Re: [meteorite-list] metachondrite
All: I wondering if at some time as more of these meta or'7-s' are found, there could be classification system implemented like there currently is for the 3-type. There is 3.0 through 3.9 based on further analysis; how about a 6.1 through 6.9, were the higher number represent more metamorphism, and other unique changes in the re-crystallization. Just a thought. Greg S. Date: Sun, 24 Oct 2010 17:56:03 -0400 From: jgross...@usgs.gov CC: meteorite-list@meteoritecentral.com Subject: Re: [meteorite-list] metachondrite I don't think it's appropriate to say that somebody who does not like a term suggested in a couple of abstracts is a purist who sh[ies] away from any thinking out of the conventional box! As far as I understand the term, there do not seem to be any concepts behind metachondrite that are outside the boxes of the existing terminology. It just appears to me to be a new word for something we already have terms to describe. So it comes down to a question of semantics. Type 7 chondrites have not been excommunicated either. It has been a problematic term because some of the rocks that led to the coining of this term turned out to be impact melt rocks, which is a different phenomenon from the thermal metamorphism we are trying to describe with petrologic types. Once you take these out, there are a few rocks that arguably are metamorphosed to slightly higher temperatures than normal type 6 chondrites, with the primary indicator of this being high CaO content of pyroxene. I have no strong objection to these being called type 7, although I'm not convinced that the term is particularly necessary. Still, if we're sure we're not dealing with impact melted rocks or rocks that have experienced partial melting, then I think the term is ok. That's why some of these got through the nomcom. Once again, this is not an outside the box term, just a minor extension of the usual classification scheme (when used carefully). And finally, as I said before, the word primitive in PAC refers to the composition, which is close to chondritic compared to, say, that of a eucrite, aubrite, or angrite. The same word is frequently used by geologists to describe the Earth's mantle before it gets depleted in certain elements by generation of melts. The word is perfectly fine in this context. Jeff On 2010-10-24 4:20 PM, Ted Bunch wrote: Jeff and the LIST members: Yes, Van Schmus and Wood (V W) did a classic study over 40 years ago, they worked with the available classic OC meteorites and made a workable classification scheme. That was 43 years ago and things change, especially the 10s of thousands of non-classic meteorites available for study and advanced instrumentation including the now common usage of SEM BSE imagery and elemental distribution mapping. V W probably never saw a completely recrystallized OC, they are not even common now. Investigators started seeing OCs that had absolutely NO relict chondrules or chondrule fragments. So, apparently, the V W scheme became inadequate over time and the petrologic classification scheme was unofficially amended with L7, LL7, H7, etc. Seemed reasonable to us. But, not to the purists who shy away from any thinking out of the conventional box. Sevens were excommunicated, a few got through a couple of NOM COMs. Because sevens are completely recrystallized with some elemental loss, we thought that metachondrite was appropriate, but not until our paper on metachondrites goes through the peer review process - if you are clever handicappers, don't bet on this horse. I think we have the same chance as did Joan of Arc with her Inquisition. Metamorphism of chondrites took place over hundreds of thousands of years at elevated temperatures and not necessarily under closed systems. With this concept in mind -- What is a primitive achondrite? Actually, they are metamorphosed/recrystallized rocks that are not the same, even compositionally, as their parent rocks. Primitive? I think not. One dictionary definition of primitive is “not derived from other things”. Acapulcoites and lodranites _are derived from other things, hence not primitive. _A primitive meteorite to me means a CI or may be a CM1, although even these types sustained aqueous alteration. However, Orgueil, even with aqueous alteration, appears to have retained its elemental solar abundances. Because of the huge number of meteorites that have been discovered over the last 20 years, it is time to re-invent other classification schemes for other meteorite classes, namely Martians, in addition to OCs and “primitives”. A recent paper in MAPs has suggested a new scheme for diogenites. We need to get our heads out of the sand box and address these issues. Moreover, in a few years, the few members of the “ungrouped “ meteorites will probably reach the necessary
