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Abundances in the Universe/Crust Fe Be Mg Al Si Pb.

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Presentation on theme: "Abundances in the Universe/Crust Fe Be Mg Al Si Pb."— Presentation transcript:

1 Abundances in the Universe/Crust Fe Be Mg Al Si Pb

2 Melting Temperature

3 Goldschmidt Classification

4 Chondrite Siderophile (Fe, Ni...) Lithophile (Si, Mg, Ca, Al, K...) Atmophile (N, He...)

5 INCOMPATIBLES U Th Al He COMPATIBILITY/INCOMPATIBILITY DURING PARTIAL MELTING

6 From Doin Sea surface (Geoid)

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8 Background velocity Poiseuille Stokes Guess? Measured

9 Background velocity Poiseuille Stokes Hawaii 7.0 t/s Bowie 0.3 t/s All hostpots 55 t/s Slabs 650 t/s

10 From Hofmann

11 " DEPLETED MORB SOURCE " ENRICHED HIMU, EM, CC SOURCES " PRIMITIVE/DEPLETED LOIHI SOURCE? " CC and MORB SOURCE complementary " Nb, Pb, Ti anomalies due to subduction (CC, MORB and OIB)

12 D/N=D 0 /N+P 0 /N(1-exp(t/T)) D=daughter P=parent N=reference stable isotope of D T=time constant

13 ISOTOPIC RATIOS

14 Rares Gas From Hart & Zindler

15 Primitive Himu EM2 EM1

16 MORB Midocean ridge basalt extracted from MORB source or DMM OIB Oceanic ridge basalt extracted from????? Primitive Mantle (PREMA) Loihi-Icelandic Type (Primitive HE Mantle) EM1 (Enriched Mantle=oceanic sediments?) EM2 (Enriched Mantle=continental sediments?) HIMU (high U/Pb=oceanic crust?) FOZO-C

17 M Mass Balance for trace elements Primitive Mantle = Crust+Morb source+Hidden res

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20 40 Argon Produced in the Earth 940 pmol/g Atmosphere 44% Crust 3.5% Upper mantle.9 % (25 pmol/g) Lower mantle 52 % (720 pmol/g) But K/U?? 50-200 pmol/g Another K-rich reservoir? From Davies

21 " OIBs are more heterogeneous than MORBs " But the same trends are seen in MORBs and OIBs " There is a hidden reservoir = Slightly depleted=lower mantle = Primitive=50% of the mantle = Enriched (D'' with MORBs composition)

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25 Hiding a layer: Density and density jumps Phase changes Coupling between chemistry and phase jumps Viscous stratification

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27 Less density chemical density difference is required at larger depth

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29 MINERALOGY VS SEISMOLOGY From Matas

30 CLAPEYRON SLOPE P T Phase Dense Light Phase AveragePhase transition depth

31 From Machetel

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33 Crust density: Mineralogy

34 Mantle, Lithosphere and oceanic crust

35 DOUBLE PHASE CHANGES P T Dense Phase A Light Phase A Average Phase transition depths for A and B Light Phase B Dense Phase B

36 Seismic tomography

37 From Grant/Van der Hilst

38 Seismic tomography

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40 Paleomap

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44 Geoid Comp. Geoid

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46 The Mantle viscosity increases with depth by a factor 10-100 Can it help preserving primitive compositions?

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49 Poloidal/Toroidal Bercovici

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53 Poincar₫ Section

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55 From Ferrachat

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63 F arnetani or Schmalzl and Hansen Hotspot (no) Entrainment

64 Persistance of blobs Spence, Manga

65 Persistance of blobs Merveilleux Stretching Reorientation

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69 500 myrs 2 byrs

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71 Mantle, Lithosphere and oceanic crust

72 MANTLE Atmosphere C. Crust D '' Residual lith.

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74 MANTLE Atmosphere C. Crust D '' Residual lith. Flux from hotspots Uniform growth Uniform growth Degassing No crustal recycling Fractionation + Fractionation -

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83 No real geochemical indication of the existence of primitive material Strong indications that the 670 km depth boundary is permeable Strong indications of a viscosity increase with depth by 10-100 This viscosity increase does not stratify the mixing 3D convection more efficient mixer with, than without plates Highly viscous, small, primitive blobs may survive(?) Need of a reservoir to store incompatible elements Seems difficult to hide a dense reservoir in the mantle Crust segregation in D'' may be the deep enriched reservoir (EM, HIMU) The remaining lithosphere may be the depleted (''primitive-like'') reservoir

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