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Table 3 Composition of run products (wt.%)

From: Reactions between komatiite and CO2-rich seawater at 250 and 350 °C, 500 bars: implications for hydrogen generation in the Hadean seafloor hydrothermal system

Experiment-250 °C Experiment-350 °C
Sample Serp or Sme/Chl mixtureb Dolomite Siderite Serp or Sme/Chl mixtureb Calcite Olivinec Magnetite
SiO2 41.37 40.89 33.38 0.00 0.00 0.00 3.80 38.55 35.52 38.87 0.00 0.00 0.00 41.60 2.76
TiO 0.44 0.43 0.64 0.01 0.05 0.15 2.96 0.52 0.47 0.17 0.00 0.00 0.00 0.01 0.18
Al2O3 7.00 6.88 11.56 0.06 0.00 0.01 0.13 6.82 6.84 6.38 0.07 0.00 0.01 0.06 0.02
Cr2O3 0.47 0.43 0.29 0.11 0.06 0.12 1.46 0.37 0.47 0.39 0.04 0.00 0.02 0.14 0.23
FeOtotal a 13.32 13.65 15.55 3.22 6.66 9.05 39.55 16.84 16.51 13.77 0.18 0.37 0.77 5.33 85.06
MnO 0.16 0.14 0.18 0.53 0.49 0.49 0.12 0.19 0.34 0.20 0.13 0.36 0.72 0.05 0.40
MgO 24.05 23.48 24.10 17.69 17.39 17.43 1.32 23.13 25.21 25.98 0.17 0.74 0.79 51.46 0.36
CaO 0.83 0.81 0.17 26.01 29.47 23.75 0.26 0.28 0.13 0.46 56.29 54.95 58.68 0.32 0.29
Na2O 0.06 0.08 0.03 0.03 0.11 0.04 0.09 0.16 0.07 0.15 0.01 0.00 0.00 0.00 0.02
K2O 0.09 0.11 0.02 0.03 0.02 0.02 0.05 0.04 0.01 0.03 0.01 0.01 0.01 0.02 0.03
NiO 0.17 0.20 0.12 0.00 0.00 0.08 0.10 0.10 0.00 0.16 0.01 0.00 0.05 0.45 0.10
Total 87.96 87.10 86.05 47.67 54.25 51.13 49.84 86.98 85.59 86.56 56.91 56.43 61.04 99.43 89.45
Mg# d 76.30 75.40 73.43 90.73 82.31 77.43 5.63 71.00 73.13 77.08 61.52 78.23 64.50 94.51 0.74
  1. aTotal iron as FeO
  2. bSerpentine or smectite/chlorite mixture
  3. cAlterlation or relict olivine
  4. dMg# = [Mg / (Mg+Fe)] × 100