Deep beneath the surface of the African continent, a dynamic and pulsating plume of molten mantle is reshaping the very foundation of the Earth’s crust. This groundbreaking discovery, led by a team of Earth scientists at the University of Southampton, reveals that the mantle upwelling beneath the Afar region of Ethiopia behaves like a rhythmic heartbeat, driving the gradual rifting apart of the continent and the embryonic formation of a new ocean basin. Published in Nature Geoscience, this research sheds new light on the intimate coupling between the Earth’s deep interior and the tectonic processes shaping its surface.
The Afar triple junction, where three major tectonic rifts converge—the Main Ethiopian Rift, the Red Sea Rift, and the Gulf of Aden Rift—is an extraordinary geological laboratory for studying continental breakup and ocean genesis. For decades, geologists have hypothesized that a mantle plume, a column of buoyantly rising hot rock originating from deep within the mantle, lies beneath this region, fueling tectonic extension and volcanism. Until now, however, the internal structure and dynamic behavior of this mantle plume remained poorly understood, largely due to the challenges involved in directly sampling and imaging these deep Earth processes.
To tackle this mystery, the team collected and meticulously analyzed over 130 volcanic rock samples across the Afar region and the Main Ethiopian Rift. By integrating these geochemical data with existing datasets and employing sophisticated statistical modeling techniques, the researchers were able to map the architecture of the mantle plume with unprecedented detail. Their analysis reveals that the plume is not a simple, uniform upwelling but instead features distinctive chemical banding that repeats across the rift system, akin to a series of geological barcodes. These compositional stripes correlate with pulse-like surges of partially molten mantle material ascending from depths far below the lithosphere.
Crucially, the rhythmic pulses of the mantle plume appear to be modulated by the tectonic plates overriding them. The Earth’s rigid lithospheric plates—massive slabs of the crust and upper mantle—play an active role in channeling these upwelling pulses. The variability in chemical band spacing across the rift arms reflects differing tectonic regimes and plate motions. For example, in faster-spreading arms such as the Red Sea Rift, pulses propagate more efficiently and regularly, resembling the pulsatile flow through a narrow artery, while in slower-spreading or thicker plate regions, the mantle dynamics are more subdued and irregular. This interplay between mantle flow and plate tectonics is critical for understanding the rates and styles of continental breakup.
According to Dr. Emma Watts, the study’s lead author, the mantle beneath Afar is far from stationary. “Our findings demonstrate that the mantle pulses are chemically distinct and that these pulses are actively shaped by the rifting plates above,” she explains. This revelation challenges the traditional view of mantle plumes as isolated upwellings and highlights their dynamic responses to tectonic forces. Dr. Watts’s multidisciplinary approach, combining geochemistry, geophysics, and statistical analysis, was vital for unraveling this complex system and connecting deep Earth processes to surface volcanism.
This discovery has major implications for interpreting volcanic activity and seismic hazards in rift zones worldwide. The mantle plume’s pulsations influence not only where melt accumulates but also how and where volcanism is focused, often aligning with zones of lithospheric thinning. Dr. Derek Keir, co-author and expert in mantle dynamics, points out that “the evolution of deep mantle upwellings is intimately linked to plate motion, which profoundly affects volcanic and earthquake activity in rifting environments.” Understanding these links provides critical insights into the fundamental mechanisms of continental fragmentation and ocean basin formation.
The mantle plume beneath Afar serves as a natural laboratory to visualize Earth’s internal workings. Its asymmetric structure, featuring chemical striping that traverses the region, offers a unique record of mantle convection patterns and melts’ chemical evolution over millions of years. These plume pulses likely transport distinct geochemical fingerprints from deep within the mantle, contributing to diverse magmatic products at the surface. The research team postulates that these pulses may reflect episodic bursts of mantle melting and melt extraction, governed by the mechanical coupling of the mantle to the moving tectonic plates.
Moreover, studying the Afar plume helps resolve longstanding debates about the role of mantle plumes in rifting processes. Traditionally, some models viewed mantle plumes as passive thermal anomalies rising independently of plate motions. This study upends that notion, revealing a feedback system where mantle upwelling and plate tectonics co-evolve. The pulses in the plume respond to the spatial and temporal variations in plate stretching rates and lithospheric thickness, indicating a two-way dynamic interaction rather than a one-sided influence.
Such complex mantle-plate dynamics herald a new era of geodynamic understanding with broad implications for geological hazards and Earth’s evolution. Enhanced knowledge of how mantle pulses modulate volcanic activity can improve volcanic eruption forecasts in rift settings. Similarly, linking mantle flow patterns to seismicity could refine earthquake hazard assessments in rapidly deforming regions. The study underlines the necessity of combining geochemical evidence with advanced modeling to decode the Earth’s interior processes comprehensively.
Looking ahead, the research team plans to investigate the detailed mechanisms controlling mantle flow rates and the coupling processes beneath tectonic plates. A pivotal question remains: How rapidly does mantle material ascend beneath the rifting plates, and how do these fluids and melts interact with the brittle lithosphere? Unraveling these processes will deepen our understanding of mantle convection, magmatism, and continental breakup, with far-reaching consequences for Earth sciences.
The multi-institutional collaboration driving this research highlights the value of integrating diverse expertise and methodologies to tackle complex Earth systems. By harmonizing geochemical sampling, seismic imaging, computational modeling, and tectonic analysis, the team has pieced together a comprehensive view of the mantle plume beneath Afar. This holistic approach is indispensable for interpreting the signals encoded in volcanic rocks and seismic data, representing a paradigm for future studies of mantle dynamics and tectonics.
In sum, the rhythmic, pulsing mantle plume beneath the Afar triple junction offers a vivid, dynamic portrait of Earth’s deep interior at work. Its interaction with overlying tectonic plates is orchestrating the slow but relentless birth of a new ocean, visible through distinct geochemical patterns and surface volcanic activity. This research not only unravels the complexities of mantle flow beneath Africa but also illuminates fundamental processes underpinning continental fragmentation and ocean formation worldwide.
Subject of Research: Not applicable
Article Title: Mantle upwelling at Afar triple junction shaped by overriding plate dynamics
News Publication Date: 25-Jun-2025
Web References: http://dx.doi.org/10.1038/s41561-025-01717-0
Image Credits: Dr Derek Keir, University of Southampton / University of Florence
Keywords: Volcanic processes, Geology, Geological events, Physical geology, Volcanic eruptions, Volcanoes
