Isotopic Fractionation

Radiocarbon dating of the Shroud of Turin

radiocarbon dating nature

Other than a true age for the meteorites, this could indicate a mixing process, which does not seem likely, or an increase in decay rates, for which a mechanism would need to be found. This also could make flows on the land appear older than they are, since their Ar40 would also have a harder time escaping. Why older dates would be found lower in the geologic column especially for K-Ar dating In general, potassium-argon dates appear to be older the deeper one goes in the crust of the earth. Gove has written in the respected scientific journal Radiocarbon that: Controls The three control samples, the approximate ages of which were made known to the laboratories, are listed below.

Navigation menu

The former would indicated adsorbed argon 40, which would not give a true age. And quite a few other dates are often much, much farther off. It would be prudent to treat these results with caution until further investigations are made. This is from a paper by Austin available at ICR. It is undoubtedly being claimed that the mean values ascend as one goes up the geologic column. If this is so, then the question remains, for super isochrons on the geologic column which can be shown not to be caused by mixing, how do they correlate with other methods, and with the expected dates for their geologic period?

So if we take a lava flow and date several minerals for which one knows the daughter element is excluded, we should always get the exact same date, and it should agree with the accepted age of the geological period. I doubt it very much. If the radiometric dating problem has been solved in this manner, then why do we need isochrons, which are claimed to be more accurate? The same question could be asked in general of minerals that are thought to yield good dates.

Mica is thought to exclude Sr, so it should yield good Rb-Sr dates. But are dates from mica always accepted, and do they always agree with the age of their geologic period? Indeed, there are a number of conditions on the reliability of radiometric dating. For example, for K-Ar dating, we have the following requirements:. There must have been no incorporation of Ar40 into the mineral at the time of crystallization or a leak of Ar40 from the mineral following crystallization.

The earth is supposed to be nearly 5 billion years old, and some of these methods seem to verify ancient dates for many of earth's igneous rocks. The answer is that these methods, are far from infallible and are based on three arbitrary assumptions a constant rate of decay, an isolated system in which no parent or daughter element can be added or lost, and a known amount of the daughter element present initially.

Heating and deformation of rocks can cause these atoms to migrate, and water percolating through the rocks can transport these substances and redeposit them. These processes correspond to changing the setting of the clock hands. Not infrequently such resetting of the radiometric clocks is assumed in order to explain disagreements between different measurements of rock ages.

It is known that neutrinos interact with atomic nucleii, so a larger density of neutrinos could have sped up radioactive decay and made matter look old in a hurry. Some more quotes from the same source:. In the lead-uranium systems both uranium and lead can migrate easily in some rocks, and lead volatilizes and escapes as a vapor at relatively low temperatures. It has been suggested that free neutrons could transform Pb first to Pb and then to Pb, thus tending to reset the clocks and throw thorium-lead and uranium-lead clocks completely off, even to the point of wiping out geological time.

Furthermore, there is still disagreement of 15 percent between the two preferred values for the U decay constant. Potassium volatilizes easily, is easily leached by water, and can migrate through the rocks under certain conditions. Furthermore, the value of the decay constant is still disputed, although the scientific community seems to be approaching agreement.

Historically, the decay constants used for the various radiometric dating systems have been adjusted to obtain agreement between the results obtained. Argon, the daughter substance, makes up about one percent of the atmosphere, which is therefore a possible source of contamination.

However, since it is possible for argon to be formed in the rocks by cosmic radiation, the correction may also be in error. Argon from the environment may be trapped in magma by pressure and rapid cooling to give very high erroneous age results. Rubidium parent atoms can be leached out of the rock by water or volatilized by heat.

All of these special problems as well as others can produce contradictory and erroneous results for the various radiometric dating systems. So we have a number of mechanisms that can introduce errors in radiometric dates. Heating can cause argon to leave a rock and make it look younger. In general, if lava was heated after the initial flow, it can yield an age that is too young. If the minerals in the lava did not melt with the lava, one can obtain an age that is too old.

Leaching can also occur; this involves water circulating in rock that can cause parent and daughter elements to enter or leave the rock and change the radiometric age. Thus it is easy to rationalize any date that is obtained. If a date is too old, one can say that the mineral did not melt with the lava. Maybe it got included from surrounding rock as the lava flowed upward.

