Lava Pulsations Below Africa Signal Continental Rift Formation

Within the Earth's mantle, steady surges of molten lava are breaking through to the surface, providing an extraordinary window into the mechanisms behind ocean basin formation. These surges stem from a colossal mantle upwelling beneath East Africa, gradually pulling the continent apart through an intense geological process. This breakthrough, uncovered by scientists, enhances our understanding of how Earth's inner dynamics influence the planet's exterior features and offer insights into its ongoing transformation.

Unveiling the Mantle Upwelling at the Afar Triple Junction

Situated at the crossroads of three tectonic plate boundaries – the Main Ethiopian Rift, the Red Sea Rift, and the Gulf of Aden Rift – the Afar Depression is a rare geological site where divergent plates converge. Scientists have long believed that an ascending mantle plume fuels the region's active volcanism and frequent seismic events. Until now, the precise characteristics of this mantle activity were unclear. New investigations have now brought remarkable clarity to this phenomenon.

The research, conducted by a team at the University of Southampton, involved gathering lava samples from more than 130 volcanoes throughout the Afar region. By examining the chemical makeup of these volcanic rocks and integrating this data with existing geological frameworks, the researchers revealed that the mantle beneath Afar is complex. Instead of a solitary, uniform plume, it comprises several distinct mantle upwellings that create a patchwork mosaic of ascending hot rock.

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Spatially-heterogeneous-nature-of-the-mantle-upwelling-beneath-Afar-dc68b0e5b5e7f67e3b4ba114023a8023.webp — Credit: Nature

The Pulsating Behavior of Earth's Mantle

A particularly intriguing aspect of this study is the discovery of rhythmic pulses within the mantle below the surface. Emma Watts, the study’s principal investigator, describes the mantle beneath Afar as actively pulsing, each surge carrying distinct chemical fingerprints from partially molten mantle material. These pulses travel upward through the rift zones, where tectonic plates are actively stretching and thinning.

Co-author Tom Gernon compares this pulsing to a heartbeat: “The layered chemical pattern indicates the plume pulses much like a heartbeat. The behavior of these pulses varies depending on plate thickness and the rate at which the plates are diverging.”

Ethiopian-rift_Erta-Ale-volcano_Africa_mantle-pulse_lava_ocean-forming-6775d8aac15f5fd1aaca4cb233ada0d4.jpg — Credit: Dr Derek Keir, University of Southampton/ University of Florence

Interplay Between Mantle Dynamics and Tectonic Activity

The findings underscore the intimate link between mantle upwelling and tectonic plate movement. Derek Keir, contributing co-author, emphasizes that mantle flow and tectonic drift are intertwined. “This interaction governs surface vulcanism, seismicity, and the fragmentation of the continent,” he notes. Such coupling between deep Earth processes and surface geology is fundamental to our planet’s evolutionary narrative.

Underneath Afar, the mantle upwelling erodes and thins the lithosphere—the Earth's outermost layer—to depths as shallow as 15 kilometers in some areas. This weakening, combined with tectonic extension, catalyzes widespread volcanic eruptions. Lava from volcanoes like Ethiopia’s Erta Ale spreads extensively, forming new crustal material and marking zones where the continent is actively rifting apart.