Here I want to concentrate on another source of error, namely, processes that take place within magma chambers. To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating. Radiometric dating is largely done on rock that has formed from solidified lava. Lava properly called magma before it erupts fills large underground chambers called magma chambers. Most people are not aware of the many processes that take place in lava before it erupts and as it solidifies, processes that can have a tremendous influence on daughter to parent ratios. Such processes can cause the daughter product to be enriched relative to the parent, which would make the rock look older, or cause the parent to be enriched relative to the daughter, which would make the rock look younger. This calls the whole radiometric dating scheme into serious question.
Volatiles e. It is possible that these physical processes have an impact on the determined radiometric age of the rock as it cools and crystallizes. Time is not a direct measurement. The actual data are the ratios of parent and daughter isotopes present in the sample. Time is one of the values that can be determined from the slope of the line representing the distribution of the isotopes.
Isotope distributions are determined by the chemical and physical factors governing a given magma chamber. Rhyolites in Yellowstone N. Most genetic models for uranium deposits in sandstones in the U.
Most of the uranium deposits in Wyoming are formed from uraniferous groundwaters derived from Precambrian granitic terranes. Uranium in the major uranium deposits in the San Juan basin of New Mexico is believed to have been derived from silicic volcanic ash from Jurassic island arcs at the edge of the continent.
From the above sources, we see that another factor influencing radiometric dates is the proportion of the magma that comes from subducted oceanic plates and the proportion that comes from crustal rock. Initially, we would expect most of it to come from subducted oceanic plates, which are uranium and thorium poor and maybe lead rich.
Later, more of the crustal rock would be incorporated by melting into the magma, and thus the magma would be richer in uranium and thorium and poorer in lead. So this factor would also make the age appear to become younger with time.
There are two kinds of magma, and the crustal material which is enriched in uranium also tends to be lighter. For our topic on radiometric dating and fractional crystallization, there is nothing that would prevent uranium and thorium ores from crystallizing within the upper, lighter portion of the magma chamber and descending to the lower boundaries of the sialic portion.
The same kind of fractional crystallization would be true of non-granitic melts. I think we can build a strong case for fictitious ages in magmatic rocks as a result of fractional cystallization and geochemical processes. As we have seen, we cannot ignore geochemical effects while we consider geophysical effects. Sialic granitic and mafic basaltic magma are separated from each other, with uranium and thorium chemically predestined to reside mainly in sialic magma and less in mafic rock.
Here is yet another mechanism that can cause trouble for radiometric dating: As lava rises through the crust, it will heat up surrounding rock. Lead has a low melting point, so it will melt early and enter the magma. This will cause an apparent large age.
Uranium has a much higher melting point. It will enter later, probably due to melting of materials in which it is embedded. This will tend to lower the ages. Mechanisms that can create isochrons giving meaningless ages: Geologists attempt to estimate the initial concentration of daughter product by a clever device called an isochron.
Let me make some general comments about isochrons. The idea of isochrons is that one has a parent element, P, a daughter element, D, and another isotope, N, of the daughter that is not generated by decay.
One would assume that initially, the concentration of N and D in different locations are proportional, since their chemical properties are very similar. Note that this assumption implies a thorough mixing and melting of the magma, which would also mix in the parent substances as well.
Then we require some process to preferentially concentrate the parent substances in certain places. Radioactive decay would generate a concentration of D proportional to P.
By taking enough measurements of the concentrations of P, D, and N, we can solve for c1 and c2, and from c1 we can determine the radiometric age of the sample.
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Otherwise, the system is degenerate. Thus we need to have an uneven distribution of D relative to N at the start. If these ratios are observed to obey such a linear relationship in a series of rocks, then an age can be computed from them. The bigger c1 is, the older the rock is. That is, the more daughter product relative to parent product, the greater the age.
Thus we have the same general situation as with simiple parent-to-daughter computations, more daughter product implies an older age.
