[meteorite-list] CH or CB Chondrite?

From: Alexander Seidel <ase_at_meteoritecentral.com>
Date: Thu Apr 22 10:29:54 2004
Message-ID: <3F644700.5F19DA99_at_planet-interkom.de>

Thanks, Bernd, for your interesting answer. So both the papers by
Russell and Greshake tell us of a chondritic grouplet called CB, while
on the other hand the very latest version of MetBase (V6.0, issued
this summer) still has the CH-BEN type classification, and not CB.

Now, what makes me wonder is this: MetBase is authored by Joern
Koblitz, who in turn is a member of the NomCom of the Meteoritical
Society, which, I suppose, leads to the conclusion that he uses to
have fully accepted first-hand-information in his datafiles.

So my question is: is the CB designation still just a proposal (made
by the authors of these papers, and may be others), and has yet to
arrive at a status of general acceptance by the scientific community?
Should CH-BEN be abandoned? Are both of them valid side by side for
the time being?

Jeff Grossman, can you shed some light on this?

Alex Seidel
Berlin, Germany
  

bernd.pauli_at_paulinet.de wrote:
>
> > G'day List,
>
> Hello Down Under,
>
> > HaH 237 is formally classified as being a CH (petrologic type 3) ...
>
> RUSSELL S.S. et al. (2003) Copper isotope systematics in CR, CH-like
> and CB meteorites: A preliminary study (MAPS 38-7, 2003, A124).
>
> In this abstract, Mrs. Russell calls it "CH-like". J.A. Whitby,
> on the other hand, writes in his abstract in the same issue:
>
> Gujba and HaH 237 are both members of the metal-rich carbonaceous
> chondrite CR clan. Differences in petrography, such as the size of
> chondrules, led to the designation of Gujba as CBa and HaH as CBb.
>
> WHITBY J.A. et al. (2003) Gujba and HaH 237 (MAPS 38-7, 2003, A105).
>
> > 've seen it listed on many websites as a CH-BEN (Metal rich Bencubbinite).
> > I thought that CB or Bencubbinites are now a separate classification including
> > the 5 members:
>
> Bencubbin = CB3a
> Gujba = CB3a
> NWA 1814 = CB3a
> QUE 94411 = CBb
> Weatherford = CB3a
>
> and A. Greshake writes:
>
> Bencubbin, Weatherford, and Gujba have recently been placed together
> in a new metal-rich chondritic grouplet called CB (carbonaceous Bencubbin-
> like) chondrites. Due to their strong similarities to CR and CH chondrites,
> they are considered as part of the CR carbonaceous chondrite clan.
>
> GRESHAKE A. et al. (2002) Heavily-hydrated lithic clasts in CH chondrites
> and the related, metal-rich chondrites Queen Alexandra Range 94411 and
> Hammadah al Hamra 237 (MAPS 37-2, 2002, pp. 281-293).
>
> Best wishes,
>
> Bernd
>
> P.S.: In spite of this information, it is (as usual :-) very, very helpful to go
> to David Weir's website for further valuable details and descriptions !!!
>
> To: jeff_at_meteoritesaustralia.com
> meteorite-list_at_meteoritecentral.com
>
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Received on Sun 14 Sep 2003 06:46:24 AM PDT