'(e.g., Harland et al., 1990; Hilgen et al., 1997, p. 121-122; Baadsgaard et al., 1988; Baadsgaard et al., 1993; Queen et al., 1996; Montanari et al., 1985; and Hirschmann et al., 1997; also see Austin clearly ignores the possibility of contamination in the mass spectrometer (hypothesis #2) and the possibility that the phenocrysts in his samples may be much older than the 1986 AD eruption (hypothesis #3).
Austin simply assumes that the first explanation is correct and then he proceeds to use the 'presence' of 'excess argon' in his samples to question the reliability of all K-Ar dates on other rocks and minerals.
Similarly, Swenson also fails to comprehend the indisputable history that is associated with the plagioclase zoning and to properly recognize the important age differences between the coarsest phenocrysts and the volcanic glass.
Specifically, Austin admits that most of his fractions are impure when he includes the term 'etc.' after most of the mineral 'fractions' in his table (see above).'Although NOT a complete separation of non-mafic minerals, this concentrate included plagioclase phenocrysts (andesine composition with a density of about 2.7 g/cc) and the major quantity of glass (density assumed to be about 2.4 g/cc). New palaeomagnetic analysis confirmed the results o f previous studies that these rocks were magnetized during a reversed regime of geomagnetic field.The basanite (plug and lava) K-Ar dates spread over reversed parts of the magnetozones C6A and C6B.These mafic microphenocrysts and fragments of mafic phenocrysts evidently increased the density of the attached glass particles above the critical density of 2.85 g/cc, which allowed them to sink in the heavy liquid. This sample also had recognizable hornblende, evidently not completely isolated by magnetic separation.' 'The 'pyroxene concentrate' (DOME-IP) was dominated by orthopyroxene and much less clinopyroxene.