[meteorite-list] Meteorite reclassification questions

From: ALAN RUBIN <aerubin_at_meteoritecentral.com>
Date: Wed, 13 Mar 2019 23:00:54 -0700
Message-ID: <CACWzm1xjUiSvwgm0ZLQ7+wwLA_JM8DtedpuuX5bg=vwoEN9PvA_at_mail.gmail.com>

When I initially classified Ningqiang, there were no known CKs. We
classified it as CV3 because that was the closest group, but we noted that
its refractory lithophile element abundances didn't match CV that well.
Later, when we defined the CK group, it became obvious that Ningqiang was
more like CK than CV. Later, upon additional reflection and analyses, we
thought it most likely that Ningqiang was sufficiently different from
normal CKs, that it was probably an ungrouped carbonaceous chondrite that
was closely related to CK and CV.

If you want a meteorite to be reclassified int the Bulletin, you need to
let the folks know (i.e., through Jeff Grossman) that this is warranted and
explain the reasons. Sometimes, the rock will indeed be reclassified and
sometimes it won't. It can be frustrating. I'm not familiar with Hart or
NWA 6047. You could email Tasha Dunn and ask her.
Alan Rubin

On Wed, Mar 13, 2019 at 9:07 PM Michael Doran via Meteorite-list <
meteorite-list at meteoritecentral.com> wrote:

> As a newbie, I've come to rely pretty heavily on the Meteoritical
> Bulletin database for information about particular meteorites as well as to
> look at aggregate data for different types.
> I've been somewhat surprised to discover that it is not unusual for
> meteorites to get reclassified and I was wondering if anybody could tell me
> how and under what circumstances a Met Bull entry gets updated to reflect
> new classification information.
> Ningqiang is a good example of reclassification updates. The Meteoritical
> Bulletin database entry shows that Ningqiang was originally classified as a
> CV3, per Meteoritical Bulletin #65 (1987) [1]. Then (if I'm interpreting
> the entry correctly) it looks like it was reclassed as a CK3, per the
> Natural History Museum's Catalogue of Meteorites, 5th edition (2000). And
> a subsequent reclassification as C3-ung came per the 7th edition of MetBase
> (2006).
> The particular example I had questions about is the entry for Hart, a
> Texas meteorite found in 2010 and that was initially classified as a CK3
> [2]. CK3 is a pretty rare carbonaceous chondrite type and Hart was
> apparently the only meteorite in the U.S. to get that classification.
> However, I recently came across a scientific paper ("Reclassification of
> Hart and Northwest Africa 6047: Criteria for distinguishing between CV and
> CK3 chondrites" [3]) that appears to make a persuasive case for Hart being
> reclassified as a CV3. This paper was published in 2017, but there is no
> update yet in the Met Bull entry.
> So my questions are:
> 1) Will the Meteoritical Bulletin database entry for Hart eventually get
> updated to reflect a change in classification?
> 2) What mechanisms (if any) are in place to keep track of these types of
> reclassifications and make updates? (From what I've seen, there is a
> mechanism for Antarctic meteorites via the Antarctic Meteorite Newsletter.
> See, for example AMN item on reclassifications [4] and subsequent Met Bull
> database entry update [5].)
> 3) Is there some body that mediates between competing classification
> claims? E.g. what if the original classifier disagrees with a
> reclassification?
> -- Michael
> [1] https://www.lpi.usra.edu/meteor/metbull.php?code=16981
> [2] https://www.lpi.usra.edu/meteor/metbull.php?code=56555
> [3] Dunn, TL, Gross, J. 2017 Reclassification of Hart and Northwest Africa
> 6047: Criteria for distinguishing between CV and CK3 chondrites.
> Meteoritics & Planetary Science 52(11):2412?2423
> [4] https://curator.jsc.nasa.gov/antmet/amn/amnfeb10/reclassifications.htm
> [5] E.g. for EET 96010
> https://www.lpi.usra.edu/meteor/metbull.php?code=9604
> Michael Doran
> Fort Worth, TX
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Alan Rubin
Institute of Geophysics and Planetary Physics
Department of Earth, Planetary, and Space Sciences
University of California
3845 Slichter Hall
603 Charles Young Dr. E
Los Angeles, CA  90095-1567
office phone: 310-825-3202
fax: 310-206-3051
e-mail: aerubin at ucla.edu
website: http://cosmochemists.igpp.ucla.edu/Rubin.html
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Received on Thu 14 Mar 2019 02:00:54 AM PDT

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