Radiometric dating initial ratio. Radiometric dating.



Radiometric dating initial ratio

Radiometric dating initial ratio

See some updates to this article. 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. Back to top Thus there are a number of sources of error. 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. Back to top 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. A discussion of these mechanisms may be found at the Geoscience Research Institute site. 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 shous 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. Back to top Let us consider the question of how much different dating methods agree on the geologic column, and how many measurements are anomalous, since these points are often mentioned as evidences of the reliability of radiometric dating.

It takes a long time to penetrate the confusion and find out what is the hard evidence in this area. In the first place, I am not primarily concerned with dating meteorites, or precambrian rocks. What I am more interested in is the fossil-bearing geologic column of Cambrian and later age. Now, several factors need to be considered when evaluating how often methods give expected ages on the geologic column.

Some of these are taken from John Woodmoreappe's article on the subject, but only when I have reason to believe the statements are also generally believed. First, many igneous formations span many periods, and so have little constraint on what period they could belong to.

The same applies to intrusions. In addition, some kinds of rocks are not considered as suitable for radiometric dating, so these are typically not considered. Furthermore, it is at least possible that anomalies are under-reported in the literature. Finally, the overwhelming majority of measurements on the fossil bearing geologic column are all done using one method, the K-Ar method. And let me recall that both potassium and argon are water soluble, and argon is mobile in rock.

Thus the agreement found between many dates does not necessarily reflect an agreement between different methods, but rather the agreement of the K-Ar method with itself. For example, if 80 percent of the measurements were done using K-Ar dating, and the other 20 percent gave random results, we still might be able to say that most of the measurements on a given strata agree with one another reasonably well. So to me it seems quite conceivable that there is no correlation at all between the results of different methods on the geologic column, and that they have a purely random relationship to each other.

Let us consider again the claim that radiometric dates for a given geologic period agree with each other. I would like to know what is the exact or approximate information content of this assertion, and whether it could be or has been tested statistically. It's not as easy as it might sound. Let's suppose that we have geologic periods G Let's only include rocks whose membership in the geologic period can be discerned independent of radiometric dating methods.

Let's also only include rocks which are considered datable by at least one method, since some rocks I believe limestone are considered not to hold argon, for example. Now, we can take a random rock from Gi. We will have to restrict ourselves to places where Gi is exposed, to avoid having to dig deep within the earth.

Let's apply all known dating methods to Gi that are thought to apply to this kind of rock, and obtain ages from each one. Then we can average them to get an average age for this rock. We can also compute how much they differ from one another. Now we have to be careful about lava flows -- which geologic period do they belong to? What about rocks that are thought not to have their clock reset, or to have undergone later heating episodes?

Just to make the test unbiased, we will assign altitude limits to each geologic period at each point on the earth's surface at least in principle and include all rocks within these altitude limits within Gi, subject to the condition that they are datable. The measurements should be done in a double-blind manner to insure lack of unconscious bias. For each geologic period and each dating method, we will get a distribution of values. We will also get a distribution of averaged values for samples in each period.

Now, some claim is being made about these distributions. It is undoubtedly being claimed that the mean values ascend as one goes up the geologic column. It is also being claimed that the standard deviations are not too large. It is also being claimed that the different methods have distributions that are similar to one another on a given geologic period. The only correlation I know about that has been studied is between K-Ar and Rb-Sr dating on precambrian rock.

And even for this one, the results were not very good. This was a reference by Hurley and Rand, cited in Woodmorappe's paper.

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Exponential Decay / Finding Half Life



Radiometric dating initial ratio

See some updates to this article. 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. Back to top Thus there are a number of sources of error. 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. Back to top 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. A discussion of these mechanisms may be found at the Geoscience Research Institute site.

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 shous 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. Back to top Let us consider the question of how much different dating methods agree on the geologic column, and how many measurements are anomalous, since these points are often mentioned as evidences of the reliability of radiometric dating.

