NWA 5958 (C3.0-ung)

[karmaka]

NWA 5958 (C3.0-ung, S1,W1)

So spannend ein neuer Fall auch ist, mein Highlight heute ist: NWA 5958

Ich warte bereits seit fast eineinhalb Jahren auf seine Präsentation.

Dieser Meteorit verdient einen eigenen Thread, da wir von ihm noch einiges hören werden!

http://www.lpi.usra.edu/meteor/metbull.php?sea=nwa+5958&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&code=50844

Carbonaceous chondrite (ungrouped, 3.0), S1, W1. This is an unequilibrated chondrite with an extremely 16O-rich bulk oxygen isotopic composition plotting on an extension of the CCAM line.

PETROLOGY AND EXTREME OXYGEN ISOTOPIC COMPOSITION OF TYPE 3.00 CARBONACEOUS
CHONDRITE NORTHWEST AFRICA 5958: A UNIQUE, PRIMITIVE, O-RICH EARLY SOLAR
SYSTEM SAMPLE.
http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2343.pdf


THE TRACE ELEMENT CHEMISTRY OF NORTHWEST AFRICA 5958, A CURIOUS PRIMITIVE
CARBONACEOUS CHONDRITE.
http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2325.pdf

Martin

[styria-met]

wirklich mal wieder was einmaliges C 3.0 

und ich hab auch schon ein Stückchen 

Stefan

[schwede-jens]

Hej Stefan .....

zeigen-zeigen   

J

[Andyr]

wo bekommt man das zu kaufen? Und zu welchem Preis?

Liebe Grüße
AndyR

[Rob L]

wo bekommt man das zu kaufen? Und zu welchem Preis?

http://six.pairlist.net/pipermail/meteorite-list/2012-March/083831.html

Rob  

[Andyr]

Thanks

Grüße
AndyR

[karmaka]

Kürzlich wurden zwei neue abstracts zu NWA 5958 veröffentlicht:

PRESOLAR  GRAINS  IN  PRIMITIVE  CARBONACEOUS
CHONDRITE NORTHWEST AFRICA 5958.

http://www.lpi.usra.edu/meetings/metsoc2012/pdf/5233.pdf

EARLY  STAGES  OF  HYDROTHERMAL  ALTERATION
IN ANOMALOUS PRIMITIVE CCs NWA 5958 & PARIS.

http://www.lpi.usra.edu/meetings/metsoc2012/pdf/5389.pdf

[karmaka]

Auch zu NWA 5958 gibt es neue Erkenntnisse, die eine Vermutung
von A. Elmaleh,  B. Zanda et al (2012) zu bestätigen scheinen:


COMPARATIVE  TRANSMISSION  ELECTRON  MICROSCOPY  STUDIES  OF  PRESOLAR  SILICATE
AND  OXIDE  GRAINS  FROM  THE  DOMINION  RANGE  08006  AND  NORTHWEST  AFRICA  5958
METEORITES.  R. M. Stroud, B. T. De Gregorio,  L. R. Nittler and C. M. O’D. Alexander

LINK

Results  and  Discussion:  Three  matrix  sections
containing  two  O-rich  presolar  grains  were  extracted
from NWA 5958. TEM analysis of the matrix (Fig. 1)
reveals it contains fine-grained, sub-micron nominally
anhydrous silicates, phyllosilicates, Fe- and Fe-Ni sul-
fides,  with  little  glass.  Cronstedtite  was  identified  in
one  section.  These  results  support  the  conclusions  of
A. Elmaleh,  B. Zanda et al (2012) that NWA 5958 is better classified as petrographic type 2 than as type 3. 

EARLY  STAGES  OF  HYDROTHERMAL  ALTERATION
IN ANOMALOUS PRIMITIVE CCs NWA 5958 & PARIS.
A. Elmaleh,  B. Zanda et al (2012)

Microscopic  observations  also show that NWA 5958 contains alteration features including partially  destroyed  chondrules.  We  consequently  suggest  that  it should  be  considered  a  type  2  (2.9?)  rather  than  a  3.0.

[karmaka]

Challenging analyses of organic content in Saharan carbonaceous chondrites

Yutaro Osawa (Kyushu University), Sandra Pizzarello (Arizona State University)

LINK

Only  one  sample, NWA5958,  displayed  less  contamination  and  contained  a  few  non-α-amino  acids;  we  detected  glycine, β-alanine and γ-aminobutyric acid (γ-ABA)  as well as L- and D-alanine (Fig. 1). L- and D-alanine were  not  found  as  a  racemic  mixture,  as  in  most uncontaminated carbonaceous chondrite analyzed so far, however, D-alanine is rare in the biosphere and it is  possible  that  D-alanine  and  an  equal  amount  of  L-alanine  are  indigenous  in  this  meteorite.
[...] It  is  apparent  that  more  labile  compounds  such  as  amino  acids  are  easier to be broken down or leached from meteorites,  therefore,  the  fact  that  NWA5958  seems  to  still  contain  indigenous  amino  acids  implies  that  our  sample  was  the  least  altered  of  all  meteorites analyzed in this study.
[...] Our  investigation  revealed  that  the  Saharan conditions are severe for meteoritic amino acids and, likely, could be for other labile compounds e.g. alkyl hydrocarbons.  However,  at  least  one  sample  still  contained extraterrestrial amino acids that appear to  have  survived  these  conditions.  Although  there  are variations of the extent to which each meteorite stone is  altered  in  the  desert,  meteorite  IOMs  are  less  susceptible to the terrestrial processing and could still retain primitive organic material.

[karmaka]

Vorschlag einer Reklassifikation von NWA 5958:

Northwest Africa 5958: A weakly altered CM-related ungrouped chondrite, not a CI3.

Jacquet, E., Barrat, J.-A., Beck, P., Caste, F., Gattacceca, J., Sonzogni, C. and Gounelle, M.

Meteoritics & Planetary Science. doi: 10.1111/maps.12628

LINK

"Northwest Africa (NWA) 5958 is a carbonaceous chondrite found in Morocco in 2009. Preliminary chemical and isotopic data leading to its initial classification as C3.0 ungrouped have prompted us to conduct a multitechnique study of this meteorite and present a general description here. The petrography and chemistry of NWA 5958 is most similar to a CM chondrite, with a low degree of aqueous alteration, apparently under oxidizing conditions, and evidence of a second, limited alteration episode manifested by alteration fronts. The oxygen isotopic composition, with ∆'17O = −4.3‰, is more 16O-rich than all CM chondrites, indicating, along with other compositional arguments, a separate parent body of origin. We suggest that NWA 5958 be reclassified as an ungrouped carbonaceous chondrite related to the CM group"