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Arie van den Berg, Utrecht University David Yuen, University of Minnesota

Convection modeling of the postperovskite transition and constraints on the thermal conditions near the core mantle boundary. Arie van den Berg, Utrecht University David Yuen, University of Minnesota. Outline. Seismic observations of irregular D” old and new

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Arie van den Berg, Utrecht University David Yuen, University of Minnesota

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  1. Convection modeling of the postperovskite transition and constraints on the thermal conditions near the core mantle boundary Arie van den Berg, Utrecht University David Yuen, University of Minnesota

  2. Outline • Seismic observations of irregular D” old and new • Interpretation related to Pv/PPv transition > estimate thermal conditions near CMB • Modelling results of slab interaction with Pv/PPv feasibility of heat flow estimates and thermal conductivity • Conclusions

  3. Cleary and Haddon, 1972

  4. Van den Berg, Cloetingh and Doornbos, 1978

  5. Pv/PPv Slope 11 MPa/K, CMB intercept ~3550 K Hirose, 2007

  6. Boehler, Annu. Rev. Earth Planet. Sci. 1996

  7. Van den Berg, Rainey and Yuen, 2005

  8. Mantel profiles based on a modified Hofmeister (1999) model

  9. model of subducting slab interacting with the PV/PPv zone of D” • Extended Boussinesq – ppv phase boundary • T,P dep.visc. dv_T=1000, dv_P=100 • Layered piecewise uniform thermal conductivity • 2D domain 3000X3000km - element resolution down to 5 km near CMB • Crustal (100) marker chain

  10. Spinel/Pv Crustal markers Pv PPv

  11. K_cmb=5 W/(mK)

  12. K_cmb=5 W/(mK)

  13. K_cmb=5 W/(mK)

  14. K_cmb=15 W/(mK)

  15. K_cmb=15 W/(mK)

  16. K_cmb=15 W/(mK)

  17. Single tracer T-depth paths Crustal markers in bottom PV (high k case)

  18. Some conclusions Precursors to PKP from small scale scatterers near CMB can be related to heterogeneity in the Pv/PPv region due to complex phase distribution and/or crustal remnants PPv linked to D” allowstemperature estimates near CMB from seismic mapping of PPv > Pv in the thermal boundary layer Heatflow estimates based on simple linear T profiles are feasible but require better constraints of k_cmb

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