This is a very clever idea. However, there are some problems with it. First, in order to have a meaningful isochron, it is necessary to have an unusual chain of events. Initially, one has to have a uniform ratio of lead isotopes in the magma.
Usually the concentration of uranium and thorium varies in different places in rock. This will, over the assumed millions of years, produce uneven concentrations of lead isotopes.
To even this out, one has to have a thorough mixing of the magma. Even this is problematical, unless the magma is very hot, and no external material enters. Now, after the magma is thoroughly mixed, the uranium and thorium will also be thoroughly mixed. What has to happen next to get an isochron is that the uranium or thorium has to concentrate relative to the lead isotopes, more in some places than others. So this implies some kind of chemical fractionation. Then the system has to remain closed for a long time.
This chemical fractionation will most likely arise by some minerals incorporating more or less uranium or thorium relative to lead.
Anyway, to me it seems unlikely that this chain of events would occur. Another problem with isochrons is that they can occur by mixing and other processes that result in isochrons yielding meaningless ages. Sometimes, according to Faure, what seems to be an isochron is actually a mixing line, a leftover from differentiation in the magma.
Fractionation followed by mixing can create isochrons giving too old ages, without any fractionation of daughter isotopes taking place.
To get an isochron with a false age, all you need is 1 too much daughter element, due to some kind of fractionation and 2 mixing of this with something else that fractionated differently. Since fractionation and mixing are so common, we should expect to find isochrons often.
How they correlate with the expected ages of their geologic period is an interesting question. There are at least some outstanding anomalies. Faure states that chemical fractionation produces "fictitious isochrons whose slopes have no time significance. As an example, he uses Pliocene to Recent lava flows and from lava flows in historical times to illustrate the problem.
He says, these flows should have slopes approaching zero less than 1 million yearsbut they instead appear to be much older million years. Steve Austin has found lava rocks on the Uinkeret Plateau at Grand Canyon with fictitious isochrons dating at 1.
Then a mixing of A and B will have the same fixed concentration of N everywhere, but the amount of D will be proportional to the amount of P. This produces an isochron yielding the same age as sample A.
This is a reasonable scenario, since N is a non-radiogenic isotope not produced by decay such as lea and it can be assumed to have similar concentrations in many magmas.
Magma from the ocean floor has little U and little U and probably little lead byproducts lead and lead Magma from melted continental material probably has more of both U and U and lead and lead Thus we can get an isochron by mixing, that has the age of the younger-looking continental crust.
The age will not even depend on how much crust is incorporated, as long as it is non-zero. However, if the crust is enriched in lead or impoverished in uranium before the mixing, then the age of the isochron will be increased.
If the reverse happens before mixing, the age of the isochron will be decreased. Any process that enriches or impoverishes part of the magma in lead or uranium before such a mixing will have a similar effect. So all of the scenarios given before can also yield spurious isochrons. I hope that this discussion will dispel the idea that there is something magical about isochrons that prevents spurious dates from being obtained by enrichment or depletion of parent or daughter elements as one would expect by common sense reasoning.
So all the mechanisms mentioned earlier are capable of producing isochrons with ages that are too old, or that decrease rapidly with time. The conclusion is the same, radiometric dating is in trouble. I now describe this mixing in more detail. Suppose P p is the concentration of parent at a point p in a rock.
Talkorigins radiometric dating
The point p specifies x,y, and z co-ordinates. Let D p be the concentration of daughter at the point p. Let N p be the concentration of some non-radiogenic not generated by radioactive decay isotope of D at point p. Suppose this rock is obtained by mixing of two other rocks, A and B. Suppose that A has a for the sake of argument, uniform concentration of P1 of parent, D1 of daughter, and N1 of non-radiogenic isotope of the daughter. Thus P1, D1, and N1 are numbers between 0 and 1 whose sum adds to less than 1.
Suppose B has concentrations P2, D2, and N2. Let r p be the fraction of A at any given point p in the mixture. So the usual methods for augmenting and depleting parent and daughter substances still work to influence the age of this isochron.