Re: [meteorite-list] metachondrite
together under a PAC label although they are so heterogeneous and stemming from so many different parent bodies. But they easily can be finer specified, in attaching their individual prefix: L-metachondrite, H-metachondrite, CV-metachondrite ect. And everyone knows immediately, what the stone is about. Not so if you have only a PAC standing there. H, supersimply one could say, metachondrites are chondrites which were longer in the oven. We hope that was relatively correct? If not, please experts, correct us! Aaaand because we were so nice, to try to explain that, and because Eric and Steve could be now hungry for such a whack and extremely rare representative of such a meteorite, we shall be allowed, to note shortly, that from NWA 6438 prov. we still have left the 5.868g-slice http://www.chladnis-heirs.com/nwa6348-5.868g.JPG and the 6.655g corner-cut. http://www.chladnis-heirs.com/nwa6348-6.655g-part-encut.JPG Both from the cleaner not so stained part, nicely fresher. And that the main mass of that first L-meta is now free again, Accepting offers: http://www.chladnis-heirs.com/nwa6348-48.119g-end-cut.JPG Btw. David has added NWA 6348 already to his systematics and wrote an article about. http://www.meteoritestudies.com/ (Click in the side menu on Metachondrites). Best! Martin Stefan PS: Eric wrote: My understanding is a chondrite with multiple lithologies. That would be regolith breccias or polymict breccias, where different fragments of rocks were mixed together and solified by various impacts on the surface of an asteroid. -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Steve Dunklee Gesendet: Freitag, 22. Oktober 2010 18:09 An: jgross...@usgs.gov; meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite So by what I have read metachondrites are material that was once chondrite based on tfL what this suggests is you can take condrite material and have it accrete on a large parent body and make meta chondrite. I think it would be material that formed closer to the sun cooling quickly on one side giving it chondritic attributes and o isotopes closer to the tfL. Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
is hefty, then the rock beneath simply melts - making these IMB, impact melt breccias meteorites, usually quite black, homogenous and with textureless glasses.. The metachondrites are different from them. If you take that idea with that heating by decay, then you can suppose, that they once sat more deeper, closer to the core of their parent body than the 3ers, 4ers,... where it got hotter and where it was longer hot. Now, cause 6 was obviously not the end, Dodd in the 1970ies thought it is necessary to have also a 7. Problem: Most of these crazy stones have no chondrules left. Therefore some say: A chondrite is called a chondrite because it has chondrules! A stone, that has no chondrules has to be called: achondrite!! Therfore a 7er-chondrite would be per definition not allowed. And because the stuff is directly derived from chondrites, which are the most primitive matter we have, we put these stones into the group, we already have, where the ACAPs, LODs, WINs are already sitting in and call them primitive achondrites. And that is somewhat unhappy. Achondrites we have all that stuff from differentiated, non-chondritic parent bodies, like the Vesta matters eucrites, diogenites, howardites, but also the aubrites, ureilites, brachinites, angrites, Martians, Lunars... But from these stones, we know exactly from their composition that they were chondrites. And primitive doesn't fit so well neither - because they aren't that primitive but among the chondrites the most metamorph, most evolved, most equilibrated ones of all. And they are not an unchanged primary meteorite, they are a product of them. The opposite of primitive. The term Metachondrite is there more exact, it says: Look I was a chondrite - I am a metamorph chondrite. So in the name the genesis of the rock is already visible. And it allows to be more specific, as one hasn't to lump all these rocks, from ACAPs, WINs and all these diverse ex-chondrites together under a PAC label although they are so heterogeneous and stemming from