Indian Plate
Indian Plate | |
---|---|
Type | Minor |
Approximate area | 11,900,000 km2 (4,600,000 sq mi)[1] |
Movement1 | North-east |
Speed1 | 26–36 mm/a (1.0–1.4 in/year)[citation needed] |
Features | Indian subcontinent, Indian Ocean, Arabian Sea, Himalayas |
1Relative to the African Plate |
The Indian Plate (or India Plate) is a
Plate movements
Until roughly 140 million years ago, the Indian Plate formed part of the supercontinent, Gondwana, together with modern Africa, Australia, Antarctica, and South America. Gondwana fragmented as these continents drifted apart at different velocities;[9] a process which led to the opening of the Indian Ocean.[10]
In the late Cretaceous approximately 100 million years ago, and subsequent to the splitting from Gondwana of conjoined Madagascar and India, the Indian Plate split from Madagascar and formed Insular India. It began moving north, at about 20 cm (7.9 in) per year,[9] and is believed to have begun colliding with Asia as early as 55 million years ago,[11] in the Eocene epoch of the Cenozoic. However, some authors suggest the collision between India and Eurasia occurred much later, around 35 million years ago.[12] If the collision occurred between 55 and 50 Mya, the Indian Plate would have covered a distance of 3,000 to 2,000 km (1,900–1,200 mi), moving more quickly 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 (~1,300 km or 800 mi) and the amount of convergence between India and Asia (~3,600 km or 2,200 mi).[13] 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 Mya. This was followed by the "hard collision" between India and Asia occurred at ~25 Mya. 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. However, the proposed ocean basin was not constrained by paleomagnetic data from the key time interval of ~120 Mya to ~60 Mya. New paleomagnetic results of this critical time interval from southern Tibet do not support this Greater Indian Ocean basin hypothesis and the associated dual collision model.[14]
In 2007, German geologists[9] suggested the reason the Indian Plate moved so quickly is that it is only half as thick (100 km or 62 mi) as the other plates[15] 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 more quickly and farther than the other parts.[9] The remains of this plume today form the Marion Hotspot (Prince Edward Islands), the Kerguelen hotspot, and the Réunion hotspots.[10][16] As India moved north, it is possible the thickness of the Indian Plate degenerated further as it passed over the hotspots and magmatic extrusions associated with the Deccan and Rajmahal Traps.[10] 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.[17]
In 2020, however, geologists at the University of Oxford and the Alfred Wegener Institute found that new plate-motion models displayed increased movement speeds in all mid-ocean ridges during the late Cretaceous, a result irreconcilable to current theories of plate tectonics and a refutation of the plume-push hypothesis. Pérez-Díaz concludes that the accelerated movement of the Indian Plate is an illusion wrought by large errors in geomagnetic reversal timing around the Cretaceous–Paleogene boundary, and that a recalibration of the time scale shows no such acceleration exists.[18][19]
The collision with the
The Indian Plate is currently moving north-east at five cm (2.0 in) per year, while the Eurasian Plate is moving north at only two cm (0.79 in) per year. This is causing the Eurasian Plate to deform, and the Indian Plate to compress at a rate of four mm (0.16 in) per year.[citation needed]
Geography
The westerly side of the Indian Plate is a transform boundary with the
]See also
- Historical geology
- List of tectonic plate interactions
- List of tectonic plates
- Palaeogeography
- Seychelles Microcontinent
Notes
- ^ "Sizes of Tectonic or Lithospheric Plates". Geology.about.com. 2014-03-05. Retrieved 2016-01-13.
- ^ Oskin, Becky (2013-07-05). "New Look at Gondwana's Breakup". Livescience.com. Retrieved 2016-01-13.
- ISBN 9781118670446. Retrieved 2015-12-25.
- ISBN 978-0-07-014456-9
- JSTOR 24102967.
- ISBN 978-1-86239-061-4
- ISBN 978-99929-52-21-4
- ISBN 978-0-7923-0067-0
- ^ a b c d Kind 2007
- ^ a b c Kumar et al. 2007
- ^ Scotese 2001
- ^ Aitchison, Ali & Davis 2007
- PMID 22547792.
- S2CID 134469511.
- ^ The lithospheric roots in South Africa, Australia, and Antarctica are 300 to 180 km (190 to 110 mi) thick. (Kumar et al. 2007) See also Kumar et al. 2007, figure 1
- .
- S2CID 2659741.
- doi:10.1130/G47859.1.
- ^ Andrews, Robin George (14 April 2021). "The New Historian of the Smash That Made the Himalayas". Quanta Magazine. Retrieved 15 April 2021.
References
- Aitchison, Jonathan C.; Ali, Jason R.; Davis, Aileen M. (2007). "When and where did India and Asia collide?". Journal of Geophysical Research. 112 (B5): B05423. ISSN 0148-0227. Retrieved January 12, 2016.
- Chen, Ji (January 4, 2005). "Magnitude 9.0 off W coast of northern Sumatra Sunday, December 26, 2004 at 00:58:49 UTC: Preliminary rupture model". U.S. Geological Survey. Archived from the originalon March 5, 2005. Retrieved 28 December 2004.
- Kind, Rainer (17 October 2007). "The fastest continent: India's truncated lithospheric roots" (Press release). Helmholtz Association of German Research Centres. Retrieved 2 October 2019.
- Kumar, Prakash; Yuan, Xiaohui; Kumar, M. Ravi; Kind, Rainer; Li, Xueqing; Chadha, R. K. (18 October 2007). "The rapid drift of the Indian tectonic plate". Nature. 449 (7164): 894–897. S2CID 4339656.
- Scotese, Christopher R. (January 2001). "The collision of India and Asia (90 mya – present)". Paleomap Project. Retrieved 28 December 2004.
External links
- Media related to Indian tectonic plate at Wikimedia Commons