Final Report Summary - COMITAC (An integrated geoscientific study of the thermodynamics and composition of the Earth's core-mantle interface)
The core-mantle interface is the central cog in the Earth's titanic heat engine. As the boundary between the two major convecting parts of the Earth system (the solid silicate mantle and the liquid iron outer core) the properties of this region have a profound influence on the thermochemical and dynamic evolution of the entire planet, including tectonic phenomena at the surface. Evidence from seismology shows that the lowermost few hundred kilometres of the mantle is strongly heterogeneous in temperature, chemistry, structure and dynamics; this may dominate the long term evolution of the Earth's magnetic field and the morphology of mantle convection and chemical stratification, for example. Mapping and characterising this heterogeneity requires a detailed knowledge of the properties of the constituents and dynamics of D”. The CoMITAC project has built a new generation of multidisciplinary models incorporating modelling strain in the mantle, petrofabrics and seismic wave propagation to understand this region. It has assembled the largest, most robust dataset of seismic observations of the lowermost mantle, and has combined this to provide the most complete picture of the dynamics of this region ever assembled. This is providing a step change in understanding this enigmatic region, and has motivated a whole new range of studies for the future. As well as the core project CoMITAC contributed expertise and technology to a broad range of related projects as diverse as understanding the role of salt dynamics in hydrocarbon reservoirs, the transport of water into the mantle by subduction zones, and a NASA-funded mission to put the first seismometer on Mars.