More daughter product means an older age, and less daughter product relative to parent means a younger age. In fact, more is true. Any isochron whatever with a positive age and a constant concentration of N can be constructed by such a mixing. It is only necessary to choose r p and P1, N1, and N2 so as to make P p and D p agree with the observed values, and there is enough freedom to do this. Anyway, to sum up, there are many processes that can produce a rock or magma A having a spurious parent-to-daughter ratio.
Then from mixing, one can produce an isochron having a spurious age.
This shows that computed radiometric ages, even isochrons, do not have any necessary relation to true geologic ages. Mixing can produce isochrons giving false ages. But anyway, let's suppose we only consider isochrons for which mixing cannot be detected. How do their ages agree with the assumed ages of their geologic periods? As far as I know, it's anyone's guess, but I'd appreciate more information on this.
I believe that the same considerations apply to concordia and discordia, but am not as familiar with them. It's interesting that isochrons depend on chemical fractionation for their validity. They assume that initially the magma was well mixed to assure an even concentration of lead isotopes, but that uranium or thorium were unevenly distributed initially. So this assumes at the start that chemical fractionation is operating. But these same chemical fractionation processes call radiometric dating into question.
The relative concentrations of lead isotopes are measured in the vicinity of a rock.
For radiometric dating the system, usually a rock or some specific mineral grains, need only be closed to the parent and daughter isotopes. 2 Approximately one percent of the Earth's atmosphere is argon, of which percent is 40 Ar. 3 These paths will be at an angle of 45° if the scales on the abscissa and ordinate are the same. Aug 27, I was wondering if there is any way that one of your staff members could do an article on exactly why radiometric dating is definitely unreliable. I read the articles here that I found, but all their claims appear to be refuted on keitaiplus.com's [sic] listing of creationist claims (as are pretty much everything on your site that I have seen.
The amount of radiogenic lead is measured by seeing how the lead in the rock differs in isotope composition from the lead around the rock. This is actually a good argument.
But, is this test always done? How often is it done?
And what does one mean by the vicinity of the rock? How big is a vicinity? One could say that some of the radiogenic lead has diffused into neighboring rocks, too. Some of the neighboring rocks may have uranium and thorium as well although this can be factored in in an isochron-type manner. Furthermore, I believe that mixing can also invalidate this test, since it is essentially an isochron. Finally, if one only considers U-Pb and Th-Pb dates for which this test is done, and for which mixing cannot be detected.
The above two-source mixing scenario is limited, because it can only produce isochrons having a fixed concentration of N p. To produce isochrons having a variable N pa mixing of three sources would suffice. This could produce an arbitrary isochron, so this mixing could not be detected. Also, it seems unrealistic to say that a geologist would discard any isochron with a constant value of N pas it seems to be a very natural condition at least for whole rock isochronsand not necessarily to indicate mixing.
I now show that the mixing of three sources can produce an isochron that could not be detected by the mixing test. First let me note that there is a lot more going on than just mixing. There can also be fractionation that might treat the parent and daughter products identically, and thus preserve the isochron, while changing the concentrations so as to cause the mixing test to fail.
It is not even necessary for the fractionation to treat parent and daughter equally, as long as it has the same preference for one over the other in all minerals examined; this will also preserve the isochron. Now, suppose we have an arbitrary isochron with concentrations of parent, daughter, and non-radiogenic isotope of the daughter as P pD pand N p at point p.
Suppose that the rock is then diluted with another source which does not contain any of D, P, or N.
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Then these concentrations would be reduced by a factor of say r' p at point p, and so the new concentrations would be P p r' pD p r' pand N p r' p at point p. Now, earlier I stated that an arbitrary isochron with a fixed concentration of N p could be obtained by mixing of two sources, both having a fixed concentration of N p.
