Mohorovičić discontinuity and Lithosphere-Asthenosphere Boundary

Introduction

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.

Importance of the LAB

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 age. However, what happens during the early part of their lives remains an enigma.

Coupling and Exchange

Together, the Moho and LAB serve as the location where coupling and exchange take place between the shallow and deep mantle. Therefore, it is fundamental to understand their formation and evolution during the early stages of their existence.

Proposed Research

Here, I propose to acquire exceptional seismic data using the most advanced technology available in the industry, including:

1. Over 2500 Ocean Bottom Nodes
2. Advanced analysis techniques of full waveform inversion

This approach aims to quantify the nature of the Moho and the LAB during the first 5 million years of their lives at the fast-spreading East Pacific Rise.

Technological Advancements

This new technology will allow us to record multi-component seismic reflection and refraction data continuously up to 400 km offset at approximately 200 m intervals, thus opening up a new frontier of research.

Expected Outcomes

These new seismic data will provide:

• Quantitative P-wave and S-wave velocities of the whole crust
• The Moho
• The upper mantle
• The LAB at unprecedented resolution

Combined with petrological studies, this will allow us to develop a comprehensive geodynamical model for:

• Mantle melting
• Melt migration
• Crustal accretion
• Lithospheric evolution

Conclusion

The quantitative imaging of structures down to 20-30 km depth on a few hundred metre scale would be revolutionary. It would develop synergy between academic and industrial research and open up new horizons for deep seismic imaging for upper mantle studies.