[meteorite-list] Composition of Tektites

From: barrat at univ-brest.fr <barrat_at_meteoritecentral.com>
Date: Sun, 29 Aug 2010 10:40:21 +0200
Message-ID: <1283071221.4c7a1cf5295b4_at_webmail-sdt.univ-brest.fr>

Hi,

to give you a fast answer, the vast majority of tectites and impact glasses from
Earth are like average upper crust lithologies, i.e. granitic rocks. The
exceptions are lonar glasses (basaltic) and libyan desert glasses (silica)
because of the particular composition of the melted target rocks.
As pointed before, a particular feature of the impact glasses and tectites is
their very low water content.

Recently, water has been detected in lunar glasses. lunar glasses have two
possible origins. Some of them are impact glasses, others are pyroclastic
(volcanic). Water has been detected in lunar volcanic glasses not impact
glasses.

cheers

Jean-Alix




Selon "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>:

> Water content of glasses, parts per million:
> -----------------------------------------------------------
> Obsidian 30,000ppm
> Rio Curao Glass 12,900ppm
> Darwin Glass 4,600ppm
> Bediasites, Georgiaites 2,000ppm
> Moldavite 1,000ppm
>
> Atomic Bomb Glass 700ppm
> Ivory Coast Tektite 300ppm
> Moon (surface) 200ppm
> -----------------------------------------------------------
> Volcanic glass wet. Inpact glasses less wet.
> Oldest tektites have had time for water to
> difuse into them (30,000,000 years). New
> tektites dry as bomb glass or the Moon.
>
>
> Sterling
> -------------------------------------------------------------
> ----- Original Message -----
> From: <cdtucson at cox.net>
> To: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
> Sent: Saturday, August 28, 2010 11:51 PM
> Subject: Re: [meteorite-list] Composition of Tektites
>
>
> > Sterling,
> > I cannot get the down load to complete for some reason. Also there was
> > a recent finding of water found in lunar glass. So, if it would be
> > considered to be a lunar tektite then there is H2o in some tektites .
> > or whatever the lunar glass ended up being.
> > By the way. I loved all of that info you forwarded.
> > Seems to me it is still a matter of opinion? or who you believe?
> > Thanks Carl
> > --
> > Carl or Debbie Esparza
> > Meteoritemax
> >
> >
> > ---- "Sterling K. Webb" <sterling_k_webb at sbcglobal.net> wrote:
> >> Hi, Walter, List
> >>
> >> The chief proponent of tektites as ejecta from
> >> lunar volcanoes was John O'Keefe (d. 2000).
> >> Of course Nininger thought of the idea, too,
> >> but neither of them was the first.
> >>
> >> The chief expert on lunar glass and tektite analysis
> >> is B. P. Glass, yes, his name is BILLY GLASS. This
> >> makes trying to Google up articles about lunar glasses
> >> by Glass very difficult, but he has a trunkful of papers
> >> on lunar glasses:
> >> http://www.geology.udel.edu/glass/bghistory.html
> >>
> >> I think this is the one you may be talking about:
> >> "Glass, B. P. (1986) Lunar sample 14425: Not a lunar
> >> tektite, Geochimica et Cosmochimica Acta 50, 111-113."
> >>
> >> In 1985, O'Keefe and Glass published a paper saying
> >> the biggest glass bead from the Moon (eight mm!) was
> >> a high-magnesium tektite. One year later, in 1986, they
> >> took it all back. Experimental error. Here's the abstract:
> >> http://www.sciencemag.org/cgi/pdf_extract/229/4720/1410
> >>
> >> Still, lunar volcanism, IF it exists, still leaves us with
> >> the problem that we don't know what lunar magma
> >> would be like, if it exists. How would you know anything
> >> was a product of lunar volcanism if you didn't know
> >> what lunar volcanic product was?
> >>
> >> There is no such thing as a single "tektite" composition.
> >> There are Hi-Si, Lo-Si, Hi-Mg, Hi-Na, Lo-Na... and on
> >> and on. The one sure thing is H2O -- they ain't got any.
> >>
> >> I tried posting this to the List earlier but it doesn't
> >> seem to have gone through. For a lot of information on
> >> tektites, O'Keefe's 1976 is still quite a good read.
> >>
> >> The first five chapters of John O'Keefe's 1976 book,
> >> "Tektites and Their Origin," long out-of-print (Amazon
> >> $200) had been posted for many years on a website
> >> ("originoftektikes.com") but is now a dead link.
> >>
> >> Those first five chapters of O'Keefe's "Tektites and Their
> >> Origin" is now available for download as a book in PDF
> >> format at:
> >>
> >> http://www.sendspace.com/file/2y55kt
> >>
> >> That link will only be good for a limited time before it
> >> expires, so don't save it as a reference -- use it. Just
> >> click on the orange download button near the bottom
> >> of the page.
> >>
> >> Regards,
> >>
> >>
> >> Sterling K. Webb
> >> --------------------------------------------------------------------------
> >> ----- Original Message -----
> >> From: "Walter Branch" <waltbranch at bellsouth.net>
> >> To: <meteorite-list
Received on Sun 29 Aug 2010 04:40:21 AM PDT