New Delhi: Scientists have decoded the evolution of the Ladakh Magmatic Arc (LMA) in the northwestern Himalaya, shedding new light on the geological processes that led to the formation of the Himalayan mountain range.
According to the Ministry of Science and Technology, the Ladakh Magmatic Arc preserves a nearly 130-million-year record of plate tectonic activity, documenting the subduction, maturation and eventual collision of the Indian and Eurasian plates.
The study, conducted by researchers from the Wadia Institute of Himalayan Geology, Dehradun, an autonomous institute under the Department of Science and Technology (DST), traced the origin of the arc through detailed geochemical and isotopic analysis of rocks.
Scientists found that the LMA formed due to the northward subduction of the Neo-Tethys Oceanic plate beneath the Eurasian margin, millions of years before the rise of the Himalayas. The arc represents a belt of igneous rocks formed between the Jurassic and Eocene periods, roughly 201 million to 34 million years ago.
The researchers identified three major phases of magmatic activity—160–110 million years ago, 103–45 million years ago, and after 45 million years—each marked by distinct chemical signatures linked to tectonic processes beneath the Earth’s surface.
During its earliest phase, the region resembled a chain of volcanic islands above the Neo-Tethys Ocean. Over time, as tectonic plates converged, large granite bodies known as the Ladakh Batholith formed deep underground, reflecting increasing interaction with continental material.
The study also highlights how the eventual collision of the Indian and Eurasian plates led to the closure of the Neo-Tethys Ocean and the uplift of the Himalayas. Even after the collision, volcanic activity continued in the form of mafic dykes—narrow sheets of solidified magma cutting through older rocks.
Using isotopic markers such as strontium and neodymium, scientists were able to reconstruct the complex tectono-magmatic history of the region, providing insights into the sources of magma, including mantle material, recycled sediments and continental crust.
The findings underline the critical role of ancient oceanic subduction and sediment recycling in shaping the geology of Ladakh and the broader Himalayan region, offering a deeper understanding of one of the world’s most dramatic geological transformations.
