Plate Movements
140 million years ago the Indian Plate formed part of the supercontinent Gondwana together with modern Africa, Australia, Antarctica, and South America. Gondwana broke up as these continents drifted apart with different velocities, a process which led to the opening of the Indian Ocean.
In the late Cretaceous about 90 million years ago, subsequent to the splitting off from Gondwana of conjoined Madagascar and India, the Indian Plate split from Madagascar. It began moving north, at about 20 centimetres (7.9 in) per year, and is believed to have begun colliding with Asia between 55 and 50 million years ago, in the Eocene epoch of the Cenozoic, although this is contested, with some authors suggesting it was much later at around 35 million years ago. If the collision occurred between 55 and 50 Ma, the Indian Plate would have covered a distance of 3,000 to 2,000 kilometres (1,900 to 1,200 mi), moving faster than any other known plate. In 2012, paleomagnetic data from the Greater Himalaya was used to proposed two collisions to reconcile the discrepancy between the amount of crustal shortening in the Himalaya (~1300 km) and the amount of convergence between India and Asia (~3600 km). These authors propose a continental fragment of northern Gondwana rifted from India, traveled northward, and initiated the "soft collision" between the Greater Himalaya and Asia at ~50 Ma. This was followed by the "hard collision" between India and Asia occurred at ~25 Ma. Subduction of the resulting ocean basin that formed between the Greater Himalayan fragment and India explains the apparent discrepancy between the crustal shortening estimates in the Himalaya and paleomagnetic data from India and Asia.
In 2007, German geologists suggested that the reason the Indian Plate moved so quickly is that it is only half as thick (100 kilometres (62 mi)) as the other plates which formerly constituted Gondwana. The mantle plume that once broke up Gondwana might also have melted the lower part of the Indian subcontinent, which allowed it to move both faster and further than the other parts. The remains of this plume today form the Marion, Kerguelen, and Réunion hotspots. As India moved north, it is possible that the thickness of the Indian plate degenerated further as it passed over the hotspots and magmatic extrusions associated with the Deccan and Rajmahal Traps.
The collision with the Eurasian Plate along the boundary between India and Nepal formed the orogenic belt that created the Tibetan Plateau and the Himalaya Mountains, as sediment bunched up like earth before a plow.
The Indian Plate is currently moving north-east at 5 centimetres (2.0 in) per year, while the Eurasian Plate is moving north at only 2 centimetres (0.79 in) per year. This is causing the Eurasian Plate to deform, and the India Plate to compress at a rate of 4 millimetres (0.16 in) per year.
Read more about this topic: Indian Plate
Famous quotes containing the words plate and/or movements:
“Say “Yessum” to the ladies, an’ “Yessur” to the men,
And when they’s company, don’t pass yer plate for pie again;
But, thinkin’ of the things yer’d like to see upon that tree,
Jes ‘fore Christmas be as good as yer kin be!”
—Eugene Field (1850–1895)
“The short lesson that comes out of long experience in political agitation is something like this: all the motive power in all of these movements is the instinct of religious feeling. All the obstruction comes from attempting to rely on anything else. Conciliation is the enemy.”
—John Jay Chapman (1862–1933)