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Table 5 Representative results of calculations of MELTS, densities, and volumes of bubbles of the magmas. The calculations were done for six types of magmas (A1, A2, A3, B1, B2, and B3) at a temperature of 1079 °C

From: Petrological characteristics and volatile content of magma of the 1979, 1989, and 2014 eruptions of Nakadake, Aso volcano, Japan

Magma A1 A1 A1 A1 A1 A2 A2 A2 A2 A2 A3 A3 A3 A3 A3
Bulk H2O (wt%) 1 1 1 1 1 2 2 2 2 2 0.5 0.5 0.5 0.5 0.5
Temperature (°C) 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079
Pressure (MPa) 400 200 100 50 25 400 200 100 50 25 400 200 100 50 25
Phase (vol%)b
 Melt 65.6 72.3 76.9 79.2 80.4 87.0 92.5 96.1 98.2 88.3 48.9 55.5 59.8 62.4 63.7
 Plagioclase (An) 17.9 (63) 15.8 (68) 14.1 (71) 13.4 (72) 13.2 (73) 0.2 (74) 0.6 (79) 0.4 (81) 0.2 (82) 7.7 (77) 31.8 (56) 29.0 (60) 26.8 (63) 25.5 (64) 24.9 (65)
 Olivine (Fo) 0.0 0.0 0.0 0.2 (73) 0.5 (74) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 Clinopyroxene (Mg#) 15.8 (64) 10.8 (69) 8.0 (71) 6.2 (72) 5.1 (73) 12.8 (67) 6.9 (70) 3.5 (73) 1.6 (73) 3.7 (74) 18.1 (62) 13.8 (67) 11.5 (69) 10.2 (70) 9.6 (71)
 Orthopyroxene (Mg#) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 Spinel 0.7 1.0 1.1 1.0 0.9 0.0 0.0 0.0 0.0 0.3 1.3 1.7 1.8 1.8 1.8
Chemical composition of melt (wt%)
 SiO2 57.8 57.4 57.0 56.8 56.7 55.7 55.0 54.6 54.5 55.5 59.7 59.5 59.2 59.0 58.9
 TiO2 1.1 1.0 1.0 1.0 1.0 0.9 0.9 0.9 0.9 1.0 1.3 1.1 1.1 1.1 1.1
 Al2O3 18.3 17.6 17.3 17.0 16.9 20.0 19.0 18.4 18.2 17.3 17.1 16.5 16.2 16.0 16.0
 FeOt 7.7 8.0 8.2 8.3 8.4 8.0 8.5 8.6 8.6 8.8 6.7 7.1 7.3 7.4 7.5
 MnO 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.3 0.3 0.3
 MgO 1.9 2.6 3.1 3.4 3.4 2.2 3.0 3.5 3.7 3.7 1.5 2.1 2.5 2.7 2.9
 CaO 5.7 6.3 6.7 7.0 7.2 6.6 7.6 8.2 8.6 7.7 5.4 5.9 6.2 6.4 6.4
 Na2O 3.6 3.5 3.4 3.4 3.3 3.5 3.3 3.2 3.1 3.2 3.2 3.3 3.4 3.4 3.4
 K2O 3.1 2.8 2.6 2.5 2.5 2.4 2.2 2.1 2.0 2.3 4.1 3.6 3.4 3.2 3.2
 P2O5 0.5 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.3 0.6 0.5 0.5 0.5 0.5
 H2Oc 1.6 1.5 1.3 1.3 1.2 2.4 2.2 2.1 1.9 1.5 1.1 1.0 0.9 0.8 0.8
 CO c2 0.146 0.098 0.040 0.015 0.004 0.215 0.113 0.043 0.012 0.001 0.089 0.078 0.039 0.016 0.006
Gas (wt%)d 0.00 0.04 0.09 0.13 0.20 0.00 0.10 0.19 0.31 1.00 0.00 0.00 0.04 0.06 0.08
H2O in gas (in mol)d   0.15 0.24 0.39 0.67   0.27 0.42 0.67 0.90    0.14 0.24 0.43
Volume of bubbles (vol%)d 0.00 0.13 0.64 1.85 6.67 0.00 0.50 1.81 6.51 33.48 0.00 0.00 0.18 0.60 1.78
Density (kg m−3)d 2696 2632 2586 2531 2400 2623 2536 2458 2320 1704 2743 2692 2662 2633 2594
Magma B1 B1 B1 B1 B1 B2 B2 B2 B2 B2 B3 B3 B3 B3 B3
Bulk H2O (wt%) 1 1 1 1 1 2 2 2 2 2 0.5 0.5 0.5 0.5 0.5
Temperature (°C) 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079 1079
Pressure (MPa) 400 200 100 50 25 400 200 100 50 25 400 200 100 50 25
Phase (vol%)b
 Melt 66.3 73.3 78.0 80.3 81.5 87.7 93.9 97.5 99.4 93.1 49.2 56.0 60.4 63.0 64.3
 Plagioclase (An) 17.4 (63) 15.2 (68) 13.3 (71) 12.7 (72) 12.5 (73) 0.0 0.0 0.0 0.0 4.7 (78) 31.5 (56) 28.6 (60) 26.4 (63) 25.2 (64) 24.5 (65)
