[meteorite-list] Chelyabinsk - IMB or SMB? The nomenclature of Melts.

From: Jim Wooddell <jimwooddell_at_meteoritecentral.com>
Date: Wed, 24 Apr 2013 20:49:58 -0700
Message-ID: <CAH_zgwH-sW6eMU_rGLfGA=fZ2rAqTp6mqcOr5TuSowx3D3xmZQ_at_mail.gmail.com>

Hi Jeff!

To me, Impact Melt should mean total melt to liquid...no fragments of
any kind. In the case of the classified S4, partial melting
occurred, confirmed by fragments. Still, various flavors
understandable especially at boundaries.
Yep, I think nodules is the keyword that is questionable. Graphite
"nodules" are found in Canyon Diablo, for example. Once they find
large enough pieces of this meteorite, they might confirm nodules but
they would not be abnormal or a special anomaly if they are impact
melt.

On Wed, Apr 24, 2013 at 8:24 PM, Jim Wooddell <jimwooddell at gmail.com> wrote:
> Hi Jeff!
>
> To me, Impact Melt should mean total melt to liquid...no fragments of any
> kind. In the case of the classified S4, partial melting occurred,
> confirmed by fragments. Still, various flavors understandable especially at
> boundaries.
> Yep, I think nodules is the keyword that is questionable. Graphite "nodules"
> are found in Canyon Diablo, for example. Once they find large enough pieces
> of this meteorite, they might confirm nodules but they would not be abnormal
> or a special anomaly if they are impact melt.
>
> Jim
>
>
>
> On Wed, Apr 24, 2013 at 7:53 PM, Jeff Kuyken <info at meteorites.com.au> wrote:
>>
>> Definitely IMB although you will find variations within different stones.
>> Some will be shocked to the point of melt and others will not quite get
>> there. Personally I think IMB and SMB are the exact same terms as both are
>> "melt breccias" and shock is derived from impact.
>>
>> The official classification of Chely states: "A significant portion (1/3)
>> of
>> the stones consist of a dark, fine-grained impact melt containing mineral
>> and chondrule fragments."
>>
>> http://www.lpi.usra.edu/meteor/metbull.php?code=57165
>>
>> I personally don't think "nodules" is really the correct terminology
>> either.
>> They are just individuals / fragments of the same material shocked to a
>> higher degree in the parent body. For example... compare it to Gao. We
>> don't
>> call the IMB pieces, nodules. They are IMB individuals. The term "nodules"
>> would seem to me to be better reserved for things like "iron nodules" in a
>> stony Mesosiderite or a "Troilite nodule" in an iron meteorite.
>>
>> Good question Mike.
>>
>> Cheers,
>>
>> Jeff
>>
>> -----Original Message-----
>> From: meteorite-list-bounces at meteoritecentral.com
>> [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Galactic
>> Stone & Ironworks
>> Sent: Thursday, 25 April 2013 10:42 AM
>> To: Meteorite List
>> Subject: [meteorite-list] Chelyabinsk - IMB or SMB? The nomenclature of
>> Melts.
>>
>> Hi List,
>>
>> We keep hearing about the "IMB nodules" that have been recovered -
>> these have an all-black lithology with no chondrules, shock veins, or
>> grey matrix material.
>>
>> However, these nodules were not created on impact. Had there been
>> such an impact, we would have a visible crater and the nodules would
>> be located in a radius directly adjacent to the crater amidst the
>> ejecta. Instead, these nodules were apparently created during the
>> fragmentation events that took place while the body was still in
>> atmospheric flight.
>>
>> If this is true, shouldn't these nodules be called "shock melt" and
>> not "impact melt" ?
>>
>> Is there any distinction in the official nomenclature between an
>> impact melt and a shock melt?
>>
>> Is it correct to continue using IMB in reference to these Chelyabinsk
>> specimens?
>>
>> Best regards,
>>
>> MikeG
>>
>> --
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>
>
>
> --
> Jim Wooddell
> jimwooddell at gmail.com
> 928-247-2675

-- 
Jim Wooddell
jimwooddell at gmail.com
928-247-2675

Received on Wed 24 Apr 2013 11:49:58 PM PDT