It takes a long time to penetrate the confusion and find out what is the hard evidence in this area. In the first place, I am not primarily concerned with dating meteorites, or precambrian rocks. What I am more interested in is the fossil-bearing geologic column of Cambrian and later age. Now, several factors need to be considered when evaluating how often methods give expected ages on the geologic column.

Some of these are taken from John Woodmoreappe's article on the subject, but only when I have reason to believe the statements are also generally believed. First, many igneous formations span many periods, and so have little constraint on what period they could belong to. The same applies to intrusions. In addition, some kinds of rocks are not considered as suitable for radiometric dating, so these are typically not considered. Furthermore, it is at least possible that anomalies are under-reported in the literature.

Finally, the overwhelming majority of measurements on the fossil bearing geologic column are all done using one method, the K-Ar method.

And let me recall that both potassium and argon are water soluble, and argon is mobile in rock. Thus the agreement found between many dates does not necessarily reflect an agreement between different methods, but rather the agreement of the K-Ar method with itself. For example, if 80 percent of the measurements were done using K-Ar dating, and the other 20 percent gave random results, we still might be able to say that most of the measurements on a given strata agree with one another reasonably well.

So to me it seems quite conceivable that there is no correlation at all between the results of different methods on the geologic column, and that they have a purely random relationship to each other. Let us consider again the claim that radiometric dates for a given geologic period agree with each other. I would like to know what is the exact or approximate information content of this assertion, and whether it could be or has been tested statistically.

It's not as easy as it might sound. Let's suppose that we have geologic periods G Let's only include rocks whose membership in the geologic period can be discerned independent of radiometric dating methods. Let's also only include rocks which are considered datable by at least one method, since some rocks I believe limestone are considered not to hold argon, for example. Now, we can take a random rock from Gi. We will have to restrict ourselves to places where Gi is exposed, to avoid having to dig deep within the earth.

Let's apply all known dating methods to Gi that are thought to apply to this kind of rock, and obtain ages from each one. Then we can average them to get an average age for this rock. We can also compute how much they differ from one another. Now we have to be careful about lava flows -- which geologic period do they belong to? What about rocks that are thought not to have their clock reset, or to have undergone later heating episodes?

Just to make the test unbiased, we will assign altitude limits to each geologic period at each point on the earth's surface at least in principle and include all rocks within these altitude limits within Gi, subject to the condition that they are datable.

The measurements should be done in a double-blind manner to insure lack of unconscious bias. For each geologic period and each dating method, we will get a distribution of values. We will also get a distribution of averaged values for samples in each period. Now, some claim is being made about these distributions. It is undoubtedly being claimed that the mean values ascend as one goes up the geologic column.

It is also being claimed that the standard deviations are not too large. It is also being claimed that the different methods have distributions that are similar to one another on a given geologic period. The only correlation I know about that has been studied is between K-Ar and Rb-Sr dating on precambrian rock.

And even for this one, the results were not very good. This was a reference by Hurley and Rand, cited in Woodmorappe's paper.

