Scientists tapped into the mysteries of dynamic forces that shape the Earth’s landforms particularly – ‘escarpments’ and plateaus’ described as ‘expansive topographic features’.
Such landscapes have long influenced planet’s climate and biology and now we may finally have some answers to their mechanics.
Thomas Gernon, Professor of Earth Science at the University of Southampton and lead author of the study told Interesting Engineering that Earth’s continents today are derived from supercontinents — united landmasses that broke apart at episodic intervals in geological history.
Gernon alongside a team of scientists undertook a research project to investigate the impact of global tectonic forces on landscape evolution over hundreds of millions of years.
The lead author told IE that the last, arguably best-known, example is the breakup of the Pangea supercontinent, which began around 240 million years ago.
“This event led to the separation of North America and Europe,” he says.
“The southern part of Pangea, known as Gondwana, fragmented 135 million years ago, resulting in the separation of South America and Africa. This classic ‘jigsaw fit’ was originally recognized by Alfred Wegener”
The scientist further explained a possibility that hot, buoyant plumes that rose from Earth’s deep interior heated and weakened the tectonic plates, making them more prone to rupture.
A similar process has been observed in the East African Rift System where the continental plate is stretching and forming a rift valley.
This rifting also set a ‘deep mantle wave’ in motion, moving along the continent’s base at a speed of 15-20 kilometers per million years.
The team deduced the wave likely convectively removes layers of rock from the continental roots.
“Eventually, persistent stretching will cause the plate to completely rupture and separate, leading to continental breakup and the formation of a new ocean,” Gernon told IE.
The new study described this new process as a chain of convective instabilities that forms during the rifting process and crucially migrates toward the continental interior over tens to even hundreds of millions of years after rifting.
Model to show climate impact
Aiming to answer why cratons (strong cores of the continents) are considered some of the most stable features on the planet, the study developed a model explaining the systematic geological mechanism.
Only to discover that even the stable regions of continents are susceptible to uplift and several kilometers of erosion over a relatively brief interval of time (millions to tens of millions of years) when compared to the age of such regions (~3 billion years in many cases), the scientist told IE .
Therefore, scientists developed a new landscape evolution model based on advanced computer models and statistical methods and ran simulations to explain the phenomena.
The new model is critical as it allows scientists to document massive rock erosions as the chemical weathering of this influences ocean chemistry and Earth’s climate.
“Such continental or ‘silicate’ weathering is often regarded as a major regulator of Earth’s climate state over geological time,” Gernon told IE .
He emphasized that nutrients released during this erosion and weathering of rock can induce primary production in the ocean leading to enhanced burial of organic carbon and climatic cooling.
For example, the chemical weathering of certain phosphorus-rick rocks such as basalts can trigger deoxygenation. This can cause major biological crises (and in extreme cases, mass extinctions, in the ocean).
The model recording the uplifting of plateaus could ascertain the movement’s impact on ice sheet growth and stability.
The mountain uplifts described in the study provide anchors for the ice to grip onto, potentially enhancing the stability of ice sheets.
Alluding to ecosystems, the lead author told IE that the formation of great escarpments and elevated continental plateaus could also shape terrestrial or land-based ecosystems.
“The growth of plateaus may fundamentally shape vegetation patterns across vast areas of the continents by elevating the land surface by hundreds of meters to over a kilometer,” he added.
“In effect, this could either push some plants out of their comfort zone or cause them to adapt to different climatic environments.”
Over the team devised a landscape evolution model to exhibit a sequence of events causing rifting – likely a consequence of escarpment or even a stable, flat plateau.
Scientists also believe that mantle disturbance may have also triggered diamonds to rise from Earth’s core, likely also shaping continental landscapes.
The study was published earlier today [August 6, 2024] in the journal – Nature .
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