[meteorite-list] petrological type

From: Alan Rubin <aerubin_at_meteoritecentral.com>
Date: Fri, 11 Apr 2014 22:10:25 -0700
Message-ID: <02d901cf560d$84cceda0$8e66c8e0$_at_ucla.edu>

Several people have informally suggested a two-tier system. It would work
something like this. For example, on a metamorphic scale, Semarkona is type
3.00, but on an independent aqueous alteration scale it would be 2.8 or 2.9.
Similarly, CR chondrites could all be 3.0 on a metamorphic scale, but range
from 2.0 to 2.8 on an aqueous alteration scale. This is admittedly
cumbersome, but it would be fairly useful. However, there are some
carbonaceous chondrites that seem to have been altered and then
metamorphosed; they would be hard to deal with. Also, if a rock is
hydrothermally altered (i.e., subjected to metamorphic heating and aqueous
alteration at the same time), that would also not be covered by such a
scheme. Fitting complex rocks into classificatory straightjackets might
obscure more than it reveals.
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

office phone: 310-825-3202
fax: 310-206-3051
e-mail: aerubin at ucla.edu
website: http://cosmochemists.igpp.ucla.edu/Rubin.html

-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Mark
Bowling
Sent: Friday, April 11, 2014 10:01 PM
To: meteorite-list at meteoritecentral.com
Subject: Re: [meteorite-list] petrological type


Are there any better alternatives that could someday replace the current
one, and do you have any references/links for them?

Thanks,
Mark

________________________________
From: Jeff Grossman <jngrossman at gmail.com>
To: meteorite-list at meteoritecentral.com
Sent: Friday, April 11, 2014 5:22 PM
Subject: Re: [meteorite-list] petrological type


Answer: you can't.? The classification scheme is lousy.

Jeff

On 4/11/2014 1:21 PM, Michael Mulgrew wrote:
> Two sequences, one for aqueous alteration and one for thermal
> metamorphism (http://www.meteoritemarket.com/PetTypeGroup.jpg).? Makes
> one wonder how we would classify a meteorite that is both thermally
> and aqueously altered...
>
>
>
Michael in so. Cal.
> IMCA 3963
>
> On Fri, Apr 11, 2014 at 10:14 AM, Francesco Moser <cojack at tiscali.it>
wrote:
>> Hello, I have a question about chondrites' petrological type number
assigned
>> after the letters (like H, L, CM or CR ...).
>> I have just read something in internet but I think I have misunderstood
>> something.
>>
>> Are the numbers from 1 to 7 in sequence or there are two different
>> sequences: 1 to 2 - 3 to 7 ??
>> 1 to 2 is for the aqueous alteration degree in carbonaceous chodrites (1
>> high degree, 2 low degree)
>> 3 to 7 is for thermal metamorphism? degree?
>>
>>
>> Thanks a lot
>>
>> Ciao
>>
>> <x>x<x>x<x>
>> Francesco
>>
>>
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Received on Sat 12 Apr 2014 01:10:25 AM PDT