With you uranium thorium dating problems sorry
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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.
The problem with plutonium is that it can be chemically separated from the waste and perhaps used in bombs.
Uranium thorium dating problems
It is publicly known that even reactor-grade plutonium can be made into a bomb if done carefully. By avoiding plutonium altogether, thorium cycles are superior in this regard. Besides avoiding plutonium, Thorium has additional self-protection from the hard gamma rays emitted due to U as discussed above. This makes stealing Thorium based fuels more challenging.
Also, the heat from these gammas makes weapon fabrication difficult, as it is hard to keep the weapon pit from melting due to its own heat. Note, however, that the gammas come from the decay chain of U, not from U itself. This means that the contaminants could be chemically separated and the material would be much easier to work with.
U has a 70 year half-life so it takes a long time for these gammas to come back. Then, it will decay directly to pure U By this challenging route, one could obtain weapons material. But Pa has a 27 day half-life, so once the waste is safe for a few times this, weapons are out of the question. So concerns over people stealing spent fuel are largely reduced by Th, but the possibility of the owner of a Th-U reactor obtaining bomb material is not.
ate: See our full page on Molten Salt Reactors for more info. In these, fuel is not cast into pellets, but is rather dissolved in a vat of liquid salt. The chain reaction heats the salt, which naturally convects through a heat exchanger to bring the heat out to a turbine and make electricity. Online chemical processing removes fission product neutron poisons and allows online refueling eliminating the need to shut down for fuel management, etc.
The MSRE successfully proved that the concept has merit and can be operated for extended amounts of time. It competed with the liquid metal cooled fast breeder reactors LMFBRs for federal funding and lost out.
How Carbon Dating Works
Alvin Weinberg discusses the history of this project in much detail in his autobiography, The First Nuclear Era [amazon. Instead, it calculates an age from the degree to which secular equilibrium has been restored between the radioactive isotope thorium and its radioactive parent uranium within a sample. Thorium is not soluble in natural water under conditions found at or near the surface of the earth, so materials grown in or from this water do not usually contain thorium.
As time passes after such material has formed, uranium in the sample with a half-life ofyears decays to thorium At secular equilibrium, the number of thorium decays per year within a sample is equal to the number of thorium produced, which also equals the number of uranium decays per year in the same sample.
InJohn Jolya professor of geology from the University of Dublinfound higher radium contents in deep sediments than in those of the continental shelf, and suspected that detrital sediments scavenged radium out of seawater.
Piggot and Urry found inthat radium excess corresponded with an excess of thorium. It took another 20 years until the technique was applied to terrestrial carbonates speleothems and travertines.
In the late s the method was refined by mass spectrometry. After Viktor Viktorovich Cherdyntsev 's landmark book about uranium had been translated into English, U-Th dating came to widespread research attention in Western geology. U-series dating is a family of methods which can be applied to different materials over different time ranges.
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. 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. 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?
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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.
Thorium As Nuclear Fuel
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. 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.
Meet Kenya call girls and Nairobi massage girls waiting to give you sweet extras. See the best Nairobi escorts providing hot kuma Uranium Thorium Dating Problems For Short tamu, tantalising campus divas ready to give you the real Nairobi xxx/ Thorium is a naturally occurring radioactive metal found in soil, rock, and water. Thorium is a naturally occurring radioactive metal that is found in soil, rock, and water. It is formed by the radioactive decay of uranium. Minerals such as monazite, thorite, and thorianite are rich in thorium and may be mined for the metal. Jan 23, Uranium-lead radioisotope dating is now the preferred absolute dating method among geochronologists. Consequently, the scientific community and the general public around the world appear convinced of the earth's claimed great antiquity. But there are several problems with this particular radiometric dating treasuresforthesoul.com: Troy Lacey.
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. I did see in one reference the statement that some parent-to-daughter ratio yielded more accurate dates than isochrons.
To me, this suggests the possibility that geologists themselves recognize the problems with isochrons, and are looking for a better method. The impression I have is that geologists are continually looking for new methods, hoping to find something that will avoid problems with existing methods. But then problems also arise with the new methods, and so the search goes on. Furthermore, here is a brief excerpt from a recent article which also indicates that isochrons often have severe problems.
If all of these isochrons indicated mixing, one would think that this would have been mentioned: The geological literature is filled with references to Rb-Sr isochron ages that are questionable, and even impossible.
Woodmorappepp. Faurepp. Zhengpp. Zheng pp. He comes closest to recognizing the fact that the Sr concentration is a third or confounding variable in the isochron simple linear regression. Snelling discusses numerous false ages in the U-Pb system where isochrons are also used. However, the U-Th-Pb method uses a different procedure that I have not examined and for which I have no data. Many of the above authors attempt to explain these "fictitious" ages by resorting to the mixing of several sources of magma containing different amounts of Rb, Sr, and Sr immediately before the formation hardens.
AkridgeArmstrongArndtsBrown, Helmick and Baumann all discuss this factor in detail. Anyway, if isochrons producing meaningless ages can be produced by mixing, and this mixing cannot be detected if three or maybe even two, with fractionation sources are involved, and if mixing frequently occurs, and if simple parent-to-daughter dating also has severe problems, as mentioned earlier, then I would conclude that the reliability of radiometric dating is open to serious question.
The many acknowledged anomalies in radiometric dating only add weight to this argument. I would also mention that there are some parent-to-daughter ratios and some isochrons that yield ages in the thousands of years for the geologic column, as one would expect if it is in fact very young.
One might question why we do not have more isochrons with negative slopes if so many isochrons were caused by mixing. This depends on the nature of the samples that mix.
It is not necessarily true that one will get the same number of negative as positive slopes. If I have a rock X with lots of uranium and lead daughter isotope, and rock Y with less of both relative to non-radiogenic lea then one will get an isochron with a positive slope.
If rock X has lots of uranium and little daughter product, and rock Y has little uranium and lots of lead daughter product relative to non-radiogenic lea then one will get a negative slope.
This last case may be very rare because of the relative concentrations of uranium and lead in crustal material and subducted oceanic plates. Another interesting fact is that isochrons can be inherited from magma into minerals. Earlier, I indicated how crystals can have defects or imperfections in which small amounts of magma can be trapped. This can result in dates being inherited from magma into minerals. This can also result in isochrons being inherited in the same way.
So the isochron can be measuring an older age than the time at which the magma solidified. This can happen also if the magma is not thoroughly mixed when it erupts. If this happens, the isochron can be measuring an age older than the date of the eruption.
This is how geologists explain away the old isochron at the top of the Grand Canyon. From my reading, isochrons are generally not done, as they are expensive.
Isochrons require more measurements than single parent-to-daughter ratios, so most dates are based on parent-to-daughter ratios. So all of the scenarios given apply to this large class of dates.
Of course, any process that tends to concentrate or deplete uranium or thorium relative to lead would have an influence on the radiometric ages computed by uranium-lead or thorium-lead dating. Also, the fact that there are two kids of magma could mean that the various radiometric ages are obtained by mixing of these kinds of magma in different. Oct 01, The reliability of radiometric dating is subject to three utreasuresforthesoul.comovable assumptions that every geologist must make when using the radioactive "clock". Radioactive rocks offer a similar "clock." Radioactive atoms, such as uranium (the parent isotopes), decay into stable atoms, such as lead (the daughter isotopes), at a measurable treasuresforthesoul.com: Dr. Andrew A. Snelling.
Another thing to keep in mind is that it is not always possible to do an isochron. Often one does not get a straight line for the values. This is taken to imply re-melting after the initial solidification, or some other disturbing event.
Anyway, this also reduces the number of data points obtained from isochrons.