Geoscience Reference
In-Depth Information
6.5
Concluding Remarks and Outlook
the earth and planetary sciences,
Annu Rev Phys
Chem
,
50
, 279-313.
Abramson, E.H., Brown, J.M., Slutsky, L.J. & Zaug, J.,
1997. The elastic constants of San Carlos olivine to
17 GPa,
J Geophys Res
,
102
, 12253-12263.
Aizawa, Y., Yoneda, A., Katsura, T., Ito, E., Saito, T. &
Suzuki, I., 2004. Temperature derivatives of elastic
moduli of MgSiO3 perovskite,
Geophys Res Lett
,
31
,
L01602.
Allegre, C.J., Poirier, J.P., Humler, E. & Hofmann, A.W.,
1995. The Chemical-Composition of the Earth,
Earth
Planet Sci Lett
,
134
, 515-526.
Anderson, D.L., 1989.
Theory of the Earth
, Blackwell
Scientific Publications, Boston.
Anderson, O.L., 1982. The Earth's core and the phase
diagram of iron,
Phil Trans Roy Soc Lond. Series A
,
306
, 21-35.
Anderson, O.L. & Isaak, D.G., 1995.
Elasticity of mantle
minerals at high temperature
, American Geophysical
Union, Washington, DC.
Badro, J., Fiquet, G., Guyot, F., Rueff, J.-P., Struzhkin,
V.V., Vanko, G. & Monaco, G., 2003. Iron partition-
ing in Earth's mantle: toward a deep lower mantle
discontinuity,
Science
,
300
, 789-791.
Badro,J.,Rueff,J.P.,Vanko,G.,Monaco,G.,Fiquet,G.&
Guyot, F., 2004. Electronic transitions in perovskite:
possible nonconvecting layers in the lower mantle,
Science
,
305
, 383-386.
Badro, J., Struzhkin, V.V., Shu, J., Hemley, R.J., Mao,
H.-k., Kao, C.-c., Rueff, J.-P. & Shen, G., 1999.
Magnetism in FeO at megabar pressures from x-ray
emission spectroscopy,
Phys Rev Lett J1 - PRL
,
83
,
4101.
Bassett, W.A., Reichmann, H.-J., Angel, R.J., Spetzler,
H. & Smyth, J.R., 2000. New diamond anvil cells for
gigahertz ultrasonic interferometry and X-ray diffrac-
tion,
Amer Mineral
,
85
, 283-287.
Brown, J.M. & Shankland, T.J., 1981. Thermodynamic
parameters in the earth as determined from seismic
profiles,
Geophys J Roy Astron Soc
,
66
, 579-596.
Brown, J.M., Slutsky, L.J., Nelson, K.A. & Cheng, L.-T.,
1989. Single-crystal elastic constants for San Car-
los peridot: An application of impulsive stimulated
scattering,
J Geophys Res
,
95
, 9485-9492.
Caracas, R. & Cohen, R.E., 2005. Effect of chemistry
on the stability and elasticity of the perovskite and
post-perovskite phases in the MgSiO3-FeSiO3-Al2O3
system and implications for the lowermost mantle,
Geophys Res Lett
,
32
, L16310.
Considerable uncertainties have prohibited us
from making the reliable lower mantle miner-
alogical model. Much of those uncertainties were
associated with the lack of elasticity data such
as shear wave velocities under relevant condition
of the lower mantle. The recent decade has seen
dramatic progress in determining the soundwave
velocities under high-pressures relevant to the
lower mantle. This advancement enables to suc-
cessfully determine the shear wave velocities of
MgSiO
3
post-perovsktie in situ under high pres-
sures, and to address the seismic structures at the
base of the mantle. Mineralogical modeling com-
bined with those new sound velocity data offers
that a lower mantle with at least
90% silicate
perovskite by volume can satisfy the global seis-
mological 1-D velocity profile, implying that the
bulk composition of lower mantle is likely not to
be the conventional peridotitic (pyrolitic) model
but more chondritic one.
The continued development of new experi-
mental techniques promises major advances in
the very near future. One important direction
of future work will be the soundwave velocity
measurements at high temperature. Although the
difficulties involved in such measurements were
discussed in some details above, the soundwave
velocity measurement system at simultaneously
high pressures and temperatures has recently
developed that allows us to give better under-
standing of the lower mantle mineralogy.
∼
Acknowledgements
Most of the works on the sound velocity mea-
surements were done in collaboration with Jay
Bass, Stanislav Sinogeikin, Nagayoshi Sata, Yuki
Asahara, Yasuo Ohishi, Naohisa Hirao and Kei
Hirose. I greatly appreciate their supports.
References
Abramson, E.H., Brown, J.M. & Slutsky, L.J., 1999.
Applications of impulsive stimulated scattering in