 Olivine (Fo) 0.0 0.0 0.0 0.2 (73) 0.4 (74) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 Clinopyroxene (Mg#) 15.5 (63) 10.5 (69) 7.6 (71) 5.8 (72) 4.6 (73) 12.3 (65) 6.1 (70) 2.5 (73) 0.6 (74) 2.0 (72) 18.0 (61) 13.7 (66) 11.4 (69) 10.0 (70) 9.4 (71)
 Orthopyroxene (Mg#) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 Spinel 0.8 1.1 1.1 1.0 0.9 0.0 0.0 0.0 0.0 0.2 1.3 1.7 1.8 1.9 1.9
Chemical composition of melt (wt%)
 SiO2 57.8 57.4 57.0 56.8 56.6 55.6 54.8 54.5 54.4 55.0 59.6 59.4 59.2 58.9 58.8
 TiO2 1.1 1.0 1.0 1.0 1.0 1.0 1.0 0.9 0.9 1.0 1.3 1.2 1.1 1.1 1.1
 Al2O3 18.4 17.7 17.3 17.1 16.9 20.0 19.0 18.4 18.0 17.5 17.2 16.5 16.2 16.1 16.0
 FeOt 7.5 7.8 8.0 8.2 8.3 8.0 8.4 8.5 8.5 8.7 6.6 7.0 7.2 7.4 7.4
 MnO 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.3 0.3 0.3
 MgO 1.9 2.7 3.2 3.4 3.5 2.3 3.1 3.6 3.9 3.9 1.5 2.1 2.5 2.8 2.9
 CaO 5.9 6.5 6.8 7.1 7.3 6.8 7.8 8.4 8.8 8.2 5.5 6.0 6.3 6.4 6.5
 Na2O 3.6 3.5 3.4 3.3 3.3 3.5 3.3 3.1 3.0 3.1 3.2 3.3 3.4 3.4 3.4
 K2O 3.1 2.8 2.6 2.5 2.5 2.3 2.1 2.0 2.0 2.1 4.0 3.6 3.4 3.2 3.1
 P2O5 0.5 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.3 0.6 0.5 0.5 0.5 0.5
 H2Oc 1.6 1.4 1.3 1.2 1.0 2.3 2.1 1.9 1.6 1.2 1.1 1.0 0.9 0.8 0.7
 CO c2 0.245 0.102 0.043 0.017 0.006 0.289 0.118 0.047 0.017 0.005 0.224 0.093 0.040 0.017 0.007
Gas (wt%)d 0.59 0.66 0.70 0.77 0.91 0.97 1.10 1.22 1.43 2.04 0.22 0.30 0.34 0.36 0.41
H2O in gas (in mol)d 0.11 0.15 0.22 0.35 0.53 0.17 0.24 0.36 0.52 0.69 0.07 0.09 0.14 0.23 0.38
Volume of bubbles (vol%)d 1.33 2.48 4.74 9.95 22.52 2.97 5.40 10.55 22.60 46.51 0.37 0.86 1.73 3.60 8.33
Density (kg m−3)d 2676 2586 2494 2345 2007 2579 2444 2272 1959 1378 2740 2681 2630 2562 2430
  1. See Additional file 4: Table S3 for detail calculation procedures
  2. FeOt, total FeO
  3. aBulk CO2 and S contents of the magmas before degassing are given in Table 6
  4. bValues in parenthesis show chemical composition of the minerals. An, anorthite content (mol%) in plagioclase (An/(An + Ab) × 100%), Fo, forsterite content (mol%) in olivine, Mg#, Mg/(Mg + Fe) × 100%
  5. cWater and CO2 contents of the melt were calculated from the pressure, temperature chemical composition of the melt and the bulk H2O and CO2 contents using the solubility model of Papale et al. (2006)
  6. dGas contents (H2O + CO2, wt%) of the fluid (melt and gas) and mol fractions of H2O in the gases were calculated from the pressure, temperature chemical composition of the melts, and the bulk H2O and CO2 contents of the fluids using the solubility model of Papale et al. (2006). The volumes of bubbles were calculated from the masses of H2O and CO2 gases exsolved from the melt and densities of H2O and CO2 gases that were calculated with Modified Redlich–Kwong equation of state (Holloway 1981) . The densities of the magmas were calculated from the bubble volumes and masses and densities of the melt and crystal calculated by MELTS, assuming that the bubbles do not separate from the magma