In other words, the decay of the parent radioisotopes was accelerated by different amounts, the decay of those yielding older "ages" (the alpha-decayers) having been accelerated more.
Obviously, if radioisotope decay was accelerated, say during the Genesis Flood, then the radioisotope decay "clocks" could never be relied upon to "date" rocks as many millions of years old.
Irreconcilable disagreement within and between the methods is the norm, even at the outcrop scale.
This is a devastating "blow" to the long ages that are foundational to uniformitarian geology and evolutionary biology.
Both laboratories use standard, best-practice procedures on state-of-the-art equipment.
The model K-Ar ages for each of the samples ranged from 405.1±10 Ma to 2574.2±73 Ma.
Yet the RATE research has uncovered much evidence, including the patterns of these discordances between the "dates" from the different radioisotope systems, For example, if accelerated radioisotope decay occurred, then alpha-decaying radioisotopes would yield older isochron "ages" than beta-decaying radioisotopes, which is exactly the pattern in the Brahma amphibolites (see diagram above).
Because the different radioisotopes are dating the same geologic event, to have produced different "dates" has to mean that the parent radioisotopes have decayed at different rates over the same time period.
The computer program Isoplot was used to plot isochrons and calculate isochron ages from the other radioisotope analyses.
The best isochron plots, where all the variation from the line of best fit to the data incorporates all the analytical errors, yielded an Rb-Sr isochron age of 1240±84 Ma, an Sm-Nd isochron age of 1655±40 Ma, and a Pb-Pb isochron age of 1883±53 Ma.
Furthermore, the seven samples from the small amphibolite unit near Clear Creek, which should all be the same age because they belong to the same metamorphosed basalt lava flow, yielded K-Ar model ages ranging from 1060.4±28 Ma to 2574.2±73 Ma.
This includes two samples only 0.84 meters apart that yielded K-Ar model ages of 1205.3±.2±73 Ma.
These included seven samples from a 150 meter long and 2 meter wide amphibolite body outcropping just upstream from the mouth of Clear Creek at river mile 84 (measured from Lees Ferry).