The densest meteorite collection area in hot deserts: The San Juan meteorite field (Atacama Desert,Chile) |
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| Authors: | Jérôme GATTACCECA Millarca VALENZUELA Minoru UEHARA A J Timothy JULL Marlène GISCARD Pierre ROCHETTE Régis BRAUCHER Clement SUAVET Matthieu GOUNELLE Diego MORATA Pablo MUNAYCO Michèle BOUROT‐DENISE Didier BOURLES François DEMORY |
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| Institution: | 1. CEREGE (CNRS/Aix‐Marseille University), BP 80, 13545 Aix‐en‐Provence Cedex 4, France;2. Dpto. Geologia, Universidad de Chile, Chile Plaza Ercilla 803, Santiago, Chile;3. Arizona AMS Laboratory, The University of Arizona, Tucson, Arizona, USA;4. Natural History Museum, London, UK;5. EAPS Department, MIT, 77 Massachusetts Ave., Cambridge, Massachusetts 02139–4307, USA;6. LMCM, UMR 7202, CNRS & MNHN, CP 52, 57 rue Cuvier, 75005 Paris, France;7. CBPF, Rua Xavier Sigaud 150, 222909‐180 Rio de Janeiro, Brazil |
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| Abstract: | Abstract– We describe the geological, morphological, and climatic setting of the San Juan meteorite collection area in the Central Depression of the Atacama Desert (Chile). Our recovery activities yielded 48 meteorites corresponding to a minimum of 36 different falls within a 3.88 km2 area. The recovery density is in the range 9–12 falls km?2 depending on pairing, making it the densest among meteorite collection areas in hot deserts. This high meteorite concentration is linked to the long‐standing hyperaridity of the area, the stability of the surface pebbles (> Ma), and very low erosion rates of surface pebbles (approximately 30 cm Ma?1 maximum). The San Juan meteorite population is characterized by old terrestrial ages that range from zero to beyond 40 ka, and limited weathering compared with other dense collection areas in hot desert. Chemical weathering in San Juan is slow and mainly controlled by the initial porosity of meteorites. As in the Antarctic and other hot deserts, there is an overabundance of H chondrites and a shortage of LL chondrites compared with the modern falls population, suggesting a recent (< few ka) change in the composition of the meteorite flux to Earth. |
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