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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?? 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 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 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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