Text S1
MT-measured electrical conductivity beneath the Hengshan Mountains, north
China
In the initial report by Wei et al. [2008], the upper limit of the electrical conductivity
was ~0.25 S/m. However, a careful re-examination of the “resistivity profile model by
MT” provided by them yields an upper boundary of ~0.15 S/m. In our calculation we
used a value of ~0.2 S/m as approximation.
References:
Wei, W. B., et al. (2008), Geoelectric structure of lithosphere beneath eastern North China:
features of a thinned lithosphere from magnetotelluric soundings, paper presented at The
19th International Workshop on Electromagnetic Induction in the Earth, Beijing, China.
Figure S1
Sample assembly for the electrical conductivity measurement of
single crystal. The Pt-capsule was used to seal the sample and also as a shielding layer
to minimize the influence of leakage current through the assembly. Dimensions of the
sample are ~0.70×0.95 mm for the cross section and ~0.15 mm for the thickness.
Figure S2
Profile analysis of FeO content across the boundary between
Pt-electrode foil and sample. The relative loss of Fe to the electrode was not
significant, and only the outmost ~1-2 m lost ~25% Fe and the adjacent ~2-9 m lost
~12-20% Fe.
Figure S3
The complex impedance spectra of a single crystal mantle
clinopyroxene determined with the same assembly, from 400 to 1000 °C, as in the
measurements of polycrystalline lower crustal clinopyroxene. Inset is the spectrum at
900 °C but on a different scale. The composition of this sample is dramatically
different from that of the lower crust clinopyroxene, and the purpose of these
measurements on this crystal was only to address the shape of the spectra, as well as
its shifting with increasing temperatures. The general shapes of the spectra of this
crystal, and also the shifting to higher frequency with increasing temperature, are
almost the same as those on the polycrystalline lower crustal clinopyroxene, with the
same assembly, and as those on the lower crustal clinopyroxene crystal, with the
assembly in Figure 1. Note that grain size of clinopyroxene derived from the lower
crust is usually up to ~1 mm, which cannot be used for the assembly of the powdered
samples, e.g. ~3.0 mm in diameter and ~2.0 mm in length. Obtained data on the
mantle clinopyroxene will be published elsewhere.
Figure S4
Representative (a) Complex and (b) Bode diagram of impedance
spectra in the frequency range of 0.01 to 106 Hz. These spectra are from the mixture
of lower crustal clinopyroxene with 190 ppm H2O and <0.1% NaCl at 400 ºC. |Z| and
Theta are the modulus of Z’ and Z’’ and phase angle, respectively. No essential
changes in the spectra shapes are observed from 1 to 0.03 Hz.
Figure S5
Impedance spectra obtained from the background (dense ceramic
Al2O3) measurements in the range of 106 to 0.1 Hz (from left to right along the
Z’-axis).
1
0.1
 (S/m)
0.01
1E-3
1E-4
1E-5
1E-6
6
8
10
12
14
16
18
-1
10000/T (K )
Figure S6
Comparison of activation enthalpies between a failed and a normal
experiment. Data in black color are from the sample with ~375 ppm H2O; data in red
color are from a failed experiment in which the water content changed from ~190
ppm to ~350 ppm after the run.
Figure S7
Lower crustal granulite with typical layering. The starting material
used in our experiments was separated from this sample (Hannuoba, north China).
The mineral assemblages present in this sample are clinopyroxene (cpx),
orthopyroxene (opx) and plagioclase (plag), without other phases in visible amount
(e.g. <1%).