Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001 |
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| Authors: | Carles E Moyano‐Cambero Josep M Trigo‐Rodríguez M Isabel Benito Jacinto Alonso‐Azcárate Martin R Lee Narcís Mestres Marina Martínez‐Jiménez Francisco J Martín‐Torres Jordi Fraxedas |
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| Institution: | 1. Institute of Space Sciences (IEEC‐CSIC), Campus UAB, Cerdanyola del Vallès, Barcelona, Spain;2. Departamento de Estratigrafía‐IGEO, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid‐CSIC, Madrid, Spain;3. Fac. de Ciencias Ambientales y Bioquímica, Universidad de Castilla‐La Mancha, Toledo, Spain;4. School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 800, UK;5. Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC), Campus UAB, Bellaterra, Barcelona, Spain;6. Instituto Andaluz de Ciencias de la Tierra (CSIC‐UGR), Armilla, Granada, Spain;7. Division of Space Technology, Department of Computer Science, Electrical and Space Engineering, Lule? University of Technology, Kiruna, Sweden;8. Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and the Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, Barcelona, Spain |
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| Abstract: | Martian meteorites can provide valuable information about past environmental conditions on Mars. Allan Hills 84001 formed more than 4 Gyr ago, and owing to its age and long exposure to the Martian environment, and this meteorite has features that may record early processes. These features include a highly fractured texture, gases trapped during one or more impact events or during formation of the rock, and spherical Fe‐Mg‐Ca carbonates. In this study, we have concentrated on providing new insights into the context of these carbonates using a range of techniques to explore whether they record multiple precipitation and shock events. The petrographic features and compositional properties of these carbonates indicate that at least two pulses of Mg‐ and Fe‐rich solutions saturated the rock. Those two generations of carbonates can be distinguished by a very sharp change in compositions, from being rich in Mg and poor in Fe and Mn, to being poor in Mg and rich in Fe and Mn. Between these two generations of carbonate is evidence for fracturing and local corrosion. |
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