Thursday 24 March, 4PM CET
DR. LISA KRÄMER RUGGIU
ABSTRACT: The study of meteorites provides access to the formation and dynamic evolution of our Solar System. The different meteorites sample both the asteroids of the main belt, but also the planet Mars. These bodies have an intense and complex geological history: thermal metamorphism, shocks, aqueous alteration, and for some a differentiation stage. This studyattempts to untangle part of this story, focusing on aqueous alteration. First, this work aims to study the products formed by aqueous alteration on primitive asteroids, by analyzing their fragments, called the "primitive" chondrites. The various techniques usually used for the characterization of secondary phases were tested on four chondrites, in order to identify an ideal methodology for the study of the various secondary phases, including in meteorites showing incipient alteration. Then, in order to interpret the analyzes of meteorites and their secondary processes in the context of the solar system, it is necessary to relate them to their parent asteroids. We have measured infrared spectra of ungrouped chondrites and other meteorites from rare groups in laboratory, in order to compare them with the spectra of different classes of asteroids, allowing the suggestion of new links between meteorites and certain families of asteroids. Finally, the study of aqueous alteration in Martian meteorites provides access to the conditions of aqueous alteration on the planet Mars. We studied thenakhlites, which are Martian basaltic rocks, whose olivines have been altered by circulations of fluids on Mars, forming an alteration product called “iddingsite”. The detailed study of this iddingsite made it possible to constrain the mineralogy and chemical composition of these aqueous alteration products, and to provide information on the history of the Martian fluid alteration condition.