation force and potential, gravity
    2. gravitational acceleration external to the rotationally distorted earth, MacCullagh's formula.
    3. rotational potential, geopontential, geoid, reference geoid, geoid anomaly, reference g
    4. moment of inertia, evidence of the existence of a dense core in Earth; J2, f; Moon, Mars, Venus
    5. surface gravity anomalies, Bouguer formula, reduction of gravity data, compensation, admittance
    6. isostatic geoid anormaly, compensation models
    7. HW5: 5-1, 5-3, 5-6, 5-7, 5-9, 5-10, 5-13, 5-18, 5-20, 5-24. due Monday, 11/11
    8. Q4
  7. Fluid Mechanics (Week 11-12)
    1. instroduction, fluids vs. solids, constitutive law, linear fluids, viscosity, Prandtl number
    2. 1-D flow
      equations and solutions
      asthenosphere counter flow
    3. pipe flow
      equations and solutions
      larminar flow and turbulent flow, friction factor, Renolds number
      artesian aquifer flows
      flow through volcanic pipe
    4. 2-D flow
      equations, stream function, biharmonic eq.
      postglacial rebound, mantle viscosity
      angle of subduction
      diapirism
      folding
    5. Stokes flow, plume heads and tails
    6. thermal convection
      equations with velocity, and temperature field
      pipe flow, Nusselt number
      linear stability ananlysis, Rayleigh number
      a transient BL theory
      a steady-state BL theory
      the forces that drive plate tectonics
    7. heating by viscous dissipation
    8. mantle recycling and mixing
    9. HW6: due Monday 11/25
    10. Q5
  8. Rock Rheology (Week 14-15)
  9. Final exam: Wed., 12/8, 10:00-12:00AM