Geoscience Reference
In-Depth Information
Table 5.1
Electrical conductivity of some representative minerals.
Mineral
P (GPa)
T (K)
r
log
10
A(S/m)
d
H* (kJ/mol)
Remarks
ref.
α
573-1273
-
2.39 (18)
105( 3)
Dry, Mg#=67, NNO
(1)
0.6-1.2
orthopyroxene
0.90 (4)
3.83 (10)
81 (1)
Wet, Mg#=67, NNO
573-1273
-
4.12 (34)
161 (6)
Dry, NNO
(1)
Lower
crust
plagioclase
0.6-1.2
0.83 (6)
2.49 (14)
77 (2)
Wet, NNO
1.2
773-1273
-
2.16 (27)
102( 5)
Dry, En:Fs:Wo=44:6:50, NNO
(2)
clinopyroxene
0.6-1.2
573-1273
1.13 (5)
3.56 (10)
71 (1)
Wet, En:Fs:Wo=44:6:50, NNO
10
−
4
Dry, Mg#=90, fo2=10
−
4
Pa
olivine
995-1775
2.40 (10)
154 (4)
(3)
3.00 (40)
a)
4
873-1273
0.62 (15)
87 (5)
Wet, Mg#=90, NNO
(4)
olivine
2.70 (40)
b)
olivine
a
1.90 (44)
a)
10
500-1000
-
0.16 (2)
88 (4)
Wet, Mg#=90, MMO
(5)
8
873-1473
-
2.73 (1)
147 (6)
[001], dry, Mg#=82, MMO
(6)
Upper
mantle
-
2.26 (3)
80 (2)
[001], wet, Mg#=86, MMO
orthopyroxene
b
8
873-1273
-
2.21 (4)
82 (3)
[100], wet, Mg#=86, MMO
-
2.18 (3)
85 (2)
[010], wet, Mg#=86, MMO
873-1473
-
3.02 (20)
128 (6)
Dry, Py:Alm:Grs=73:14:13,
MMO
(7)
c
8
pyrope
873-1273
1.09 (5)
3.29 (17)
68 (3)
Wet, Py:Alm:Grs=73:14:13
MMO
ringwoodite
14-16
773-1273
0.69 (3)
3.61 (10)
104 (2)
Wet, Mg#=90, MMO
(8)
Transition
zone
(9)
c
873-1673
-
2.10 (10)
147 (3)
Dry, Mg#=90, MMO
15
wadsleyite
873-1273
0.70 (3)
2.57 (16)
90 (3)
Wet, Mg#=90, MMO
Notes
1. Numbers in the parenthesis is an error in the last digit (with one standard deviation) (e.g., 0.90 (4) means 0.90
±
0.04).
2. NNO is the Ni-NiO buffer, MMO is the Mo-MoO
2
buffer. Electrical conductivity under ''wet'' and ''dry'' condition is expressed by the following relationship,
σ
w
=
A
·
f
O
2
f
O
2
q
w
f
O
2
f
O
2
q
d
RT
(dry) respectively where A and r are constants,
f
O
2
is oxygen fugacity,
f
O
2
is the reference
oxygen fugacity (such as NNO which is shown in the ''remarks'' in the table), Cw is the water content in wt%, H
*
is activation enthalpy, R is the gas constant and T
is temperature. When these results are to be applied to other oxygen fugacity conditions, a correction needs to be made using the above formula. The oxygen fugacity
exponent,
q
, was determined for some minerals.
q
d
=
0.17 for dry conditions and
q
w
=−
0.1 for wet conditions.
The correction for pressure effect is not large in most cases (because conductivity was measured near the relevant pressure in most cases).
a
Yoshino
et al
. (2009) used
σ
·
C
r
w
·
exp
RT
(wet),
σ
d
=
A
·
·
exp
H
∗
H
∗
−
−
=
A
·
C
w
·
exp
, which is not an appropriate formula as discussed in the text.
H
∗
−
α
C
1/3
w
−
RT
=
A
·
exp
RT
.
H
∗
b
The sample has 0.042 wt% water. The electrical conductivity for wet opx is fitted to
σ
−
c
Data are re-analyzed.
d
The values of A for wet samples of olivine depend on the water content measurement for which different calibrations for FT-IR measurement give a factor of
∼
3 difference
in water content. Such a difference does not exist (or is not known) for other minerals listed here.