If the date is too young, one can say that there was a later heating event. One can also hypothesize that leaching occurred. But then it is claimed that we can detect leaching and heating. But how can we know that this claim is true, without knowing the history of rocks and knowing whether they have in fact experienced later heating or leaching? The problems are compounded because many of the parent and daughter substances are mobile, to some extent.

I believe that all parent substances are water soluble, and many of the daughter products as well. A few sources have said that Sr is mobile in rock to some extent. This could cause trouble for Rb-Sr dating. In fact, some sources say that Sr and Ar have similar mobilities in rock, and Ar is very mobile.

Especially the gaseous radioactive decay byproducts such as argon, radon, and helium are mobile in rock. So if a rock has tiny cracks permitting gas to enter or escape or permitting the flow of water, the radiometric ages could be changed substantially even without the rock ever melting or mixing. Now, there is probably not much argon in a rock to start with. So the loss of a tiny amount of argon can have significant effects over long time periods.

A loss of argon would make the rock look younger. In a similar way, argon could enter the rock from the air or from surrounding rocks and make it look older. And this can also happen by water flowing through the rock through tiny cracks, dissolving parent and daughter elements. It would be difficult to measure the tiny changes in concentration that would suffice to make large changes in the radiometric ages over long time periods.

I also question the assertion that argon, for example, is excluded from certain minerals when they crystallize and never enters later on.

Geologists often say that ages that are too old are due to excess argon. So it must be possible for that excess argon to get in, even though the crystal is supposed to exclude it. Here is one such reference, although this is to a mineral that does not exclude argon:. In a few cases, argon ages older than that of the Earth which violate local relative age patterns have even been determined for the mineral biotite.

Such situations occur mainly where old rocks have been locally heated, which released argon into pore spaces at the same time that new minerals grew. Under favourable circumstances the isochron method may be helpful, but tests by other techniques may be required. For example, the rubidium-strontium method would give a valid isotopic age of the biotite sample with inherited argon.

Another problem is that the crystal structure typically has imperfections and impurities. For example, different kinds of quartz have different colors due to various impurities that are included but not part of the repetitive unit of the quartz crystal.

So even if the crystal excludes the daughter element, it could be present in impurities. Thus crystals, as they form, may have tiny imperfections that accept parent and daughter products in the same ratios as they occur in the lava, so one can inherit ages from the lava into minerals in this way.

It is also possible that parent and daughter elements could be present in boundaries between regular crystal domains. I don't know how we can be sure that a crystal will exclude argon or other daughter substances except by growing it in the laboratory under many conditions.

There can also be argon or other daughter products added from the air or from other rocks. One could say that we can detect whether the daughter is embedded in the crystal structure or not.

But this would require an atom by atom analysis, which I do not believe is practical. Why K-Ar dating is inaccurate Since K-Ar potassium-argon dating is one of the most prevalent techniques, some special commentary about it is in order.

Potassium is about 2. Argon is about 3. This is about one ten millionth of the mass of the rock, a very tiny percentage. And yet, with a large amount of argon in the air and also filtering up from rocks below, and with excess argon in lava, with argon and potassium water soluble, and argon mobile in rock, we are still expecting this wisp of argon to tell us how old the rock is! The percentage of Ar40 is even less for younger rocks. For example, it would be about one in million for rocks in the vicinity of 57 million years old.

To get one part in 10 million of argon in a rock in a thousand years, we would only need to get one part in 10 billion entering the rock each year. This would be less than one part in a trillion entering the rock each day, on the average. This would suffice to give a rock having an average concentration of potassium, a computed potassium-argon age of over million years! We can also consider the average abundance of argon in the crust.

This implies a radiometric age of over 4 billion years. So a rock can get a very old radiometric age just by having average amounts of potassium and argon. It seems reasonable to me that the large radiometric ages are simply a consequence of mixing, and not related to ages at all, at least not necessarily the ages of the rocks themselves.

The fact that not all of the argon is retained would account for smaller amounts of argon near the surface, as I will explain below. This could happen because of properties of the magma chambers, or because of argon being given off by some rocks and absorbed by others.

