[Values in weight percent unless otherwise indicated. Values are
means; parentheses contain one standard deviation. GI, glass
inclusion from hosts in phenocryst-rich and phenocryst-poor pumice;
MG, matrix glass from phenocryst-rich pumice; Hnb, hornblende; Mgt,
magnetite; Plag, plagioclase; Qtz, quartz. FeO analyzed as ferrous
iron. Na2O data are not adjusted for sodium-loss during electron
beam excitation. Sulfur analyzed as SO3; ppm S calculated by
multiplying percent SO3 by 4,000. n is number of electron
microprobe analyses. n[H2O] is number of ion probe analyses for
H2O. H2O (max) is the maximum water content determined in the
n[H2O] ion probe analyses.]
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Oxide Hnb GI Mgt GI Plag GI Qtz GI MG
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SiO2 77.06 76.59 75.15 75.61 78.53
TiO2 0.14 0.29 0.11 0.10 0.13
Al2O3 12.88 12.44 12.44 11.83 12.86
FeO 1.11 1.27 0.71 0.61 1.01
MnO 0.05 0.03 0.03 0.04 0.04
MgO 0.19 0.19 0.17 0.15 0.21
CaO 1.27 1.17 1.04 1.08 1.21
K2O 2.94 2.79 2.96 2.82 2.99
Na2O 3.17 2.84 2.45 2.70 3.18
P2O5 0.04 0.03 0.03 0.02 0.03
SO3 0.017 0.018 0.022 0.022 0.015
Cl 0.109 0.093 0.106 0.088 0.112
(0.010) (0.009) (0.025) (0.014) (0.012)
H2O 1.34 3.51 3.09 4.37 0.31
(0.88) (1.54) (0.87) (1.03) (0.15)
Total: 100.32 101.26 98.31 99.44 100.63
n 25 12 10 18 21
n[H2O] 8 5 4 10 3
S (ppm) 68 72 88 88 60
(40) (32) (68) (56) (32)
H2O (max) 3.30 4.55 3.52 6.56 0.43
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