[meteorite-list] Type 7 chondrites

[Richard Montgomery]

What thoughts about Taffessasset in this regard?  Anyone wish to chime in?
Richard M


----- Original Message ----- 
From: "Alan Rubin" <aerubin at ucla.edu>
To: "Peter Scherff" <PeterScherff at rcn.com>; "'Adam'" 
<meteorite-list at meteoritecentral.com>
Sent: Monday, March 04, 2013 3:41 PM
Subject: Re: [meteorite-list] Type 7 chondrites


> Most classifiers don't use the type-7 designation because many of the 
> chondrites that have been called type-7 seem to be impact-melt breccias. 
> Most researchers believe that thermal metamorphism probably caused by 
> asteroidal heating engendered by the decvay of short-lived radionuclides 
> like 26-Al heated chondrites from type 3 to 4 to 5 to 6.  If shock was 
> responsible for causing a rock to be called type 7, then it seemed more 
> prudent to just call it shocked and not use the type-7 designation.  Most 
> researchers believe that the primitive achondrites were also partly (or 
> completely) melted by heating caused by the decay of 26-Al.  I am not of 
> these camps; it seems to me that heating of chondrites from type 3 to type 
> 6 also results from impact heating and that the primitive achondrites 
> formed in an analogous way, but that is another story.
> 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: "Peter Scherff" <PeterScherff at rcn.com>
> To: "'Adam'" <meteorite-list at meteoritecentral.com>
> Sent: Monday, March 04, 2013 3:14 PM
> Subject: [meteorite-list] Type 7 chondrites
>
>
>>
>> Hi,
>>
>> Is there any consensus about petrologic type 7 chondrites? Are they 
>> better
>> classified as Primitive Achondrites? If type 7 is different from 
>> primitive
>> achondtites what is the line between them?
>>
>> Thanks,
>>
>> Peter Scherff
>>
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