synchrotron xrd
DESCRIPTION
synchrotron XRD. chemical analysis by TEM. olivine. Discovery of post-perovskite phase transition. Determination of crystal structure by MD simulations. “Si” CN=6 x 6 8 x 2. “Mg” CN=6 x 2 8 x 6. exchanged. (1) Compositional effect on - PowerPoint PPT PresentationTRANSCRIPT
synchrotron XRD chemical analysisby TEM
olivine
Discovery of post-perovskite phase transition
Determination of crystal structure by MD simulations
“Si”
CN=6 x 6
8 x 2
“Mg”
CN=6 x 2
8 x 6
exchanged
(1) Compositional effect on post-perovskite phase transition
Post-perovskite phase transition in:
pure MgSiO3
Pyrolite (8% FeO* 4%Al2O3) MORB (10% FeO* 16%Al2O3)
all occur at 110 to 115GPa @ 2500K
based on gold scale
Compositional effect is small!
Mg-Fe partitioning between PPv, Pv & Mw
PPv & CaPv
Mw
110GPa & 2550K
Pv should be more Fe-rich than PP
Murakami, Hirose, Sata, Ohishi, 2005 GRL
Core-mantle chemical reaction
(2) Light elements in the core?
S in the core?
Only 1.2-1.7 wt% S in the core
8 wt% S is necessary to account for the 7% core density deficit
Larger simultaneous solubilities of Si & O at high pressures?
OMg
Si
(3) What is going on at CMB?
Any reaction products?
No reaction products!
in pv
What is the chemical composition of the mantle in contact with the core?
Core liquid should be in equilibrium,at least with the base of the mantle.
(Fe-depleted)
How has chemical reaction at CMB changed the core composition over the geological time?
Core can dissolve more Si & O when the Fe-depleted bottom of the mantle is replaced by the normal mantle
Core is not saturated in Si & O
Si & O contents in the core may have increased with time!
Dissolution of Si & O into the core from partially molten layer in D”?
Thank you.