Re: [meteorite-list] H2 or L2 CLASS METEORITES
Steve, No. By definition, ordinary chondrites have a petrologic classification of 3 to 6. Sometimes 7 depending on the meteoriticist. Petrologic types 1 and 2 do not occur in ordinary chondrites Richard Norton R.F.S. 2ed pg 185 Richard Norton has much more to say about this in both Rocks from Space and The Cambridge Encyclopedia of Meteorites. Cheers, Mike Tettenborn and - Original Message - From: steve arnold [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 7:57 PM Subject: [meteorite-list] H2 or L2 CLASS METEORITES Hi list.I was thinking about this today and I have not had time to research it.Are there any H2 or L2 class meteorites that have been classified?This is a real must thread for me.Any help would be welcome. steve arnold,chicago Steve R.Arnold,chicago,Ill,Usa!! Collecting Meteorites since 06/19/1999!! www.chicagometeorites.net Ebay I.D. Illinoismeteorites The fish are biting. Get more visitors on your site using Yahoo! Search Marketing. http://searchmarketing.yahoo.com/arp/sponsoredsearch_v2.php __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] H2 or L2 CLASS METEORITES
I was thinking about this today and I have not had time to research it. Hello Steve, I hope you can do some research sometime, Steve. As H and L are thought to be two unique and real parent bodies, your question can be stated alternately: Were there any places on the H parent body or the L parent body that did not experience the thermally-induced alteration characteristic of unequilibrated chondrites 3, and if so, did any residue from them reach earth and drop meteorites? I think the answer is no. Harry McSween explains that on these parent bodies, especially with reference to the onion-skin model of asteroids, the incubation caused by radioactive disintegration warmed the whole of the parent body uniformly enough to cook all of our H- and L-chondrites enough according to 'current' understanding. But that doesn't mean chance could have thermally isolated or provided a shady heat sink somewhere on the surface where the legendary H2 or L2 could have been protected from its mother planetoid. Carbonaceous chondrites meteorites show 2 and essentially 1 not because they were heated, but rather because of their setting of primordial material, like celestial cementing that formed them, altered them to varying degrees with water, but not the heat on the H- and L- assumed to be larger parent bodies. Note since there are just two parent bodies here, it is easy to write off the possibility of H2 and L2 just by saying, these bodies were simply too warm for this to occur. If you calculate an asteroid diameter to explain the H3-6 distributions we know, for example, you can say how big the parent body was, and once you say how big it was, you can argue by its thermal properties how it all got warm and sufficiently metamorphic. But this is all still conjecture. The University of Chicago is always in need of a few good men!! Go Steve!! Best Wishes and Best Health, Doug - Original Message - From: steve arnold [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 5:57 PM Subject: [meteorite-list] H2 or L2 CLASS METEORITES Hi list.I was thinking about this today and I have not had time to research it.Are there any H2 or L2 class meteorites that have been classified?This is a real must thread for me.Any help would be welcome. steve arnold,chicago Steve R.Arnold,chicago,Ill,Usa!! Collecting Meteorites since 06/19/1999!! www.chicagometeorites.net Ebay I.D. Illinoismeteorites The fish are biting. Get more visitors on your site using Yahoo! Search Marketing. http://searchmarketing.yahoo.com/arp/sponsoredsearch_v2.php __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] H2 or L2 CLASS METEORITES
No, and there probably never will be, at least I don't think such a classification would ever be widely accepted. Type 2 is an old convention, and has only ever been applied to carbonaceous chondrites. It originated with Wiik (1956), who divided the carbonaceous chondrites into 3 chemical groups, I, II, and III. Group II had ~13 wt% H2O, no metal, and a lot of FeS. The meteorites of this type were Cold Bokkeveld, Nogoya, Mighei, Nawapali, Haripura, Santa Cruz, Murray, and Boriskino, all of which we now call CM2. In 1967, Van Schmus and Wood wrote the landmark paper that established the modern petrologic types. The unequilibrated chondrites were divided into types 1, 2, and 3, basically along the same lines as Wiik's roman-numeral classes for carbonaceous chondrites. Type 2 was specifically tailored to encompass Wiik's group II, and defined as having abundant fine-grained matrix, 4-18 wt% H2O, low metal, and Ni-bearing sulfides. All of the meteorites called type 2 by Van Schmus and Wood were again our modern CM2 chondrites, with the addition of Al Rais and Renazzo (which we now call CR2), and Kaba (which is no longer called type 2). Ordinary chondrites could not strictly be called type 2, even if one was found