[meteorite-list] Question About Potassium-Argon (K/Ar) dates for North American and Australasian Tektites

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 14 Oct 2008 16:55:36 -0500
Message-ID: <098901c92e47$97ad9120$144ee146_at_ATARIENGINE>

Hi, Paul, List

    Potassium Argon Dating has been applied to tektites
since the method was first available. It dates the "arrival"
date of the tektite, the time of the last secondary melt that
resets the K-Ar "clock." The arrival date of each strewn-
field is the same; the arrival date of each strewnfield is
different from the others. The date of the primary melt of
all tektites, their formation date (by Rb-Sr isochron), is the
same -- about 450+/-50 million years. And their initial
87Sr/86Sr ratio, which is what the isochron points at,
is different that any other material in the solar system yet
examined by us; their original source is unknown.

    Guy Heinen's "Tektites" is the most recent complete
work on the subject, published in 1998. It has a complete
(up to that date) bibliography of the scientific literature,
many 100's of references. Hal Povenmire's books are
still available. Going back, there's John O'Keefe's 1976 book,
"Tektites" and his many papers, some of which are listed:
http://en.wikipedia.org/wiki/John_A._O'Keefe

    It appears that the complete text of O'Keefe's 1976
book is online! (There will a short delay while I download
the entire thing):
http://originoftektites.com/index.php
I'd forgotten about Chap. 6. Take a look at Chap. 6, Paul;
there may be enough recent bulk compositional data for you.
(Putting this on the web must be a new project; Chaps. 7-10
are incomplete, and the References are empty.) It's copyright-
free, though.

    The largest source for bulk composition data of a large
number of tektites is: J.A. O'Keefe, Editor, Tektites,
Univ. of Chicago Press, Chicago, Illinois (1963), Long
out of print, hard to get, costly, though there are xeroxes
that sell for $90-$100. It has pages and pages of these
analyses, performed by the USGS, in the course of which
they destroyed about 8000 tektites. In the pre-Apollo space
boom, O'Keefe, who believed in the lunar volcanic origin
of tektites, got the US government to spring for this massive
study. Dates are based on hundreds of samples.

A List of sources from this website (lots of list members there):
http://www.meteoriteassociationofgeorgia.org/GATektitesList.htm
chosen for their relevance to Georgiaites:
Tektites: A Cosmic Enigma, by Hal Povenmire
Tektites in the Geological Record: Showers of Glass from the Sky, by G. J.
H. McCall
Rocks from Space, by O. Richard Norton
Tektites: Witnesses of Cosmic Catastrophies, by Guy Heinen
Moon Trip, by Bert King
Georgiaites, the New Georgia Encyclopedia
Bediasites / Georgiaites, by Aubrey Whymark
Georgia Tektites, by Paul Harris
Upper Eocene impact horizon in east-central Georgia, R. Scott Harris

    A prominent recent researcher is Billy Glass. Yeah,
I know... He's an authority on tektites and his name is
"Glass." And everybody calls him Billy Glass, not
William. Google "Billy Glass"

Don't want to forget the late Darryl Futrell:
http://www.meteorite.com/Darryl_Futrell/
One of Darryl's papers is referenced in:
http://www.edamgaard.dk/Bibliography_final.htm
That bibliography is excellent for the entire
subject of tektites, but only covers Australites.

    You could Google for "tektite potassium argon dates"
and get 2380 hits, but you will have to dodge Young
Earthers. Here's some GoodGoogles:

A very geological take:
http://www.utexas.edu/tmm/npl/meteorites/tektites/tektite_info.html
Vergil Barnes was an important pre-radiometric
researcher of tektites. Also George Baker, who
first explained the origin of the shapes.

1999 text on Geochronolgy by K-Ar, pp. 35-36
http://books.google.com/books?id=FgeSnj9OnFsC&pg=PA35&lpg=PA35&dq=tektite+potassium+argon+dates&source=web&ots=-Yq2NQj1Q8&sig=-3fOLu7vkys2lUJwceWJdEIMd5g&hl=en&sa=X&oi=book_result&resnum=6&ct=result
They say few K-Ar data-sets are as "concordant"
as the K-Ar of tektites, and it's true. In general,
there seem to be few quarrels about these dates.

Or are there?
http://www.australites.com/theories.htm


In Conclusion:

"To anyone who has worked with them,
tektites are probably the most frustrating
stones ever found on earth." -- Henry Faul, 1966

The Tektite:

1. Never was there so much data
with so little return in certainty.

2. Every researcher, in his heart, believes
all the other researchers are wrong, and every
one of them, however associated in "schools,"
have theories that contradict the others.

3. The last time I compiled a list of all the
proposed theories-of-origin, there were
eighty-three of them.

4. Dr. Geoge Seddon remarked, "When
first hearing of tektites, I thought them
quite incredible. But after learning more,
I realize they are impossible."

5. If you research them long enough,
you too will have yet another theory of
tektites, incompatible with all the others.



Sterling K. Webb
----------------------------------------------------------------------
----- Original Message -----
From: "Michael L Blood" <mlblood at cox.net>
To: <bristolia at yahoo.com>; "Meteorite List"
<meteorite-list at meteoritecentral.com>
Sent: Tuesday, October 14, 2008 12:56 PM
Subject: Re: [meteorite-list] Question About Potassium-Argon (K/Ar) dates
for North American and Australasian Tektites


Hi Paul & all,
        K-A dating is only applicable to volcanic material, therefore,
It would not be applicable to tektites.
        Best wishes, Michael

on 10/14/08 9:14 AM, Paul at bristolia at yahoo.com wrote:

> Dear Friends,
>
> Can anyone recommend a publication that provides a
> comprehensive listing of Potassium-Argon (K/Ar) dates
> that have been published for the North American and
> Australasian tektites?
>
> Also, what the authorative reference(s) work for
> the bulk composition of tektites from each of these
> strewn fields?
>
> Any citations, which you can recommend would be
> greatly appreciated.
>
> Best Regards,
>
> Paul H.
>
Received on Tue 14 Oct 2008 05:55:36 PM PDT