Volatiles and Fluids in Earths Core

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					   Volatiles and Fluids
     in Earth’s Core
                        Jie Jackie Li!
                   University of Michigan





July 6, 2010   
    
         
      
CIDER Water and Volatiles

Discover Earth’s Core




                                 Mineral
                                 Physics

                             1/3
        1/6


                                    1


               Oldham 06

               Lehmann 36

               Dziewonski and Anderson 81

               Study the Core
Field

Seismology

PREM (1D), tomography (2D), anisotropy (3D)

Geo- and Cosmochemistry

Meteorites, rocks

Geo and Paleomagnetism

Magnetic field


Lab
                                      Mineral
Mineral physics
                          Physics

Material properties


Computer

Geodynamics

Convection, thermal evolution, chemical
differentiation

Volatiles in the Core
        Light(er): H, C, O, Si, S, (N, P)

        Radioactive: K

        Other: Pb




                                    Mineral
                                    Physics

Density Deficit in the Core
                          100
                                          Fe 7000K

                          150       CMB                      Hugoniot
          Pressure, GPa



                          200

                          250                             PREM


                          300

                          350                                         ICB

                                9         10         11          12         13   14
                                                 Density, g/cm3
Birch 1952

Li & Fei 07 ToG

Role of Light Elements
                        Nature

              Composition (volatile budget)

                    Temperature

                      State (IC)


                      Dynamics

                  Chemical convection

                    Dynamo power

               Chemical exchange at CMB


                       Evolution

                    Earth accretion

                     Core formation

                   Inner core growth

Clues from Meteorites


  Taenite & Kamacite. Fe-Ni

  Widmanstätten Pattern




                               Troilite, FeS, brown

                               Cohenite. (Fe,Ni)3C, white 

                               in Taenite and Kamacite matrix 





          Schreibersite

          (Fe,Ni)3P
            Fe-silicide in Moissanite (SiC)

Mass Balance




           McDonough & Sun 95

Solubility in the Core




                                        3Fe2+ - 2Fe3+ + Fe

                  Li & Agee 96 

                                             Frost et al. 04 

    Allègre 92
   Gessmann et al. 01

                                             Wood et al. 06, 07 

                  Rubie et al. 06

Match Density
                          100
                                          Fe 7000K

                          150       CMB                      Hugoniot
          Pressure, GPa



                          200

                          250                             PREM


                          300

                          350                                         ICB

                                9         10         11          12         13   14
                                                 Density, g/cm3
Birch 1952

