Structure, composition, and location of organic matter in the enstatite chondrite Sahara 97096 (EH3) - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Meteoritics and Planetary Science Année : 2012

Structure, composition, and location of organic matter in the enstatite chondrite Sahara 97096 (EH3)

Résumé

The insoluble organic matter (IOM) of an unequilibrated enstatite chondrite Sahara(SAH) 97096 has been investigated using a battery of analytical techniques. As the enstatitechondrites are thought to have formed in a reduced environment at higher temperatures thancarbonaceous chondrites, they constitute an interesting comparative material to test theheterogeneities of the IOM in the solar system and to constrain the processes that could affectIOM during solar system evolution. The SAH 97096 IOM is found in situ: as submicrometergrains in the network of fine-grained matrix occurring mostly around chondrules and asinclusions in metallic nodules, where the carbonaceous matter appears to be moregraphitized. IOM in these two settings has very similar d15N and d13C; this supports the ideathat graphitized inclusions in metal could be formed by metal catalytic graphitization ofmatrix IOM. A detailed comparison between the IOM extracted from a fresh part and aterrestrially weathered part of SAH 97096 shows the similarity between both IOM samples inspite of the high degree of mineral alteration in the latter. The isolated IOM exhibits aheterogeneous polyaromatic macromolecular structure, sometimes highly graphitized, withoutany detectable free radicals and deuterium-heterogeneity and having mean H- and N-isotopiccompositions in the range of values observed for carbonaceous chondrites. It contains somesubmicrometer-sized areas highly enriched in 15N (d15N up to 1600&). These observationsreinforce the idea that the IOM found in carbonaceous chondrites is a common componentwidespread in the solar system. Most of the features of SAH 97096 IOM could be explainedby the thermal modification of this main component.

Dates et versions

hal-01095357 , version 1 (15-12-2014)

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Laurette Piani, François Robert, Olivier Beyssac, Laurent Binet, Michèle Bourot-Denise, et al.. Structure, composition, and location of organic matter in the enstatite chondrite Sahara 97096 (EH3). Meteoritics and Planetary Science, 2012, 47 (1), pp.8-29. ⟨10.1111/j.1945-5100.2011.01306.x⟩. ⟨hal-01095357⟩
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