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Re: Glass bombs impactite or tektite


-----Original Message-----
From: Michael Blood <mblood@access1.net>
To: Darryl S. Futrell <futrelds@gte.net>
Cc: Gaetan Cormier - Meteorites & Tektites <shattercone@videotron.ca>;
meteorite-list@meteoritecentral.com <meteorite-list@meteoritecentral.com>
Date: Saturday, March 20, 1999 3:20 AM
Subject: Re: Glass bombs impactite or tektite


Michael,
    I knew I'd be opening up a hornet's nest with what I said last night,
but so be it.  For me, it's got to be now, or it'll be never.
    Did you read my R & G tektite origin article?  There was a stack of free
copies at the tektite party.  If you would, you might better understand what
I'm saying.  Can send you a copy.
    I never said the Ries bombs (fladle) are tektites.  Technically, the
bombs do fall under the classification of impact melts, but they could
contain various amounts of recycled tektite glasses in them (from the
projectile).  After all, the Wabar impact melts are full of millions to
billions of microscopic nickel-iron spherules from their NiFe projectile.
    The numerous "impact" scientists have refused to accept that any impact
craters could have been formed by tektite family glass projectiles, but that
doesn't mean it isn't so.  Darwin and Zhamanshin are a few of the others.
Ries is only "connate" to the moldavites, just as Bosumtwi is connate to the
Ivory Coast tektites (Dean Chapman, 1971 JGR).  And,  even Virgil Barnes, in
one of his earlier papers (or was it an abstract) stated that he didn't
think the moldavites could be from the Ries (can't quickly find the
reference).  Later, he decided to change his mind.
    So, I say the Ries bombs could have varying percentages of tektite glass
in them, mixed with  granitic terrestrial impact melts.  Both types would be
compatible silica wise.  Generally, all natural terrestrial glasses
(obsidians, fulgurites, real impact melts, etc.) devitrify over tens or
hundreds of  thousands of years.  But the Ries has glasses that are still
glassy after 14 million years.  That indicates that they contain some % of
tektite glass, as tektite glasses basically don't devitrify (example, the
367 m.y. old Belgian microtektites) except when they have become
contaminated by being remelted in a terrestrial impact.  Some tektite
glasses have compositions in the "ballpark" with terrestrial andesitic and
granitic glasses (ignoring the trace elements).  So, it's tempting for the
majority to assume the Ries bombs & glasses mixed in with the breccias are
all melted from the Ries granitic bedrock.
    It's a complex subject.  That's enough from me for now, as it's way past
my lunchtime.

>Darryl,
> I sometimes have Ries Crater Glass Bombs & have ALWAYS heard they were
>impact melt - NOT tektites. I have always thought they LOOK LIKE impact
>melt and NOT tektites - and, I have always sold them as impact melts and
>not tektites.
> As of this time, my opinion has not changed.
> Best wishes, Michael
>
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