that was water-rich: they don't have enough matrix and have too much metal to fit the old petrologic definition, which was customized for only CM and CR carbonaceous chondrites. In fact, Semarkona does have hydrous minerals, especially in its matrix, and I know that a number of my colleagues have been tempted to call it type 2 (including Sears et al., 1980, of which I am an al). But that would have caused a classification crisis in ordinary chondrite nomenclature since the petrologic types of those groups designate something quite different: they are strictly a metamorphic sequence. So it just wasn't done. Semarkona has stayed a type 3, despite the fact that it has probably experienced a similar degree of alteration as some CR2s. It's really just a matter of tradition at this point. Jeff At 06:57 PM 3/29/2007, steve arnold wrote: Hi list.I was thinking about this today and I have not had time to research it.Are there any H2 or L2 class meteorites that have been classified?This is a real must thread for me.Any help would be welcome. steve arnold,chicago Steve R.Arnold,chicago,Ill,Usa!! Collecting Meteorites since 06/19/1999!! www.chicagometeorites.net Ebay I.D. Illinoismeteorites The fish are biting. Get more visitors on your site using Yahoo! Search Marketing. http://searchmarketing.yahoo.com/arp/sponsoredsearch_v2.php __ 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 __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] H2 or L2 CLASS METEORITES
Doug, Does petrologic grade 3, in essence, mean little to no thermal alteration? If so, then there can not be a type 2 even with a nice heat sink to protect these primordial chondrules. In fact, McSween's chart on pg 63 2nd ed. shows type 3 as neither aqueous altered or thermally altered. However, he does mention that these classifications are simplifications and intended to represent a range of alteration. Why we now have LL3.7's etc. Although I have not found this plainly stated, I believe the intent of the classification system was that H3.0 or L3.0 or LL3.0 are thermally unaltered and hence have pristine baby fresh chondrules. The parent bodies for the carbonaceous chondrites did not experience the same temperatures leading to thermal alteration of their chondrules. At least, I guess this is so. Cheers, Mike Tettenborn - Original Message - From: MexicoDoug [EMAIL PROTECTED] To: Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 9:05 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES I was thinking about this today and I have not had time to research it. Hello Steve, I hope you can do some research sometime, Steve. As H and L are thought to be two unique and real parent bodies, your question can be stated alternately: Were there any places on the H parent body or the L parent body that did not experience the thermally-induced alteration characteristic of unequilibrated chondrites 3, and if so, did any residue from them reach earth and drop meteorites? I think the answer is no. Harry McSween explains that on these parent bodies, especially with reference to the onion-skin model of asteroids, the incubation caused by radioactive disintegration warmed the whole of the parent body uniformly enough to cook all of our H- and L-chondrites enough according to 'current' understanding. But that doesn't mean chance could have thermally isolated or provided a shady heat sink somewhere on the surface where the legendary H2 or L2 could have been protected from its mother planetoid. Carbonaceous chondrites meteorites show 2 and essentially 1 not because they were heated, but rather because of their setting of primordial material, like celestial cementing that formed them, altered them to varying degrees with water, but not the heat on the H- and L- assumed to be larger parent bodies. Note since there are just two parent bodies here, it is easy to write off the possibility of H2 and L2 just by saying, these bodies were simply too warm for this to occur. If you calculate an asteroid diameter to explain the H3-6 distributions we know, for example, you can say how big the parent body was, and once you say how big it was, you can argue by its thermal properties how it all got warm and sufficiently metamorphic. But this is all still conjecture. The University of Chicago is always in need of a few good men!! Go Steve!! Best Wishes and Best Health, Doug - Original Message - From: steve arnold [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 5:57 PM Subject: [meteorite-list] H2 or L2 CLASS METEORITES Hi list.I was thinking about this today and I have not had time to research it.Are there any H2 or L2 class meteorites that have been classified?This is a real must thread for me.Any help would be welcome. steve arnold,chicago Steve R.Arnold,chicago,Ill,Usa!! Collecting Meteorites since 06/19/1999!! www.chicagometeorites.net Ebay I.D. Illinoismeteorites The fish are biting. Get more visitors on your site using Yahoo! Search Marketing. http://searchmarketing.yahoo.com/arp/sponsoredsearch_v2.php __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] H2 or L2 CLASS METEORITES
