Thaindian News

London, April 7 (ANI): Scientists have long thought that a very hot and very weak lower and middle crust underlies the Tibetan plateau, flowing like a fluid.

However, researchers at the California Institute of Technology (Caltech) have put forward a new theory - a really strong Indian crust lies beneath the plateau.

“The idea that Tibet is more or less floating on a layer of partially molten crust is accepted in the research community,” said Jean-Philippe Avouac, professor of geology at the California Institute of Technology.

“Our research proposes the opposite view - that there is actually a really strong lower crust that originates in India,” he added.

The insights could lead to a better understanding of the processes that have shaped the Himalaya Mountains and Tibet, the most tectonically active continental area in the world.

Avouac pointed out that underground plate collisions, which cause earthquakes and drive up the Himalaya and Tibet, are common geological processes that have occurred repeatedly in the course of Earth’s history, but are presently happening with a vigor and energy only found in that area.

The researchers propose that the region’s tectonic activity is the result of the Indian crust thrusting strongly underneath the southern portion of the Tibetan Plateau and locking into the upper crust.

They believe that the locked Indian crust alters the state of stress in the southern Tibetan crust, which can explain the contrast in the type of faulting seen between southern Tibet and northern Tibet.

To test their theory, the team performed a series of numerical experiments, assigning different material properties to the Indian crust.

The simulations revealed evidence for a strong Indian lower crust that couples, or locks in, with the upper crust.

This suggests that the “channel flow” model proposed by many geophysicists and geologists-in which a low-viscosity magma oozes through weak zones in the middle crust- is not correct.

“We have been able to create a model that addresses two long-standing debates,” said Alex Copley, a former postdoctoral scholar with Caltech’s Tectonics Observatory and now a research fellow at the University of Cambridge.

“We have constrained the mechanical strength of the Indian crust as it plunges beneath the Tibetan Plateau, and by doing so have explained the variations in the types of earthquakes within the plateau. This is interesting because it gives us new insights into what controls the behavior of large mountain ranges, and the earthquakes that occur within them,” he added.

The study is published in the April 7 issue of the journal Nature. (ANI)