[meteorite-list] NWA 5402 LL6 Melt Rock [was Primitive Achondrite Question]

From: Greg Hupé <gmhupe_at_meteoritecentral.com>
Date: Tue, 6 Dec 2011 14:04:47 -0500
Message-ID: <1558C9FAE20B43A1B11FBF84A2A0D0FA_at_Gregor>

Hello All,

With today's conversation regarding the "Primitive Achondrite Question"
thread, I thought I would draw your attention to a 'melt rock' I have had
for 3 1/2 years but have not done anything with it, and still am not
offering any of it at this point.

Here is a link to the Officially recognized Bulletin entry for NWA 5402, an
'LL6 Ungrouped Achondrite', or recommended "LL Melt Rock", not sure which is
preferred as both are in the Official entry. Also find here a quickie photo
I just took of the unpolished face of the mass the type sample was cut from:

Meteoritical Bulletin entry:
http://www.lpi.usra.edu/meteor/metbull.php?code=49128

Image of NWA 5402 cut face:
http://www.lunarrock.com/NWA5402/NWA5402mass.jpg

Best Regards,
Greg

The Dead Horse Society-EL3
"Dead Horses Can't Live Until They Are Buried Standing UP!"
====================
Greg Hup?
The Hup? Collection
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-----Original Message-----
From: Alan Rubin
Sent: Tuesday, December 06, 2011 1:05 PM
To: raremeteorites at yahoo.com ; meteorite-list at meteoritecentral.com
Subject: Re: [meteorite-list] Primitive Achondrite Question

I thought I would add my tuppance worth. I don't use the type-7
classification. If a chondrite shows no evidence of melting, I'll classify
it as type-6 no matter how recrystallized it may be -- whether there are
recognizable chondrules or not. If the rock does show evidence of melt,
there are invariably indications that the melt has been impact-generated and
I'll call the rock an impact-melt breccia. If the rock has been essentially
totally melted, I'll call it an impact-melt rock. Almost all of these rocks
can be assigned to a known chondrite group on the basis of olivine Fa, O
isotopes, bulk chemistry, etc. If a rock is a winonaite or acapulcoite, it
can be classified as such. But if we want to understand how these
"primitive achondrite" groups formed (not required for classification
purposes), there are basically two schools of thought. Most researchers
maintain that primitive achondrites are rocks that have been partly melted
by internal heating processes (ala Al-26) and the heating and fractionation
just did not proceed as far as in the case of true achondrites. A minority
of researchers (including me) believe it is more likely that primitive
achondrites are impact-melted chondrites and are thus not that different
than chondrite impact-melt breccias and chondrite impact-melt rocks. As I
said earlier, the origin of these meteorites is not important for their
proper classification, but it can lead to heated debates.
Alan



Alan Rubin
Institute of Geophysics and Planetary Physics
University of California
3845 Slichter Hall
603 Charles Young Dr. E
Los Angeles, CA 90095-1567
phone: 310-825-3202
e-mail: aerubin at ucla.edu
website: http://cosmochemists.igpp.ucla.edu/Rubin.html


----- Original Message -----
From: "MexicoDoug" <mexicodoug at aim.com>
To: <raremeteorites at yahoo.com>; <meteorite-list at meteoritecentral.com>
Sent: Tuesday, December 06, 2011 9:31 AM
Subject: Re: [meteorite-list] Primitive Achondrite Question


> Adam wrote:
>
> "NWA 3133 is a CV Primitive Achondrite"
>
> Hi Adam, thanks ... The asteroid belt ought to be called the asteroid zoo!
>
> The question I have on this one, if CV is for certain, would be whether it
> is the result of a collision with a typical CV type, or is it certain that
> it is a fully baked CV (what happened to the possible CAI's - are there
> any, or is the CV possibly just impact regolith?), or, whether some
> innocent CV got hot all by itself.
>
>
> Kinest wishes
> Doug
>
> (Why does my wallet retract down my pocket every time ths stuff comes up!)
>
>
>
>
> -----Original Message-----
> From: Adam Hupe <raremeteorites at yahoo.com>
> To: Adam <meteorite-list at meteoritecentral.com>
> Sent: Tue, Dec 6, 2011 11:47 am
> Subject: Re: [meteorite-list] Primitive Achondrite Question
>
>
> Doug wrote: I can't wait until someone turns up a CV6+. Theoretically,
> there is
> no reason to
> bar the possibility,, or is there...
>
> NWA 3133 is a CV Primitive Achondrite
>
> All of these oxygen isotope compositions
> plot on the CV3 mixing line, suggesting that this achondritic meteorite
> has
> affinities with CV chondrites (Irving et al., 2004).
>
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Received on Tue 06 Dec 2011 02:04:47 PM PST