Geoscience Reference
In-Depth Information
the lower mantle mineralogy. As mentioned
above, the bulk modulus and its pressure
derivatives of those phases have been extensively
investigated, and some consensus is obtained on
these properties (e.g., Fiquet
et al
., 1998; Fei
et al
.,
2007; Ricolleau
et al
., 2009; Dewaele
et al
., 2000;
Speziale
et al
., 2001). Here, I review the recent
elasticity data of those lower mantle phases,
especially focusing on the shear properties (shear
modulus and its pressure derivatives).
(Sinogeikin
et al
., 2004) conducted the sound
velocity measurements for both single-crystal
and polycrystalline MgSiO
3
perovskite by Bril-
louin spectroscopy, and showed that the results
on polycrystalline samples agree well with the
isotropic average of single crystal properties. The
shear wave velocity of polycrystalline MgSiO
3
under ambient condition was also determined
by using resonant sphere technique (or resonant
ultrasound spectroscopy: RUS) (Aizawa
et al
.,
2004). The first determination of the shear mod-
ulus and its pressure and temperature derivatives
at conditions above ambient condition was
made on a polycrystalline MgSiO
3
perovskite
using ultrasonic interferometric technique with
multi-anvil large volume press up to the condi-
tion of 8 GPa and 573 K (Sinelnikov
et al
., 1998).
Using the same technique as Sinelnikov
et al
.
(1998), Li and Zhang (2005) determined the sound
velocity of a polycrystalline MgSiO
3
perovkskite
under broader conditions (to 9 GPa and 873 K).
The shear elastic properties determined by those
previous experimental works are summarized in
Table 6.1. The values of
V
S
,and
G
0
at ambient
condition are in excellent agreement among
those works, and the pressure derivative of shear
modulus at ambient condition (
G
0
) determined
by ultrasonic interferometry also showed results
consistent with each other.
Those previous works have provided critical
parameters of shear modulus and its pressure/
temperature derivatives, which can be used to
6.3.1 MgSiO
3
perovskite
It is widely accepted that MgSiO
3
perovskite
(space group:
Pbnm
) is the primary component
in the Earth's lower mantle, and that magnesian
silicate perovskite is the most abundant phase
in the Earth. Since the discovery of this phase
in 1976 (Liu, 1976), its density and compress-
ibility have been extensively investigated up to
pressures of the lower mantle by static and dy-
namic experiments (Mao
et al
., 1991; Duffy &
Ahrens, 1993; Fiquet
et al
., 1998, 2000). How-
ever, the experimental studies on the acoustic
properties on MgSiO
3
perovskite were limited
to 9 GPa (Yeganeh-Haeri, 1994; Sinogeikin
et al
.,
2004; Aizawa
et al
., 2004; Sinelnikov
et al
., 1998;
Li & Zhang, 2005).
Yeganeh-Haeri (1994) first measured the
soundwave velocity of MgSiO
3
perovskite using
synthetic single-crystal sample by Brillouin
scattering spectroscopy under ambient condition.
Table 6.1
Aggregate shear elastic properties of MgSiO
3
perovskite.
Source
G
0
G
0
(GPa)
V
S0
(km/s)
V
P0
(km/s)
P
,
T
conditions
Remarks
Brillouin scattering:
Murakami
et al
. (2007a)
172.9(15)
1.56(4)
6.49(3)
10.85(3)
to 96 GPa, 300 K
pollycrystalline
Sinogeikin
et al
. (2004)
172(3)
6.47(6)
10.84(10)
ambient
pollycrystalline
Sinogeikin
et al
. (2005)
175(2)
6.53(3)
10.88(6)
ambient
single-crystal
Yaganeh-Haeri (1994)
177(4)
6.57
11.04
ambient
single-crystal
Ultrasonic interferometry:
Sinelnikov
et al
. (1998)
176(5)
1.8(4)
6.51
to 8 GPa, 573 K
pollycrystalline
Li
et al
. (2005)
173(1)
2.0(1)
6.49(2)
10.86(2)
to 9 GPa, 873 K
pollycrystalline
Resonant sphere
:
Aizawa
et al
. (2004)
174.1(5)
6.51
10.70
ambient
pollycrystalline
