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Table 1 Average chemical composition of pseudotachylyte matrix, and volume fraction and average aspect ratio of unmelted grains

From: Earthquake faulting in subduction zones: insights from fault rocks in accretionary prisms

  Mugi area Okitsu area
Mg-1 Mg-2 Mg-3 Mg-4 Ok-1 Ok-2 Ok-3
ϕ 0.09 0.26 0.26 0.26 0.13 0.18 0.12
R 1.58 1.56 1.55 1.54 1.39 1.5 1.41
n 11 6 13 5 13 8 10
SiO2 52.55 ± 0.85 51.80 ± 1.50 52.79 ± 0.31 51.65 ± 1.24 53.40 ± 0.92 53.05 ± 0.66 52.46 ± 1.13
TiO2 0.27 ± 0.08 0.16 ± 0.11 0.08 ± 0.01 0.13 ± 0.03 0.14 ± 0.07 0.29 ± 0.05 0.21 ± 0.02
Al2O3 30.22 ± 0.65 27.88 ± 1.15 27.97 ± 0.00 27.03 ± 0.58 29.25 ± 0.80 29.03 ± 0.37 28.92 ± 0.36
FeO 2.55 ± 0.48 4.68 ± 1.88 3.72 ± 0.12 5.32 ± 0.39 2.40 ± 0.49 2.32 ± 0.09 2.28 ± 0.11
MnO 0.21 ± 0.29 0.16 ± 0.04 0.13 ± 0.01 0.19 ± 0.02 0.03 ± 0.02 0.05 ± 0.02 0.02 ± 0.01
MgO 1.63 ± 0.08 1.96 ± 0.29 1.60 ± 0.08 2.15 ± 0.15 2.51 ± 0.14 2.52 ± 0.14 2.51 ± 0.05
CaO 0.55 ± 0.08 0.66 ± 0.10 0.94 ± 0.49 0.57 ± 0.02 0.45 ± 0.40 0.33 ± 0.04 0.42 ± 0.33
Na2O 0.13 ± 0.02 0.13 ± 0.01 0.11 ± 0.03 0.15 ± 0.01 0.06 ± 0.02 0.06 ± 0.01 0.06 ± 0.01
K2O 7.82 ± 0.35 6.92 ± 0.51 6.97 ± 0.08 6.88 ± 0.14 6.90 ± 0.81 8.38 ± 0.52 8.23 ± 0.19
Total 95.93 94.34 94.30 94.11 95.15 96.04 95.12
Missing mass 4.07 5.66 5.7 5.89 4.85 3.96 4.88
  1. Modified from Ujiie et al. (2007b). ϕ, volume fraction of unmelted grains; R, average aspect ratio of unmelted grains; n, numbers of analyses.