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Noble gases
I'm not sure, but I don't think it is the specific noble gases, but the
ratios of the gases that are important. I think the assumption is that
when the meteorites accreted, they trapped nebular concentrations of
noble gases.
Then the solar wind removed most of the dust, and had its own distinct
noble gas
signature. So after that time objects on a surface or otherwise exposed
to
solar wind would then start trapping the noble gases (so long as there
is no planetary
atmosphere to contend with).
The book 'Solar System Evolution' that I mentioned recently has some
charts
and tables on this, for example, the ratio of He4:Ne20 is 570+/-70 and
Ne20:Ar36 is 45+/-10 in the solar wind. The amount of Kr84 in meteorites
is
almost identical to the solar wind, and Xe132 is only a little higher,
so these aren't as useful.
Anyway, this is my understanding, if it's wrong please correct me.
Martin Horejsi wrote:
> I am curious about what
> specific solar gasses are trapped inside breccias? In particular, the
> gasses which are used to determine the depth at which the welding took
> place (such as deep buried breccias (fragmental) like Cumberland Falls vs.
> shallow depth breccias (regolith) such as Plainview). Also, are the
> measurements of the trapped gasses refined enough to offer an indication of
> depth of formation rather than only a relative measurement comparing two or
> more brecciated meteorites?
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