so many different parent bodies. But they easily can be finer specified, in attaching their individual prefix: L-metachondrite, H-metachondrite, CV-metachondrite ect. And everyone knows immediately, what the stone is about. Not so if you have only a PAC standing there. H, supersimply one could say, metachondrites are chondrites which were longer in the oven. We hope that was relatively correct? If not, please experts, correct us! Aaaand because we were so nice, to try to explain that, and because Eric and Steve could be now hungry for such a whack and extremely rare representative of such a meteorite, we shall be allowed, to note shortly, that from NWA 6438 prov. we still have left the 5.868g-slice http://www.chladnis-heirs.com/nwa6348-5.868g.JPG and the 6.655g corner-cut. http://www.chladnis-heirs.com/nwa6348-6.655g-part-encut.JPG Both from the cleaner not so stained part, nicely fresher. And that the main mass of that first L-meta is now free again, Accepting offers: http://www.chladnis-heirs.com/nwa6348-48.119g-end-cut.JPG Btw. David has added NWA 6348 already to his systematics and wrote an article about. http://www.meteoritestudies.com/ (Click in the side menu on Metachondrites). Best! Martin Stefan PS: Eric wrote: My understanding is a chondrite with multiple lithologies. That would be regolith breccias or polymict breccias, where different fragments of rocks were mixed together and solified by various impacts on the surface of an asteroid. -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Steve Dunklee Gesendet: Freitag, 22. Oktober 2010 18:09 An: jgross...@usgs.gov; meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite So by what I have read metachondrites are material that was once chondrite based on tfL what this suggests is you can take condrite material and have it accrete on a large parent body and make meta chondrite. I think it would be material that formed closer to the sun cooling quickly on one side giving it chondritic attributes and o isotopes closer to the tfL. Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list -- Dr. Jeffrey N. Grossman phone: (703) 648-6184 US Geological Survey fax: (703) 648-6383 954 National Center Reston, VA 20192, USA __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
Hello Jeff, we tried this time more to explain, what these stones are and not so the terminology, because to some list-members it seemed unclear, what these metachondrites/PACs/7ers are and how they formed. How they shall be called, we leave to each one individually (cause it doesn't change the stones). But Jeff note, that at least the term chondrite vs. achondrite shouldn't be too dogmatically handled, if you remember, that there is also a class formally reckoned among the chondrites, although it hasn't any chondrules, the CI-chondrites - which, if one would be in that sense consequent, would then belong nominally also in the PAC-pot, wouldn't they? For us at least, the metachondrite-terminology would have some advantages. If we read L-metachondrite, LL-metchondrite, CR-metachondrite, we simply know, what the stone IS. An L-metachondrite - everybody knows immediately, aha, precursor material was an L-chondrite, that stone belongs into the L-group. With PAC? PAC can be everything. And if we open a pot labeled PAC - then we lump together meteorites from many different parent bodies. That would be unique in the nomenclature and inconsistent. Because no class/denomination there, under which you have meteorites from different parent bodies. Traditionally you have in a group only stones from more or the less of one kind, from one parent body, and they were named according the first find/fall described. Aubrites from Aubres, Acapulcoites from Acapulco, Brachinites from Brachina, Shergottites from Shergotty...and so on (and we were lucky, that none of the namesake was from Poland, Święcanites, ostrzeszówites... ) - or which were historically named like the eucrites, diogenites, howardites, or where the relations were understood, then at least with the initial from the 1st find/fall. CI from Ivuna, CV from Vigarano, CK from Karoonda ect. With that metamorph chondrites it doesn't work. Simply because they are not a class of their own, they clearly belong into the existing groups. To the Hs, to the Ls, to the CVs ect. (so ungrouped they are in no case). If you would call them 7, then we wouldn't haven't a problem. And of course, one could also pack everything, which has a relic chondrule left, to the 6ers. But to throw all