Magma-assisted rifting in Ethiopia.

Area of Science:

• Geophysics
• Tectonics
• Seismology

Background:

• Continental break-up and ocean basin evolution are key to plate tectonics.
• The process of continental rupture is debated, with plate driving forces potentially too small for thick lithosphere.
• Mantle upwelling and magma production may facilitate lithospheric rupture at lower stresses (Buck's model).

Purpose of the Study:

• To test mechanical versus magma-assisted continental extension models.
• To investigate the Northern Ethiopian Rift as a natural laboratory for continental break-up.
• To analyze seismic anisotropy in the upper mantle of the rift zone.

Main Methods:

• Observation of shear-wave splitting to detect seismic anisotropy.
• Analysis of upper mantle structure and seismic anisotropy patterns.
• Integration of seismic data with existing geological information.

Main Results:

• Evidence of significant seismic anisotropy in the Northern Ethiopian Rift's upper mantle.
• Observations indicate a dominant melt-induced anisotropy.
• Minimal crustal stretching was detected, contrasting with purely mechanical models.

Conclusions:

• The findings support a magma-assisted rifting model for the Northern Ethiopian Rift.
• Melt-induced anisotropy plays a crucial role in the break-up of cold, thick continental lithosphere.
• This study provides critical evidence for understanding the mechanisms of continental break-up.