[meteorite-list] Am I an idiot? Rumuruti pairings

From: meteoriteplaya_at_comcast.net <meteoriteplaya_at_meteoritecentral.com>
Date: Fri Aug 19 13:45:53 2005
Message-ID: <081920051745.12216.43061ACC000E20CC00002FB822073000330E970E049F0A9B079D010A9B0A03_at_comcast.net>

Hi Martin
The short answer is 23 of 39 studied. The long answer is from an article in a recent issue of MAPS. Here is the abstract:

Rumuruti chondrites: Noble gases, exposure ages, pairing, and parent body history
Authors: Schultz, Ludolf; Weber, Hartwig W.; Franke, Luitgard

Source: Meteoritics & Planetary Science, Volume 40, Number 4, April 2005, pp. 557-571(15)

Publisher: Arizona Board of Regents (University of Arizona)

Abstract:

In this paper, we present concentration and isotopic composition of the light noble gases He, Ne, and Ar as well as of 84Kr, 132Xe, and 129Xe in bulk samples of 33 Rumuruti (R) chondrites. Together with previously published data of six R chondrites, exposure ages are calculated and compared with those of ordinary chondrites. A number of pairings, especially between those from Northwest Africa (NWA), are suggested, so that only 23 individual falls are represented by the 39 R chondrites discussed here. Eleven of these meteorites, or almost 50%, contain solar gases and are thus regolithic breccias. This percentage is higher than that of ordinary chondrites, howardites, or aubrites. This may imply that the parent body of R chondrites has a relatively thick regolith. Concentrations of heavy noble gases, especially of Kr, are affected by the terrestrial atmospheric component, which resides in weathering products. Compared to ordinary chondrites, 129Xe/132Xe ratios of R chondrites a
 re high.

Hope that answers some of your questions.
Mike

--
Mike Jensen IMCA 4264
Jensen Meteorites
16730 E Ada PL
Aurora, CO 80017-3137
303-337-4361
website: www.jensenmeteorites.com
> Quiet boys,
> 
> I have another question concerning the pairings of the NWA-Rumurutis.
> Has anyone a little an insight or suspection, which of them are likely
> paired?
> 
> I mean it's not common stuff like howardites, eucrites, olivine diogenites
> (just a joke).
> And if one takes a closer look,
> please use the new database:
> http://tin.er.usgs.gov/meteor/metbull.php
> (Mr.Grossman I revise my opinion - it's great, saves many hours of searching
> the new bulletins).
> 
> There we have 50 entries, hence by numbers Rumuruti chondrites are as rare
> as Mars and Moon,
> and rarer then Mars and Moon bei weight.
> And if we look more detailled, one tends to suppose - not to say it's
> striking - that most NWAs should be paired, isn't it?
> 
> First let's speculate about the rareness - to escape from the NWA-salad, it
> is always helpfull, to take a glimpse to the Antarctic meteorites, which are
> still the majority of all finds, - although each crumb of an unusual stone
> gets an own number:
> >From 50 Rumurutis, only 14 are from Antarctica
> and there are respectievely paired both from LaPaz Icefield, the four from
> Mount Prestrud, both from Pecora Escarpment,
> 
> hence the number is shrinking to 9 Antarctic Rumis.
> 
> We have 1 single observed fall: Rumuruti.
> 
> Striking also, that from all Oman, where the stones must be hunted and can't
> be bought,
> we have only 1 Rumuruti
> (hehe AD, AD, AD wanna some?) - and the guys there are tough, reckognise
> even Moons without crust.
> 
> And a remark to the SAH 995xx Rs - tell me, what you want, if they are true
> finds and if the numbers are chosen chronoligically, then I'd say -
> regarding how rare those type is (Antarctica, Oman, falls, as told), it's
> simply impossible that 3 stones of 3 different Rumurutis were lying around
> in desert on the very same spot, they are the same. - Remember also that
> mess with the EH3-Sahara, which got almost 50 different SAH97xxx numbers.
> 
> So all in all we have 20 different Rumurutis from all over the globe,
> including the most productive search grounds,
> 
> plus now  28 NWA-Rumurutis, where I include Ouzina, as it stems from that
> corner, but was found 1999 as there weren't NWA-nummers given yet.
> and from those 28 not less than 20 have a classification +/-R4
> 
> So all in all I guess moooooost of the NWA-R-chondrites are paired.
> 
> Imagine another aubrite of let's say 10kg would appear in Morocco, then you
> could expect not to have only 2 NWA-Aubrites, but soon 20 under different
> numbers.
> 
> Btw. did you see the R-s last 4 weeks on ebay? Wow, how underrated they
> ended - s i c k!!!
> Seems the people have no idea, how rare the stuff is - or, dealers take
> care, this is the other side of the coin of excessive
> NWA-number-multiplying - they are lost in numbers and not aware anymore,
> that R is one of the rarest types in existance.
> 
> Buckleboo!
> Martin
> 
> 
> 
> 
> 
> 
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Received on Fri 19 Aug 2005 01:45:49 PM PDT