With mixing from a third source as indicated above, we obtain an isochron with a variable concentration of N pand in fact an arbitrary isochron can be obtained in this manner. So we see that it is actually not much harder to get an isochron yielding a given age than it is to get a single rock yielding a given age. This can happen by mixing scenarios as indicated above. Thus all of our scenarios for producing spurious parent-to-daughter ratios can be extended to yield spurious isochrons. The condition that one of the sources have no P, D, or N is fairly natural, I think, because of the various fractionations that can produce very different kinds of magma, and because of crustal materials of various kinds melting and entering the magma.
In fact, considering all of the processes going on in magma, it would seem that such mixing processes and pseudo-isochrons would be guaranteed to occur. Even if one of the sources has only tiny amounts of P, D, and N, it would still produce a reasonably good isochron as indicated above, and this isochron could not be detected by the mixing test. I now give a more natural three-source mixing scenario that can produce an arbitrary isochron, which could not be detected by a mixing test.
P2 and P3 are small, since some rocks will have little parent substance. Suppose also that N2 and N3 differ significantly. Such mixings can produce arbitrary isochrons, so these cannot be detected by any mixing test.
Also, if P1 is reduced by fractionation prior to mixing, this will make the age larger. If P1 is increased, it will make the age smaller. If P1 is not changed, the age will at least have geological significance.
But it could be measuring the apparent age of the ocean floor or crustal material rather than the time of the lava flow. I believe that the above shows the 3 source mixing to be natural and likely.
We now show in more detail that we can get an arbitrary isochron by a mixing of three sources. Thus such mixings cannot be detected by a mixing test.
Assume D3, P3, and N3 in source 3, all zero. One can get this mixing to work with smaller concentrations, too. All the rest of the mixing comes from source 3. Thus we produce the desired isochron. So this is a valid mixing, and we are done. We can get more realistic mixings of three sources with the same result by choosing the sources to be linear combinations of sources 1, 2, and 3 above, with more natural concentrations of D, P, and N.
The rest of the mixing comes from source 3. This mixing is more realistic because P1, N1, D2, and N2 are not so large. Application of in situ analysis Laser-Ablation ICP-MS within single mineral grains in faults have shown that the Rb-Sr method can be used to decipher episodes of fault movement. A relatively short-range dating technique is based on the decay of uranium into thorium, a substance with a half-life of about 80, years.
It is accompanied by a sister process, in which uranium decays into protactinium, which has a half-life of 32, years. While uranium is water-soluble, thorium and protactinium are not, and so they are selectively precipitated into ocean-floor sedimentsfrom which their ratios are measured. The scheme has a range of several hundred thousand years. A related method is ionium-thorium datingwhich measures the ratio of ionium thorium to thorium in ocean sediment.
Radiocarbon dating is also simply called carbon dating. Carbon is a radioactive isotope of carbon, with a half-life of 5, years   which is very short compared with the above isotopesand decays into nitrogen. Carbon, though, is continuously created through collisions of neutrons generated by cosmic rays with nitrogen in the upper atmosphere and thus remains at a near-constant level on Earth.
The carbon ends up as a trace component in atmospheric carbon dioxide CO 2. A carbon-based life form acquires carbon during its lifetime. Plants acquire it through photosynthesisand animals acquire it from consumption of plants and other animals. When an organism dies, it ceases to take in new carbon, and the existing isotope decays with a characteristic half-life years. The proportion of carbon left when the remains of the organism are examined provides an indication of the time elapsed since its death.
This makes carbon an ideal dating method to date the age of bones or the remains of an organism. The carbon dating limit lies around 58, to 62, years. The rate of creation of carbon appears to be roughly constant, as cross-checks of carbon dating with other dating methods show it gives consistent results. However, local eruptions of volcanoes or other events that give off large amounts of carbon dioxide can reduce local concentrations of carbon and give inaccurate dates.
The releases of carbon dioxide into the biosphere as a consequence of industrialization have also depressed the proportion of carbon by a few percent; conversely, the amount of carbon was increased by above-ground nuclear bomb tests that were conducted into the early s.
