Potassium argon dating is only done with
This preparation is the purest mineral concentrate.'However, because Austin ignores the analytical inadequacies of Geochron's mass spectrometer (hypothesis #2), except for possibly the pyroxenes, there is no evidence that excess argon is present in any of the other mineral or glass components in this sample.'Another critic said that Dr Austin should only have dated the volcanic glass from his sample, because the glass would have solidified when the lava dome formed.
However, Dalrymple  found that even volcanic glass can give wrong ages and rationalized that it can be contaminated by argon from older rock material.'Clearly, Swenson simply assumes that the volcanic glass contains 'excess argon.' However, dating a mixture of older plagioclase and younger volcanic glass with inadequate equipment (hypothesis #2) does not prove that any of these components contain excess argon.
No attempt was made to separate the hornblende from the Fe-Ti oxides, but further finer milling and use of heavy liquids should be considered.''The 'heavy-nonmagnetic concentrate' (DOME-1H) was dominated by orthopyroxene with much less clinopyroxene, but had a significant quantity of glassy particles attached to mafic microphenocrysts and fragments of mafic phenocrysts along incompletely fractured grain boundaries.
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.
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.
'The 'heavy-magnetic concentrate' also had glassy particles (more abundant than in the 'heavy-nonmagnetic concentrate'). De Paolo, 1985, 'Radiometric Time Scale for the Upper Eocene and Oligocene Based on K/Ar and Rb/Sr Dating of Volcanic Biotites from the Pelagic Sequence of Gubbio, Italy', Geology, v.
Furthermore, many studies (for example, the Haulalai basalt; Funkhouser and Naughton, 1968) demonstrate that Swenson and other YECs cannot automatically assume that modern volcanic glass contains excess argon.
Although hypothesis #1 is plausible, until the argon isotope concentrations of the PURE glass are accurately measured for Austin's dacite (if this is even possible) we cannot properly evaluate this hypothesis.'The origin of the excess 40Ar is not entirely clear, but the discovery of excess 40Ar in Holocene quenched basalt glass [Dalrymple and Moore, 1968] indicates that radiogenic argon, released when older rocks are heated or melted, is dissolved in the melt and may be occluded by minerals as they crystallize.''Up to 2.6 x 10 to the -11 mole/gram of excess radiogenic 40Ar has been found in SUBMARINE basalts of Holocene age from Kilauea [Dalrymple and Moore, 1968; plus another reference], BUT IT'S OCCURRENCE THERE IS NOT SURPRISING IN VIEW OF THE HYDROSTATIC PRESSURE IN THE OCEAN DEPTHS and the rapidity with which SUBAQUEOUS flows are quenched.' [my emphasis]Although high-pressure ocean water may prevent argon gas from escaping from the rims of a lava flow on the ocean floor, the centers of modern submarine flows typically provide K-Ar dates of 'zero years' (Young, 1982, p. While YECs explain geology by invoking talking snakes, magical fruit, and a mythical 'Flood', Dalrymple (1969) discusses legitimate chemistry and fluid physics, which is hardly relying on flimsy 'rationalizations' or implausible excuses.'With the exception of the Hualalai flow [which contains noticeable ultramafic xenoliths, Dalrymple, 1969, p.
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.
Because it was composed of finer particles (170-270 mesh), it contained far fewer mafic particles with attached glass fragments than DOME-IH.