University of Southampton researchers have discovered that the same process that triggers diamonds to quickly rise from Earth’s deep interior also shapes continental landscapes, influencing a host of factors – from regional climates to biodiversity over Earth’s history.
A team of experts led by Thomas Gernon, Professor of Earth Science at Southampton, has found that when tectonic plates break apart, powerful waves are triggered deep within the Earth. These waves can cause continental surfaces to rise by over a kilometre.
The results help explain why parts of the continents which were previously thought of as 'stable' experience substantial uplift and erosion. They also help explain how such processes can move hundreds or even thousands of kilometres inland, forming sweeping elevated regions known as plateaus, like the Central Plateau of South Africa.
Using advanced computer models and statistical methods to investigate how the Earth’s surface has responded to the breakup of continental plates through time, we discovered that when continents split apart, the stretching of the continental crust causes stirring movements in Earth’s mantle.
Thomas Gernon, Professor of Earth Science
Foundations of research excellence
The research, which was published in the scientific journal 'Nature', examined the effects of global tectonic forces on landscape evolution over hundreds of millions of years. This research builds on the team’s previous study linking diamond eruptions to continental breakup, which was also published in 'Nature'.
We found that the speed of the mantle ‘waves’ moving under the continents in our simulations closely match the speed of major erosion events that swept across the landscape in Southern Africa following the breakup of the ancient supercontinent Gondwana.
Thomas Gernon, Professor of Earth Science
Modelling landscape evolution
The scientists show that the Great Escarpments – steep slopes or long cliffs – originate at the edges of ancient rift valleys, much like the steep walls seen at the margins of the East African Rift today.
Meanwhile, the rifting event also sets about a ‘deep mantle wave’ that travels along the continent’s underbelly at about 15 to 20 kilometres per million years.
We also modelled how landscapes respond to this mantle-driven uplift. We found that migrating mantle instabilities give rise to a wave of surface erosion that lasts tens of millions of years and moves across the continent at a similar speed. This intense erosion removes a huge weight of rock that causes the land surface to rise further, forming elevated plateaus.
Thomas Gernon, Professor of Earth Science
The landscape evolution models show how a sequence of events linked to rifting can result in an escarpment as well as a stable, flat plateau, even though a layer of several thousands of metres of rocks has been eroded away.
Influencing climate and biodiversity
Researchers at Southampton worked alongside colleagues from the Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences and the University of Birmingham.
The team has concluded that the same chain of mantle disturbances that trigger diamonds to quickly rise from Earth’s deep interior also fundamentally shape continental landscapes. This influences a host of factors, from regional climates to biodiversity over Earth's history.
Thomas has been awarded two major philanthropic grants by the WoodNext Foundation, a component fund administered by the Greater Houston Community Foundation. These grants, totalling over £6 million, support his group’s ambitious study of the drivers of Earth's ice ages over the past billion years.
The funding also supports the development of evidence-based tools to understand and predict the emergence of extreme future climate states.