I don't see how one can possibly know that there are no tiny cracks in rocks that would permit water and gas to circulate. The rates of exchange that would mess up the dates are very tiny.

It seems to me to be a certainty that water and gas will enter rocks through tiny cracks and invalidate almost all radiometric ages. Let me illustrate the circulation patterns of argon in the earth's crust. So argon is being produced throughout the earth's crust, and in the magma, all the time. In fact, it probably rises to the top of the magma, artificially increasing its concentration there.

Now, some rocks in the crust are believed not to hold their argon, so this argon will enter the spaces between the rocks. Leaching also occurs, releasing argon from rocks. Heating of rocks can also release argon. Argon is released from lava as it cools, and probably filters up into the crust from the magma below, along with helium and other radioactive decay products.

All of this argon is being produced and entering the air and water in between the rocks, and gradually filtering up to the atmosphere. But we know that rocks absorb argon, because correction factors are applied for this when using K-Ar dating. So this argon that is being produced will leave some rocks and enter others.

The partial pressure of argon should be largest deepest in the earth, and decrease towards the surface. This would result in larger K-Ar ages lower down, but lower ages nearer the surface.

So this confirms that argon can travel from rock to rock when one rock is heated. Now, argon is very soluble in magma, which can hold a lot of it:. After the material was quenched, the researchers measured up to 0.

They noted, 'The solubility of Ar in the minerals is surprisingly high'. I note that this concentration of argon, if it were retained in the rock, would suffice to give it a geological age well over nillion years, assuming an average concentration of potassium.

This is from a paper by Austin available at ICR. This paper also discusses Mount St. Helens K-Ar dating, and historic lava flows and their excess argon. So magma holds tremendous amounts of argon. Now, consider an intrusive flow, which cools within the earth. All its argon will either remain inside and give an old age to the flow, or will travel through surrounding rock, where it can be absorbed by other rocks.

So magma should have at least 20 times as much argon as a rock million years old by K-Ar dating. In fact, the argon in the magma may well be even higher, as it may concentrate near the top. This amount of argon is enough to raise 20 times the volume of magma to a K-Ar age of million years, and probably times the volume of the magam to an age of 57 million years.

So one sees that there is a tremendous potential for age increases in this way. It is not necessary for this increase in age to happen all at once; many events of this nature can gradually increase the K-Ar ages of rocks. In general, older rocks should have more argon because they have been subject to more exposure to such argon, but their true age is not necessarily related to their K-Ar radiometric age.

We can also consider that most volcanoes and earthquakes occur at boundaries between plates, so if the lava has flowed before, it is likely to flow again nearby, gradually increasing the age. I suppose earthquakes could also allow the release of argon from the magma. Other mechanisms include dissolving of rock, releasing its argon, fracturing of rock, with release of argon, argon from cooling lava under water entering the water and entering other rocks, and argon from cooling lave entering subterranean water and being transported to other rock.

There are so many mechanisms that it is hard to know what pattern to expect, and one does not need to rely on any one of them such as more argon in the magma in the past to account for problems in K-Ar dating.

Since even rocks with old K-Ar dates still absorb more argon from the atmosphere in short time periods, it follows that rocks should absorb quite a bit of argon over long time periods, especially at higher pressures.

In fact, if a rock can absorb only a ten millionth part of argon, that should be enough to raise its K-Ar age to over million years, assuming an average amounts of potassium. It wouldn't require many internal cracks to allow a ten millionth part of argon to enter. Also, as the rock deforms under pressure, more cracks are likely to form and old ones are likely to close up, providing more opportunity for argon and other gases to enter.

I mentioned a number of possibilities that could cause K-Ar dates to be much older than the true ages of the rocks. Here is another way that K-Ar dates can be too old: If we assume the earth went through a catastrophe recently, then the crustal plates might have been agitated, permitting lava and argon to escape from the magma. Thus a lot of argon would be filtering up through the crust.

As intrusive flows of lava cooled inside the crust, they would have been in an environment highly enriched in argon, and thus would not have gotten rid of much of their argon. Thus they would have hardened with a lot of argon inside. This would make them appear old.