Also, an increase in the solar wind or the Earth's magnetic field above the current value would depress the amount of carbon created in the atmosphere. This involves inspection of a polished slice of a material to determine the density of "track" markings left in it by the spontaneous fission of uranium impurities.
The uranium content of the sample has to be known, but that can be determined by placing a plastic film over the polished slice of the material, and bombarding it with slow neutrons. This causes induced fission of U, as opposed to the spontaneous fission of U. The fission tracks produced by this process are recorded in the plastic film. The uranium content of the material can then be calculated from the number of tracks and the neutron flux.
This scheme has application over a wide range of geologic dates. For dates up to a few million years micastektites glass fragments from volcanic eruptionsand meteorites are best used. Older materials can be dated using zirconapatitetitaniteepidote and garnet which have a variable amount of uranium content. The technique has potential applications for detailing the thermal history of a deposit. The residence time of 36 Cl in the atmosphere is about 1 week. Thus, as an event marker of s water in soil and ground water, 36 Cl is also useful for dating waters less than 50 years before the present.
Luminescence dating methods are not radiometric dating methods in that they do not rely on abundances of isotopes to calculate age. Instead, they are a consequence of background radiation on certain minerals.
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Over time, ionizing radiation is absorbed by mineral grains in sediments and archaeological materials such as quartz and potassium feldspar. The radiation causes charge to remain within the grains in structurally unstable "electron traps". Exposure to sunlight or heat releases these charges, effectively "bleaching" the sample and resetting the clock to zero.
The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried. Stimulating these mineral grains using either light optically stimulated luminescence or infrared stimulated luminescence dating or heat thermoluminescence dating causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral.
These methods can be used to date the age of a sediment layer, as layers deposited on top would prevent the grains from being "bleached" and reset by sunlight. Pottery shards can be dated to the last time they experienced significant heat, generally when they were fired in a kiln.
Absolute radiometric dating requires a measurable fraction of parent nucleus to remain in the sample rock. For rocks dating back to the beginning of the solar system, this requires extremely long-lived parent isotopes, making measurement of such rocks' exact ages imprecise.
To be able to distinguish the relative ages of rocks from such old material, and to get a better time resolution than that available from long-lived isotopes, short-lived isotopes that are no longer present in the rock can be used.
At the beginning of the solar system, there were several relatively short-lived radionuclides like 26 Al, 60 Fe, 53 Mn, and I present within the solar nebula. These radionuclides-possibly produced by the explosion of a supernova-are extinct today, but their decay products can be detected in very old material, such as that which constitutes meteorites.
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By measuring the decay products of extinct radionuclides with a mass spectrometer and using isochronplots, it is possible to determine relative ages of different events in the early history of the solar system. Dating methods based on extinct radionuclides can also be calibrated with the U-Pb method to give absolute ages. Thus both the approximate age and a high time resolution can be obtained. Generally a shorter half-life leads to a higher time resolution at the expense of timescale.
The iodine-xenon chronometer  is an isochron technique. Samples are exposed to neutrons in a nuclear reactor.
This converts the only stable isotope of iodine I into Xe via neutron capture followed by beta decay of I. After irradiation, samples are heated in a series of steps and the xenon isotopic signature of the gas evolved in each step is analysed.
Samples of a meteorite called Shallowater are usually included in the irradiation to monitor the conversion efficiency from I to Xe. This in turn corresponds to a difference in age of closure in the early solar system. Another example of short-lived extinct radionuclide dating is the 26 Al - 26 Mg chronometer, which can be used to estimate the relative ages of chondrules.
The 26 Al - 26 Mg chronometer gives an estimate of the time period for formation of primitive meteorites of only a few million years 1. From Wikipedia, the free encyclopedia. Technique used to date materials such as rocks or carbon. See also: Radioactive decay law. Main article: Closure temperature. Main article: Uranium-lead dating. Main article: Samarium-neodymium dating. Main article: Potassium-argon dating. Main article: Rubidium-strontium dating.
