The East African Rift System is slowly breaking apart, with Madagascar splitting into parts

Geosciences doctoral student Taheri Rajaunarison places a GPS instrument in northern Madagascar in this 2016 photo. Image credit: Rina Andrianasolo. Credit: Reina Andrianasolo

The African continent slowly splits into several large and small tectonic blocks along the East African Forked Rift System, continuing to Madagascar – the long island off the coast of Southeast Africa – which will also break up into smaller islands.

These developments will redefine Africa and the Indian Ocean. This discovery comes in a new study conducted by Dr. Sarah Stamps from the journal’s geosciences department geology. The separation is a continuation of the shattering of the supercontinent Pangea about 200 million years ago.

Rest assured, though, this isn’t going to happen anytime soon.

“The rate of degradation at present is millimeters per year, so millions of years will pass before new oceans start forming,” said Stamps, assistant professor at Virginia Tech School of Science. “The rate of expansion is the fastest in the north, so we’ll see new oceans forming there first.”

Geosciences doctoral student Taheri Rajaunarison places a GPS in northern Madagascar in this 2016 photo. Behind the immaculate Indian Ocean and a rocky island. Image credit: Reina Andrianasolo.

“Most of the previous studies indicated that the extension is concentrated in narrow regions around the fine plates that move independently of the surrounding large tectonic plates,” Stamps said. The new GPS dataset of extremely fine surface motions in East Africa, Madagascar, and several islands in the Indian Ocean has revealed that the dissociation process is more complex and more distributed than previously thought, according to the study, which Stamps completed with researchers from the University of Nevada Reno and the University of Beira Inland in Portugal. The Institute and Observatory of Geophysics in Antananarivo at the University of Antananarivo in Madagascar itself.

The East African Rift System is slowly breaking apart, with Madagascar splitting into parts

The Final Model of the East African Rift System. Segmented lines indicate a newly discovered broad deformation region. Arrows represent expected tectonic plate movements. ABFZ – Andrew Payne fracture zone; IFZ – indirect fracture region; RSZ – Ranutsara mowing area. Credit: Figure created by DS Stamps.

In one area, the researchers found that the sprawl is distributed over a large area. The distributed area of ​​ u200b u200bthe span is about 600 km (372 miles) wide, and stretches from East Africa to entire parts of Madagascar. More precisely, Madagascar actively separates from southern Madagascar and moves using the Lwandle Plate – a small tectonic mass – and a piece of central Madagascar moving with the Somalis . The stamp added that the rest of the island was found loosely deformed.

He also worked on the PhD paper in Earth Sciences. Student Taheri Rajaunarison, who was previously a master’s student at the University of Antananarivo in Madagascar. Stamps in 2012 helped collect the GPS data that was used in this study. He joined Virginia Tech in 2015 and later returned to Madagascar to collect more data as a lead for the National Geographic Society Scholarship. “Leading a team to collect GPS data in Madagascar in the summer of 2017 was an amazing field experience,” said Rajaunarison.

The team used new surface motion data and additional geological data to test the different formations of tectonic blocks in the area using computer models. Through a comprehensive suite of statistical tests, researchers have identified new limits for Lwandle’s microplate and Somali plate. This approach allowed testing whether the surface movement data are compatible with the movement of the solid plate.

“Accurately delineating plate boundaries and assessing whether continents diverge along narrow deformed regions or through large areas of diffuse deformation are critical to unraveling the nature of continental divide,” Stamps said. “In this work, we have redefined how the largest continental rift in the world is expanding using a new GPS speed solution.”

The discovery of the vast deformation zone helps geologists understand recent and ongoing seismic and volcanic activity occurring in the Comoros, located in the Indian Ocean between East Africa and Madagascar. The study also provides a framework for future studies of global plate motions and investigations of the driving forces of plate tectonics for stamps and their team.

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more information:

DS Stamps et al. Redefining the dynamics of the East African Rift System, geology (2020). DOI: 10.1130 / G47985.1

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The East African Rift System Slowly Breaking Apart, with Madagascar Splitting into Parts (2020, November 13)
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