Hi Mike, In light of Jeff's post I'd tend to yield if I were in an argument and just agree. But if the purpose is to get a feel for what is happening and why, it's more fun to keep these ideas alive. Scientists can make conventions, and it is very hard to keep conventions written in stone. Until a new stone causing them to go back to the drawing board. The purpose of my post was to complement your ideas and get an understanding of the processes. If the scientists want to define 3.0 as the lowest and take into consideration a well thought out scheme, that's fine. Then, someone, somewhere, will come up with something that doesn't fit some class and it will be worth $1000/gram and have everyone buzzing. Yielding with a good fight, and remembering the 4 billion year old rocks found in Australia, Doug PS as to McSween's chart, I think that is a red herring. After all, if you were to interpret it literally as you do, type I carbonaceous would be more altered by water than type 2!! - Original Message - From: tett [EMAIL PROTECTED] To: MexicoDoug [EMAIL PROTECTED]; Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 7:31 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES Doug, Does petrologic grade 3, in essence, mean little to no thermal alteration? If so, then there can not be a type 2 even with a nice heat sink to protect these primordial chondrules. In fact, McSween's chart on pg 63 2nd ed. shows type 3 as neither aqueous altered or thermally altered. However, he does mention that these classifications are simplifications and intended to represent a range of alteration. Why we now have LL3.7's etc. Although I have not found this plainly stated, I believe the intent of the classification system was that H3.0 or L3.0 or LL3.0 are thermally unaltered and hence have pristine baby fresh chondrules. The parent bodies for the carbonaceous chondrites did not experience the same temperatures leading to thermal alteration of their chondrules. At least, I guess this is so. Cheers, Mike Tettenborn - Original Message - From: MexicoDoug [EMAIL PROTECTED] To: Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 9:05 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES I was thinking about this today and I have not had time to research it. Hello Steve, I hope you can do some research sometime, Steve. As H and L are thought to be two unique and real parent bodies, your question can be stated alternately: Were there any places on the H parent body or the L parent body that did not experience the thermally-induced alteration characteristic of unequilibrated chondrites 3, and if so, did any residue from them reach earth and drop meteorites? I think the answer is no. Harry McSween explains that on these parent bodies, especially with reference to the onion-skin model of asteroids, the incubation caused by radioactive disintegration warmed the whole of the parent body uniformly enough to cook all of our H- and L-chondrites enough according to 'current' understanding. But that doesn't mean chance could have thermally isolated or provided a shady heat sink somewhere on the surface where the legendary H2 or L2 could have been protected from its mother planetoid. Carbonaceous chondrites meteorites show 2 and essentially 1 not because they were heated, but rather because of their setting of primordial material, like celestial cementing that formed them, altered them to varying degrees with water, but not the heat on the H- and L- assumed to be larger parent bodies. Note since there are just two parent bodies here, it is easy to write off the possibility of H2 and L2 just by saying, these bodies were simply too warm for this to occur. If you calculate an asteroid diameter to explain the H3-6 distributions we know, for example, you can say how big the parent body was, and once you say how big it was, you can argue by its thermal properties how it all got warm and sufficiently metamorphic. But this is all still conjecture. The University of Chicago is always in need of a few good men!! Go Steve!! Best Wishes and Best Health, Doug - Original Message - From: steve arnold [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 5:57 PM Subject: [meteorite-list] H2 or L2 CLASS METEORITES Hi list.I was thinking about this today and I have not had time to research it.Are there any H2 or L2 class meteorites that have been classified?This is a real must thread for me.Any help would be welcome. steve arnold,chicago Steve R.Arnold,chicago,Ill,Usa!! Collecting Meteorites since 06/19/1999!! www.chicagometeorites.net Ebay I.D. Illinoismeteorites
Re: [meteorite-list] H2 or L2 CLASS METEORITES
