Indian Plate

From Wikipedia, the free encyclopedia
  (Redirected from India Plate)
Jump to: navigation, search
  The Indian plate shown in red

The India Plate or Indian Plate is a tectonic plate that was originally a part of the ancient continent of Gondwana from which it split off, eventually becoming a major plate.[1] About 55 to 50 million years ago it fused with the adjacent Australian Plate. It is today part of the major Indo-Australian Plate, and includes most of South Asia – i.e., the Indian subcontinent – and a portion of the basin under the Indian Ocean, including parts of South China and Eastern Indonesia,[2][3][4] and extending up to but not including Ladakh, Kohistan and Balochistan.[5][6][7]

Plate movements[edit]

Due to plate tectonics, the India Plate split from Madagascar and collided (c. 55 Ma) with the Eurasian Plate, resulting in the formation of the Himalayas.

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,[8] a process which led to the opening of the Indian Ocean.[9]

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,[8] and is believed to have begun colliding with Asia between 55 and 50 million years ago,[10] 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.[11] 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 propose 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).[12] 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.

Closeup of the boundary with the Eurasian, African and Arabian plates; the 2005 Kashmir earthquake occurred at the northern tip of the Indian plate.

In 2007, German geologists[8] suggested that the reason the Indian Plate moved so quickly is that it is only half as thick (100 kilometres or 62 miles) as the other plates[13] 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.[8] The remains of this plume today form the Marion, Kerguelen, and Réunion hotspots.[9] 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.[9] The massive amounts of volcanic gases released during the passage of the Indian Plate over the hotspots have been theorised to have played a role in the Cretaceous–Paleogene extinction event, generally held to be due to a large asteroid impact.[14]

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 Indian Plate to compress at a rate of 4 millimetres (0.16 in) per year.

See also[edit]

Notes[edit]

  1. ^ "Thirty-eight Indian cities in high-risk earthquake zones". 
  2. ^ Sinvhal, Understanding Earthquake Disasters, page 52, Tata McGraw-Hill Education, 2010, ISBN 978-0-07-014456-9
  3. ^ Harsh K. Gupta, Disaster management, page 85, Universities Press, 2003, ISBN 978-81-7371-456-6
  4. ^ James R. Heirtzler, Indian ocean geology and biostratigraphy, page American Geophysical Union, 1977, ISBN 978-0-87590-208-1
  5. ^ M. Asif Khan, Tectonics of the Nanga Parbat syntaxis and the Western Himalaya, page 375, Geological Society of London, 2000, ISBN 978-1-86239-061-4
  6. ^ Srikrishna Prapnnachari, Concepts in Frame Design, page 152, Srikrishna Prapnnachari, ISBN 978-99929-52-21-4
  7. ^ A. M. Celâl Şengör, Tectonic evolution of the Tethyan Region, Springer, 1989, ISBN 978-0-7923-0067-0
  8. ^ a b c d Kind 2007
  9. ^ a b c Kumar et al. 2007
  10. ^ Scotese 2001
  11. ^ Aitchison, Ali & Davis 2007
  12. ^ van Hinsbergen, D.; Lippert, P.; Dupont-Nivet, G.; McQuarrie, N.; Doubrivine, P.; Spakman, W.; Torsvik, T. (2012). "Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia". Proceedings of the National Academy of Sciences 109 (20): 7659–7664. Bibcode:2012PNAS..109.7659V. doi:10.1073/pnas.1117262109. 
  13. ^ The lithospheric roots in South Africa, Australia, and Antarctica are 300 to 180 kilometres (190 to 110 mi) thick. (Kumar et al. 2007) See also Kumar et al. 2007, figure 1,
  14. ^ Schulte, Peter et al. (5 March 2010). "The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary". Science (AAAS) 327 (5970): 1214–1218. Bibcode:2010Sci...327.1214S. doi:10.1126/science.1177265. ISSN 1095-9203. PMID 20203042. Retrieved 5 March 2010. 

References[edit]

Coordinates: 34°25′55″N 73°32′13″E / 34.43194°N 73.53694°E / 34.43194; 73.53694