Movement of the Indian Plate

At a Glance

• Origin Part of Gondwanaland
• Drift Northward, at up to about 15 to 20 cm a year
• Volcanic episode Deccan Traps, about 66 million years ago
• Collision With the Eurasian plate about 50 million years ago
• Present Moving north at about 5 cm a year
• Exam link UPSC Prelims, Geography: Geomorphic Movements and Plate Tectonics

Where Does It Fit?

This is the sixth topic of the category on geomorphic movements and plate tectonics. The previous topic gave the theory of plates, and this one applies it to India. The next topic covers ocean-ocean convergence and island arcs. Previous topic: Plate Tectonics and Types of Plate Boundaries. Next topic: Ocean-Ocean Convergence and Island Arcs.

Where Did the Indian Plate Come From?

In short: India was once attached to Africa, Antarctica and Australia, and it travelled thousands of kilometres north.

The Indian plate includes the Indian subcontinent and parts of the Indian Ocean floor, and it is part of the larger Indo-Australian plate. About 140 million years ago, the Indian landmass was located south of the equator, next to Australia and Antarctica, as part of Gondwanaland, the southern landmass described in Continental Drift Theory of Alfred Wegener. Gondwanaland began to break up in the Cretaceous period, and India separated from Madagascar around 90 million years ago and started drifting northward. The northern margin of the plate faced a large sea, the Tethys Sea, which lay between Gondwanaland and the northern landmass, Laurasia.

How Did India Move North?

After separating, the Indian plate moved north at a very high speed, up to about 15 to 20 cm a year, which is fast for a continental plate, covering a distance of several thousand kilometres. The drift was driven by seafloor spreading along the ridges south of India and by the pull of the subducting Tethyan oceanic plate to the north. As the plate moved, the oceanic crust of the Tethys was consumed at a trench along the southern margin of Asia, and sediments from the Tethys were scraped off. The movement of the plate across the Indian Ocean is traced by the ridges and the magnetic stripes of the ocean floor, which allow its position at different times to be calculated.

What Is the Link with the Deccan Traps?

About 66 million years ago, as the Indian plate moved over the Reunion hotspot, a mantle plume in the Indian Ocean, huge outpourings of basaltic lava covered much of western and central India, forming the Deccan Traps. The lava flows covered more than half a million sq km and built the black soil region of the Deccan. The island of Reunion, a volcanic island, still lies above the hotspot, and the line of volcanic features from the Deccan to the Maldives, Chagos and Mascarene islands marks the track of India over it. The Deccan eruptions occurred around the time of the end of the Cretaceous period, and their possible role in the mass extinction is a matter of continuing study. Such hotspots are treated in Hotspots, Mantle Plumes, Geysers and Hot Springs.

How Did the Collision Form the Himalayas?

About 50 to 55 million years ago, the Indian plate collided with the Eurasian plate. Both plates carried continental crust, so neither could subduct completely, and the sediments of the Tethys Sea were squeezed, folded and thrust upward into the Himalayas, while the Tibetan Plateau was raised to the north. The collision continues, as the Indian plate pushes north at about 5 cm a year, and the Himalayas are rising by a few millimetres a year. This continuing convergence explains the frequent earthquakes of the Himalayan belt. The process is explained in Continent-Continent Convergence – Himalayas and Tibetan Plateau.

The Indian plate has other boundaries too. The Carlsberg and Central Indian ridges, divergent boundaries, lie to the south and west. The north is convergent, along the Himalayas. To the east, the plate meets the Burma plate along the Arakan Yoma and the Sunda trench, where the 2004 earthquake occurred, as in The 2004 Indian Ocean Tsunami and Warning Systems. As an analytical point, the Indian plate shows that the same process can leave several signatures: a hotspot volcanic plateau, a collision mountain range and a seismic belt.

Why Is This Topic Important?

• India Origin of the subcontinent
• Himalayas Why they exist and rise
• Deccan Traps Volcanic and soil link

What Came Next?

The next topic describes ocean-ocean convergence and island arcs. Next topic: Ocean-Ocean Convergence and Island Arcs.

Key People and Terms

• Gondwanaland Southern supercontinent
• Tethys Sea Sea between Gondwana and Laurasia
• Reunion hotspot Mantle plume under the Indian Ocean
• Deccan Traps Basalt flows of western India
• Indo-Australian plate Plate that includes India
• Eurasian plate Plate north of India

Exam Corner

Mains Angle

Questions ask for the geological history of India. These points add depth.

• History Gondwana to Himalayas
• Volcanism Reunion hotspot and Deccan lava
• Hazard Continuing collision causes earthquakes