[meteorite-list] OFF TOPIC : Oldest material out in the solar system aka Asteroids/Meteorite.

From: Shawn Alan <photophlow_at_meteoritecentral.com>
Date: Thu, 17 Mar 2011 12:33:55 -0700 (PDT)
Message-ID: <903753.43920.qm_at_web35404.mail.mud.yahoo.com>

Hello Listers,

Off topic considering the way the List has been this past month :)

I had done some looking around awhile back ( And I mean awhile back) and I had found an article by Dr Sunshine called Ancient Asteroids Enriched in Refractory Inclusions, which covered the topic of what is the oldest material out in the solar system.
 
Sunshine reported that her team found three asteroids, 234 Barbara, 387 Aquitania, and 980 Anacostia to contain "two to three times more CAI material, appear less altered, and are more ancient than any known sample in our meteorite collection" (Sunshine 2008), making these objects the oldest material in the solar system.

http://haroldconnolly.com/Publications/Refeered%20Journal%20Articles/Sunshineetal2008.pdf

However, the question still was unanswered about the oldest meteorite till the discovery of NWA 2364, which a few scientists discovered that this meteorite pre dated to 4.5682 billions years compared to Pb-Pb ages for CAIs range from 4567.1 ? 0.1 Ma [1] to 4568.5 ? 0.5 Ma [2] for inclusions from the CV3 chondrites Efremovka and Allende ( Amelin et al. (2006) 37th Lunar Planet. Sci. Conf., abstr. #1970. [2] Bouvier et al. (2007) Geochim. Cosmochim. Acta., 71, 1583-1604), making this meteorite the oldest know material from the solar system from Al-Mg dating. Now I wonder if this meteorite had came from those three asteroids Sunshine?s team investigated, and if so, how this might be proved or disproved.

http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2184.pdf

Now this also brings up another question, if dating the oldest material out there, can one could date from the time the solar system formed or pre date before it was formed aka pre solar grains. Now with that in mind would Tagish Lake be the oldest meteorite to have to oldest material ever found in a meteorite which has been published?
 
All in all I have to say that the new (discovery) CC/ NWA 2364 has to be exciting news for scientists and the meteorite community. I am wondering in the next few years where science will take us and if there will be new dating techniques that will make PB-PB/238U/235U/Al-Mg dating look obsolete?

But......... why is Allende and Efremovka CIA PB-PB dating younger then NWA 2364 shouldn't they be the same or is the answer in U isotope composition?

Shawn Alan
IMCA 1633
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Received on Thu 17 Mar 2011 03:33:55 PM PDT