U-Pb geochronology and micro-tectonics of the pre-Stephanian metamorphic series of Aubrac and of the Marvejols region (Massif Central)

This thesis first reminds the state of knowledge and the problems posed by the geology of the basement of the Massif Central mountains. In a second part it situates the regional framework of this study then exposes the geological and radiometric results obtained for each of the two major sets (Series of the Lot department and 'supergroup' of Marvejols) which constitute the metamorphic base of Aubrac and region of Marvejols. Then, a chapter is dedicated to the examination of the relations between these two domains. Finally, an attempt to synthesize current data in the form of a hypothetical geological history of this region of the Massif Central is proposed. An overview of the principles and elements of interpretation of U/Pb results are given in the appendix, as well as the description of the techniques used