[meteorite-list] Oblique impacts on Mars and elsewhere (Rio Cuarto)

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:48 2004
Message-ID: <20020512193640.11176.qmail_at_web11603.mail.yahoo.com>

Hello all -

Most entertaining to read the National Geographic
piece on Rio Cuarto. Here I was wondering how to
tackle the incredible work load that I am already
facing, and now I find my schedule for the next week
or so pretty much determined for me.

Among the many other fascinating things which I read
in the National Geographic summary, I was quite amazed
to learn from these folks that there was only one
oblique impact which occured in our Solar System, and
that its remains were found on the Moon.

Now if I am not mistaken, there are many long straight
valleys which have been have been observed on Mars.
Hell, I know I am not mistaken, I attended one of the
annual Mars lectures up at the National Academy of
Sciences several years back and was shown them for 45
minutes or so.

If anyone here has any mechanism for the creation of
these very linear features on Mars other than oblique
impact with the heat of the entry setting of clathrate
reactions, I sure would like to hear about it.

Detailed comment is going to have to wait getting to a
library to read the Science article, but my first
estimate from the synopsis is that what has happened
is that some folks have confused themselves pretty
well and are now going on to share their confusion
with the general public.

Are there other linear features on the Pampas? Yes -
but remembering Schultz's original article, he found
glass in the crater rim, not isolated as tektites.

Was there an earlier impact in the area which formed
tektites? Clearly yes, but IF the dating of these
tektites is correct then they resulted from an impact
separate from the Rio Cuarto impact.

The orientation of the other craters is also of
interest, as they may reflect not dune activity but
the impact of other fragments of a single oblique
impactor.

Contrary to the summary, Schultz found no meteorites,
but instead found the miniscule particles left after
impact. Unless the meteorites found in the craters
agree with the particles, then they represent entirely
different later meteorite falls.

Given the volumes of Native American material which
refer to a major impact event, if Rio Cuarto turns out
not to be the site of that impact, then a major effort
will have to be made to find out where the thing did
hit. It strikes me that the easiest way to determine
whether or not Rio Cuarto was the site of that impact
would be through excavations peripheral ot the area
looking for the burn level, which should be datable by
C14

ep





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Received on Sun 12 May 2002 03:36:40 PM PDT