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Himalayan Mountains built on a ‘Crust-Mantle-Crust Sandwich,’ New Research Suggests
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A groundbreaking study challenges long-held beliefs about the formation of the world’s highest mountain range, proposing a complex geological structure beneath the Himalayas and the Tibetan Plateau.
For decades, most geologists have attributed the immense height of the himalayas to the thickening of the Earth’s crust through the collision of the Indian and Asian continents. Though, new research published in the journal Tectonics suggests a far more intricate process at play, revealing a “crust-mantle-crust sandwich” structure supporting the region’s colossal elevation.
Did you know?– The Himalayas began forming roughly 50 million years ago when the Indian and Asian continents collided. The collision caused the crusts to thicken, creating the towering peaks and the Tibetan Plateau.
Decoding the Himalayan formation
The himalayan mountains began to form roughly 50 million years ago as the Indian and Asian continents collided. The prevailing theory, first proposed by Swiss geologist Émile Argand in 1924, posited that the continuous collision caused the crusts of both plates to thicken, reaching depths of 70-80 kilometers. This immense crustal layer was thought to provide the necessary support for the towering peaks and the expansive Tibetan Plateau.
Though, as scientific instrumentation and data analysis techniques have advanced, cracks began to appear in Argand’s model. A key concern emerged: a crust exceeding 40 kilometers in thickness is likely too weak to sustain a massive plateau like Tibet.
Pro tip:– A crust exceeding 40 kilometers in thickness is likely too weak to sustain a massive plateau like Tibet. This led researchers to question the original theory of how the Himalayas formed.
“Crustal thickness above ∼40 km implies reduced strength of the continental lithosphere, which may become unable to sustain a plateau the size of Tibet throughout much of the Cenozoic,” the study noted. Moreover, geochemical and seismic data increasingly indicated the presence of mantle rock at depths where it shouldn’t exist, directly contradicting Argand’s original hypothesis.
Reader question:– how does the new research explain the presence of mantle rock? The study suggests a “crust-mantle-crust sandwich” structure. This layered architecture better explains the observed data.
A Novel ‘Sandwich’ Structure
To reconcile these inconsistencies,researchers from the university of Milano-Bicocca in italy conducted over 100 complex 2D numerical simulations of the continental collision. By varying the properties of the crust and mantle, they sought to understand the deep dynamics driving the formation of the Himalayas. The simulations offered a compelling option to the customary model.
Instead of a single, overly thick crust, the simulations demonstrated that the collision likely formed a structure the researchers call “crustal doubling” – a layer of Indian crust, a central layer of rigid Asian mantle, and an upper layer of Asian crust. This arrangement suggests the region’s elevation is supported by a complex, layered architecture rather than a monolithic slab of crust.
How the ‘Sandwich’ Forms
the research reveals that the Indian crust didn’t simply slide beneath the Asian crust. Rather, it moved under the entire Asian lithosphere, a rigid layer encompassing both the crust and the upper mantle. As it descended, the Indian crust was subjected to intense heat, causing it to partially melt. Portions of this molten crust then rose and were “underplated,” or pushed upwards, into the area beneath the Asian mantle section.
“We propose that viscous underplating of Indian crust beneath Asian lithosphere, not crust, forms the overall architecture of the Himalayan-Tibetan orogen,” the study stated. This process effectively created the deep, layered geological structure observed today.
This new explanation aligns more closely with existing observations, including the presence of mantle rock closer to the surface than previously expected. The researchers believe their findings provide a more
