Description of a very dense meteorite collection area in western Atacama: Insight into the long-term composition of the meteorite flux to Earth

• Published in: Meteoritics & Planetary Science
• Main Authors: Hutzler, Aurore, Gattacceca, Jérôme, ROCHETTE, Pierre, BRAUCHER, Regis, Carro, Bertrand, Christensen, Eric, Cournede, Cécile, Gounelle, Matthieu, Laridhi Ouazaa, Nejia, Martinez, Rodrigo, Valenzuela, Millarca, Warner, Michael, Bourles, Didier
• Other Authors: Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Lunar and Planetary Laboratory Tucson (LPL), University of Arizona, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement IRD : UR206-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Université de Tunis El Manar (UTM), Consejo Superior de Investigaciones Científicas Madrid (CSIC), Pontifical Catholic University of Chile, Cerro Tololo Inter-American Observatory (CTIO), National Optical Astronomy Observatory (NOAO)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDE.MCG]Environmental Sciences/Global Changes; Antarc*; Antarctica
• Online Access: https://hal-amu.archives-ouvertes.fr/hal-01420768; https://hal-amu.archives-ouvertes.fr/hal-01420768/document; https://hal-amu.archives-ouvertes.fr/hal-01420768/file/HutzleretalMPS.pdf; https://doi.org/10.1111/maps.12607

International audience –We describe the geological, morphological, and climatic settings of two new meteorite collections from Atacama (Chile). The " El M edano collection " was recovered by systematic on-foot search in El M edano and Caleta el Cobre dense collection areas and is composed of 213 meteorites before pairing, 142 after pairing. The " private collection " has been recovered by car by three private hunters and consists of 213 meteorites. Similar to other hot desert finds, and contrary to the falls and Antarctica finds, both collections show an overabundance of H chondrites. A recovery density can be calculated only for the El M edano collection and gives 251 and 168 meteorites larger than 10 g km À2 , before and after pairing, respectively. It is by far the densest collection area described in hot deserts. The Atacama Desert is known to have been hyperarid for a long period of time and, based on cosmic-ray exposure ages on the order of 1–10 Ma, to have been stable over a period of time of several million years. Such a high meteorite concentration might be explained invoking either a yet unclear concentration mechanism (possibly related to downslope creeping) or a previously underestimated meteorite flux in previous studies or an average terrestrial age over 2 Myr. This last hypothesis is supported by the high weathering grade of meteorites and by the common terrestrial fragmentation (with fragments scattered over a few meters) of recovered meteorites.