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Estimating mantle temperature and composition from seismic models (and other data)

Estimating mantle temperature and composition from seismic models (and other data). Colleen Dalton, Boston University with Allie Gale, Charlie Langmuir, Uli Faul, Mollie Celnick, and others . Seismological Models. S362ANI 300 km Kustowski et al. (2008). S40RTS 300 km

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Estimating mantle temperature and composition from seismic models (and other data)

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  1. Estimating mantle temperature and composition from seismic models (and other data) Colleen Dalton, Boston University with Allie Gale, Charlie Langmuir, Uli Faul, Mollie Celnick, and others

  2. Seismological Models S362ANI 300 km Kustowski et al. (2008) S40RTS 300 km Ritsema et al. (2010) QRFSI12 300 km Dalton et al. (2008) Transition Zone Thickness Lawrence & Shearer (2008)

  3. MORB Composition • Hotter mantle: • melting initiates deeper • larger extent of melting • lower Na in MORB • higher Fe in MORB • thicker oceanic crust • shallow ridge depths modified from Langmuir & Forsyth 2007

  4. 540 segments without “8 values” Definition of Ridge Segments

  5. Humler et al. (1993) This study MORB Composition

  6. Ridge Depth vs. S-Velocity

  7. Calculation of Water Depth: Isostasy P = Dwwg+Dccg+Drrg+Dmmg

  8. 1250oC 1370oC Calculation of Water Depth and Seismic Velocity

  9. Comparison of Na8 and Seismic Velocity

  10. garnet facies spinel facies 0.1 km/s ~ 2% pyrolite Effect of Composition on VS 3 GPa (~90 km) and 800oC Mg# = Mg / (Mg + Fe)

  11. Cratonic Temperature & Composition 150 km Lee et al. (2010)

  12. CIDER 1. Possible themes: tectonic settings: cratons; ridges; transform faults; hotspots no theme? research projects based on who is there 2. Other things to consider: more time for research: start research projects right away some research lectures in addition to overview lectures opportunity to make progress with collaborators support for meetings in person after summer crucial

  13. Seismological Models Transition zone thickness

  14. Previous Studies Wiens et al. (2006) Zhang et al. (1994)

  15. Na8.0 Velocity variation (%) Previous Studies Courtier et al. (2007) Humler et al. (1993)

  16. median = -3246 m Definition of Ridge Segments

  17. MAR SEIR EPR Resolution of Seismic Models

  18. Resolution of Seismic Models

  19. SWIR SEIR MAR longitude longitude latitude

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