The same goes for extrusive flows on the surface, since argon would be filtering up through the earth and through the lava as it cooled. In areas where tremendous tectonic activity has taken place, highly discordant values for the ages are obtained. The difficulties associated are numerous and listed as follows:. There seems to be a great deal of question regarding the branching ratio for K40 into Ar40 and Ca But the value is not really known. The observed value is between 0.

However, this doesn't remedy the situation and the ages are still too high [low? The geochronologists credit this to "argon leakage". There is far too much Ar40 in the earth for more than a small fraction of it to have been formed by radioactive decay of K This is true even if the earth really is 4. In the atmosphere of the earth, Ar40 constitutes This is around times the amount that would be generated by radioactive decay over the age of 4.

Certainly this is not produced by an influx from outer space. Thus, a large amount of Ar40 was present in the beginning. Since geochronologists assume that errors due to presence of initial Ar40 are small, their results are highly questionable. Argon diffuses from mineral to mineral with great ease. It leaks out of rocks very readily and can move from down deep in the earth, where the pressure is large, and accumulate in an abnormally large amount in the surface where rock samples for dating are found.

They would all have excess argon due to this movement. This makes them appear older. Rocks from deeper in the crust would show this to a lesser degree. Also, since some rocks hold the Ar40 stronger than others, some rocks will have a large apparent age, others smaller ages, though they may actually be the same age. If you were to measure Ar40 concentration as function of depth, you would no doubt find more of it near the surface than at deeper points because it migrates more easily from deep in the earth than it does from the earth into the atmosphere.

It is easy to see how the huge ages are being obtained by the KAr40 radiometric clock, since surface and near-surface samples will contain argon due to this diffusion effect. Some geochronologists believe that a possible cause of excess argon is that argon diffuses into mineral progressively with time. Significant quantities of argon may be introduced into a mineral even at pressures as low as one bar.

If such [excessive] ages as mentioned above are obtained for pillow lavas, how are those from deep-sea drilling out in the Atlantic where sea-floor spreading is supposed to be occurring? Potassium is found to be very mobile under leaching conditions. This could move the "ages" to tremendously high values.

Ground-water and erosional water movements could produce this effect naturally. Rocks in areas having a complex geological history have many large discordances.

In a single rock there may be mutually contaminating, potassium- bearing minerals. There is some difficulty in determining the decay constants for the KAr40 system. Geochronologists use the branching ratio as a semi-emperical, adjustable constant which they manipulate instead of using an accurate half-life for K A number of recent lava flows within the past few hundred years yield potassium-argon ages in the hundreds of thousands of years range.

This indicates that some excess argon is present. Where is it coming from? And how do we know that it could not be a much larger quantity in other cases? If more excess argon were present, then we could get much older ages. It is true that an age difference in the hundreds of thousands of years is much too small to account for the observed K-Ar ages.

But excess argon is commonly invoked by geologists to explain dates that are too old, so I'm not inventing anything new. Second, there may have been a lot more more argon in the magma in the past, and with each eruption, the amount decreased. So there would have been a lot more excess argon in the past, leading to older ages.

For rocks that are being dated, contamination with atmospheric argon is a persistent problem that is mentioned a number of times. Thus it is clear that argon enters rock easily.

It is claimed that we can know if a rock has added argon by its spectrum when heated; different temperatures yield different fractions of argon. It is claimed that the argon that enters from the atmosphere or other rocks, is less tightly bound to the crystal lattice, and will leave the rock at a lower temperature.

But how do we know what happens over thousands of years? It could be that this argon which is initially loosely bound if it is so initially gradually becomes more tightly bound by random thermal vibrations, until it becomes undetectable by the spectrum technique. The fact that rock is often under high pressure might influence this process, as well.

The branching ratio problem We now consider in more detail one of the problems with potassium-argon dating, namely, the branching ratio problem. Here is some relevant information that was e-mailed to me. There are some very serious objections to using the potassium-argon decay family as a radiometric clock.

The geochronologist considers the Ca40 of little practical use in radiometric dating since common calcium is such an abundant element and the radiogenic Ca40 has the same atomic mass as common calcium. Here the actual observed branching ratio is not used, but rather a small ratio is arbitrarily chosen in an effort to match dates obtained method with U-Th-Pb dates. The branching ratio that is often used is 0. Thus we have another source of error for K-Ar dating.

