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Transition Zone Discontinuities

Transition Zone Discontinuities. Why focus here? 1. Deeper than “normal” melt sources 2. Very sensitive to changes in temperature and chemistry . Transition Zone Phase Transitions. Olivine (α). 410. Wadsleyite (β). 520. Ringwoodite (γ). 660. Perovskite. Olivine (Mg,Fe) 2 SiO 4.

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Transition Zone Discontinuities

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  1. Transition Zone Discontinuities Why focus here? 1. Deeper than “normal” melt sources 2. Very sensitive to changes in temperature and chemistry

  2. Transition Zone Phase Transitions Olivine (α) 410 Wadsleyite (β) 520 Ringwoodite (γ) 660 Perovskite

  3. Olivine (Mg,Fe)2SiO4 0-14 GPa (0 - 410 km)

  4. Olivine (Mg,Fe)2SiO4 Wadsleyite + 8% density 0-14 GPa (0 - 410 km) 14-19 GPa (410 - 520 km)

  5. Wadsleyite Ringwoodite + 2% density 1 – 140,000 atm (0 - 410 km) 19-24 GPa (520 - 660 km) 14-19 GPa (410 - 520 km)

  6. ‘Perovskite’ (Mg,Fe)SiO3 Ringwoodite (Mg,Fe)2SiO4 24-127 GPa (660 - 2740 km) + + 12% density Ferropericlase (Mg,Fe)O 19-24 GPa (520 - 660 km)

  7. ‘Perovskite’ ‘Post-Perovskite’ ‘Perovskite’ (Mg,Fe)SiO3 + 2% density 24-127 GPa (660 - 2740 km) 127 GPa-136 GPa (2740 - 2890 km) Discovered in 2004

  8. Transition Zone Topography

  9. Clapeyron Slope Describes changes in phase transition with temperature and pressure “Normal” TZ Thickness Colder Warmer

  10. Mineralogy: Not Just Olivine “Garnet” Component “Olivine Component”

  11. Mineralogy: Not Just Olivine From http://www.mantleplumes.org/

  12. Detecting Discontinuities Triplications Receiver Functions ScS Reverberations SS Precursors

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