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“The assumption of constant radioisotope decay rates has undergirded the interpretation of all radioisotope data and the establishment of the absolute dates in the uniformitarian geologic timescale. Anomalous radioisotope dates that do not fit the chosen timescale are usually explained by open-system behavior and/or inheritance, and then discarded.”
“Because most anomalous radioisotope dates are not published, it is difficult to know just what proportion of dating analyses in geochronology laboratories are discarded. Furthermore, rock samples are often only dated using the one radioisotope method. Thus, it is difficult to quantify just how significant are the few multiple radioisotope concordances published in the literature, and how reliable and consistent is the apparent overall trend of progressively decreasing dates from lower strata in the geologic record through to upper strata.”
“However, the impression gained from a detailed examination of the primary radioisotope dating systems is that, if the absolute dates of the uniformitarian timescale were ignored,”
“and both accepted (those that conform to the already established age of the earth) and anomalous radioisotope dates were considered, where more than one radioisotope system has been utilized to date specific rock strata, radioisotope discordances would be in the MAJORITY. That such discordances are often the case has already been discussed, and has been thoroughly tested and documented on some specific strata.”
“A very relevant example is the stark contrast between the U-Pb radioisotope age of 1500 Ma (Ma means millions of years ago) for the zircon grains in the Jemez granodiorite of New Mexico AND the He (derived from U decay) diffusion age of the SAME zircon grains of only about 6,000 years. This huge discrepancy can be explained if the rate of 238U decay was grossly accelerated at some time(s) in the past. A proposed test of this explanation is to document whether there is a systematic pattern in the discordances between the different radioisotope systems.
If there is a systematic pattern, it may reflect differing amounts of such accelerated nuclear decay in the different radioisotope systems over the same real time interval, due to their different modes of decay and parent half-lives. The amphibolites in the Precambrian basement of the Grand Canyon were chosen for this study for three reasons. First, the Grand Canyon is a well known and well studied area that contains a good, clear strata cross-section representative of much of earth history.
Second, as metamorphosed basalts, amphibolites consist of a very simple two-component system, essentially just the minerals plagioclase and hornblende, which simplifies the geochemistry of radioisotope systematics. And third, being Precambrian, these rocks should have accumulated large enough amounts of the radioisotope decay products to produce isochrons with good statistics.”
‘Twenty-seven Brahma Schist amphibolite samples were collected in the Upper and Middle Granite Gorges (with a Scientific Research and Collecting Permit issued by the Grand Canyon National Park): (1) three samples from the Cottonwood Canyon area, (2) nine samples from the Clear Creek area, including seven samples from a single 50 m long and 2 m wide amphibolite body just upstream from the mouth of Clear Creek, (3) one sample from the Cremation Creek area, (4) one sample from near the mouth of Pipe Creek, (5) seven samples from outcrops just upstream of Blacktail Canyon (fig. 2), and (6) six samples from outcrops along the Colorado River between miles 126.5 and 129.”
Approximately 100 gram splits of each sample were then dispatched to the Amdel laboratory in Adelaide, South Australia, where each sample was crushed and pulverized. Whole-rock analyses were undertaken by total fusion and digestion of each powdered sample followed by ICPOES (inductively coupled plasma-optical emission spectrometry) for major and minor elements, and ICP-MS (inductively coupled plasma-mass spectrometry) for trace and rare earth elements.
A second representative set of 100 gram pieces of each sample was sent to the K-Ar dating laboratory at Activation Laboratories in Ancaster, Ontario, Canada, for whole-rock K-Ar dating under the direction of the laboratory manager, Dr. Yakov Kapusta.
Finally, a third representative set of 100 gram pieces of each sample was sent to the PRISE laboratory in the Research School of Earth Sciences at the Australian National University in Canberra, Australia, where under the direction of Dr. Richard Armstrong, whole-rock Rb-Sr, Sm-Nd, and Pb-Pb isotopic analyses were undertaken.
These 27 samples of the Brahma amphibolites in Grand Canyon yielded an enormously wide range of K-Ar model “ages,” from 405.1 ± 10 Ma to 2574.2 ± 73 Ma, for a rock unit that is supposed to be 1740–1750 Ma. Even samples only 0.84 meters apart in the same outcrop of the small amphibolite body near Clear Creek yielded K-Ar model “ages” of 1205.3 ± 31 Ma and 2574.2 ± 73 Ma.
By contrast, the Rb-Sr, Sm-Nd, and Pb-Pb radioisotope systems yielded good, statistically consistent, isochron ages of 1240 ± 84 Ma, 1655 ± 40 Ma, and 1883 ± 53 Ma, respectively.
Explanations for these discordances have been attempted. For example, different isotope pairs have different closure temperatures that can therefore result in different ages. There may also have been an open-system, magma mixing, inheritance, and/or paleoweathering.
However, in this study all four radioisotope methods were used on the same whole-rock samples. This rules out the possibility of any of these postulated processes having any significant effect on the resultant radioisotope ages. The high-grade metamorphism would have affected all four radioisotope systems similarly. Using whole-rocks for the analyses homogenizes any different chemical or system behaviors in the different minerals. In any case, these amphibolites are essentially just simple, two-mineral systems. Thus, this somewhat uniform approach makes it more likely that the discordances are due to the radioisotope decay rates having not always been constant.
These examples, together with the large number of other examples recorded by Snelling strongly suggest that, where two or more of the commonly-used radioisotope pairs are applied to date rock units, discordances are the norm and not the exception.
Originally posted by trueperspective
reply to post by lambs to lions
It really is amazing how much faith people put into scientist without knowing about the processes they use and what data they accept and reject. Like I said everything should be considered and explained. If a scientist can't do that, then maybe they are wrong in their assumptions.
Second, this is a new study that has just been published
This paper was originally published in the Proceedings of the Sixth International Conference on Creationism, pp. 407–424 (2008)
Originally posted by weedwhacker
Yeah, heard it all before.
"creationists" like to jump on ANY perceived 'flaw', as soon as it is announced.
But, you see, science is, by its very definition, about searching and studying and yes, even accepting those flaws when discovered. The REAL research then continues, in order to minimize errors, alter original ideas (in light of new information) and refine the models of the hypothesis, or theory, as the case may be.
Originally posted by Protostellar
reply to post by trueperspective
Independent of the ridiculous claims made in this article and your bold stance on supporting it, relative dating proves the earth is not young.
Originally posted by weedwhacker
No, it's not a scientifically written paper, but it is succinct, and a bit more entertaining as foil to your OP. And, this particular YT poster has a lot of other good stuff, as well.
[edit on 16 April 2010 by weedwhacker]