MICROMÉTÉORITES CONCORDIA: DES NEIGES ANTARCTIQUES AUX GLACES COMÉTAIRES

• Main Author: Dobrica, Elena
• Other Authors: Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris Sud - Paris XI, Cécile Engrand([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2010
• Subjects: micrométéorite; comète; matière carbonée; système solaire; minéralogie; [SDU]Sciences of the Universe [physics]; Antarctic; Antarc*; Antarctique*
• Online Access: https://theses.hal.science/tel-00602286; https://theses.hal.science/tel-00602286/document; https://theses.hal.science/tel-00602286/file/Elena-Dobrica-These---.pdf

Antarctic micrometeorites (AMMs) represents large cosmic dust, sampling the primitive materials formed in the solar system. Two new families of AMMs, well preserved by the terrestrial weathering have been identified in the 2006 CONCORDIA collection: (i) the Fine-grained Fluffy (FgF) particles, and (ii) the Ultracarbonaceous Antarctic Micrometeorites (UCAMMs). The first ones, FgFs present similar characteristics with the interplanetary dust particles (IDPs). UCAMMs are exceptionally rich in carbon (50-90 vol%). The characteristics of the AMMs were compared with the recent results obtained by the Stardust mission on the cometary samples. We performed mineralogical, petrological and isotopic studies of the AMMs. The degree of structural order of the carbonaceous material in AMMs were analysed by Raman spectroscopy. The results show that about 65% of AMMs contain a carbonaceous material with a high degree of disorder. The radical nitrile was identified in an UCAMM. The mineralogy of UCAMMs has been described by transmission electron microscopy to better understand the process of their formation and evolution. Generally, the minerals (olivine, pyroxene and iron sulphides) are usually present as aggregates, rarely as isolated minerals or objects with an igneous texture. Objects similar to GEMS (Glass with Embedded Metal and Sulphide) of IDPs have been identified in a UCAMM. The carbonaceous material identified in UCAMMs exhibits large enrichment in deuterium, up to 30 times the terrestrial value. The close association between the carbonaceous matter and the mineral component formed at high temperatures supports the idea of the presence of outward transport and mixing in the protoplanetary disk. The study of AMMs represents an exceptionally opportunity to study the primitive asteroid (carbonaceous chondrite) - comet continuum in the early solar nebula. Les micrométéorites antarctiques (MMAs) échantillonnent le matériel présent lors des premiers instants de la formation du système solaire. Deux nouvelles familles de ...