Re: extreme flow beaches
Kent Crispin (kent@songbird.com)
Fri, 3 Oct 1997 13:41:35 -0700
On Fri, Oct 03, 1997 at 01:52:56PM -0600, David Yeamans, CST-7, 5-8832, dryeamans@lanl.gov wrote:
> In response to my query about isotopic signatures in quartz crystals being
> used to identify the nature of perched sediment fields I received this.
>
> >David,
> > Interesting question. Certainly, all quartz is not alike. There are
> >minor but measureable chemical differences which lead also to crystal
> >structural differences from sample to sample. The difficulty is not in
> >measuring the differences but in relating the differences to source, etc.
> >What you propose may be possible.
>
> and
>
> >Hi,
> >
> >I'm not sure I understand a couple of aspects of your email...are you
> >asking for collaborators or just information? How does the source of the
> >quartz tell you it is lacustrine or fluvial? I would say yes, it is
> >possible to fingerprint quartz from sufficiently different sources.
> >Probably a combination of techniques would give the most unambiguous
> >answers. Two methods that come to mind are oxygen isotopes and electron
> >spin resonance. A lot of work would have to be done to characterize the
> >potential source formations; furthermore, the quartz in each has to be of
> >sufficiently different origin for this to work (eg. plutonic vs. volcanic
> >vs. metamorphic) for the oxygen. Regarding ESR fingerprinting of quartz
> >you should check out the paper by Toyoda and Goff (1996) in the 47th New
> >Mexico Geological Society Guidebook, "Jemez Mountains Region."
> >
>
>
> So, fellow dilletantes, the stakes may have been raised.
However, it is important to keep in mind that there may be totally
different approaches to localizing sources -- statistical distribution
of different kinds of grains, coupled with good models of transport,
might actually give some good clues. Heavy duty study of chemical
composition might be done for a few clear-cut reference sources, for
calibration. But it might not be necessary...
--
Kent Crispin "No reason to get excited",
kent@songbird.com the thief he kindly spoke...
PGP fingerprint: B1 8B 72 ED 55 21 5E 44 61 F4 58 0F 72 10 65 55
http://songbird.com/kent/pgp_key.html
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