Washington, Sep 12 (IANS) Researchers have created the most complete seismic map of the upper mantle beneath the rugged Himalayas, stumbling on some unusual geologic features that may explain how the region came into being.
Researchers discovered that as the Indian and Eurasian tectonic plates collided, the Indian lower crust slid under the Tibetan crust, while the upper mantle pealed away from the crust and dropped down in a diffuse manner.
‘The building of Tibet is not a simple process,’ said John Nabelek, Oregon State University (OSU) geophysicist and study co-author.
‘In part, the mountain building is similar to pushing dirt with a bulldozer except in this case, the Indian sediments pile up into a wedge that is the lesser Himalayan mountains.
‘However, an important component of the mass transfer from the upper crust of India to the Himalayas also occurs at depth through viscous processes, while the lower crust continues sliding intact farther north under the Tibet plateau,’ Nabelek added.
He said the lower part of the Indian crust slides about 450 kms under the southern Tibetan plate and the mantle appears to shear off and break into sub-parallel segments.