Backing up and extending what Alan said, in current usage, a slash means
one of two things: 1) there are properties of this meteorite that are
intermediate or transitional between the two classes, or 2) The
classifier could not decide which group it was due to some kind of
limitation in methodology or samples. In the case of Holbrook, it is
the first meaning. A variety of properties have been measured that put
Holbrook near the L/LL boundary, including O isotopes and metal composition.
So what does that mean? Nobody knows. Either the L and LL asteroids
had overlapping properties, in which case we don't know which was
originally home to Holbrook, or there are other asteroids with
intermediate properties that could be the parent of Holbrook.
The L and LL groups are not particularly well resolved from each other
in many properties, although it is certain they are not all from one
asteroid. I am confident that quite a number of classified L chondrites
are from the LL body and vice versa, and not just limited to the ones
that are called L/LL.
Jeff
Dave Gheesling wrote:
Bernd, Alan, and List,
Thank you both for the diplomatic and informative responses. While we're on
the subject, might one of you (or anyone else) expand on, say, the L/LL6
classification designation? Holbrook was recently moved from an L6 to such
a classification, and I have a few others in my collection which are not
breccias (and presumably are entirely from one parent body and not two) but
yet have this classification assigned to them...which, "by definition,"
would imply connection with both the L and LL parent bodies, presumably
anyway.
Thanks, and all best,
Dave
www.fallingrocks.com
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Wednesday, September 09, 2009 12:47 PM
To: [email protected]
Subject: [meteorite-list] Chondritic parent bodies
Hello Dave, Alan, and List,
Here is a paper that may be of interest with regard to LL chondrite parent
bodies:
Dixon E.T., Bogard D.D. and Garrison D.H. (2002) 40Ar-39Ar Chronology of LL
Chondrites (Lunar and Planetary Science XXXIII, 1114.pdf).
They even discuss *three* models:
1. The onion-shell model
2. The rubble-pile model
3. The re-assembly model
Best wishes,
Bernd
______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
[email protected]
http://six.pairlist.net/mailman/listinfo/meteorite-list
______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
[email protected]
http://six.pairlist.net/mailman/listinfo/meteorite-list
--
Dr. Jeffrey N. Grossman phone: (703) 648-6184
US Geological Survey fax: (703) 648-6383
954 National Center
Reston, VA 20192, USA
______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
[email protected]
http://six.pairlist.net/mailman/listinfo/meteorite-list
