Volatiles and Fluids in Earth s Core

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1 Volatiles and Fluids in Earth s Core Jie Jackie Li! University of Michigan July 6, 2010 CIDER Water and Volatiles

2 Discover Earth s Core Mineral Physics 1/3 1/6 1 Oldham 06 Lehmann 36 Dziewonski and Anderson 81

3 Study the Core Field Seismology PREM (1D), tomography (2D), anisotropy (3D) Geo- and Cosmochemistry Meteorites, rocks Geo and Paleomagnetism Magnetic field Lab Mineral physics Material properties Mineral Physics Computer Geodynamics Convection, thermal evolution, chemical differentiation

4 Volatiles in the Core Light(er): H, C, O, Si, S, (N, P) Radioactive: K Other: Pb Mineral Physics

5 Density Deficit in the Core 100 Fe 7000K 150 CMB Hugoniot Pressure, GPa PREM 350 ICB Birch 1952 Li & Fei 07 ToG Density, g/cm 3

6 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

7 Clues from Meteorites Taenite & Kamacite. Fe-Ni Widmanstätten Pattern Troilite, FeS, brown Cohenite. (Fe,Ni) 3 C, white in Taenite and Kamacite matrix Schreibersite (Fe,Ni) 3 P Fe-silicide in Moissanite (SiC)

8 Mass Balance McDonough & Sun 95

9 Solubility in the Core Allègre 92 Li & Agee 96 Gessmann et al. 01 Rubie et al. 06 3Fe Fe 3+ + Fe Frost et al. 04 Wood et al. 06, 07

10 Match Density 100 Fe 7000K 150 CMB Hugoniot Pressure, GPa PREM 350 ICB Birch 1952 Li & Fei 07 ToG Density, g/cm 3

11 Match Velocities Gao et al. 08 GRL Hirose 08 GRC

12 Match Density Jump at ICB Mineral Physics ASM Handbook

13 Match Gradients Birchʼs Law

14 Hydrogen Williams and Hemley 01 ANEPS Mao et al. 04 GRL Hirao et al. 04 GRL IC wt.% H

15 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 FeS 2 FeSi FeS Fe FeO

16 Deep Carbon Reservoirs Fe 3 C IC >10 9 pg Carbon

17 Oxygen Alfe et al. 02 Rubie et al. 06 Science Seagle et al. 08 EPSL

18 Silicon Alfe et al. 02 Kuwayama et al. 04 AM Lin et al. 09 EPSL Polyakov 09 Science Asanuma et al. 10 PCM

19 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

20 Oxygen+Silicon Takafuji et al. 05 GRL Sakai et al. 06 Personal. Comm

21 Sulfur+Silicon Sanloup and Fei 04 PEPI

22 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,... Reviews Ni ~10% 1990 Jeanloz ~5% 1994 Poirier 2000 Hillgren et al. 2003,2007,2011 Li and Fei Fe ~85 wt.% Others < 1% Mcdonougn & Sun 95

23 K in the Core Murthy et al. 03 Nature Hirao et al. 06 GRL Lee et al. 03 GRL

24 Pb in the Core McDonough and Sun 95 CG Wood and Halliday 10 Nature

25 Earth s Magnetic Field is Essential for Human Survival and Civilization Magnetosphere Aurora, northern light

26 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 Light elements Buffett 03 Science

27 Formation of Earth s IC T Adiabat P Liquidus

28 Magnetic Fields in Terrestrial-Like Bodies NASA

29 Inner Core Growth in Ganymede Hauck et al. 06 JGR

30 Ganymede s Snowing Core T Liquidus Adiabat P Hauck et al. 06

31 Martian Core Fei and Bertka 05 Stewart et al. 07

32 Mercury s Double Dynamo S > 7 wt.% S < 7 wt.% Chen et al. 08 GRL Vilim et al. 09 JGR

33 Snowfall in Earth s Core? Fe10wt%S negative melting gradient Li et al AGU Fall Meeting Seagle et al. 09 Abstract Zou et al. 08

34 Inner Core Anisotropy Morelli et al. 86 GRL Woodhouse et al. 86 JGR Shearer et al. 88 Nature Creager 92 Nature Song and Helmberger 93 JGR Romanowicz et al. 96 Science Tromp 01 AREPS Mao et a. 98 Nature Stixrude and Cohen 95 Science Steinle-Neumann 01 Nature Belonoshko et al. 07 Science Belonoshko et al. 08 Science Buffett and Wenk 01 Nature

35 Inner-Most Inner Core (IMIC) IC fine structure Song and Helmberger 95 JGR Ishii & Dziewonski 02 Sun and Song 08

36 Hemispheric Dichotomy Niu and Wen 01 Nature Sun and Song 08 Duess et al. 10 Science

37 IC Shear Wave Anisotropy Larger equatorial heat flow Dendritic solidification Maxwell stress Wookey & Helffrich 08 Nature

38 Features on ICB Surface Topography at ICB Mosaic IC surface Cao et al. 07 PNAS Krasnoshchekov et al. 05 Nature

39 Origin of Hemispheric Dichotomy Aubert 08 Nature Monnereau et al. 10 Science Deguen and Cardin 09 NG

40 Effect of Ni Kuwayama et al. 08 EPSL

41 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