The rhythmic surges of molten rock beneath Africa, described as a “heartbeat,” are gradually tearing the continent apart, according to a new study published in Nature Geoscience. This geological phenomenon, concentrated below Ethiopia’s Afar region, is driven by vertical mantle movements known as mantle plumes. These upwellings are hypothesized to play a crucial role in continental drifting and other large-scale geological changes.
The discovery highlights the complex interactions between Earth’s interior and its surface, as these mantle pulses are channelled by the rifting of the Arabian, Nubian, and Somalian tectonic plates. Over millions of years, this process is expected to thin and weaken the continent, eventually leading to the formation of a new ocean.
Geological Intrigue in the Afar Region
The Afar region is a geologically significant area where three tectonic plates intersect. The rifting of these plates occurs at varying rates, creating a dynamic environment for studying mantle upwellings. Dr. Emma Watts, the lead author of the study, explains, “We found that the mantle beneath Afar is not uniform or stationary – it pulses, and these pulses carry distinct chemical signatures.”
For years, geologists have speculated about a hot mantle plume beneath Africa, but the precise mechanisms remained elusive. The study by Earth scientists at the University of Southampton sheds new light on this phenomenon by analyzing over 130 volcanic rock samples from the Afar and the Main Ethiopian Rift.
Understanding Mantle Dynamics
Using advanced mathematical and computational models, researchers gained insights into the Earth’s depth and composition beneath the Afar surface. They discovered a single spatial upwelling under the three rifts, each with a unique chemical composition. These upwellings repeat in a specific rhythm, akin to geological barcodes.
“The work shows that deep mantle upwellings can flow beneath the base of tectonic plates and help to focus volcanic activity to where the tectonic plate is thinnest,” says Dr. Derek Keir, an associate author of the study.
The plumes originate from depths of 1,000 to 2,800 km (621 to 1,740 miles) and contain varying isotopes, possibly from primordial mantle material. This makes the region slightly hotter than the surrounding mantle. The study reveals that the upwelling’s behavior changes with the lithosphere’s thickness; thicker plates slow the molten pulses.
Implications for Future Research
The findings have significant implications for understanding how mantle flow occurs beneath tectonic plates. The study’s authors suggest that follow-up research should focus on the rate and nature of mantle flow beneath these plates. This could provide further insights into the processes that drive continental drift and ocean formation.
Meanwhile, the idea of a nascent ocean forming in the Afar region is a tantalizing prospect for geologists. It underscores the dynamic nature of Earth’s geology and the ongoing changes shaping our planet’s surface.
As scientists continue to unravel the mysteries of mantle dynamics, this study represents a significant step forward in understanding the complex interactions between Earth’s interior and its surface. The research not only enhances our knowledge of geological processes but also highlights the potential for future discoveries in this field.