[meteorite-list] Tektite QUESTION

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:28 2004
Message-ID: <3D8ACB0F.8EBD6CED_at_lehrer.uni-karlsruhe.de>

Michael Blood wrote:

> I am sure I have it in more than one text SOMEWHERE, but can anyone
> tell me quick short the estimated age of the Austro-asian strewn field
> Tektites?

"Sterling K. Webb" wrote:

> The figure given for the age of the Australasian field has been
> estimated at 770,000 to 780,000 years for the past 30 or 40 years;
> however, somewhere on a posting on CCNET which I can no longer find
> (&%$!), attempts to refine the precision of those isotopic ages came
> up with a figure about 10% to 12% older, more like 850,000 to 900,000
> years, which made sense as there have always been a few australites
> with anomalous ages (about 10% older). Maybe we should just call it
> somewhere short of a million.


Hello Michael and List,

BARNES V.E. (1990) Tektite research 1936-1990
(Meteoritics 25-3, 1990, 149-159).

p. 155: Ages of tektites

Lovering et al. (1972) determined that the stratigraphic age
of australites is between 24 000 and 16 000 years, which is
at considerable variance with the 700 000-year age found for
australites and the rest of the tektites in the Australasian
strewnfield by fission-track (Fleischer and Price, 1964) and
potassium-argon (K/Ar) dating (Zähringer and Gentner, 1963).
Supporting the older age value, we found nannofossils in a
crust firmly attached to a tektite dredged from the South China
Sea (Saurin and Millies-Lacroix, 1961), indicating a minimum
age of about 1 Ma for the indochinite portion of the Austral-
asian strewnfield, on the basis of a 3 Ma duration for the
Quaternary Period (Smith and Barnes, 1969; Barnes, 1971a).

The ages of the various strewn-fields, as determined by
fission-track dating (Fleischer and Price, 1964; Fleischer
et al., 1965; Storzer and Gentner, 1970; Storzer and Wagner,
1971) and by K/Ar dating (Gentner and Zähringer, 1960;
Gentner et al., 1963, 1969, 1970) are listed as follows:

(1) Ivory Coast strewn-field, 1.1-1.3 Ma;
(2) Australasian strewn-field, which includes australites,
    indochinites, philippinites, and javanites, about 0.7 Ma;
(3) Moldavite strewn-field of Czechoslovakia, Austria, and
    eastern Germany near Dresden, 14-15 Ma;
(4) Libyan Desert glass, Egypt, 28-29 Ma;
(5) North American strewn-field, 32-34 Ma.


Off to school :-(

Bernd
Received on Fri 20 Sep 2002 03:15:27 AM PDT