[meteorite-list] What is Age of Campo del Cielo meteorites?

From: Piper R.W. Hollier <piper_at_meteoritecentral.com>
Date: Thu Apr 22 09:52:25 2004
Message-ID: <5.1.0.14.2.20020830095242.02642e60_at_pop.xs4all.nl>

Hello Keith, Steven, and list,

The crater field at Campo del Cielo was the subject of a scientific study=20
which continued for several years in the late 1960s and early 1970s. This=20
research team was led by William A. Cassidy, who later led the search for=20
meteorites in Antarctica. Cassidy wrote several long papers about this=20
study, one of which (co-authored with Marc L Renard) was presented as The=20
Barringer Award Address on 13 September 1995 in Washington DC. This paper,=
=20
"Discovering research value in the Campo del Cielo, Argentina, meteorite=20
craters", was published in Meteoritics, vol. 31 (July 1996), pp. 433-448,=20
and is also available from NASA's ADS online database:

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=3D1996M%26PS...31..4=
33C&db_key=3DAST&high=3D3d3fec058b20409

(Sorry about the length of the URL. You can also find the paper from the=20
ADS search page by entering "Cassidy" in the author field.)

Cassidy has this to say about the age of the fall:

Age of the event

 From C-14 analysis of three charcoal samples, the age of the crater field=
=20
was determined to be ~4000 years B.P. One sample was found in sediments=20
infilling Crater 1 and was assumed to be younger than the event. The second=
=20
sample was found in an ancient subsoil below an ancient soil that had been=
=20
buried by outthrown material from Crater 2, an explosion-analog-type=20
crater; this sample was assumed to be the same age or older than the time=20
of crater formation. The third sample was found at the bottom of Crater 10,=
=20
at the beginning of the tunnel. This sample was assumed to be the same age=
=20
as the event.

[end of quote]

In the accompanying table, the sample listed as "age of impact" was dated=20
at 3945 +/- 85 years.

Cassidy's detailed description of the circumstances of the "discovery" of=20
the crater field and associated meteorites by the Spanish is quite=
 interesting:

Historical background

The written history of discovery at Campo del Cielo dates from the earliest=
=20
times of the Spanish conquest. After successfully defeating the Pizarro=20
brothers in 1548, armies of the Regent of Peru were granted land as spoils=
=20
of war in what is now Argentina and Chile. In their single-minded search=20
for gold and silver, the conquistadores were told of legends among the=20
natives of the Charco region that described the fall of a large piece of=20
iron from the sky. Disbelieving this legend and hoping that it might be a=20
deposit of silver, Spanish explorers induced the natives to lead them to=20
it. In 1576, a Spanish expedition was led along a well-developed trail=20
system used by the "meleros" (honey-gatherers). The object of the=20
expedition was located on the flat, semi-arid Chaco plains in a field knows=
=20
as "Piguem Nonralt=E1" or, in Spanish, "Campo del Cielo" (Field of the Sky).=
=20
The piece of iron they examined, estimated to weigh ~14 tons, became known=
=20
as the "Meson de Fierro" (Large Table of Iron). The Meson was visited at=20
intervals by Spanish expeditions until 1783, when it may have been rolled=20
over into a hole so that the soil beneath it could be sampled. The specific=
=20
location of the meteorite was subsequently lost and the Meson has not been=
=20
seen since the 1783 expedition.

[end of quote]

The investigation of the crater field by Cassidy's research team was very=20
thorough, and one of his more interesting conclusions was that the entry=20
angle had been very low, about 9 degrees, a fact which contributed to the=20
survival of exceptionally large masses, which would ordinarily have been=20
fragmented by impact explosions or pre-impact aerodynamic forces if the=20
entry angle had been steeper.

Also interesting is this comment on the conditions at the research site:

The field investigator at Campo del Cielo must take precautions against two=
=20
natural hazards. One is the "vinchuca", a nocturnal, flying, blood-sucking=
=20
bug that is the principal vector of a parasite causing "mal de chagas", a=20
fatal condition without a known cure. The other is a high population of the=
=20
"jarar=E1", an aggressive snake with neurotoxic venom whose bite can be=20
deadly if not treated with antivenin. The precautions consist of wearing=20
boots that cover the ankle and sleeping in tents with integral floors and=20
zippered doors.

[end of quote]

Best wishes to all,

Piper

At 20:43 29/08/02 -0400, you wrote:

>What is the age of the Campo del Cielo
>meteorites fall in Argentina?
>
>Yours
>
>Keith Littleton
>New Orleans, LA
>
>
>______________________________________________
>Meteorite-list mailing list
>Meteorite-list_at_meteoritecentral.com
>http://www.pairlist.net/mailman/listinfo/meteorite-list
Received on Fri 30 Aug 2002 04:30:07 AM PDT