Researchers, led by D. Sarah Stamps, have employed 3D thermomechanical modeling to identify the cause of atypical deformations running parallel to the East African Rift System. The study reveals that the African Superplume, a vast upward movement of the mantle, is responsible for these peculiar rift-parallel distortions. This discovery complicates the ongoing debate about the main driving forces behind the rifting process. It suggests a combination of forces related to the buoyancy of the lithosphere and the traction forces exerted by the mantle.
Computer simulations have confirmed that the African Superplume indeed leads to these distinctive deformations as well as the rift-parallel seismic anisotropy that has been detected beneath the East African Rift System.
In continental rifting, a process involving stretching and fracturing that extends deep within the Earth, the lithosphere’s rigid outer layer undergoes changes. As the lithosphere becomes more taut, its upper parts experience brittle modifications, resulting in rock fractures and earthquakes.
D. Sarah Stamps, a geophysicist, uses computer modeling and GPS data with millimeter precision to investigate these processes. She likens the various deformation styles in a rifting continent to playing with Silly Putty. Just as Silly Putty can either crack when struck or stretch when pulled apart slowly, Earth’s lithosphere behaves differently over varying time scales.
Typically, deformation caused by continental rifting follows predictable patterns relative to the rift. It tends to be perpendicular to the rift. However, Stamps and her team observed deformations going in the opposite direction—parallel to the rift—in the East African Rift System after more than a decade of GPS measurements.
In a recent study published in the Journal of Geophysical Research, the team explored the underlying processes of the East African Rift System. They used 3D thermomechanical modeling to reveal that the unusual, rift-parallel deformations are due to northward mantle flow connected to the African Superplume. This massive upwelling of mantle material rises from deep within the Earth beneath southwest Africa and extends northeast across the continent.
The findings, combined with insights from a previous study, could help resolve the scientific debate surrounding the dominant forces driving the East African Rift System’s deformations, both rift-perpendicular and rift-parallel.
By utilizing GPS data and computational simulations, the team determined that while lithospheric buoyancy forces explain the predictable, rift-perpendicular deformation, they fail to account for the anomalous, rift-parallel deformation observed by Stamps’s GPS measurements.
The recently published study further establishes that the African Superplume is responsible for both the unusual deformations and the rift-parallel seismic anisotropy beneath the East African Rift System.
In the context of this study, seismic anisotropy refers to the alignment of rocks in response to mantle flow, melt pockets, or pre-existing structural features in the lithosphere. The alignment of rocks in this case corresponds to the northward mantle flow of the African Superplume.
This research contributes to a better understanding of the intricate processes involved in continental rifting, shedding light on anomalies like these. Stamps emphasizes the significance of this result in unraveling the complexities that shape the Earth’s surface during continental rifting.
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Frequently Asked Questions (FAQs) about Continental rifting
What is the main focus of this study?
The study’s main focus is to understand the source of unusual deformations observed in the East African Rift System and to determine the driving forces behind these deformations.
What is the African Superplume?
The African Superplume is a massive upward movement of the mantle beneath the Earth’s surface, specifically located beneath southwest Africa, extending northeast across the continent.
How do researchers study continental rifting?
Researchers utilize 3D thermomechanical modeling, computer simulations, and GPS data to investigate and analyze the processes of continental rifting, including the deformations and movements of the Earth’s lithosphere.
What are the key findings of this research?
The study shows that the African Superplume is responsible for the unique rift-parallel deformations observed in the East African Rift System. These deformations are driven by northward mantle flow associated with the superplume.
How does continental rifting affect the Earth’s lithosphere?
Continental rifting involves the stretching and fracturing of the Earth’s lithosphere, which is the rigid outer layer. This process leads to various forms of deformation, including rock fractures and earthquakes.
What factors contribute to the complexity of rift deformations?
The study suggests that a combination of lithospheric buoyancy forces and mantle traction forces are at play in causing the rift deformations observed in the East African Rift System, adding to the complexity of understanding the process.
What is seismic anisotropy?
Seismic anisotropy refers to the alignment of rocks in response to mantle flow, melt pockets, or pre-existing structural features in the lithosphere. In this case, it reflects the direction of mantle flow caused by the African Superplume.
How does this research contribute to understanding continental rifting?
By identifying the role of the African Superplume in causing rift deformations, the study provides valuable insights into the complex processes that shape the Earth’s surface during continental rifting, advancing our understanding of geology and tectonics.
More about Continental rifting
- Journal of Geophysical Research Solid Earth
- Virginia Tech College of Science
- A Geodynamic Investigation of Plume-Lithosphere Interactions Beneath the East African Rift
