26 September 2023

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African Superplume Causes Unusual Deformations in East African Rift System

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African Superplume Causes Unusual Deformations in East African Rift System

Research led D. Sarah Stamps has uncovered new insights into the forces that drive the East African Rift System, the Earth’s largest continental rift system. Using 3D thermomechanical modeling, the study reveals that the African Superplume, a massive mantle upwelling, is responsible for the unusual rift-parallel deformations observed in the region. These findings challenge previous theories and suggest that a combination of lithospheric buoyancy forces and mantle traction forces contribute to the rifting process.

Continental rifting involves the stretching and fracturing of the Earth’s lithosphere, its rigid outer layer. As the lithosphere becomes taut, it undergoes brittle changes, leading to rock fractures and earthquakes. Traditionally, deformation during rifting occurs perpendicular to the rift. However, Stamps’ research, which involved measuring the East African Rift System using GPS instruments for over 12 years, identified deformation that occurred parallel to the rift.

The study conducted Stamps and her team used 3D thermomechanical modeling to investigate the processes behind the rift-parallel deformations. The models demonstrated that the African Superplume, which flows from southwest Africa to northeast across the continent, drives the anomalous deformation parallel to the rift. Seismic anisotropy, the alignment of rocks in response to mantle flow, further supports this conclusion.

The research contributes to the ongoing scientific debate on the primary forces driving the East African Rift System. Some scientists argue that lithospheric buoyancy forces, attributed to the high topography and density variations in the rift system’s lithosphere, are the main drivers. Others propose that horizontal mantle traction forces are responsible. The findings of this study suggest a combination of the two forces.

Understanding the complex processes involved in continental rifting is vital for unraveling the mechanisms behind the Earth’s surface evolution. By shedding light on the unusual deformations and the role of the African Superplume, this research enhances our knowledge of the forces shaping the planet.

Source: Journal of Geophysical Research Solid Earth