Li & Fei 07 ToG

Match Velocities




                   Gao et al. 08 GRL

                   Hirose 08 GRC

Match Density Jump at ICB



                           Mineral
                           Physics





           ASM Handbook

Match Gradients




                  Birchʼs Law

Hydrogen




                             Williams and Hemley 01 ANEPS

                             Mao et al. 04 GRL

                             Hirao et al. 04 GRL


     IC 0.1 – 0.5 wt.% H 

Carbon   Wood 93 EPSL

         Li et al. 03 PCM

         Scott et al. 01 GRL

         Vocadlo et al. 02 EPSL

         Lin et al. 04 PRB

         Gao et al. 08 GRL

         Gao et al. 09 AGU

         Fiquet et al. 09 PEPI

         Ono & Mibe 10 PEPI

                                         FeSi

                              FeS2

                                         FeS





                                                 Fe


                                      FeO

Deep Carbon Reservoirs




Fe3C IC >109 pg Carbon





                          http://www.globe.gov

Oxygen




         Alfe et al. 02

         Rubie et al. 06 Science

         Seagle et al. 08 EPSL 

Silicon




   Alfe et al. 02

   Kuwayama et al. 04 AM

   Lin et al. 09 EPSL

   Polyakov 09 Science

   Asanuma et al. 10 PCM

Sulfur   Fe10wt%S negative melting gradient





                 Lin et al. 04 EPSL 

                 Seagle et al. 06 JGR

                 Chen et al. 07 PNAS

                 Campbell et al. 07 EPSL

                 Seagle et al. 08 AGU

Oxygen+Silicon




                 Takafuji et al. 05 GRL

                 Sakai et al. 06 Personal. Comm

Sulfur+Silicon




       Sanloup and Fei 04 PEPI

Lighter Elements in the Core
 1952 
Birch     
Fe,Ni + a lighter element

 1981 
Stevenson 
“no reason to be clean” 

 1984 
Brett     
“too few data, too many extrapolations”


                                Lighter element

                                H,C,O,Si,S,...
     Others < 1%

 Reviews
                               Ni
 ~10%

 1990 
            
Jeanloz
               ~5%

 1994 
            
Poirier

 2000 
            
Hillgren et al.

 2003,2007,2011    
Li and Fei
           Fe ~85 wt.%




                                       Mcdonougn & Sun 95

K in the Core




   Murthy et al. 03 Nature
   Lee et al. 03 GRL

   Hirao et al. 06 GRL

Pb in the Core




   McDonough and Sun 95 CG
   Wood and Halliday 10 Nature

Earth’s Magnetic Field is Essential for
Human Survival and Civilization




        Magnetosphere
      Aurora, northern light

Sustain Geodynamo
 Dynamo theories

 need 15 TW 


 Thermal convection

 Primordial heat

 Radiogenic heat

 Latent heat 

 Fourierʼs Law


 heat flux at CMB 6-12 TW


 Chemical convection
       Buffett 03 Science 

 Light elements 

Formation of Earth’s IC
       T

               Adiabat

  P

       Liqu
        idus
          

Magnetic Fields in Terrestrial-Like Bodies




                                       NASA

Inner Core Growth in Ganymede




           Hauck et al. 06 JGR

Ganymede’s “Snowing” Core
              T

       Liquidus
                   Adiabat

       

  P





                              Hauck et al. 06

Martian Core




   Fei and Bertka 05 
   Stewart et al. 07 

Mercury’s Double Dynamo


                            S > 7 wt.%




                            S < 7 wt.%



          Chen et al. 08 GRL

          Vilim et al. 09 JGR

Snowfall in Earth’s Core?
                                      Fe10wt%S negative melting gradient





   Li et al. 2008 AGU Fall Meeting
               Zou et al. 08

   Seagle et al. 09 Abstract

Inner Core Anisotropy





    Morelli et al. 86 GRL
    Woodhouse et al. 86 JGR
              Mao et a. 98 Nature

    Shearer et al. 88 Nature
       Stixrude and Cohen 95 Science

    Creager 92 Nature
                Steinle-Neumann 01 Nature

    Song and Helmberger 93 JGR
      Belonoshko et al. 07 Science

    Romanowicz et al. 96 Science
    Belonoshko et al. 08 Science

    Tromp 01 AREPS
                   Buffett and Wenk 01 Nature

Inner-Most Inner Core (IMIC)

    IC fine structure





   Song and Helmberger 95 JGR

                                 Sun and Song 08

   Ishii & Dziewonski 02

Hemispheric Dichotomy




    Niu and Wen 01 Nature

                             Duess et al. 10 Science

    Sun and Song 08

IC Shear Wave Anisotropy

 Larger equatorial heat flow
                      Maxwell stress

                          Dendritic solidification





                      Wookey & Helffrich 08 Nature

Features on ICB Surface

   Topography at ICB
        Mosaic IC surface





     Cao et al. 07 PNAS 
   Krasnoshchekov et al. 05 Nature

Origin of Hemispheric Dichotomy




         Aubert 08 Nature





     Monnereau et al. 10 Science
   Deguen and Cardin 09 NG

Effect of Ni




               Kuwayama et al. 08 EPSL

Project Proposal: The Role of
Volatiles on IC Growth
  Seismology

  Anisotropy structure

  Velocity gradient

  Tomography


  Mineral Physics

  Melting relation

  Density

  Velocity


  Geodynamics

  Heat flow

  Maxwell stress


  Geochemistry


				
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posted:7/16/2011
language:English
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