Henke criticized some statements in my article taken from Slusher about the branching ratio for potassium. Slusher asserted that the best known value of the branching ratio was not always used in computing K-Ar radiometric ages. Unfortunately, Dalrymple says nothing about the calculation of the branching ratio.

He simply gives the correct value for the K-Ar system. The issue is not just how well this was known in the past, but which value was actually used, and whether dates published in the past have been computed with the most recent value.

Often values for constants are standardized, so that the values actually used may not be the most accurate known. All that Dalrymple says is that his ages were all recomputed using the most accurate values of the constants. This implies that some of them were originally computed using less accurate values, which is similar to Slusher's point.

He admits that Slusher's statements about it would have been true in the 's and early 's, but are no longer true. But he didn't say when the correct value for the branching ratio began to be used. Even some figures from Faure, Principles of Isotope Geology, are based on another constant that is 2 or 3 percent too low, according to Dalrymple, and so there may be many ages in the literature that need revision by small amounts.

However, Harland et al imply that nearly the correct value for the branching ratio has been known and used since the mid-fifties. We now consider whether they can explain the observed dates. In general, the dates that are obtained by radiometric methods are in the hundreds of millions of years range. One can understand this by the fact that the clock did not get reset if one accepts the fact that the magma "looks" old, for whatever reason.

That is, we can get both parent and daughter elements from the magma inherited into minerals that crystallize out of lava, making these minerals look old. Since the magma has old radiometric dates, depending on how much the clock gets reset, the crust can end up with a variety of younger dates just by partially inheriting the dates of the magma. Thus any method based on simple parent to daughter ratios such as Rb-Sr dating is bound to be unreliable, since there would have to be a lot of the daughter product in the magma already.

And Harold Coffin's book Creation by Design lists a study showing that Rb-Sr dates are often inherited from the magma. Even the initial ratios of parent and daughter elements in the earth do not necessarily indicate an age as old as 4.

Radioactive decay would be faster in the bodies of stars, which is where scientists assume the heavy elements formed. Imagine a uranium nucleus forming by the fusion of smaller nucleii. At the moment of formation, as two nucleii collide, the uranium nucleus will be somewhat unstable, and thus very likely to decay into its daughter element.

The same applies to all nucleii, implying that one could get the appearance of age quickly. Of course, the thermonuclear reactions in the star would also speed up radioactive decay. But isochrons might be able to account for pre-existing daughter elements. Furthermore, some elements in the earth are too abundant to be explained by radioactive decay in 4.

Some are too scarce such as helium. So it's not clear to me how one can be sure of the 4. Why older dates would be found lower in the geologic column especially for K-Ar dating In general, potassium-argon dates appear to be older the deeper one goes in the crust of the earth. We now consider possible explanations for this. There are at least a couple of mechanisms to account for this. In volcano eruptions, a considerable amount of gas is released with the lava. This gas undoubtedly contains a significant amount of argon Volcanos typically have magma chambers under them, from which the eruptions occur.

It seems reasonable that gas would collect at the top of these chambers, causing artificially high K-Ar radiometric ages there. In addition, with each successive eruption, some gas would escape, reducing the pressure of the gas and reducing the apparent K-Ar radiometric age.

Thus the decreasing K-Ar ages would represent the passage of time, but not necessarily related to their absolute radiometric ages. As a result, lava found in deeper layers, having erupted earlier, would generally appear much older and lava found in higher layers, having erupted later, would appear much younger. This could account for the observed distribution of potassium-argon dates, even if the great sedimantary layers were laid down very recently.

In addition, lava emerging later will tend to be hotter, coming from deeper in the earth and through channels that have already been warmed up. This lava will take longer to cool down, giving more opportunity for enclosed argon to escape and leading to younger radiometric ages.

Another factor is that rocks absorb argon from the air. It is true that this can be accounted for by the fact that argon in the air has Ar36 and Ar40, whereas only Ar40 is produced by K-Ar decay.

But for rocks deep in the earth, the mixture of argon in their environment is probably much higher in Ar40, since only Ar40 is produced by radioactive decay. As these rocks absorb argon, their radiometric ages would increase. This would probably have a larger effect lower down, where the pressure of argon would be higher.

