[meteorite-list] Could an impact crater on a meteorite survive passage to earth?

From: STARSANDSCOPES at aol.com <STARSANDSCOPES_at_meteoritecentral.com>
Date: Wed, 18 Jul 2007 12:34:15 EDT
Message-ID: <c44.1a2959f3.33cf9b07_at_aol.com>

In a message dated 7/18/2007 9:41:54 A.M. Mountain Daylight Time,
bernd.pauli at paulinet.de writes:
Stimpy, one of the rocks seen at Mars Pathfinder's landing site, bears an
obvious,
circular depression (arrowed) that some researchers believe to be an impact
crater. Small meteorites may lie in abundance across the Martian landscape.

A recent thread raises the possibility of a meteorite on Mars with an impact
 crater.

I was wondering if this evidence could be found on earth meteorites or would
the passage to earth destroy the features of an impact.

I have a 5+ Kilo NWA unclassified that exhibits a crater looking feature.
The crater is about 3cm wide with slightly raised edges and filled with a
material that is completely different to all other portions of the main mass I
have cut into. This material is highly shocked embedded into the main mass. I
have cut the feature down the middle an examined it at high magnification.

The fist guess to the origins of such a feature would obviously be a
weathered out inclusion. It might be just that but it looks enough like a mini
impact crater to be interesting.

Email me if you want some pictures. I was thinking of doing a Micro Visions
article on it but I didn't want to look like an idiot if it is not possible
for my hole in a rock to be from impact.

One further observation that supports an impact, on other portions of this
meteorite there are rather large areas of dark colored regolith breccia. Or
at least what looks like it. It is a fine powder hardened into 50mm and
larger dark patches. I can get detailed micrographs of the details between
barred chondrules but I can't get close enough to bring out the details of this
fine structure. Like brown baby powder hardened with no continuity of
structure within the areas. Certainly no chondrule structure. Think sand only a lot
 smaller.

Thanks, Tom Phillips




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Received on Wed 18 Jul 2007 12:34:15 PM PDT