Hazards

The structuring element of the Primitive Earth theme is that it brings together people interested either in internal geodynamics or in surface processes, and using complementary methodologies. It is a question of studying the potential relations between the evolution of the internal geodynamics of the Earth, in particular the beginning of the processes of subduction and formation of continental crust, and the evolution of the external envelopes (atmosphere, hydrosphere and biosphere) , including the onset of photosynthesis and oxygenation of the atmosphere and oceans. The question is how the evolution of the Earth’s dynamics and the emergence of continental surfaces could have influenced the appearance and evolution of life. A corollary question is how the irreversible oxidation of the Earth’s surface has generated biological and mineralogical diversity, including minerals of economic interest. We will discuss the history of plate tectonics and outer envelopes using field observations on the five continents, sedimentological, mineralogical, geochemical and structural analyses, measurements of magnetic properties, dating and thermo-mechanical modelling.