Or it could be that such a distribution of argon pressures in the rocks occurred at some time in the past. This would also make deeper rocks tend to have older radiometric ages. Recent lava flows often yield K-Ar ages of about , years.

This shows that they contain some excess argon, and not all of it is escaping. If they contained a hundred times more excess argon, their K-Ar ages would be a hundred times greater, I suppose. And faster cooling could increase the ages by further large factors. I also read of a case where a rock was K-Ar dated at 50 million years, and still susceptible to absorbing argon from the air.

This shows that one might get radiometric ages of at least 50 million years in this way by absorbing Ar40 deep in the earth without much Ar36 or Ar38 present. If the pressure of Ar40 were greater, one could obtain even greater ages. Yet another mechanism that can lead to decreasing K-Ar ages with time is the following, in a flood model: One can assume that at the beginning of the flood, many volcanoes erupted and the waters became enriched in Ar Then any lava under water would appear older because its enclosed Ar40 would have more trouble escaping.

As time passed, this Ar40 would gradually pass into the atmosphere, reducing this effect and making rocks appear younger. In addition, this would cause a gradient of Ar40 concentrations in the air, with higher concentrations near the ground. This also could make flows on the land appear older than they are, since their Ar40 would also have a harder time escaping. Plaisted wants to give his readers the impression that argon can readily move in and out of minerals and, therefore, the gas is too volatile for radiometric dating.

Specifically, he quotes one of his anonymous friends that claims that argon easily diffuses from minerals p. Of course, these statements are inaccurate generalizations. Geochronologists are aware that excess argon may accumulate on mineral surfaces and the surface argon would be removed before analysis.

However, Henke admits that this can happen in some cases. He states that geologists are aware of this problem, and make allowances for it. But it is more difficult to remove argon that has deposited on cracks in the mineral, which can be difficult to see.

Henke referenced Davis A. Young frequently, but I was not able to find Young referenced in any of the other sources I examined except Dalrymple Henke states that hornblendes retain argon very well, but then later says that they can easily absorb excess argon.

Geologists also recognize that heating causes argon to leave minerals, and that dissolved argon in a mineral that does not escape will become incorporated into it, artificially increasing its K-Ar age. I will comment more on this below, but a few comments now are appropriate. For a temperature of K 27 degrees C , there is no significant argon loss from biotite.

At K degrees C , there is a slow but significant diffusion rate. At K degrees C , loss of argon is quite rapid. To lose one percent in one year requires a temperature of nearly degrees centigrade. Thus the temperature does not have to be very high for argon to move through rock. This also justifies Slusher's statements about argon moving in and out of rocks with ease. However, it does not seem likely that sedimentary rocks would be this hot very often, except near lava or magma flows.

But argon does not need to move through all rock in order to influence radiometric dates, it only has to reach ancient lava flows. This it can do by following the path of the ancient lava flow itself, coming up along the path of the magma. As the magma or lava cools, this path will consist entirely of hot magma or lava, and so the argon will have a free path, and will continue to enter the magma as it cools.

Thus in many cases, the lava or magma will never completely degas, and extra argon will end up trapped in the cooled rock. This will result in artificially increased K-Ar ages. Many ancient lava flows are relatively flat, in contrast to modern ones. Also, they appear to have been covered over quickly. The flatness means that the lava is a contiguous mass, and can still be reached from the hot magma by a continuous path of hot rock.

The fact that they soon are covered over means that the argon has a hard time escaping vertically from the lava, so argon coming up from the mantle will tend to enter the cooling rock. Both facts will tend to produce artificially high K-Ar ages in these flows which will not be seen in modern lava flows in the same manner. Modern lava flows often come down the sides of volcanoes, and thus become separated from their source by large distances. Also, they do not get quickly buried by additional sediment.

Thus modern lava flows are not subject to the same mechanism of artificial increases in their K-Ar ages as are ancient ones. Also, it is reasonable to assume that as argon leaves the mantle in successive eruptions, the amount of argon remaining is reduced, so that later lava flows are less susceptible to such artificial increases in age.

