Télédétection hyperspectrale : minéralogie et pétrologie, Application au volcan Syrtis Major (Mars) et à l'ophiolite d'Oman

Abstract : Mafic to ultramafic rocks can trace formation and evolution processes of planetary surfaces. To characterize these surfaces, visible-near infrared reflectance spectroscopy is well-suited because of its sensitivity to iron present in minerals. The objective of this thesis is to determine the modal composition of rocks and the chemical composition of minerals (olivine and pyroxenes).
A systematic procedure based on the Modified Gaussian Model (MGM) has been developed for characterizing spectra associated with complex mineralogies involving mixtures of olivine, orthopyroxene and clinopyroxene. Once this procedure is validated on simple cases (powders), it is implemented on complex cases corresponding to natural rocks (Martian meteorites and ophiolite samples).
Based on these learnings, mineralogical mappings are then produced from airborne and space data, respectively for the Syrtis Major volcano on Mars and the Sumail ophiolite (Oman). Our results demonstrate that Syrtis Major lavas present an enrichment in olivine (Fo50-80) and that the pyroxenes, depending on crystallisation conditions, may have compositions ranging from augite to enstatite. For Oman's ophiolite, we identify and map for the first time organized spatial variations of the modal composition within the harzburgite unit. We also characterize changes in crustal clinopyroxene compositions with petrogenetic implications.
These contributions are essential in characterizing and understanding petrologic processes inherent to the formation of planetary surfaces and should motivate the use of imaging spectroscopy for geological purposes.
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Sciences de la Terre. Université Paul Sabatier - Toulouse III, 2009. Français
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Harold Clenet. Télédétection hyperspectrale : minéralogie et pétrologie, Application au volcan Syrtis Major (Mars) et à l'ophiolite d'Oman. Sciences de la Terre. Université Paul Sabatier - Toulouse III, 2009. Français. 〈tel-00379877〉

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