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Picture Courtesy:  PIB

Why in the News? 

Scientists from the Wadia Institute of Himalayan Geology (WIHG) decoded the 130-million-year-old evolutionary history of the Ladakh Magmatic Arc (LMA) in the North-Western Himalaya.  

What is Ladakh Magmatic Arc (LMA)?

It is a belt of igneous rocks (formed from cooled magma or lava) located in the Trans-Himalayan region. 

It was formed over a long period from the Jurassic to the Eocene epoch (approximately 201.3 to 33.9 million years ago). Before the Himalayas rose, this region was part of the Neo-Tethys Ocean.

Mechanism of Formation: The LMA was formed by the continuous northward subduction (a process where one tectonic plate moves under another) of the Neo-Tethyan oceanic plate beneath the Eurasian continental plate. 

• This process generated enormous heat and pressure, creating magma that rose to form the arc.

Geochemical Analysis: Scientists used isotopes of elements like Strontium (Sr) and Neodymium (Nd) as "geological time machines." 

The Three Phases of LMA's Tectonic Evolution

Phase 1: Pre-Collisional Island Arc (160–110 Million Years Ago)

• During this phase, the region resembled a chain of volcanic islands, known as the Dras-Nidar Island Arc Complex (DNIAC).
• Geochemical evidence shows that the magma originated primarily from the Earth's deep mantle, with minimal contribution from oceanic sediments.

Phase 2: Pre- to Syn-Collisional Maturation (103–45 Million Years Ago)

• As the Indian and Eurasian plates moved closer, large amounts of oceanic sediment were dragged down into the mantle.
• This led to the formation of the Kohistan-Ladakh Batholith (KLB)—large bodies of granite. The magma from this period shows a high degree of contamination from continental material and recycled sediments, signaling the continental collision.

Phase 3: Post-Collisional Fracturing (< 45 Million Years Ago)

• Even after the Neo-Tethys Ocean closed and the Himalayas began to rise, magmatic activity continued.
• Molten rock forced its way up through tectonic cracks, forming narrow sheets of dark volcanic rock called "mafic dykes." The magma for these originated from a mantle source already enriched by the previous subduction phases.

Strategic Significance

Critical Mineral Exploration

Mapping the LMA’s geology identifies potential deposits of copper, gold, and molybdenum, directly supporting the National Critical Minerals Strategy 2024 for self-reliance in green technology.

Geothermal Energy Potential

The residual heat from ancient tectonic activity makes Ladakh a prime location for geothermal energy.

• Case Study - Puga Valley Project: ONGC is developing India's first geothermal power project in Puga Valley, Ladakh. The region's geology, linked to the LMA, provides a high geothermal gradient.
• Potential: The project has an estimated potential to generate over 100 MW of clean, round-the-clock power, which is vital for this remote border region. (Source: Ministry of New and Renewable Energy)

Seismic Hazard Preparedness

Mapping the Ladakh Magmatic Arc's deep faults helps seismologists predict tectonic stress and improve earthquake preparedness for millions in high-risk zones. 

Way Forward

Expand Deep Earth Exploration

Accelerate initiatives like the 'Deep Ocean Mission' and expand the National Geoscience Data Repository (NGDR) to include high-resolution isotopic data from the LMA.

Implement Sustainable Mining Frameworks

Any future mineral exploration in Ladakh must be governed by strict Environmental Impact Assessments (EIAs) tailored to its fragile ecosystem, drawing lessons from Supreme Court rulings like the T.N. Godavarman case.

Strengthen Cross-Border Collaboration

Use platforms like the Shanghai Cooperation Organisation (SCO) to initiate collaborative geoscientific research with neighboring countries to improve regional disaster risk reduction.

Conclusion

Understanding the Ladakh Magmatic Arc provides a strategic roadmap for India to secure critical minerals, harness geothermal energy, and build seismic resilience, integrating deep-time geological insights into a sustainable and secure future for the Himalayan region.

 Source: PIB