The path of magma also becomes longer for later flows, and the magma probably also is a little cooler, inhibiting argon flow. Thus later lava flows give younger K-Ar ages. Another point to note is that even after it cools, the lava or magma may still have many cracks in it, permitting argon to flow. This argon will tend to deposit on the surface of minerals, but with the passage of time it will tend to diffuse into the interior, even if only a very small distance.

This is especially true as the lava is cooling. This will make it more difficult to detect this added argon by the spectrum test described below.

Also, the diffusion of argon in cracks and channels of a mineral is likely much less temperature-dependent than diffusion through unbroken regions of the mineral, since diffusion through cracks and channels simply involves jumps through the air.

By a combination of diffusion through cracks and channels, and short passages through unbroken regions of the mineral, argon may be able to reach a considerable distance into the mineral. At low temperatures, this may become the dominant means by which argon diffuses into a mineral, but the effect of this kind of diffusion at low temperatures may not be evident until many years have passed. Thus it may take experiments lasting 50 or years at low temperatures to detect the effects of this kind of diffusion of argon, which however could be significantly increasing the K-Ar ages of minerals over long time periods.

Dickin Radiogenic Isotope Geology, , p. She has rejected the theory of the "invisible reweaving", pointing out that it would be technically impossible to perform such a repair without leaving traces, and that she found no such traces in her study of the shroud. Prof H E Gove, former professor emeritus of physics at the University of Rochester and former director of the Nuclear Structure Research Laboratory at the University of Rochester, helped to invent radiocarbon dating and was closely involved in setting up the shroud dating project.

He also attended the actual dating process at the University of Arizona. Gove has written in the respected scientific journal Radiocarbon that: If so, the restoration would have had to be done with such incredible virtuosity as to render it microscopically indistinguishable from the real thing. Even modern so-called invisible weaving can readily be detected under a microscope, so this possibility seems unlikely. It seems very convincing that what was measured in the laboratories was genuine cloth from the shroud after it had been subjected to rigorous cleaning procedures.

Probably no sample for carbon dating has ever been subjected to such scrupulously careful examination and treatment, nor perhaps ever will again. In , professors of statistics Marco Riani and Anthony C.

Atkinson wrote in a scientific paper that the statistical analysis of the raw dates obtained from the three laboratories for the radiocarbon test suggests the presence of contamination in some of the samples.

In December Professor Timothy Jull , a member of the original radiocarbon-dating team and editor of the peer-reviewed journal Radiocarbon , coauthored an article in that journal with Rachel A Freer-Waters. They examined a portion of the radiocarbon sample that was left over from the section used by the University of Arizona in for the carbon dating exercise, and were assisted by the director of the Gloria F Ross Center for Tapestry Studies.

They found "only low levels of contamination by a few cotton fibers" and no evidence that the samples actually used for measurements in the C14 dating processes were dyed, treated, or otherwise manipulated.

They concluded that the radiocarbon dating had been performed on a sample of the original shroud material. In March Giulio Fanti, professor of mechanical and thermal measurement at the University of Padua conducted a battery of experiments on various threads that he believes were cut from the shroud during the Carbon dating, and concluded that they dated from BCE to CE, potentially placing the Shroud within the lifetime of Jesus of Nazareth. A determination of the kinetics of vanillin loss suggest the shroud is between and years old.

Even allowing for errors in the measurements and assumptions about storage conditions, the cloth is unlikely to be as young as years". Pictorial evidence dating from c. Others contend that repeated handling of this kind greatly increased the likelihood of contamination by bacteria and bacterial residue compared to the newly discovered archaeological specimens for which carbon dating was developed.

Bacteria and associated residue bacteria by-products and dead bacteria carry additional carbon that would skew the radiocarbon date toward the present. Rodger Sparks, a radiocarbon expert from New Zealand, had countered that an error of thirteen centuries stemming from bacterial contamination in the Middle Ages would have required a layer approximately doubling the sample weight.

Pyrolysis-mass-spectrometry examination failed to detect any form of bioplastic polymer on fibers from either non-image or image areas of the shroud. Professor Harry Gove, director of Rochester's laboratory one of the laboratories not selected to conduct the testing , once hypothesised that a "bioplastic" bacterial contamination, which was unknown during the testing, could have rendered the tests inaccurate.