Main article: Uranium-thorium dating. Main article: Radiocarbon dating. Main article: fission track dating.
Main article: Luminescence dating. Earth sciences portal Geophysics portal Physics portal. Part II. The disintegration products of uranium". American Journal of Science. In Roth, Etienne; Poty, Bernard eds. If the isochron line has a distinctly non-zero slope, and a fairly large number of data points, the nearly inevitable result of contamination failure of the system to remain closed will be that the fit of the data to a line will be destroyed.
For example, consider an event which removes P. The data points will tend to move varying distances, for the different minerals will have varying resistance to loss of Pas well as varying levels of D i :. Note: In the special case where the isochron line has a zero slope indicating zero agethen gain or loss of P may move the data points, but they will all still fall on the same horizontal line.
In other words, random gain or loss of P does not affect a zero-age isochron. This is an important point. If the Earth were as young as young-Earth creationists insist, then the "contamination" which they suggest to invalidate dating methods would have no noticeable effect on the results. Faurep. As with gain or loss of Pin the general case it is highly unlikely that the result will be an isochron with colinear data points:.
There are two exceptions, where it is possible for migration of D to result in an isochron with reasonably colinear data points:. These exceptions should be of little comfort to young-Earthers, for 1 they are uncommon extremely uncommon in the case of partial resetting ; and 2 the result in both cases is an isochron age which is too young to represent the time of formation. Young-Earthers necessarily insist that all ancient isochron ages are really much too old.
In the real world, nothing is perfect. There are some isochron results which are obviously incorrect. The significance of isochron plots is a bit counter-intuitive in some cases. And there are known processes which can yield an incorrect isochron age. Does this leave room to discard isochron dating as entirely unreliable? Not really One of the requirements for isochron dating is that the samples be cogeneticmeaning that they all formed at about the same time from a common pool of material in which the relevant elements and isotopes were distributed reasonably homogeneously.
As described in Figure 4this is how the data are caused to be colinear. Usually it is easy to determine whether or not this requirement is met. The check is not just the isochron plot itself which can in most cases indicate such a problem by failure of the data to fall on a linebut in addition the physical location and geological relationships of the samples selected for dating.
If this requirement is violated, it is sometimes still possible to obtain an isochron plot with reasonably colinear data points. The significance of the computed age, however, will likely not be the last time of crystallization of each sample.
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It might instead be the original time at which the samples became separated from a common pool of matter, or the age of that source material itself.
The resulting age is meaningfulbut it does not have the meaning which one might expect for the dating result i. Consider an old body of rock as evidenced by its good fit to an isochron with distinctly non-zero slope with minerals which melt at different temperatures.
In this example, the minerals with the lowest melting-point having the lowest P -to- D i and D -to- D i ratios:. The rock is heated slowly, and at various times the molten portions are moved to the surface in a series of lava flows. The earliest flows will have an isotopic composition close to that of the minerals with the lowest melting points; the latest flows will have an isotopic composition close to that of the minerals with the highest melting points.
The individual lava flows are not cogenetic. They did not separate at about the same time from an isotopically homogeneous pool of matter. For the sake of simplicity, we will assume three lava flows each with a composition matching the data points of the previous figure:.
It is likely that at least a small amount chemical differentiation will have occurred in each melt, and that as a result the minerals of each individual lava flow will exhibit a much younger isochron the actual age of each flow :. The data points for the overall composition of each flow fall on an isochron line representing the original crystallization time of the source material, which is much greater than the age of any of the flows.
This sort of inherited age is well-understood, discussed thoroughly in the literature, and usually easily avoided by proper selection of samples. Note also that chemical differentiation at the time of the latest melting resulting in the round data points in Figure 17 induces significant scatter into the isochron plot if any measure other than whole-rock is made:.
It is also possible to obtain an isochron with colinear data, whose age has no significance whatsoever. The only reasonably common way is by mixing of materials. Consider two entirely independent sources of material, A and Beach with a different isotopic composition:.