those, which haven't, into the unspecific PAC - creating almost a pseudo-class or -group, would mean an unnecessary coarsening. Also we don't know then the hierarchic structure of the terminology of the classification scheme so well. Would we have then these main groups with these hypernyms:Chondrites, Achondrites (from differentiated parent bodies), Irons, Primitive Achondrites? If so, or also in general, wouldn't it be then anyway necessary to preserve the L-metachondrites, H-metachondrites, LL-meta... as subgroups of the PACs, because we have so heterogeneous meteorites in that group then? Or could one then create rather something like a L-PAC, H-PAC, CV-PAC - (huh ACAPPAC sounds cool). Hmmm, would be much more elegant, to put the PACs (as long as we don't know so much about the precursors of the ACAP/LODs and the WINs) simply as subgroup to the achondrites and the Meta7PACs, there where they generically and chemically belong to, to the individual chondrite classes as metachondrites. If that's feasible at all. Thoughts only, Martin Stefan -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Sonntag, 24. Oktober 2010 17:45 An: meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite Here is the opposing view: The definition of type 6 chondrites comes from one of the classic papers in meteoritics, Van Schmus and Wood (1967): As mentioned above, type 6 contains the most recrystallized chondrites. These chondrites show extensive-to-complete obliteration of the primary textures (Fig. 11), extensive evidence of recrystallization of the original olivine and pyroxene crystals, and good-to-excellent development of plagioclase... Note that this definition includes chondrites that are so recrystallized that chondrules are no longer recognizable. A number of us petrologists think that most type 7 chondrites fit comfortably within this definition of type 6, and consider the former term to be superfluous. With continued heating, chondrites eventually begin to partially melt (reaching the Fe-FeS eutectic temperature and eventually the point where a feldspathic silicate liquid can form). At this point, differentiation can begin, as these liquids separate from residual solids. When some differentiation occurs, it can produce rocks that are nearly chondritic in composition, but depleted in elements that went into these liquids. That is the definition of primitive achondrite: primitive refers to the composition, which is still close to chondritic, and achondrite refers to the lack of chondrules, although rare
Re: [meteorite-list] metachondrite
it got hotter and where it was longer hot. Now, cause 6 was obviously not the end, Dodd in the 1970ies thought it is necessary to have also a 7. Problem: Most of these crazy stones have no chondrules left. Therefore some say: A chondrite is called a chondrite because it has chondrules! A stone, that has no chondrules has to be called: achondrite!! Therfore a 7er-chondrite would be per definition not allowed. And because the stuff is directly derived from chondrites, which are the most primitive matter we have, we put these stones into the group, we already have, where the ACAPs, LODs, WINs are already sitting in and call them primitive achondrites. And that is somewhat unhappy. Achondrites we have all that stuff from differentiated, non-chondritic parent bodies, like the Vesta matters eucrites, diogenites, howardites, but also the aubrites, ureilites, brachinites, angrites, Martians, Lunars... But from these stones, we know exactly from their composition that they were chondrites. And primitive doesn't fit so well neither - because they aren't that primitive but among the chondrites the most metamorph, most evolved, most equilibrated ones of all. And they are not an unchanged primary meteorite, they are a product of them. The opposite of primitive. The term Metachondrite is there more exact, it says: Look I was a chondrite - I am a metamorph chondrite. So in the name the genesis of the rock is already visible. And it allows to be more specific, as one hasn't to lump all these rocks, from ACAPs, WINs and all these diverse ex-chondrites together under a PAC label although they are so heterogeneous and stemming from so many different parent bodies. But they easily can be finer specified, in attaching their individual prefix: L-metachondrite, H-metachondrite, CV-metachondrite ect. And everyone knows immediately, what the stone is about. Not so if you have only a PAC standing there. H, supersimply one could say, metachondrites