Seismology is by far the most powerful tool to explore the inner structure of our planet. However, the ability to retrieve the physical properties, i.e. density, temperature and composition, of the Earth’s constituent materials is limited by the inherent difficulty of separating each contribution and by uncertainties in the sensitivity of seismic velocities to these parameters. The combination of seismic observations and information from mineral physics can help overcoming the limited resolution of the seismic data and obtaining an insight into the physical state of the Earth. This Ph.D. project summarizes the results of a combined interdisciplinary study that includes seismology and mineral physics. The purpose is to augment our knowledge on the thermal and chemical nature of the inner Earth. A large global seismic database has been gathered and analyzed during the project and a new global joint compressional- and shear-velocity model has been delivered. The interpretation of the new model gives an insight into lateral compositional variations within the continental lithosphere and upper mantle, as well as a new interpretation of the thermo-chemical state of the lower mantle. Two manuscripts have been prepared and submitted to international peer reviewed journals.
The first manuscript “Hydration of marginal basins and compositional variations within the continental lithospheric mantle inferred from a new global model of shear and compressional velocity.” has been accepted for publication on Journal of Geophysical Research: Solid Earth on October 2015. The second manuscript “S − to − P heterogeneity ratio in the lower mantle and thermo-chemical implications” has been submitted to Earth and Planetary Science Letters and it is currently under review process.
This thesis represents the culmination of my Ph.D. project carried out between march 2012 and November 2015 at the Department of Geosciences and Natural resource management of the University of Copenhagen, under the supervision of Professor Fabio Cammarano. The final result greatly benefit from the work accomplished during a 6 month external staying at the Universit´e Pierre et Marie Curie in Paris, under the supervision of Professor Lapo Boschi.
The project was supported by Danish Research Council, Sapere Aude grant n. 11-105974