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Tuesday, May 10, 2011

New hypothesis of Himalaya formation

Alex Copley and his colleagues from Caltech and the University of Cambridge have developed a new hypothesis about the formation of the Himalayan Mountain range.

Currently, the ‘channel flow’ model is the most widely accepted explanation for the formation of Tibetan mountains. In this model, the underthrusting Indian crust is separated from the Tibetan Plateau by a channel of magma. The molten layer of crust between the two tectonic plates finds its way through the weakest sections of the Tibetan crust, forcing the Himalayas higher. The trouble is that this theory cannot account for the different types of stress lines seen along the Tibetan Plateau.

In contrast, Copley’s suggestion that a strong hard Indian crust is locked under the Tibetan crust with no magma buffer between them is born out by simulations. If confirmed, this hypothesis may alter views about other mountain ranges as well.

Earthquake mechanisms and the style of faulting in the Himalaya-Tibet region show that the Himalayan range is under north-south compression, southern Tibet is in east-west extension, and northern Tibet is in both east-west extension and north-south compression. The study shows that this pattern can be explained if the strong Indian crust thrust under southern Tibet is transmitting the north-south push of India to northern Tibet.

(Credit: Caltech).