Le Code Forestier brésilien : genèse et institutionnalisation ; The Brazilian Forest Code: Genesis and Institutionalization. (The thesis was written in French - 552 pages)

Title: Isotopic archeo-biogeochemistry, reconstitution of diet and patterns of mobility, bio-cultural interactions. The plural burials of the region X of the catacomb of Saints Peter and Marcellinus (Rome, 1st-3rd cent. AD) Abstract: Between 2003 and 2010, unpublished sepulchral assemblies have been discovered and excavated in the central region, called X, of the catacomb of Saints Peter and Marcellinus (Rome, 1st-3rd cent. AD.). These assemblies have proven to be atypical and complex plural burial. Hundreds of the dead were buried extremely rigorous according to uncommon funeral practices. Archeological evidences (simultaneity of deposits) and biological ones (absence of osteological lesions) present a number of features arguing in favor of one or even several crises most likely of an epidemic nature. This or these crises would have executed over a relatively long time with different phases of resurgence and quietude. Furthermore, the discovery of precious materials in association with the deceased puts forward a kind of particular high social rank of the latter. Besides, following funerary practices which are seemed to be similar with non-Roman ones suggests a possible non local origin for the individuals buried in this place. Our doctoral research is with the primary objective to reconstruct the diet and mobility patterns of a subsample of 130 of these individuals using an archeo-biogeochemical multi-proxy (δ13C, δ15N, δ18O and 87Sr/86Sr) and multi-tissue (enamel, bone, hair) approach. In general, we have been able to show that most of these individuals had access to such a type diet based on the triad C3 cereal/C3 meat/Marine fish. This type diet would however not be exclusive. Some individuals (n = 13) would have indeed occasionally consumed other resources such as freshwater fishes or C4 cereals. Besides, this population is distinguished from other contemporary populations of Rome with regard to food they consumed. However, almost a quarter (n = 30) of them are migrants, but they do not distinguish of the Roman residents as for their diet. These migrants have complex and heterogeneous life trajectories; three distinct mobility patterns seem to be conceivable. They could be originated from supra-regions like Europe, Africa, Arabia and Asia Minor. Besides, this population does not differentiate from other Roman populations in terms of rates of migrants but however it does distinguish by its cosmopolitanism. To conclude, on the basis of these elements together with historical and archaeological data, we were able to revisit the social status of these deceased, the origin of cultural traits and the chronology of the site. We end by proposing the hypothesis of a possible Christian origin for these individuals.

Since its formation, the Earth is slowly cooling. The heat produced by the core and the radioactive decay in the mantle is evacuated toward the surface by convection. The evolving convective structures thereby created control a diversity of surface phenomena such as vertical motion of continents or sea level variation. The study presented here attempts to determine which convective structures can be predicted, to what extent and over what timescale. Because of the chaotic nature of convection in the Earth's mantle, uncertainties in initial conditions grow exponentially with time and limit forecasting and hindcasting abilities. Following the twin experiments method initially developed by {\it Lorenz} [1965] in weather forecast, we estimate for the first time the Lyapunov time and the limit of predictability of Earth's mantle convection. Our numerical solutions for 3D spherical convection in the fully chaotic regime, with diverse rheologies, suggest that a 5\% error on initial conditions limits the prediction of Earth's mantle convection to 95 million years. The quality of the forecast of convective structures also depends on our ability to describe the mantle properties in a realistic way. In 3D numerical convection experiments, pseudo plastic rheology can generate self-consistent plate tectonics compatible at first order with Earth surface behavior [{\it Tackley}, 2008]. We assessed the role of the temperature dependence of viscosity and the pseudo plasticity on reconstructing slab evolution, studying a variety of mantle thermal states obtained by imposing 200 million years of surface velocities extracted form tectonic reconstructions [{\it Seton et al.}, 2012; {\it Shephard et al.}, 2013]. The morphology and position of the reconstructed slabs largely vary when the viscosity contrast increases and when pseudo plasticity is introduced. The errors introduced by the choices in the rheological description of the mantle are even larger than the errors created by the uncertainties in initial conditions and surface velocities. This work shows the significant role of initial conditions and rheology on the quality of predicted convective structures, and identifies pseudo plasticity and large viscosity contrast as key ingredients to produce coherent and flat slabs, notable features of Earth's mantle convection.