are chondrites which were longer in the oven. We hope that was relatively correct? If not, please experts, correct us! Aaaand because we were so nice, to try to explain that, and because Eric and Steve could be now hungry for such a whack and extremely rare representative of such a meteorite, we shall be allowed, to note shortly, that from NWA 6438 prov. we still have left the 5.868g-slice http://www.chladnis-heirs.com/nwa6348-5.868g.JPG and the 6.655g corner-cut. http://www.chladnis-heirs.com/nwa6348-6.655g-part-encut.JPG Both from the cleaner not so stained part, nicely fresher. And that the main mass of that first L-meta is now free again, Accepting offers: http://www.chladnis-heirs.com/nwa6348-48.119g-end-cut.JPG Btw. David has added NWA 6348 already to his systematics and wrote an article about. http://www.meteoritestudies.com/ (Click in the side menu on Metachondrites). Best! Martin Stefan PS: Eric wrote: My understanding is a chondrite with multiple lithologies. That would be regolith breccias or polymict breccias, where different fragments of rocks were mixed together and solified by various impacts on the surface of an asteroid. -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Steve Dunklee Gesendet: Freitag, 22. Oktober 2010 18:09 An: jgross...@usgs.gov; meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite So by what I have read metachondrites are material that was once chondrite based on tfL what this suggests is you can take condrite material and have it accrete on a large parent body and make meta chondrite. I think it would be material that formed closer to the sun cooling quickly on one side giving it chondritic attributes and o isotopes closer to the tfL. Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list -- Dr. Jeffrey N. Grossman phone: (703) 648-6184 US Geological Survey fax: (703) 648-6383 954 National Center Reston, VA 20192, USA __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
I cant get the abstract to run on my phone so I am still not sure what is meant by metachondrite. Could it be material that cooled too quickly to form chondrules but still retains many of the characteristics undifferentiated chondrules have? I have some pac and acap that have in some places partial spheres which would indicate rapid cooling on at least one side. When you consider the sun side may be realy hot and the shadow side almost absolute zero it kind of makes sence some material would instantly freeze on one side and remain melted on the other. Making a kind of half chondrule. With jagged edges on one side and smooth partial spheer on the other. Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
So by what I have read metachondrites are material that was once chondrite based on tfL what this suggests is you can take condrite material and have it accrete on a large parent body and make meta chondrite. I think it would be material that formed closer to the sun cooling quickly on one side giving it chondritic attributes and o isotopes closer to the tfL. Cheers Steve Dunklee On Thu Oct 21st, 2010 9:02 AM EDT Jeff Grossman wrote: This is a term coined by Ted Bunch and Tony Irving, but to my knowledge there is no peer-reviewed publication defining the term. You'll find the definition in an AGU and a MetSoc abstract: http://www.lpi.usra.edu/meetings/metsoc2005/pdf/5218.pdf http://adsabs.harvard.edu/abs/2006AGUFM.P51E1246B The term is not in widespread use and has not been used in the Meteoritical Bulletin. Time will tell if it catches on. Jeff On 10/20/2010 11:36 PM, Steve Dunklee wrote: What is a metachondrite? Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
I understand a metachondrite to be a chondrite that has undergone metamorphism resulting in recrystalization. The composition is much the same as in the original chondrite. There are different affinities, such as 'H' 'L' or 'LL'. I think there are others including E's and 'C' chondrites. I think they are a very interesting group of meteorites. Greg S. Sent from my iPhone On Oct 20, 2010, at 8:36 PM, Steve Dunklee steve.dunk...@yahoo.com wrote: What is a metachondrite? Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Metachondrite(s)
