I. Friedman L. G. Woodruff W.I. Rose Jr. 1980 Plagioclases in the 1974 high-Al basalt from Fuego Volcano have ??O18 values of +6.0 to +8.5 per mil. Meteoric water cannot have played a significant role in Fuego's magma. Large, weakly zone clear phenocrysts had ??O18 values in the accepted mantle range, while patchyzoned and oscillatory-zoned plagioclases inferred to have formed later and shallower levels have slightly heavier oxygen isotopic ratios. ?? 1980 Intern. Association of Volcanology and Chemistry of the Earth's Interior. application/pdf 10.1007/BF02597620 en Springer-Verlag Oxygen isotopic determinations of sequentially erupted plagioclases in the 1974 magma of Fuego Volcano, Guatemala article