[meteorite-list] Libyan (looks like a) crater

From: Göran Axelsson <axelsson_at_meteoritecentral.com>
Date: Thu, 10 Dec 2009 05:02:44 +0100
Message-ID: <4B2072E4.2050504_at_acc.umu.se>

It is obviously a crater but the question is if it was produced by a
meteorite or by human hand. As for the sample he collected it could be
an accretion layer exposed by the cratering event, probably iron
hydroxides (rust) and other mineral salts that have cemented the sand
grains together.

The crater seems to be way too small to have the energy needed to melt
the sand. It looks to be in the size of some of the bigger Sikhote-Alin
craters. That brings an interesting question, what is the smallest
crater known with impact glass?

Ask him to crack the sample and check if the sand is held together with
a glass or by relatively soft material. If the sand had melted it would
have about the same hardness as quartz.

I'm no geology expert but I have collected minerals for 15 years. Over
the years I have met a lot of professional geologists and I'm surprised
of how bad many are of identifying minerals in the field. Probably
because geology today is often about regional processes and large scale
mapping and seldom about the small details.

Okay, with that disclaimer I'll even make a few guesses.
1. Meteorite crater. There will probably not be may traces left of it
unless it was an iron meteorite, compare with the crater of Carancas.
2. Bomb crater. Pieces of metal should be easily found by digging the
crater or using a metal detector around the crater. It would take a
large bomb to make a crater this big but it could be a crater from WW2.
3. Some one thought that this could be a good place for a spring, found
a promising place and added a large explosive charge in a hole to dig it
fast. If there are a water table below the surface it could also explain
the concretions and the electrical anomaly.

Interesting anyhow and I would go there to check it out if I wasn't so
close to the arctic circle.

:-)

/G?ran

Randy Korotev wrote:
> Dear List:
>
> I received this intriguing e-mail today from someone I don't know.
>
> =========================
>
> Dear Randy, I am a geophysicist and had a recent trip on Libyan desert
> for campaign of geophysical investigations, mostly GPR and Geoelectric
> tomography. Going back to the camp I found at sunset ?due to low angle
> light- something strange on the flat desert surface.
>
> I found a perfect circular crater with melt sand scattered around .
> sand grains are melt and embedding larger quartz grains. In my opinion
> that?s a impact crater and sand is melt because of the heat wave.
> Larger grains had no time to melt .
>
> That melt rock has a black matrix-nothing like that in the area, also
> there are no similar structures in that flat, flat flat desrt surface,
> sand is only silica and quartz grain and no dark matrix can be seen
> for kilometers.
>
> I made a few geophysics on the spot and found big electric anomalies
> and very anomalous readings of Geoelectric values.
>
> I took a few samples of melt rock ?very heavy really.
>
> I am posting a few photos of the crater.
>
> I have another stone found at 2500 m on the bed of a melt glacier,
> same story, that?s not a stone of the area, it is like a fuse, heavy
> and black inside with a very aerodynamic shape, I will mail you a
> photo ( after reading once more your recommendations) if interested .
> for sure not a human artifact or an original stone of the area.
>
> Sorry to disturb,
> ...
> =========================
> I put the photos here:
>
> http://meteorites.wustl.edu/meteorwrongs/libyan_crater.htm
>
> The round thing in the desert looks something like a crater. Maybe
> it's a bomb crater. Maybe it's a meteorite impact crater. The rock
> doesn't look like samples of Libyan desert glass that I've seen. I
> don't know the LDG story well. Has there ever been a crater associated
> with the glass?
>
>
> Randy Korotev
> Saint Louis, MO
> korotev at wustl.edu
>
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Received on Wed 09 Dec 2009 11:02:44 PM PST