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Re: 129I/129Xe

I don't have any resources available at the moment, but thought I'd give
this one a shot anyway. Generally isotopes used for dating are selected
upon two main criteria. First, they must be in reasonable abundance in
order to both be representative of the sample, and to provide large enough
numbers for a quality analysis. The second criteria is that the isotopic
half-life applies to the age range of the sample in question.  If the
isotope's half-life is to short, or too great, the data generated will have
a much larger margin of error.

Each half-life cycle is an estimate. One usually needs several half-life
cycles to insure an average overall half-life.  However, if there are too
many half-life cycles in the dating, the result is in question because the
instrument used was too precise (but not necessarily accurate). It is
possible to identify an elephant using a microscope, but the microscope is
too powerful a tool, maybe binoculars would be better. It also maybe
possible to identify an elephant using a radio telescope, but again, the
data would be questionable because the wrong instrument was used.

Given the assumption that meteorites formed during the formation of our
solar system, and assuming an age of about 4.56 billion years, one should
select a tool (isotopic half-life) which would be appropriate to measure a
quantity of over 4 billion years.

If no other messages are posted providing a more satisfactory answer, I
will look up some specific information to post later. By the way, I write
these posts for everyone, so if my answers are too basic, I can provide
more technical answers. However, since this List is for the hobbyist and
enthusiasts, I don't want readers to feel lost when we jump into the middle
of a scientific discussion.

Best wishes,

Martin


>Recently I have read somewhere that the 129 I/129 Xe parent-daughter
> system is appropriate for dating most meteorites.  Unfortunately, the
>source did not say why it is so.  Does anybody out there know?
>Thanks in advance.
>Best regards,
>Kasia Gorczyca





>Recently I have read somewhere that the 129 I/129 Xe parent-daughter
> system is appropriate for dating most meteorites.  Unfortunately, the
>source did not say why it is so.  Does anybody out there know?
>Thanks in advance.
>Best regards,
>Kasia Gorczyca
References: