[meteorite-list] [Announced June 8, 2010] NWA 5400: Earth-Related Meteorite
From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Wed, 29 Sep 2010 02:01:51 -0500 Message-ID: <0B6A46A467104D82A8EE77B0A2C8546C_at_ATARIENGINE2> The CRE age is the length of time this rock has been exposed in space to cosmic rays. That is, THIS rock, a chunk less than a meter or so, which the cosmic rays could penetrate (mostly) through. Now, if there was a 4 billion year old chunk that was fat enough, it would keep cosmic rays out of all but its surface layers. And if it then suffered a collision 30 ma and a chunk of its formerly protected interior floated around exposed to cosmic rays for 30 ma, it would be both Very Old (in formation age) and Very Young (in exposure age). All the Little Pieces of the solar system were made by breaking up Big Pieces... in stages. First, we started with Tiny Pieces and slapped them all together Very Quickly to make Big Pieces. And when all the Biggest Pieces were made and all the Lesser Pieces were accreted to them, all the remaining Lesser Pieces just... well, went to pieces, but very slowly, by bashing into each other once in a while. Rapid Assembly followed by a Long Slow Breakdown of the Bits, which is why after only four billion years, we still have lots of Bits. Sterling K. Webb ------------------------------------------------------------- ----- Original Message ----- From: "Shawn Alan" <photophlow at yahoo.com> To: <gmhupe at htn.net> Cc: <meteorite-list at meteoritecentral.com> Sent: Wednesday, September 29, 2010 12:39 AM Subject: [meteorite-list] [Announced June 8,2010] NWA 5400: Earth-Related Meteorite Hello Greg H and Listers, That's funny you brought that up because 10 mins ago I found that in the 2010 paper that had the CRE which I over looked, and this is what it says.... Noble Gases: Noble gases in two samples of NWA 5400 were analyzed by total melting and stepwise heating. The cosmic ray exposure age based on spal-logenic 3He and 21Ne is ~29 Ma, which is within the range of exposure ages of brachinites (3-57 Ma; [9]). The meteorite shows a large 129Xe excess (~3?10-10 cm3/g) derived from 129I decay (T1/2 = 16 Ma), indica-tive of its formation very early in Solar System history. Now if I am reading this correctly, this means that the CRE age puts the NWA 5400 at ~29 Ma. This would mean that this fragment couldn't have came from the 4 billion year old Thea impact that has been speculated? If that was the case, that this fragment came from ejecta from Earth, the CRE would have to 4 billion years old, but that's not the case. Further more in bother papers other ideas have been presented on where NWA 5400 which as follows. Alternatively, NWA 5400 may represent the ultramafic portion of an asteroidal parent body that witnessed similar processing to brachinites, but that evolved more slowly (larger?) and originated from a composi-tionally distinct reservoir, yet one with similarities to the planetary feeding zones of the Earth-Moon system. And Thus we are left with the possibility that NWA 5400 could be an ancient terrene meteorite, or else a sample from a different, differentiated Earth-like body. Now with the CRE proven and matched with other brachinites at less then 30 millions years this might contradict that NWA 5400 was ejected in space from the Thea impact, which in turn proves that NWA 5400 didn't directly come from Earth from that catastrophic event. Lastly its seems that brachinites have been the topic of interest and in the 2009 paper it stated that they formed 4.564 Ga. However, in the 2010 paper its stated that NWA 5400 is younger then brachinite. Now if NWA was formed before then, wouldn't that also contradict when Earth was formed if it came from Earth because if NWA 5400 is related to Earth, then the formation age should match up? Shawn Alan IMCA 1633 eBaystore http://shop.ebay.com/photophlow/m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p4340 [meteorite-list] [Announced June 8, 2010] NWA 5400: Earth-Related MeteoriteGreg Hupe gmhupe at htn.net Wed Sep 29 01:08:58 EDT 2010 Previous message: [meteorite-list] AD - New Stuff at KD Meteorites! Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Shawn and Others: Since some people did not read or forgot what I wrote in my very first announcement of NWA 5400 on June 8, 2010, here it is to review. You will notice in the second abstract dated 2010 that the Cosmic Ray Exposure date HAS been determined. Now how scientists compile that data with other information is for them to study, ponder and write new abstracts. June 8, 2010 [Meteorite Central List] > Dear List Members, > > I would like to announce an important new meteorite that has been > under > intense analysis over the last two years by a select group of > scientists > from around the world... > > NWA 5400: Earth-Related Ungrouped Meteorite > > Northwest Africa 5400 may be a sample from a large asteroid or dwarf > planet, > which accreted in the early solar nebula in the vicinity of > proto-Earth or > Theia. NWA 5400 has oxygen isotope ratios indistinguishable from those > of > rocks from the Earth and the Moon, which plot on the TFL (Terrestrial > Fractionation Line). A precise formation age has not yet been > measured, > but > it cannot be older than 4.54 billion years, which likely makes NWA > 5400 > anomalously young among primitive achondritic objects from the early > Solar > System. It is generally accepted that the Earth-Moon system was > created > when > Theia collided with proto-Earth about 4.3 billion years ago. Is it > possible > that NWA 5400 is somehow related to this phenomenal event? > > NWA 5400 adds valuable understanding of events that took place in the > early > evolution period of the Solar System. After two years of intense > analysis, > scientists at prominent institutions from around the world continue to > diligently study this 'stand-alone' meteorite, which will add to the > already > incredible information NWA 5400 has to offer. > > Link to 2009 LPSC abstract on NWA 5400: > http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2332.pdf > > Link to 2010 LPSC abstract on NWA 5400: > http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1492.pdf > > NWA 5400 has a Total Known Weight of 4.818 kg in a single stone that > was > discovered in Northwest Africa in 2008. The chocolate-brown mottled > matrix > takes an extremely nice polish, which reveals the dazzling olivine > crystals > exhibited in this scientifically important new meteorite! > > Cross-polarized light optical thin section image of NWA 5400 (width of > field > = 1.2mm): > http://www.lunarrock.com/NWA5400/nwa5400xpl.jpg > > Image of 58.9-gram complete slice with hologram-like olivine crystals > that > dance across the polished surface when tilted from side to side: > http://www.lunarrock.com/NWA5400/nwa5400slice.jpg > > Best regards, > Greg > > ==================== > Greg Hupe > The Hupe Collection > NaturesVault (eBay) > gmhupe at htn.net > www.LunarRock.com > IMCA 3163 > ==================== > Click here for my current eBay auctions: > http://search.ebay.com/_W0QQsassZnaturesvault > > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list at meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.829 / Virus Database: 271.1.1/2926 - Release Date: 06/08/10 14:35:00 Previous message: [meteorite-list] AD - New Stuff at KD Meteorites! Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the Meteorite-list mailing list ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list Received on Wed 29 Sep 2010 03:01:51 AM PDT |
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