Thank you Bernd, Yes a metachondrite is a meta(morphic) chondrite, nothing to do with lithologies. A good example of a CR Meta-chondrite is of course Tafassasset. Goodnight. Anne M. Black _www.IMPACTIKA.com_ (http://www.IMPACTIKA.com) _impact...@aol.com_ (mailto:impact...@aol.com) President of IMCA _www.IMCA.cc_ (http://www.IMCA.cc) In a message dated 10/21/2010 12:36:46 AM Mountain Daylight Time, bernd.pa...@paulinet.de writes: Good morning Steve, Greg and List, Greg S. wrote: I understand a metachondrite to be a chondrite that has undergone metamorphism resulting in recrystalization. The composition is much the same as in the original chondrite. There are different affinities, such as 'H' 'L' or 'LL'. I think there are others including E's and 'C' chondrites. That's right. One further, important aspect is that they are all virtually without (relic) chondrules, devoid of chondrules with a few minor exceptions. See here: http://www4.nau.edu/meteorite/Meteorite/Metachondrites.html#En Best morning wishes, Bernd Anne M. Black http://www.impactika.com/ impact...@aol.com Vice-President, I.M.C.A. Inc. http://www.imca.cc/ __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
This is a term coined by Ted Bunch and Tony Irving, but to my knowledge there is no peer-reviewed publication defining the term. You'll find the definition in an AGU and a MetSoc abstract: http://www.lpi.usra.edu/meetings/metsoc2005/pdf/5218.pdf http://adsabs.harvard.edu/abs/2006AGUFM.P51E1246B The term is not in widespread use and has not been used in the Meteoritical Bulletin. Time will tell if it catches on. Jeff On 10/20/2010 11:36 PM, Steve Dunklee wrote: What is a metachondrite? Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
Hi, Time will tell if it catches on. I suppose it will, because to list these stones as Achondrite-ungr or Achondrite-prim. is very unspecific (and as far as I can rate it as a sheer layman, also sometimes somewhat misleading), while the metachondrite concept is very coherent. Of course it can take some time. (If you remember e.g. that the Bulletin still has with the lunaites only the very coarse discrimination in LUN-A and LUN-B, as we would still be in the time, where there were only the 2 DaGs and NWA 032.) Btw. these new results and that interesting topic about the additional 7ers/chondritic PACs/Metachondrites came on the table or was incited, as far as I can see, only and solely by means of newly found stones from the hot deserts. Hence another perfect example, why all, also in the MetSoc, should take care for keeping the deserts open. It helps a lot! Best! Martin -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Donnerstag, 21. Oktober 2010 15:02 An: meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite This is a term coined by Ted Bunch and Tony Irving, but to my knowledge there is no peer-reviewed publication defining the term. You'll find the definition in an AGU and a MetSoc abstract: http://www.lpi.usra.edu/meetings/metsoc2005/pdf/5218.pdf http://adsabs.harvard.edu/abs/2006AGUFM.P51E1246B The term is not in widespread use and has not been used in the Meteoritical Bulletin. Time will tell if it catches on. Jeff __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
Even if the term metachondrite comes into use, it will not be the name of a meteorite group. It is semantically similar to the terms chondrite and achondrite, which are descriptive of the overall texture of a rock. Each of these terms encompasses objects from many parent bodies. And please don't think that the term primitive achondrite is incoherent. It is a very well-defined term, with an abundant scientific literature behind it. In fact, Irving et al. (metsoc abstract) suggest that metachondrite is essentially a synonym for PAC! Nor is the term ungrouped incoherent. This is a very precise term, meaning that the meteorite does not belong to an accepted group. If one adopts the term metachondrite, expect there to be metachondrite-ung classifications appearing. Jeff On 10/21/2010 9:57 AM, Martin Altmann wrote: Hi, Time will tell if it catches on. I suppose it will, because to list these stones as Achondrite-ungr or Achondrite-prim. is very unspecific (and as far as I can rate it as a sheer layman, also sometimes somewhat misleading), while the metachondrite concept is very coherent. Of course it can take some time. (If you remember e.g. that the Bulletin still has with the lunaites only the very coarse discrimination in LUN-A and LUN-B, as we would still be in the time, where there were only the 2 DaGs and NWA 032.) Btw. these new results and that interesting topic about the additional 7ers/chondritic PACs/Metachondrites came on the table or was incited, as far as I can see, only and solely by means of newly found stones from the hot deserts. Hence another perfect example, why all, also in