![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
![]() | Uraniumâuranium dating was a
good article, but it was removed from the list as it no longer met the
good article criteria at the time. There are suggestions below for improving the article. If you can improve it,
please do; it may then be
renominated. Review: October 23, 2005. ( Reviewed version). |
There are no images. slambo 16:55, 23 October 2005 (UTC)
Geez. Is this something you'd want? Rolinator 11:20, 19 February 2006 (UTC)
The chain of Uranium decay described in this article is very similar to Radioactive_decay#Decay_chains_and_multiple_modes. Should be united somehow Tomer Shalev 21:17, 12 May 2008 (UTC)
Hi all. The last line seems out of place. Common-Pb measurements are not necessary for 234U/238U dating and it is my understanding (although I could be wrong!) that it is not routine to measure Pb during U-Th series measurments. At least it is the case in the older alpha counting methods and on single-collector MS's. Can anyone comment on this or make it jive a little bit better with the rest of the text (which is quite good)? I understand that common-Pb measurements in, for example, corals that are well dated may provide a secular seawater Pb isotopic record, but I don't know if anyone does that. Does anyone have an interest in the Pb isotopic history of seawater (does anyone have a ref for it?).
Additionally, I would like to change the way that the mass-numbers are written in the text. In particular I would like to put the mass-numbers in superscript to the top left of the element ( e.g., U-234 would be changed to a 234U). It makes the text a little bit easier to read and is consistent with general scientific usage. Again, if no one takes offence to this I will go ahead and make the changes. Cheers, Rickert 17:25, 3 February 2006 (UTC)
A user keeps trying to link to a page (his/her own?) that attempts to use 235U/238U to determine the age of the earth on the basis of an entirely arbitray initial state assumption. This cannot work for the simple reason that the only way we can determine the 235/238 ratio at the time the earth formed is by back-calculating using a known age for this event as already determined by other means (i.e. by U-Pb dating). With one or two very notable exceptions, the 238/235 ratio is constant throughout the earth (currently at 137.88; the number of significant figures given here reflects the accuracy with which we can measure this ratio in absolute terms). Some types of U-Pb dating (there are several) utilise the change in U238/U235 ratio over time but do not do so by measuring the ratio as it is now (we know this already as it is the same everywhere).
In most U-series analytical techniques we actually use the known 238/235 ratio to aid in the measurement of unknown U and Th (sometimes Pb) isotope ratios, as in isotope mass spectrometry the best way to measure an unknown ratio is by normalising its apparent value to the apparent value of a known ratio. Actinide 00:51, 12 February 2006 (UTC)
I went from this article to trying to find an example of its use... and I couldn't find a single paper. So I took a look at Quaternary Dating Methods (1e), where it was not mentioned at all (the article seems to reference a later edition, though). I then asked a colleague who actually works in this area, who had never heard of it. I am beginning to get worried that this article is somehow based on a fundamental misunderstanding. @ Vsmith: â ÎΔÏÎŹknowledge discuss/ deeds 07:21, 11 July 2019 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
![]() | Uraniumâuranium dating was a
good article, but it was removed from the list as it no longer met the
good article criteria at the time. There are suggestions below for improving the article. If you can improve it,
please do; it may then be
renominated. Review: October 23, 2005. ( Reviewed version). |
There are no images. slambo 16:55, 23 October 2005 (UTC)
Geez. Is this something you'd want? Rolinator 11:20, 19 February 2006 (UTC)
The chain of Uranium decay described in this article is very similar to Radioactive_decay#Decay_chains_and_multiple_modes. Should be united somehow Tomer Shalev 21:17, 12 May 2008 (UTC)
Hi all. The last line seems out of place. Common-Pb measurements are not necessary for 234U/238U dating and it is my understanding (although I could be wrong!) that it is not routine to measure Pb during U-Th series measurments. At least it is the case in the older alpha counting methods and on single-collector MS's. Can anyone comment on this or make it jive a little bit better with the rest of the text (which is quite good)? I understand that common-Pb measurements in, for example, corals that are well dated may provide a secular seawater Pb isotopic record, but I don't know if anyone does that. Does anyone have an interest in the Pb isotopic history of seawater (does anyone have a ref for it?).
Additionally, I would like to change the way that the mass-numbers are written in the text. In particular I would like to put the mass-numbers in superscript to the top left of the element ( e.g., U-234 would be changed to a 234U). It makes the text a little bit easier to read and is consistent with general scientific usage. Again, if no one takes offence to this I will go ahead and make the changes. Cheers, Rickert 17:25, 3 February 2006 (UTC)
A user keeps trying to link to a page (his/her own?) that attempts to use 235U/238U to determine the age of the earth on the basis of an entirely arbitray initial state assumption. This cannot work for the simple reason that the only way we can determine the 235/238 ratio at the time the earth formed is by back-calculating using a known age for this event as already determined by other means (i.e. by U-Pb dating). With one or two very notable exceptions, the 238/235 ratio is constant throughout the earth (currently at 137.88; the number of significant figures given here reflects the accuracy with which we can measure this ratio in absolute terms). Some types of U-Pb dating (there are several) utilise the change in U238/U235 ratio over time but do not do so by measuring the ratio as it is now (we know this already as it is the same everywhere).
In most U-series analytical techniques we actually use the known 238/235 ratio to aid in the measurement of unknown U and Th (sometimes Pb) isotope ratios, as in isotope mass spectrometry the best way to measure an unknown ratio is by normalising its apparent value to the apparent value of a known ratio. Actinide 00:51, 12 February 2006 (UTC)
I went from this article to trying to find an example of its use... and I couldn't find a single paper. So I took a look at Quaternary Dating Methods (1e), where it was not mentioned at all (the article seems to reference a later edition, though). I then asked a colleague who actually works in this area, who had never heard of it. I am beginning to get worried that this article is somehow based on a fundamental misunderstanding. @ Vsmith: â ÎΔÏÎŹknowledge discuss/ deeds 07:21, 11 July 2019 (UTC)