Meteorite-Mineralien-Gold-Forum.de
Meteoriten => Meteorite => Thema gestartet von: karmaka am März 12, 2012, 19:08:46 Nachmittag
-
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
-
wirklich mal wieder was einmaliges C 3.0 :wow:
und ich hab auch schon ein Stückchen :super:
Stefan
-
Hej Stefan .....
zeigen-zeigen :einaugeblinzel:
J
-
wo bekommt man das zu kaufen? Und zu welchem Preis?
Liebe Grüße
AndyR
-
wo bekommt man das zu kaufen? Und zu welchem Preis?
http://six.pairlist.net/pipermail/meteorite-list/2012-March/083831.html
Rob :hut:
-
Thanks
Grüße
AndyR :hut:
-
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
-
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 (http://www.hou.usra.edu/meetings/lpsc2014/pdf/2806.pdf)
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) (http://www.lpi.usra.edu/meetings/metsoc2012/pdf/5389.pdf) 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. (http://www.lpi.usra.edu/meetings/metsoc2012/pdf/5389.pdf)
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.
-
Challenging analyses of organic content in Saharan carbonaceous chondrites
Yutaro Osawa (Kyushu University), Sandra Pizzarello (Arizona State University)
LINK (http://www.nipr.ac.jp/symposium2014/program/abstract/OA_Osawa_00301_01.pdf)
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.
-
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 (http://onlinelibrary.wiley.com/doi/10.1111/maps.12628/abstract)
"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"