[meteorite-list] new terminology for Vestan meteorites

From: Michael Gilmer <meteoritemike_at_meteoritecentral.com>
Date: Thu, 7 Apr 2011 15:41:14 -0400
Message-ID: <BANLkTimHS1NNdHOMY=cOX_UzExyA+jy2Gg_at_mail.gmail.com>

Aaaah, poor HEDOD, we hardly knew ye..... :)

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Mike Gilmer - Galactic Stone & Ironworks Meteorites

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On 4/7/11, Impactika at aol.com <Impactika at aol.com> wrote:
> On behalf of Dr. Tony Irving who occasionally reads the MetList archives:
> Anne M. Black
> _http://www.impactika.com/_ (http://www.impactika.com/)
> _IMPACTIKA at aol.com_ (mailto:IMPACTIKA at aol.com)
> President, I.M.C.A. Inc.
> _http://www.imca.cc/_ (http://www.imca.cc/)
>
>
> In a message dated 4/7/2011 8:23:40 AM Mountain Daylight Time,
> irving at ess.washington.edu writes:
>
> I noticed the interest on the list about the wider variety of rock types
> among HED meteorites. In fact a new terminology proposed in a paper
> last year has been adopted by the NomCom, wherein all of the rocks
> previously called olivine diogenites as well as the Vestan dunites are
> called diogenites. Under this base name there is a wide range in the
> relative amounts of orthopyroxene and olivine (from zero olivine to over
> 90% olivine). By adopting established names for terrestrial peridotites
> as qualifying adjectives, the new names are as follows:
>
> "Regular" diogenite (with up to 10 volume% olivine) = orthopyroxenitic
> diogenite
>
> "Olivine diogenite" (with >40 volume% olivine) = harzburgitic diogenite
>
> Olivine-rich Vestan rocks (with >90 volume% olivine) = dunitic diogenite
>
> By analogy with established terrestrial nomenclature, there also should be
> a category for specimens containing between 10 and 40 volume% olivine (so
> far only one is known), and that would be olivine-orthopyroxenitic
> diogenite.
>
> I realize that these names are a bit cumbersome, but they do make sense.
> In addition, diogenites with <90 volume% olivine can contain up to 10
> vol.% plagioclase, and still be called diogenites.
>
> Another effect of this nomenclature is that the acronym HEDOD (which we
> have used) is unnecessary, and so we can go back to calling the suite of
> (evidently) Vestan rocks by the traditional HED acronym.
>
> Actually there are at least three other dunitic diogenites: MIL 03443, NWA
> 5784 and NWA 5968. The first that Ted Bunch and I knew about the new
> terminology was when we submitted the classifications for NWA 5784 and NWA
> 5968, and were told (to our inital amazement) that they would be approved
> as diogenites. We presented our work on these specimens last summer at
> the MetSoc meeting in NYC:
> http://www.lpi.usra.edu/meetings/metsoc2010/pdf/5315.pdf
>
> I am not a list member but I do check the archives periodically. Please
> feel free to share any of this with both IMCA and List members.
>
> Best regards,
>
> Tony
>
>
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Received on Thu 07 Apr 2011 03:41:14 PM PDT