MohoLAB · Mohorovičić discontinuity and Lithosphere-Asthenosphere Boundary

The Moho and lithosphere-asthenosphere boundary (LAB) are two of the most important boundaries in the Earth. The Moho is the greatest manifestation of the chemically differentiated Earth, separating light rocks in the crust from dense rocks in the mantle whereas the LAB is fundamental for plate tectonics, defining the boundary between the floating rigid lithosphere and the weak, deformable asthenosphere. They are both first born at mid-ocean ridges, where two-thirds of the Earth’s crust and lithosphere are formed, and then evolve with the age, but what happens during the early part of their lives remains an enigma. Together, they serve as the location where coupling and exchange take place between the shallow and deep mantle, and therefore, it is fundamental to understand their formation and evolution during the early stages of their existence. Here, I propose to acquire exceptional seismic data using the most advanced technology available in industry, >2500 Ocean Bottom Nodes, and subject them to the advanced analysis techniques of full waveform inversion, to quantify the nature of the Moho and the LAB during the first 5 Ma of their lives at the fast-spreading East Pacific Rise. This new technology will allow us to record multi-component seismic reflection and refraction data continuously up to 400 km offset at ~200 m interval, thus opening up a new frontier of research. These new seismic data will provide quantitative P-wave and S-wave velocities of the whole crust, the Moho, the upper mantle and the LAB at unprecedented resolution, which combined with petrological studies will allow us to develop a comprehensive geodynamical model for mantle melting, melt migration, crustal accretion, and lithospheric evolution. The quantitative imaging of structures down to 20-30 km depth on a few hundred metre scale would be a revolution, develop synergy between academic and industrial research, and open up new horizons for deep seismic imaging for upper mantle studies.