Structure in Geosciences and the (future) role of SAPHiR

As a living, active planet the Earth’s surface and interior is continually modified by geological processes linked to global plate tectonics and mantle convection. At the same time, its rocks record the history of the Earth from its formation 4.6 Ga ago until more recent events at all scales in the form of the crystal structure and orientation of the stable mineral phases at various depths, their chemistry, and higher order structures such as folding, layering, and still enigmatic large provinces found in the deepest part of the lower mantle. However, investigation of the Earth’s macrostructure and unravelling Earth history is hindered by the fact that most material is situated in its deep interior and therefore subject to pressure and temperature conditions that are conventionally considered extreme. In addition, this material is largely inaccessible to direct observation; hence, knowledge of the interior structure of the Earth stems from a combination of geophysical probing methods such as the travel times of seismic waves and experimental investigations that simulate the conditions in the deep Earth. The past decades have shown that the distinctly layered structure of the mantle can be linked to phase transitions that the major constituents undergo at various depths and it was shown that even volatile phases such as water are transported into the deep Earth and stored in high pressure mineral phases. The talk will trace the structural changes of a few key mineral phases from crust to core, explain how their crystallography and rheology controls the evolution and current shape of the Earth, and highlight the role of current and future neutron research for understanding such global processes.