2. Artwork copyright 2006 Don Dixon/cosmographica.com

4. Fromearly to modern Earth Nicolas Coltice

5. J. Monteux J. Hernlund (Berkeley) Y. Ricard F. Dubuffet N. Flament B. Marty (Nancy) P. Rey (Sydney) R. Yokochi (Chicago) S. Labrosse

6. What’sleftfrom the magma ocean phase?

7. Meltingcaused by impacts

8. Heatreleased by coresegregation Monteux et al., 2009

9. ULVZ at the base of the Earth’smantle Rost et al., 2005

10. Deepmantlemelting Vp and Vs reduction up to 10 and 30% respectively (Rost et al., 2005) Density of the melt up to 50% higher than solids Thickness of 40km maximum

11. A dense melt? Chemicaleffect: Fe enrichment Structural effect: densitycross-over of the meltaround 80GPa (Mosenfelder et al., 2007)

12. Magenticfieldgenerated by a dynamo core cooling(5TW) 1000K of coolingthrough 4.5Ga Deepmelts are as old as the planet When has this melt formed?

14. Forming denser and denser piles

16. FromHadean to ArcheanEarth Artwork copyright 2006 Don Dixon/cosmographica.com

17. 129I 244Pu + 238U Xenon isotope as geodynamictracers (Kunz, Staudacher, Allègre 1998) Half-lives : 129I  16 Ma 244Pu  82 Ma 238U  4450 Ma

18. Present-day mantle mantle Closed-system mantle 6800 2-22 Constraints on the timing of degassing 30 0.25-1.5 1 1 136Xe 136Xe 129Xe 136Xe 136Xe 129Xe 244Pu 129I 244Pu 129I 238U 238U

19. How does Xe degass? Accretion(shock) Magma ocean (melting) Earthcooling (convection) Complete and instantanneous Partial and continuous (~ 4.4By)

20. Couplingdegassing and thermal history To compute D(t)weneed T(t) et S(t)

21. No hypothesis on the physics of cooling

22. No more on the melting area generated

23. Magmatic histories consistent with Xe isotopicconstraints Coltice et al., 2009

24. Thermal histories consistent with Xe isotopicconstraints Coltice et al., 2009

25. FromArchean to modern Earth

27. rare to absent throughout the Phanerozoic These lavas have interacted with differentiated material (N. Arndt, 1999)‏

29. no Eu anomaly

30. Low LREE/HREE

31. High [Sc]

32. Felsic sources:

33. Eu anomaly

34. High LREE/HREE

35. Enriched in Th, UFrom Taylor and McLennan (1985)‏ Pas de granite en surface? Pas d’érosion ?

36. Thermal causes?

37. Flat and hot Archean continents

38. Slopes develop after the Archean Rey et Coltice, 2008

40. Labrosse and Jaupart (2007)‏ Isostasy: Volume conservation: Flament et al., 2008

41. Prediction for early Archean Mantle 200 °C hotter ; continental area 20 % ; Archaean hypsometry

42. Prediction for late Archean Mantle 150 °C hotter ; continental area 80 % ; Archaean hypsometry

43. Prediction for Proterozoic Mantle 100 °C hotter ; continental area 100 % ; present-day hypsometry

44. Today

45. Fromearly to modern Earth Remnants of magma ocean stage at the base of the mantle Intese and widespsreadvolcanism in the Hadean (no plate tectonics) Flooded and flat ArcheanEarth Slowlycooling modern Earthwithstrongcrust and uppermantle