Potassium argon dating is only done with
'One critic said that Dr Austin should not have sent young samples to the dating laboratory because it potentially puts "large error-bars on the data." By this reasoning, the method could not be used on any rocks, since, if we did not see the rocks form, how would we know whether they are young?
'(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).
49], the amounts of excess 40Ar and 36Ar found in the flows with anomalous 40Ar/36Ar ratios were too small to cause serious errors in potassium-argon dating of rocks a few million years old or older.'Phenocrysts of orthopyroxene, hornblende and plagioclase are interpreted to have occluded argon within their mineral structures deep in the magma chamber and to have retained this argon after emplacement and solidification of the dacite.
The amount of argon occluded is probably a function of the argon pressure when mineral crystallization occurred at depth and/or the tightness of the mineral structure.
Again, the mineral textures, as well as the laws of chemistry and physics, dictate that the calcium-rich plagioclase cores grew at higher temperatures before the sodium-rich rims and that glasses only formed once the melt erupted at the surface.
NO ATTEMPT WAS MADE TO SEPARATE PLAGIOCLASE FROM GLASS, but further use of heavy liquids should be considered.' [my emphasis]Because Austin did NOT separate the plagioclase from the glass, we would expect this sample to contain a mixture of young glass, plagioclases with relatively old calcium-rich cores and moderately old sodium-rich rims.
Because intrusive rocks solidify deep within the Earth away from cool water and air, volcanic glass is absent and the grains may be fairly large (that is, easily reaching lengths of one centimeter or more).
In other cases, such as Austin's dacite, a partially crystallized melt erupts on the Earth's surface and produces a volcanic rock, which may be a mixture of rapidly quenched volcanic glass and coarser phenocrysts (Hyndman, 1985, p. The zoning appears as a series of concentric rings of various shades of gray within the grains (see the two obvious examples in the middle of Figure 4).
Steve Austin and his associates at the Institute for Creation 'Research' (ICR) collected a dacite sample from Mt. Helens, Washington State, USA, which probably erupted in 1986 AD. then ineffectively separated the sample into several mineral and glass 'fractions', submitted the dacite and its 'fractions' for potassium 40-argon 40 (K-Ar) dating, and subsequently used the bogus results to inappropriately attack the K-Ar method.
Considering that the half-life of potassium-40 (40K) is fairly long (1,250 million years, Mc Dougall and Harrison, 1999, p.