The Indian tectonic plate is undergoing a split beneath the Tibetan plateau, challenging previous assumptions about its subduction. This groundbreaking discovery, presented at the American Geophysical Union conference in San Francisco, provides a new perspective on the formation of the immense Himalayan mountain range.
Traditionally, the towering Himalayas were attributed to the collision between the Indian and Eurasian continental plates, akin to the crumpling of a car's hood in a head-on collision. This process, occurring over approximately 60 million years, involved the Indian plate being subducted beneath the Eurasian plate, resulting in the upward thrust of the latter and the creation of the world's highest elevations.
However, the latest seismic analysis challenges this conventional understanding. Instead of smoothly subducting into the mantle, the buoyant Indian plate seems to be undergoing a more intricate process known as delamination. The seismic data indicates that the dense base of the Indian plate is peeling away and descending into the mantle, while the lighter top portion continues to scrape just beneath the Eurasian plate.
Led by geophysicist Lin Liu from the Ocean University of China, the research team employed a comprehensive approach, combining 'up-and-down' S-wave and shear-wave splitting data from 94 seismic stations in southern Tibet with 'back-and-forth' P-wave data. This nuanced analysis reveals a complex tectonic activity where the Indian slab is not uniformly gliding or crumpling but is undergoing a dramatic structural separation. Some sections remain relatively intact, while others are fragmenting about 100 kilometers below the surface, allowing the base to deform into the Earth's core.
This seismic investigation aligns with geological models based on helium-3 enriched spring water and surface-level patterns of fractures and earthquakes. Together, these findings portray a vivid picture of tectonic turmoil deep beneath the Himalayas.
The implications of this study extend beyond mountain formation, impacting earthquake prediction methods. With a clearer three-dimensional understanding of how tectonic plates interact, scientists can enhance their comprehension of Earth's surface evolution and potentially forecast seismic events more accurately.