the MetSoc, should take care for keeping the deserts open. It helps a lot! Best! Martin -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Donnerstag, 21. Oktober 2010 15:02 An: meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite This is a term coined by Ted Bunch and Tony Irving, but to my knowledge there is no peer-reviewed publication defining the term. You'll find the definition in an AGU and a MetSoc abstract: http://www.lpi.usra.edu/meetings/metsoc2005/pdf/5218.pdf http://adsabs.harvard.edu/abs/2006AGUFM.P51E1246B The term is not in widespread use and has not been used in the Meteoritical Bulletin. Time will tell if it catches on. Jeff __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
Well, of course it won't, (like the PACs are in principle neither a group...) but chemically and from the isotopes, those 7-PAC-Metas-Howevers are evolved chondrites of the respective chondrite groups. Chondrites with no chondrules anymore. But if I hear achondrite, I'm thinking to HEDs and meteorites derived from differentiated stuff. Hence they are neither ungrouped, we can group them definitely to the Ls, to the Hs, ect. And primitive achondrites, well those 7-Meta-PAC-Howevers - they are the most metamorph, most elquilibrated (former) chondrites, hence quite the opposite of primitive. Traditionally, in my drawer labeled PAC, there are sitting already the LOD/ACAP/WIN-boys inside. And they tussle always with those Ls, Hs, LLs, CVs, which just baked a little longer in their parent bodies, than the 4ers,5ers,6ers. (Uh and horribile dictu, in these LODs, ACAPs, WINs - called PACs, there are sometime chondrules and relict chondrules found!). Quietude into that drawer I could bring, if I put them all inside and would write metachondrite on the label, but always remembering, that each of them is cut from the cloth of his own group. (Or to say it else, they are rather ex-chondrites for me, than a-chondrites :-) Or to say it else again, for me it's more precise, to call the L-meta, H-meta, LL-meta ect... than to lump them all together in the bucket labeled PAC). But Jeff, you're naturally right - that is all only for my private domestic use. And I need simplifications, as the simple mind I am. As told, we are only laymen. We're the delivery boys of the very stones - the more weird, the better - though the papers about, the scientists have to write. Apropos weird - Weir D. gives as always good information about that complex: http://www.meteoritestudies.com/ Best! Martin -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Donnerstag, 21. Oktober 2010 19:39 An: meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] metachondrite Even if the term metachondrite comes into use, it will not be the name of a meteorite group. It is semantically similar to the terms chondrite and achondrite, which are descriptive of the overall texture of a rock. Each of these terms encompasses objects from many parent bodies. And please don't think that the term primitive achondrite is incoherent. It is a very well-defined term, with an abundant scientific literature behind it. In fact, Irving et al. (metsoc abstract) suggest that metachondrite is essentially a synonym for PAC! Nor is the term ungrouped incoherent. This is a very precise term, meaning that the meteorite does not belong to an accepted group. If one adopts the term metachondrite, expect there to be metachondrite-ung classifications appearing. Jeff __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
What is a metachondrite? Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] metachondrite
My understanding is a chondrite with multiple lithologies. Eric On 10/20/2010 8:36 PM, Steve Dunklee wrote: What is a metachondrite? Cheers Steve Dunklee __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
RE: [meteorite-list] Metachondrite
I've never Metachondrite I didn't like, poikilitically speaking that is. (a thousand pardons ;-) Bob Original Message: - From: [EMAIL PROTECTED] Date: 29 Jul 2005 16:11:44 UT To: Meteorite-list@meteoritecentral.com Subject: [meteorite-list] Metachondrite Tom inquired: what in the heck is a metachondrite? Ingo responded: ... in geology Meta- stands for metamorphosis ... Hi Tom, Ingo, and List, I think what Tom saw was a compound word: met + achondrite = meteorite - achondrite Best regards, Bernd __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list mail2web - Check your email from the web at http://mail2web.com/ . __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
