Scientists have successfully decoded the long and complex geological history of the Ladakh Magmatic Arc, revealing how this ancient system records over 130 million years of tectonic activity that ultimately led to the formation of the Himalaya.
According to researchers from the Wadia Institute of Himalayan Geology, the region we now know as Ladakh was once located above the ancient Neo-Tethys Ocean. Deep beneath this ocean, a powerful geological process known as subduction took place, where an oceanic plate slowly moved under the Eurasian plate, generating heat and magma.
This continuous subduction led to the formation of the Ladakh Magmatic Arc, a vast belt of igneous rocks that developed between the Jurassic and Eocene periods, approximately 201 to 34 million years ago. By studying the chemical composition of rocks and isotopes such as strontium and neodymium, scientists were able to trace the origin and evolution of magma over millions of years.
The research highlights three major phases of geological activity. In the earliest phase, the region resembled a chain of volcanic islands rising from the ocean. During this stage, magma was mainly derived from the Earth’s mantle, with only minor contributions from sediments.
As tectonic plates continued to converge, the system evolved. Large underground bodies of granite, known as the Ladakh Batholith, began to form. These rocks showed stronger chemical signatures from continental material, indicating that sediments and fragments of the Earth’s crust were being recycled into the magma.
This shift was driven by the gradual collision between the Indian Plate and the Eurasian plate. As the Indian Plate moved northward, it carried increasing amounts of sediment into the subduction zone, enriching the magma and changing its composition.
Eventually, the collision closed the Neo-Tethys Ocean and caused the uplift of the Himalaya, giving rise to the world’s highest mountain range. Even after this major event, volcanic activity continued, with molten rock pushing through cracks in the Earth’s crust to form mafic dykes, which are narrow sheets of dark volcanic rock.
The study concludes that sediment contribution became more significant in the later stages of this geological evolution, particularly in the Kohistan-Ladakh Batholith, compared to earlier formations like the Dras-Nidar Island Arc Complex.
These findings provide valuable insights into how long-term tectonic processes, magma evolution and continental collisions shaped the Himalayan region, offering a clearer understanding of one of Earth’s most dramatic geological transformations.