Characterization of the organic matter and hydration state of Antarctic micrometeorites: A reservoir distinct from carbonaceous chondrites

• Published in: Icarus
• Main Authors: Battandier, M., Bonal, L., Quirico, E., Beck, P., Engrand, C., Duprat, J., Dartois, E.
• Other Authors: Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Centre de Sciences Nucléaires et de Sciences de la Matière (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), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales Paris (CNES)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: [PHYS]Physics [physics]; Antarc*; Antarctic
• Online Access: https://hal.science/hal-01851241; https://doi.org/10.1016/j.icarus.2018.02.002

International audience This work presents a multi-analysis on 35 Antarctic micrometeorites (AMMs) (Concordia collection 2006) by coupled Raman and Infrared (IR) spectroscopies, in comparison with samples from type 1 and 2 carbonaceous CM, CR and CI chondrites. We identified the Raman G- and D-bands revealing the presence of polyaromatic carbonaceous material on raw particles in a subset of 16 particles. Thirteen AMMs (10 Fg + 1 Fg-Sc + 1 Sc) were selected from this first subset, and analyzed by infrared microscopy along with 4 AMMs (2 Fg + 1 Fg-Sc + 1 Sc) from a previous study by Dobrica et al. (2011). These analyses showed that scoriaceous, fine-grained scoriaceous and part of the fine-grained AMMs are not hydrated, with a weak abundance of carbonaceous matter. According to the Raman criterion defined by Dobrica et al. (2011), hydrous AMMs do not show structural modifications induced by heating through the atmospheric entry. In several hydrous AMMs, the carbonaceous matter abundance is found larger than in Orgueil (CI), Murchison (CM) and QUE 99177 (CR) chondrites and their mineral content exhibit differences reflected by the structure of the silicate 10 µm band. These observations suggest that part of the AMMs originates from one, or several, distinct parent bodies with respect to primitive carbonaceous chondrites. Each hydrous Fg-AMMS displays higher CH2/CH3 ratio and a smaller carbonyl abundance than chondrites, which point toward a mild processing during atmospheric entry, possibly oxidation, which did not modify the carbon backbone and therefore do not induce differences in Raman spectroscopy.