Most tectonic plates only move at a speed of around 1.5 cm/year, but during its collision course with Eurasia India moved at around 15 cm/year! By tectonic standards that is fast.
Why did India move so fast?
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The Indian plate’s rapid motion toward Eurasia is a particularly interesting phenomenon in the context of plate tectonics, and there are several theories to explain this fast movement. The driving forces of plate tectonics are still a topic of research and debate among geologists, but several factors may have contributed to the rapid northward motion of the Indian plate:
Mantle Dynamics: The Earth’s mantle, which lies beneath the crust and is semi-fluid in consistency, convects due to heat from the core. These convection currents can push or pull tectonic plates in various directions. A model suggests that a large mantle plume or upwelling from the deep mantle beneath the Reunion Island might have facilitated the rapid movement of the Indian plate.
Slab Pull: When an oceanic plate is subducted beneath a continental plate, the sinking part (called a slab) can exert a pull on the rest of the plate. Prior to its collision with Asia, the northern edge of the Indian plate was being subducted beneath the Tethys Ocean. This “slab pull” effect might have contributed to its rapid motion.
Ridge Push: New oceanic crust forms at mid-ocean ridges and pushes the older crust away. The Indian plate separated from the African plate at the Central Indian Ridge. The push from this ridge might have contributed to the plate’s speed.
Gravitational Forces: The Indian plate was relatively dense and may have been gravitationally “sliding” down the slope of the mantle’s convection cells, causing it to move more quickly.
Geometry and Oceanic Plateau: The Indian plate had to pass over several underwater topographic highs, like the Deccan and the Kerguelen Plateaus. The interaction of the plate with these plateaus may have played a role in its fast movement.
Prior Motion: Before it began its rapid movement, the Indian plate was already in motion. The momentum and dynamics from this initial motion could have also played a role.
Plate Interactions: The interactions between the Indian plate and neighboring plates may have also affected its motion.
Despite these theories, it’s essential to note that the exact mechanisms and their relative contributions to the Indian plate’s rapid motion remain topics of research. The collision of India with Asia resulted in the uplift of the Himalayas, the highest mountain range in the world. This collision and uplift are ongoing, with the Himalayas continuing to rise even today.
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