Mike (2), Looks like I just learned a lot tonight - in fact type 1 actually is more severely altered by water! So scratch my PS, and thanks for the comment. If you read the text, though, you will see that type 3 (as far as I can see doesn't mean no alteration (as he explicitly stats with aqueous), so I think that still leave the door open. Wow, now it finally makes sense when comparing my CM2 to my CV3 - those CM2's always didn't make sense to me... Best, Doug - Original Message - From: MexicoDoug [EMAIL PROTECTED] To: tett [EMAIL PROTECTED]; Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 7:43 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES Hi Mike, In light of Jeff's post I'd tend to yield if I were in an argument and just agree. But if the purpose is to get a feel for what is happening and why, it's more fun to keep these ideas alive. Scientists can make conventions, and it is very hard to keep conventions written in stone. Until a new stone causing them to go back to the drawing board. The purpose of my post was to complement your ideas and get an understanding of the processes. If the scientists want to define 3.0 as the lowest and take into consideration a well thought out scheme, that's fine. Then, someone, somewhere, will come up with something that doesn't fit some class and it will be worth $1000/gram and have everyone buzzing. Yielding with a good fight, and remembering the 4 billion year old rocks found in Australia, Doug PS as to McSween's chart, I think that is a red herring. After all, if you were to interpret it literally as you do, type I carbonaceous would be more altered by water than type 2!! - Original Message - From: tett [EMAIL PROTECTED] To: MexicoDoug [EMAIL PROTECTED]; Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 7:31 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES Doug, Does petrologic grade 3, in essence, mean little to no thermal alteration? If so, then there can not be a type 2 even with a nice heat sink to protect these primordial chondrules. In fact, McSween's chart on pg 63 2nd ed. shows type 3 as neither aqueous altered or thermally altered. However, he does mention that these classifications are simplifications and intended to represent a range of alteration. Why we now have LL3.7's etc. Although I have not found this plainly stated, I believe the intent of the classification system was that H3.0 or L3.0 or LL3.0 are thermally unaltered and hence have pristine baby fresh chondrules. The parent bodies for the carbonaceous chondrites did not experience the same temperatures leading to thermal alteration of their chondrules. At least, I guess this is so. Cheers, Mike Tettenborn - Original Message - From: MexicoDoug [EMAIL PROTECTED] To: Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 9:05 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES I was thinking about this today and I have not had time to research it. Hello Steve, I hope you can do some research sometime, Steve. As H and L are thought to be two unique and real parent bodies, your question can be stated alternately: Were there any places on the H parent body or the L parent body that did not experience the thermally-induced alteration characteristic of unequilibrated chondrites 3, and if so, did any residue from them reach earth and drop meteorites? I think the answer is no. Harry McSween explains that on these parent bodies, especially with reference to the onion-skin model of asteroids, the incubation caused by radioactive disintegration warmed the whole of the parent body uniformly enough to cook all of our H- and L-chondrites enough according to 'current' understanding. But that doesn't mean chance could have thermally isolated or provided a shady heat sink somewhere on the surface where the legendary H2 or L2 could have been protected from its mother planetoid. Carbonaceous chondrites meteorites show 2 and essentially 1 not because they were heated, but rather because of their setting of primordial material, like celestial cementing that formed them, altered them to varying degrees with water, but not the heat on the H- and L- assumed to be larger parent bodies. Note since there are just two parent bodies here, it is easy to write off the possibility of H2 and L2 just by saying, these bodies were simply too warm for this to occur. If you calculate an asteroid diameter to explain the H3-6 distributions we know, for example, you can say how big the parent body was, and once you say how big it was, you can argue by its thermal properties how it all got warm and sufficiently metamorphic
Re: [meteorite-list] H2 or L2 CLASS METEORITES
