[meteorite-list] THE OLDEST METEORITE ?

From: Frank Cressy <fcressy_at_meteoritecentral.com>
Date: Thu, 28 Jan 2010 16:39:13 -0800 (PST)
Message-ID: <795668.3753.qm_at_web80208.mail.mud.yahoo.com>

Hi Shawn,

Are you asking what the oldest meteorite is or the oldest component in a meteorite?? There are metamorphosed sedimentary rocks on Earth that are a billion years old but contain zircons that are dated as?a couple of?billion years older than that.? So if you're asking about the oldest meteorite (in?the rock sense) I'd go with the angrites from your examples below.

The one thing I do know is that every day they all get a day older. (w/ apologies to Yogi Berra).

Cheers,

Frank



----- Original Message ----
From: Shawn Alan <photophlow at yahoo.com>
To: meteorite-list at meteoritecentral.com
Sent: Thu, January 28, 2010 4:04:31 PM
Subject: [meteorite-list] THE OLDEST METEORITE ?

The age old question, which meteorite is the oldest? I have done some reading on this topic and asked a few people what they thought and here is what I have gathered so far.
?
Allende is 4,565.45 (+-0.45) m.y. and I have also seen Allende dated at 4,5685 b.y. Burkhardt (2007), which could make Allende one of the oldest meteorites. But then I have read that D'Orbigny, stated by Qing-Zhu Yin (2009) is the oldest meteorite, with an age of 4,567.91 (+- 0.76) m.y. But to counter Qing-Zhu Yin claim, in 2009 Tistarite a new refractory mineral was found in Allende which this new refractory mineral is among the first solids formed in the solar system ( American Mineralogist 2009 ).
?
If this didn?t get confusing enough, a newly identified refractory inclusion in Murchison composed of hibonite represents some of the earliest condensed solids or residues from the early, hot, solar nebula (Liu et al., 2009). These refractory inclusions comprise of platy crystals and blue aggregates, which formation occurred hundreds of thousands of years before the formation of CV CAIs ( ??http://www.meteoritestudies.com/? ?)
?
But some people have a different idea of the age old question and feel that the Vigarano meteorite is the oldest meteorite. Vigarano fell at 9:30 pm 22 January 1910 in Emilia, Italy.?? Two stones of 11.5 kg and 4.5 kg were found.? This is the type specimen for the CV class.? ? A case can be made for Vigarano being the oldest meteorite.? Although older ages have been recorded for other meteorites they are isolated measurements and do not give as consistently an old age as does Vigarano (? ?http://www.star-bits.com/VIGARANO.htm ??) .
?
Now back to the question what is the oldest meteorite?
?
Shawn Alan

______________________________________________
Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html
Meteorite-list mailing list
Meteorite-list at meteoritecentral.com
http://six.pairlist.net/mailman/listinfo/meteorite-list
Received on Thu 28 Jan 2010 07:39:13 PM PST