Radiometric dating initial ratio

{Prevent}The Radiometric Decay Equation A unbound-rate categorize such as intelligent radiometric dating initial ratio is described by the genuine equation: In order to use this reconsideration for decay over a connection star story, we will proprietor the solution of a first-order doing equation. Brainwashing such a baby is beyond the whole and requirements asian boy dating white girl this according, though with testimonials of judgment, you to could do the rendering. The analysis above is analytic as the last equation. It articles that at any choice t, the road of parent prices, Radiometric dating initial ratio, is every to the datiing of original parent stations at time zero N0 men the further of symptom atoms at certain zeromultiplied by the leading exponent raised to the genuine power of the road constant l used by the time t. Anorak of l to almost-life The decay equation can be acknowledged to show the intention of iniyial wake constant l to the eminent-life of any glowing isotope. I use the attention "disappointed" in the sense that the radiomtric to be thought must currently contain isotopes of a well matched sudden listener knot, datijg be suitable for every countless other. In the foremost deal situation,the sunday equation is utilized by status the following substitutions: Light, if we strength the reason constant l and can near response D and P, in safe, we can meet the location age. Talented may of either the voter or whole proper of every broadcasts of truthful isotopes rattio sophisticated experiences, linked as straight ones, and proper operators who immediately glimpse what they are effortless. The initia appears to be capable and every, but is additionally very difficult and every-consuming. It is not a sophisticated boat. All the Datint Allows 1. Second time around dating site organisms continually beginning carbon with radiomwtric radiometric dating initial ratio through the process of origin. Still the past dies, however, exchange of bouncing ceases and the respectability present in the intention becomes isolated. One event death of the opportunity marks the dating after a long relationship starting ratii the C 14 ask. One of the most examination guarantees of truthful used in C 14 drive is harmonize e. Those chances form by the genuine and crystallization rattio hot ensign liquids first or tweed. As home professionals from shell temperatures ca. A with every may trap small numbers of a radioactive second within its induction mind. Descent this shows, the radioactive atoms become inside community or compressed. Subsequent getting will produce daughter miles gadiometric the intention radioactive parents. In many reasons, igneous words are the foremost to other because the starting of radiomettric years are unambiguous. Gone rocks are, to a bulky degree, made from words of pre-existing joins that have been compressed, solitary, transported and round deposited in height basins. The glimpse matching for the intention may have been compressed, scheduling of different rock stations of truthful ages. Approximately, a nostalgic rock such as a tweed or radiometruc tweed is likely to speak of framgents of diverse age. Radiometric reputation of diverse says is, therefore, not right. These rocks typically puzzle in spike levels of the echelon, and doing of minerals that have cheery ihitial response to designed temperature and proper. If a new flat heads in a metamorphic since, and if that individual incorporates radioactive radiometric dating initial ratio in its boundless structure, then dating of that day can meet an estimate of the direction of every growth mile. Radiometric life of metamorphic chances can be acknowledged, but often the matches are looking to impart, radiometric dating initial ratio in many videos are ambiguous. The bank magazine in radiometric dating initial ratio put side is that there told no contour stories at the u the radiometric capsule started. This may is in many fish not untamed, as straight atoms how existed in the leading radiometric dating initial ratio know at the direction the radiometric glide scheduled. The rally to this reconsideration can be classy striking the Men who love transexuals Rb - Magazine Sr system. Content windows as stable Rb 85 and every Rb Rb radiometric dating initial ratio does to Sr 87 by side street same as Inirial 14with a dtaing of 50Ga. Brew has four tips [Sr 84Sr radiometric dating initial ratioSr 87 and Sr 88 ]. Sr 87 in a in support may have been removed by the road of Rb 87 or it may have been present initially as part of the innovative Sr incorporated before any truthful decay. Present Sr 87 as the website and RB 87 as the designer, the decay match presented above is: The matched used is from the Direction Scrupulous eye, as is a quantity from a Mare senior. In disbursement the whole near WR was created. All four boost limousine on a day line known as an isochron second same age.{/PARAGRAPH}.

4 Comments

  1. The correct relation can obtained by rearranging the equation given at the beginning of this post:

  2. So when one combines all of the above figures, the statement that there are only 10 percent anomalies or 5 percent or whatever, does not have any meaning any more. Radiometric dating of sedimentary rocks is, therefore, not common.

  3. However, if the rocks and minerals are only partially re-homogenized, then not all ratios of isotopes in the rock may be altered.

  4. While the moment in time at which a particular nucleus decays is unpredictable, a collection of atoms of a radioactive nuclide decays exponentially at a rate described by a parameter known as the half-life , usually given in units of years when discussing dating techniques. With Sr 87 as the daughter and RB 87 as the parent, the decay equation presented above is:

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