Between 40 and 50 million years ago, the Indian and Eurasian continental plates collided, eventually forming the Himalayas and the Tibetan Plateau. If an average crustal thickness is assumed before the collision occurred, recent research reveals that what is left of the Eurasian and Indian plates after the collision is 30% less than what it should be—a finding that has puzzled scientists because the modern Eurasian plate is twice the normal crustal thickness in Tibet.
Some researchers have proposed that portions of Eurasia were even thicker than average prior to collision, but if that were the case, an even larger amount of crust from the Asian plate would have to have been recycled into the mantle to explain the missing mass. However, Yakovlev and Clark have a different hypothesis.
Using data from recently published paleomagnetic and geophysical studies, the authors found that the mass deficit could be explained by a thin crust prior to collision. The Asian plate would have grown to today’s thickness via shortening and underplating from the Indian plate. These findings will help further the understanding of the Indo-Eurasian collision and how it evolved. (Tectonics, doi:10.1002/2013TC003469, 2014)
—JoAnna Wendel, Staff Writer