[meteorite-list] Nwa 7034

From: Jim Wooddell <nf114ec_at_meteoritecentral.com>
Date: Sun, 27 Jan 2013 10:15:54 -0700
Message-ID: <4wnevkxgpfcwdpsrk44q3ig6.1359306954519_at_email.android.com>

Hi all!

It seems that over time, with our knowledge increasing, naming and systematics would follow the knowledge. If something is different, it's different. Has anyone really ever agreed on systematics?
 Kind regards

Jim

Jim Wooddell - Mobile

Carl Agee <agee at unm.edu> wrote:

>Alan,
>
>Very good point, but now because of the appearance of NWA 7034 the
>waning usefulness of distinct martian types is actually reversed and
>becomes more relevant. In the past few years we have seen so many new
>shergottite finds, but they are all more or less the same rocks as in
>the collections, so nothing really new, and we all thought
>"SNC=martian meterorite". NWA 7034 is quite different, it is not just
>another SNC, it is showing us that the SNCs are probably a small
>biased sampling of Mars -- but we already knew that from rover and
>orbiter data. So now it is useful to say "SNC+NWA7034=martian
>meteorite", and make the statement that no, this is not just another
>shergottite, only brecciated.
>
>Carl
>
>On Sun, Jan 27, 2013 at 9:38 AM, Alan Rubin <aerubin at ucla.edu> wrote:
>> The bottom line in all of this is that meteorite group names will last only
>> as long as they're useful. The literature of the past is littered with
>> group names such as grahamites and others I've forgotten because they fell
>> out of use. Similarly, the term SNC is not used much these days although
>> the individual group names survive. If scientisits no longer find it useful
>> to use the term shergottite, then it will gradually fall out of use. If
>> folks invent new names and no one uses them, then it doesn't really matter.
>> An interesting analogy is that there are some unpopular models for chondrule
>> formation, for example, (say gamma-ray bursts) that no one uses and thus
>> don't pollute the literature.
>> 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: "Carl Agee" <agee at unm.edu>
>> To: "meteoritelist meteoritelist" <meteorite-list at meteoritecentral.com>
>> Sent: Sunday, January 27, 2013 8:20 AM
>>
>> Subject: Re: [meteorite-list] Nwa 7034
>>
>>
>> Hi Jeff,
>>
>> Of course the comparison between chondrite groups and martian types is
>> not perfect. The different martian types are not from different parent
>> bodies, but we still don't know where they come from on Mars, and
>> won't for a long time, not until we know the geology of Mars better.
>> So for a large body like a planet, and given our fragmentary knowledge
>> of Mars, different regions are more or less equivalent to different
>> parent bodies. Describing martians with generic lithologic names that
>> were developed for Earth geology is useful, but for example we don't
>> hesitate to use the term mid-ocean ridge basalts (MORB) for Earth's
>> most abundant rock type, which will never be found on Mars. The same
>> is true for Mars because of a different planetary evolution. We are
>> already doing this based on rover data, the term "Gusev basalt" is one
>> example. SNC's plus ALH 84001 and NWA 7034 are, each type, glimpses of
>> diversity of Mars' unique geology.
>>
>> Carl Agee
>>
>> --
>> Carl B. Agee
>> Director and Curator, Institute of Meteoritics
>> Professor, Earth and Planetary Sciences
>> MSC03 2050
>> University of New Mexico
>> Albuquerque NM 87131-1126
>>
>> Tel: (505) 750-7172
>> Fax: (505) 277-3577
>> Email: agee at unm.edu
>> http://meteorite.unm.edu/people/carl_agee/
>>
>> ---------- Forwarded message ----------
>> From: Jeff Grossman <jngrossman at gmail.com>
>> To: <meteorite-list at meteoritecentral.com>
>> Cc:
>> Date: Sun, 27 Jan 2013 00:06:22 -0500
>> Subject: Re: [meteorite-list] Nwa 7034
>> There are two reasons why we can't get rid of carbonaceous chondrite
>> group names. First, unlike Martian meteorites, we don't know where C
>> chondrites came from. We can't point to a single asteroid as the
>> source for any of them, let alone all of them. So the group names are
>> still serving their basic purpose of ordering the chaos. Second, the
>> only language we have to describe the rocks known as chondrites is by
>> their group names. They can't be described with standard rock
>> nomenclature. So this is not a fair comparison.
>>
>> I didn't say Martian meteorite names were not useful. I said they
>> were archaic, historical artifacts.
>>
>> Jeff
>>
>> On 1/26/2013 11:38 PM, Carl Agee wrote:
>>
>> Hi Jeff and all you Nomenclature Enthusiasts out there:
>>
>> I think the martian meteorite names do serve a useful purpose, they
>> are a sort of short-hand, so that you don?t have to be an igneous
>> petrologist to know that one type of martian is different from
>> another. So when we say a martian meteorite is a ?NWA7034-ite?, or
>> ?blackbeauty-ite?, or a ?saharite? or whatever name you want to pick,
>> we are implicitly talking about a breccia, that is water-rich, alkali
>> basalt, with higher-than-SNC oxygen isotope values, ~ 2 byo, etc. For
>> example, like it or not, when we say ?Allan Hills? the first thing
>> comes that comes to mind is ALH 84001. When you say orthopyroxenite
>> maybe not so much. If it?s such a great idea to do away with martian
>> types, why don?t we go ahead and do away with all the carbonaceous
>> chondrite groups like CI, CM, CV, etc. and just call them all
>> carbonaceous chondrites, that of course have a wide range of
>> compositions, textures, mineralogies etc.? Meteoritics isn?t the only
>> science that has colorful nomenclature. Mineralogists still like to
>> name new minerals after famous mineralogists, instead of just naming
>> them by their chemical composition or crystal structure.
>>
>> Carl Agee
>> ______________________________________________
>>
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>>
>
>
>
>--
>Carl B. Agee
>Director and Curator, Institute of Meteoritics
>Professor, Earth and Planetary Sciences
>MSC03 2050
>University of New Mexico
>Albuquerque NM 87131-1126
>
>Tel: (505) 750-7172
>Fax: (505) 277-3577
>Email: agee at unm.edu
>http://meteorite.unm.edu/people/carl_agee/
>______________________________________________
>
>Visit the Archives at http://www.meteorite-list-archives.com
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Received on Sun 27 Jan 2013 12:15:54 PM PST