Yes... several times. You always forget your objections were answered.
This times I will let someone else answer you...
"In order to be meaningful, all samples must have formed at the same time, and must have the same initial concentration of nonradiogenic isotope. In addition, the system in which the rocks cooled must be closed, so that nothing can change the concentrations of the three nuclides other than radioactive decay. The final assumption is the most problematic: different samples must have different concentrations of parent nuclide. Otherwise, all the samples would plot on one point, and no unique solution would be obtainable.
"The problem: mineral isochrons, those that examine different mineral crystals within a melt, often produce the different parent-nuclide concentrations that the method requires. But a whole-rock isochron should not produce this result. And when it does, then the original melt was not homogeneous at all. This violates the central assumption of the method.
"The usual explanation given for a false isochron is that the rocks formed from a partially mixed, thus nonhomogeneous, melt. Other explanations include:....."http://www.examiner.com/article/isochron-dating-and-its-unsafe-assumptions
?????????? The Examiner? A newspaper article written by Terry Hurlbut, self-described "creationism examiner"? Seriously? What did you do, Google "isochron" and some other creationist terms and go with the first hit that told you what you wanted to hear?
If this is how you approach science, I'll just let that speak for itself. Now....
Geologists invented isochron dating to make the initial daughter-isotope concentration irrelevant to radiometric analysis.
So at the very least, we've established that of the 3 items you listed previously, the first two have been shown to be irrelevant, even by your own creationist source.
In order to be meaningful, all samples must have formed at the same time, and must have the same initial concentration of nonradiogenic isotope. In addition, the system in which the rocks cooled must be closed, so that nothing can change the concentrations of the three nuclides other than radioactive decay. The final assumption is the most problematic: different samples must have different concentrations of parent nuclide.
Yep, and if that isn't the case, the resulting plot and non-linear relationships will show it. IOW, as with your previous irrelevant objections, isochron dating actually tests for these conditions. The creationist author even admits this...
An isochron that is too shallow, or slopes downward, is an obvious example.
Exactly. If any of the conditions are violated, it will show up in the resulting plot.
But sometimes, as in this Russian study, one obtains a perfectly reasonable-looking isochron that the investigators still reject because the age thus obtained doesn't fit the narrative.
Well sure. Just the other day I used a tire pressure gauge. The first 3 times it said the pressure was ~40 psi, but the next time it said it was 120 psi, and the next 3 times it said ~40 psi. Does that mean tire pressure gauges are useless? Should I have gone into a tire place and said I had no idea what my tire pressure is?
Then your source actually has the gall to cite creationist S. Austin's infamous misuse of dating protocols as evidence that the method doesn't work. In a nutshell, Austin violated the basic protocol of homogeneity of samples, in that he took samples from four different lava flows and one phenocryst.
IOW, a creationist went out, misused a tool, and then declared the tool to be useless.
Also, I have to wonder why you think anyone should care what Terry Hurlbut,
a medical doctor who has no training or experience in geochemistry, thinks about geochemistry. Couldn't Google find you a creationist with some actual qualifications? :chuckle:
Further, you once again blew off most of my response to you. To repeat...
If you have a mechanism by which radioactive decay can be accelerated enough to make rocks that are only 6,000 years old appear to be billions of years old, you should let everyone know. You know why? Because you would solve mankind's energy problems forever. We'd be able to generate all the nuclear power we wanted, and use your mechanism to dispose of the leftover material. Right now we're stuck with the leftovers, and since nothing anyone has ever tried has caused decay rates to accelerate, all we can do is bury it, wait, and hope.
Also, I believe we previously covered the fact that different isotopes decay via different mechanisms. For example, K40 decays to Ar40 via electron capture, whereas Rb87 decays to Sr87 via beta decay....two entirely different processes.
So what mechanism do you propose that would affect different isotopes that decay via completely different mechanisms, in exactly the same way (such that they would give the apparent age of millions/billions of years, when they are both really only ~6,000 years old)?