Kathmandu, Nepal – august 30, 2025, 14:32 Nepal Standard Time – A groundbreaking study published August 29, 2025, in the journal Tectonics challenges long-held assumptions about the geological composition beneath the Himalayas, suggesting a layer of Earth’s mantle is sandwiched between colliding continental crusts. The findings could reshape understanding of mountain building processes and seismic activity in the region, impacting geological hazard assessments for the over 1.6 billion people living in the surrounding river basins.
For decades, geologists believed the material forming the Himalayas originated entirely from the continental crust of the Indian and Eurasian plates. This new research,utilizing advanced computer modeling,proposes that a portion of the mantle – the layer beneath the crust – also became incorporated during the collision that began approximately 50 million years ago. The implications extend beyond the Himalayas, potentially influencing models of continental collisions globally and refining predictions of earthquake behavior in similar tectonic settings.
The research team, led by researchers at the University of California, Davis, employed elegant numerical simulations to analyze the complex interactions between the Indian and Eurasian plates. These simulations consistently revealed a segment of mantle material positioned between the crustal layers of both plates. According to the study, this unexpected arrangement explains several previously puzzling geological features observed in the Himalayas.
“All prior work generally agreed that all the material beneath the Himalayas came from the crust,” explained Adam Smith, a postdoctoral research associate in numerical modeling at the University of Glasgow in Scotland, who was not involved in the study, in an email to Live Science. “I think the authors are correct that this is controversial.”
Despite the potential for debate,the study’s results are considered plausible and offer a compelling explanation for several geological anomalies within the Himalayan range. “The authors run lots of simulations using different thicknesses for all of the layers, and they seem to always get this bit of mantle sandwiched between the crust of the two plates,” Smith added.
Douwe van Hinsbergen, a professor of global tectonics and paleogeography at Utrecht University in the Netherlands, who also wasn’t involved in the research, offered a different perspective. He described the findings as “a nice new finding and an elegant interpretation” in an email to live Science. “If a continent shoves below another continent, you’d expect a sandwich that consists from top to bottom of crust and mantle lithosphere of the upper (Tibet) plate, and then the crust of the lower (Indian) plate.”