He has however also acknowledged that the samples had been carefully cleaned with strong chemicals before testing. He inspected the Arizona sample material before it was cleaned, and determined that no such gross amount of contamination was present even before the cleaning commenced.

Others have suggested that the silver of the molten reliquary and the water used to douse the flames may have catalysed the airborne carbon into the cloth. They concluded that the proposed carbon-enriching heat treatments were not capable of producing the claimed changes in the measured radiocarbon age of the linen, that the attacks by Kouznetsov et al. In Dr John Jackson of the Turin Shroud Center of Colorado proposed a new hypothesis — namely the possibility of more recent enrichment if carbon monoxide were to slowly interact with a fabric so as to deposit its enriched carbon into the fabric, interpenetrating into the fibrils that make up the cloth.

Jackson proposed to test if this were actually possible. Before conducting the tests, he told the BBC that "With the radiocarbon measurements and with all of the other evidence which we have about the Shroud, there does seem to be a conflict in the interpretation of the different evidence.

The results of the tests were to form part of a documentary on the Turin Shroud which was to be broadcast on BBC2. Other similar theories include that candle smoke rich in carbon dioxide and the volatile carbon molecules produced during the two fires may have altered the carbon content of the cloth, rendering carbon-dating unreliable as a dating tool. In March Professor Ramsey reported back on the testing that: These initial tests show no significant reaction — even though the sensitivity of the measurements is sufficient to detect contamination that would offset the age by less than a single year.

This is to be expected and essentially confirms why this sort of contamination has not been considered a serious issue before. He also added that there is as yet no direct evidence to suggest the original radiocarbon dates are not accurate. In , Ramsey commented that in general "there are various hypotheses as to why the dates might not be correct, but none of them stack up. A sample in which 14 C is no longer detectable is said to be "radiocarbon dead.

They are derived from biomass that initially contained atmospheric levels of 14 C. But the transformation of sedimentary organic debris into oil or woody plants into coal is so slow that even the youngest deposits are radiocarbon dead. The abundance of 14 C in an organic molecule thus provides information about the source of its carbon.

If 14 C is present at atmospheric levels, the molecule must derive from a recent plant product. The pathway from the plant to the molecule may have been indirect or lengthy, involving multiple physical, chemical, and biological processes.

Levels of 14 C are affected significantly only by the passage of time. If a molecule contains no detectable 14 C it must derive from a petrochemical feedstock or from some other ancient source. Intermediate levels of 14 C can represent either mixtures of modern and dead carbon or carbon that was fixed from the atmosphere less than 50, years ago.

Signals of this kind are often used by chemists studying natural environments. A hydrocarbon found in beach sediments, for example, might derive from an oil spill or from waxes produced by plants. If isotopic analyses show that the hydrocarbon contains 14 C at atmospheric levels, it's from a plant.

Iamges: radiocarbon dating nature

radiocarbon dating nature

He inspected the Arizona sample material before it was cleaned, and determined that no such gross amount of contamination was present even before the cleaning commenced. Therefore, it is clear that radiocarbon dating is not based on some imprecise science, cooking up evidence to fit the idea or data. This would knock our C, potassium-argon, and uranium-lead dating measurements into a cocked hat!

radiocarbon dating nature

We would also do well to remember the standard rule of thumb for precision in paleographic dating, Turner writes, "For book hands, a period of 50 years is the least acceptable spread of time ". Generally, excess 40Ar is observed in minerals that have been exposed to a high partial pressure of argon during regional metamorphism, in pegmatites

radiocarbon dating nature

Why methods in general are inaccurate. Let's apply radiocarbon dating nature known dating methods to Gi that are thought to apply to this kind of rock, and obtain ages from each one. Of course, in the traditional view, the matter out of which the solar system was formed would have been very old at the start, radiocarbon dating nature any event, and so the radiometric ages obtained from meteorites or from the earth do not necessarily tell us anything about the age of the solar system or the age of the earth. Radiocarbon dating nature type of lava cools quickly, leaving little time for crystals to form, and forms basalt. This would also make deeper rocks tend to have older teenage dating guidelines for parents ages.