If these sources were mixed together into a single rock, in such a way that the different samples of the rock ended up with different proportions of A and Bwithout chemical differentiation, the end result would be something like this:.
When plotted on an isochron diagram, the mixed data points are all colinear with A and B :. Mixing would appear to be a pernicious problem. Since A and B can be completely unrelated to each other, their individual compositions could plot to a fairly wide range of locations on the graph.
Talkorigins Radiometric Dating is owned by Michael J. Kalous, MA, LCPC. The main focus of his practice is: Specializing in Relationships, Family, Faith, and Self-Development. Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant. Radiometric dating methods are very accurate and very trustworthy. Creationist arguments to the contrary are riddled with flaws, as is the scientific research used by them to support their position.
The line A B could have any slope at all. That fact also allows us to make a rough estimate of the percentage of isochrons that give colinear plots due to mixing. If isochrons of negative slope which must be mixing lines were reasonably common, then we might suspect mixing to be an explanation for a significant fraction of all apparently valid "old" isochrons as well.
That is not the case, however. In addition, there is a relatively simple test which can detect mixing in most cases. If the resulting data points are colinear, then the isochron is likely a result of mixing and probably has no real age significance. Lately it seems that some creationists have latched onto Zhengand reference this paper as if it disproved isochron dating and made room for a young Earth. However, the paper is not terribly helpful to the young-Earth cause.
Zheng discusses four ways in which an incorrect isochron could result:.
Talkorigins radiometric dating - Want to meet eligible single woman who share your zest for life? Indeed, for those who've tried and failed to find the right man offline, online dating can provide. Register and search over 40 million singles: matches and more. If you are a middle-aged man looking to have a good time dating woman half your age, this article is for you. More Bad News for Radiometric Dating Most scientists today believe that life has existed on the earth for billions of years. This belief in long ages for the earth and the existence of life is derived largely from radiometric dating. These long time periods are computed by measuring the ratio of daughter to parent substance in a rock and. Jeune femme - car pour moi l'age est une affaire de ressenti - de nature zen, Talkorigins Radiometric Dating aime vivre loin du brouhaha des grandes villes hyperactives. Meme si j'en reste proche, je cheris mon petit lopin de terre et la beaute.
While each of these processes can be invoked to explain a few confusing or conflicting dating results, none could reasonably be expected to account for all or even most isochron dating results which are incompatible with a young Earth. There are known processes which can result in incorrect isochron ages, and examples of each are known in the field.
If one were to assume that a good-fitting isochron implies a reliable result, one would be correct approximately nine times out of ten. However, accuracy can be improved further with Recently Gill has published in the creationist technical literature, claiming that all Rb-Sr isochron ages can be explained away as meaningless "false" correlations. The abstract reads:. I recommend that interested parties obtain and read this paper. I see four major problems with the creationist claims - sufficient to invalidate the creationist paper rather than as Gill desires the Rb-Sr dating procedure.
The behavior of isochron data is constrained in two ways - both by what is mathematically possible on the plot, as well as by what is physically possible given the chemistry of the relevant elements.
Gill's theoretical treatment concentrates solely on mathematical behavior, while ignoring the underlying chemistry.
It therefore runs the risk of reaching false conclusions by assuming behaviors which are mathematically possible - but chemically unlikely or impossible. Gill's paper does make this sort of bad assumption: that 86 Sr and 87 Sr concentrations are essentially independent:. That is the linchpin of Gill's argument. If that assumption is not accurate, then Gill's argument falls apart.
As discussed earlier in this FAQ, isotopic homogenization occurs in molten rock and even at temperatures short of melting in many cases where the relevant elements migrate freely. Once homogenization has occurred, the quantities of 86 Sr and 87 Sr are no longer independent and cannot be made so. Gill suggests that a large percentage of Rb-Sr isochron ages are incorrect even from mainstream science's point of view:.
Gill's allegations are untrue.