AW: [meteorite-list] Lunar/Martian controversy

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Thu Apr 22 10:18:02 2004
Message-ID: <122020031929.21850.6c76_at_att.net>

Norbert,

Thanx for correction as always.

This does answer reinforce the Mars material late arrival notion? Still too
complicated is a start...

Time, time, time...

JD
> Hi Mark, John, and List,
>
> Since Eric already addressed an error in the first answer regarding
> the absolute ages of Martian, and lunar meteorites, let me address an
> error in the second answer:
>
> > Q: How long have these planetary meteorites been on earth?
> > A: Probably all less than 25,000 years. So we know the rate of finds
> > from material found that probably fell in recent times. 1 to 1
>
> Humm, this isn't true, at least not for several lunar meteorites
> in our collections. More recent studies show that some lunaites
> exhibit remarkably long terrestrial residence ages. For example,
> the terrestrial age for the lunar breccia Dhofar 025 (and pairings,
> e.g., Dho 301, 304, and 308) is estimated at 500ka (yes, that's
> 500,000 or half-a-million years!). Some Antarctic finds are also
> much, much older than 25ka, such as MAC 88104/88105 that shows a
> terrestrial age of about 200ka. In fact, most lunaites have
> terrestrial ages of 10ka (10,000 years) or more, and only a few
> are thought to have fallen in more or less recent times.
>
> I'm not sure regarding the Martian meteorites of which at least
> four represent witnessed falls - a fact that raises even more
> questions...
>
> All the best,
> Norbert
Received on Sat 20 Dec 2003 02:29:03 PM PST