Doug, I think in this debate there is no clear winner. You did yield but perhaps too easily. Like you said, a chondrite could be found that is even more pristine than the current most pristine LL3.0 and then, besides sell it for $1000/gram, what do we do? The convention system is a little hard to understand and could be simplified but I kinda like it the way it is. As for the 4 billion year old ausie rocks, my 4.03 billion year old CANADIAN acasta gneiss is still the oldest found terrestrial rock to date. My little 25 gram chip sits contently amongst a pair a 7 year old Guatemalan lava rocks from Mount Pacaya. Cheers, Mike - Original Message - From: MexicoDoug [EMAIL PROTECTED] To: tett [EMAIL PROTECTED]; Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 9:43 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES Hi Mike, In light of Jeff's post I'd tend to yield if I were in an argument and just agree. But if the purpose is to get a feel for what is happening and why, it's more fun to keep these ideas alive. Scientists can make conventions, and it is very hard to keep conventions written in stone. Until a new stone causing them to go back to the drawing board. The purpose of my post was to complement your ideas and get an understanding of the processes. If the scientists want to define 3.0 as the lowest and take into consideration a well thought out scheme, that's fine. Then, someone, somewhere, will come up with something that doesn't fit some class and it will be worth $1000/gram and have everyone buzzing. Yielding with a good fight, and remembering the 4 billion year old rocks found in Australia, Doug PS as to McSween's chart, I think that is a red herring. After all, if you were to interpret it literally as you do, type I carbonaceous would be more altered by water than type 2!! - Original Message - From: tett [EMAIL PROTECTED] To: MexicoDoug [EMAIL PROTECTED]; Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 7:31 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES Doug, Does petrologic grade 3, in essence, mean little to no thermal alteration? If so, then there can not be a type 2 even with a nice heat sink to protect these primordial chondrules. In fact, McSween's chart on pg 63 2nd ed. shows type 3 as neither aqueous altered or thermally altered. However, he does mention that these classifications are simplifications and intended to represent a range of alteration. Why we now have LL3.7's etc. Although I have not found this plainly stated, I believe the intent of the classification system was that H3.0 or L3.0 or LL3.0 are thermally unaltered and hence have pristine baby fresh chondrules. The parent bodies for the carbonaceous chondrites did not experience the same temperatures leading to thermal alteration of their chondrules. At least, I guess this is so. Cheers, Mike Tettenborn - Original Message - From: MexicoDoug [EMAIL PROTECTED] To: Meteorite Mailing List meteorite-list@meteoritecentral.com Sent: Thursday, March 29, 2007 9:05 PM Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES I was thinking about this today and I have not had time to research it. Hello Steve, I hope you can do some research sometime, Steve. As H and L are thought to be two unique and real parent bodies, your question can be stated alternately: Were there any places on the H parent body or the L parent body that did not experience the thermally-induced alteration characteristic of unequilibrated chondrites 3, and if so, did any residue from them reach earth and drop meteorites? I think the answer is no. Harry McSween explains that on these parent bodies, especially with reference to the onion-skin model of asteroids, the incubation caused by radioactive disintegration warmed the whole of the parent body uniformly enough to cook all of our H- and L-chondrites enough according to 'current' understanding. But that doesn't mean chance could have thermally isolated or provided a shady heat sink somewhere on the surface where the legendary H2 or L2 could have been protected from its mother planetoid. Carbonaceous chondrites meteorites show 2 and essentially 1 not because they were heated, but rather because of their setting of primordial material, like celestial cementing that formed them, altered them to varying degrees with water, but not the heat on the H- and L- assumed to be larger parent bodies. Note since there are just two parent bodies here, it is easy to write off the possibility of H2 and L2 just by saying, these bodies were simply too warm for this to occur. If you calculate an asteroid diameter to explain the H3-6 distributions we know, for example, you can say how big the parent body was, and once you say how big it was, you can argue by its thermal
Re: [meteorite-list] H2 or L2 CLASS METEORITES
Dear Steve; Check the updated pages in your Meteorites A to Z For new list members, it is quite a useful book to determine classification information. It was authored by our own list members Anne Black and the Jensen brothers! I cherish my signed copy that brings me luck! DF steve arnold wrote: Hi list.I was thinking about this today and I have not had time to research it.Are there any H2 or L2 class meteorites that have been classified?This is a real must thread for me.Any help would be welcome. steve arnold,chicago Steve R.Arnold,chicago,Ill,Usa!! Collecting Meteorites since 06/19/1999!! www.chicagometeorites.net Ebay I.D. Illinoismeteorites The fish are biting. Get more visitors on your site using Yahoo! Search Marketing. http://searchmarketing.yahoo.com/arp/sponsoredsearch_v2.php __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
