[meteorite-list] Question about NWA 869

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Fri, 4 Nov 2011 04:03:47 -0400 (EDT)
Message-ID: <8CE68DF69E33573-2840-3F12C_at_webmail-d132.sysops.aol.com>

PS

Referencing the same article that considered the free floating for 4-5
million year 869-parent meteoroid, also commented that the age of some
of the regolith soil/glue that formed the fantastically brecciated
meteoroid of our envy had itself exposure time of as long as 16 million
years:

"Assuming that 4 Ma is the time of transit irradiation, several
lithologies have been preirradiated up to 16 Ma in the parent body
regolith."


-----Original Message-----
From: MexicoDoug <mexicodoug at aim.com>
To: miss_meteorite <miss_meteorite at yahoo.ca>; meteorite-list
<meteorite-list at meteoritecentral.com>
Sent: Fri, Nov 4, 2011 3:49 am
Subject: Re: [meteorite-list] Question about NWA 869


NWA 869 represents an L chondritic regolith breccia containing
preirradiated components. The meteoroid had an initial radius of about
2 m with a mass of about 110 metric tons. The transit time to Earth was
about 4-5 Ma. Large variations of shielding depths between samples
indicate that break-up of the meteoroid must have occured high in
atmosphere. This would also explain the large inferred ablation loss,
which is typical for large chondrite showers.

Ref:

"The L3-6 Regolith Breccia Northwest Africa 869: Petrology, Noble
Gases, and Cosmogenic Radionuclides"
Metzler, K.; Ott, U.; Welten, K. C.; Caffee, M. W.; Franke, L.
39th Lunar and Planetary Science Conference, (Lunar and Planetary
Science XXXIX), held March 10-14, 2008 in League City, Texas.
LPI Contribution No. 1391., p.1120
Publication Date: 03/2008

http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1120.pdf



-----Original Message-----
From: Melanie Matthews <miss_meteorite at yahoo.ca>
To: MeteoriteList <meteorite-list at meteoritecentral.com>
Sent: Fri, Nov 4, 2011 2:10 am
Subject: [meteorite-list] Question about NWA 869


Hi list,

Are there any estimates in how long ago this wonderful meteorite fell
to Earth,
and how large it might have been before it entered the atmosphere? It
must have
been a massive meteoroid, much larger than the one that produced the
Buzzard
Coulees.

?
-----------
-Melanie "MetMel" - avid meteorite collector/enthusiast from Canada!
IMCA#: 2975
eBay: metmel2775


I eat, sleep and breath meteorites 24/7.
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Received on Fri 04 Nov 2011 04:03:47 AM PDT