COMPRES 2006 Snowbird, Utah

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COMPRES 2006 Snowbird, Utah David Walker,
Lamont-Doherty Earth Observatory, Columbia U.
Why ever would the Earths core leak?
(NSF CSEDI2 progress report)
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Some plume basalts show correlated Os anomalies.
Core- flavored plume
Liquid metal outer core
Inner core
solid mantle
190Pt-driven
atmosphere
187Re-driven
Maybe Re?
A.Brandon, R.J.Walker et al. (2003)
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Is the core really leaking?
What could drive it?
Manghnani and Yagi
Yes, perhaps Os isotopes
Hawaiian plume Fe/Mn Ni
Perhaps not radiogenic Sr/Os correlation
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Cooling drives changes in solubility
Reorient for buoyant slag floating on the core
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What determines oxygen solubility(P)?
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But we still need to measure Oxygen solubility
in Fe liquid at high P,T
Does it reach 2 or 20?
Manghnani and Yagi
(A year in the lab can save you an hour in the
library!)
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How to measure Oxygen solubility in molten Fe
at a megabar?
Underway with COMPRES support for the ALS 12.2.2
team
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http//xraysweb.lbl.gov/bl1222/home.htm
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LBL ALS Station 12.2.2
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Laser
LBL ALS Station 12.2.2
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In situ DAC X-Radiographic Imaging (XRI)
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Absorption(?) /or emission
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Peritectic possible to recognize when
reactants are spatially resolved.
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50 kilobars
Fe
Does this work?
FeS
Station 12.2.2 ALS
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It seems to work!
Topography convolved with chemistry -and- resolut
ion limited by phosphor sharpness and sample
preparation
What about Fe-FeO?
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550 kilobars
FeO
Fe
Consistent with the DAC results of Takafuji et
al. (2005) lt6
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(No Transcript)
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Oxygen solubility does not appear to be high
enough to be interesting.
Are there other solutions to the problem?
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Glatzmaier Roberts 1995
Earths dynamo magnetic field
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Toroidal magnetic field in the outer core
generates local anodic and cathodic areas at the
CMB 1 V Could this drive any
electrochemical transfers across the CMB?
mantle
low Fe
core
(See Abby Kavners forthcoming paper in EPSL)
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What does the presence of life do for us?
Core signal generated by recycled oxidized crust.
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Iron meets oxygen!
rusty surface
Bright inner core
When oxygen does not dissolve in iron.
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N2 O2
Most effective and quick if oxygen solubility low
Core- flavored plume
Oxidized slab
Os-Sr-Nd-O signal of recycled crust not a show
stopper. It is the key to the delivery mechanism
for the corrosive reaction.
Liquid metal outer core
Inner core
solid mantle
Revenge of the plants!
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Remaining questions
Does the biosphere-core feedback deserve to be
taken seriously?
Test when does the Os signal start? gt2.8 Gy ago
(Puchtel et al.)
Why not electrochemistry?