Ion-microprobe analyses of matrix glass and glass inclusions in anorthoclase and quartz phenocrysts in pantellerite show no major differences in chemistry except for H2O (4.3 ± 0.2 vs. 0.5 ± 0.1 wt%) and Cl (1.3 vs. 0.9 wt%), which degassed from the matrix during the process of eruption. This high measured water content contrasts with current assumptions that pantellerites are relatively dry magmas. Comparison of secondary-ion intensities from glass and phenocrysts of anorthoclase, hedenbergite, aenigmatite, quartz, and apatite gives partition coefficients (with errors of a factor of two) that are ≤ 1 for B, P, Rb, Zr, Nb, Sn, and Cs for all silicate phenocrysts. Even if individual phase partition coefficients are > 1 (Sr, Y, Ce in hedenbergite; Li in aenigmatite; Ba in anorthoclase; REE in apatite), the resulting bulk crystal/liquid partition coefficients are still < 1 so that fractional crystallization of pantelleritic liquids could generate peralkaline rare-metal granites and pegmatites.

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