Africa's Rift Valley: Magma Upwelling Drives Continental Split, Birth of New Ocean Anticipated

Tuesday - 01/07/2025 03:00
In East Africa's Afar Depression, scientists have discovered that fresh lava from deep within the Earth's mantle is driving the continent's split. The mantle upwellings pulse with distinct chemical signatures, fueling volcanic eruptions and earthquakes. This activity weakens the crust, potentially leading to a new ocean separating the Horn of Africa.

In the Afar Depression of East Africa, a geological hotspot where three tectonic plates converge, groundbreaking research indicates that magma from the Earth's mantle is driving the continent's gradual splitting. Scientists have discovered that mantle upwellings in the area are not uniform, but rather consist of complex waves of molten material. This activity fuels volcanic eruptions and seismic events, weakening the Earth's crust. Ultimately, this process is expected to lead to the formation of a new ocean, separating the Horn of Africa from the rest of the continent and dramatically altering the region's geography.

Volcanic eruption in the Afar region of Africa. *Image: A volcano erupts in the Afar region.*

Mantle Pulses Reveal Earth's Inner Workings

Researchers from the University of Southampton and Swansea University analyzed lava samples from over 130 young volcanoes across the Afar region. Their analysis revealed that the mantle beneath East Africa exhibits a pulsating behavior, with surges of partially molten rock rising to the surface. Each pulse possesses a unique chemical signature, suggesting that the mantle is composed of diverse materials. The thickness and movement of the overlying tectonic plates significantly influence this dynamic process.

In areas with rapid movement, such as the Red Sea Rift, mantle flow is more concentrated. In regions with slower rifting, it spreads more gradually. These pulses ascend through thinned areas of the Earth's crust, making them vulnerable to volcanic eruptions. The chemical variations observed in the lava provide insights into the Earth's internal processes, demonstrating how surface volcanic activity is linked to hidden processes occurring deep beneath the surface.

The upwelling plume is also eroding the lithosphere, reducing it to a mere 15 kilometers thick in certain parts of the Afar Depression. As the plates continue to stretch and thin, they create pathways for increased lava flow, triggering recurring volcanic eruptions and seismic events. This mirrors the geological events that shaped the Atlantic Ocean millions of years ago.

Continental Breakup and Ocean Formation

The geological activity in the Afar region is part of continental rifting, where the African, Arabian, and Somali tectonic plates are diverging. The resulting space is being filled with rising magma and newly formed crust. Over time, this rifting is expected to allow seawater to flood the region, creating a new ocean basin similar to the Atlantic.

The ongoing volcanic eruptions are already reshaping the landscape. Lava flows from the Erta Ale volcano cover extensive areas of Ethiopia, and frequent earthquake swarms indicate zones of intense tectonic stress. The Boset Volcano displays numerous layers of volcanic deposits, showcasing the long-term impact of mantle upwelling.

These discoveries provide a real-time view into the birth of an ocean and offer insights into Earth's climate and history. Similar mantle plumes in the past have generated massive volcanic provinces, such as the North Atlantic Igneous Province, which contributed to significant climate changes and potentially mass extinctions due to the release of CO₂ and sulfur dioxide.

Scientists highlight the importance of collaborative research across institutions and disciplines to fully understand these complex dynamics. Future research will focus on mapping mantle flows beneath other thinning tectonic plates and predicting how these deep forces influence surface geology. The Afar region serves as a natural laboratory for observing the relationship between Earth's interior and its evolving surface.

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