Geology of India
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The geology of India is diverse. Different regions of India contain
The Deccan Traps covers almost all of Maharashtra, a part of Gujarat, Karnataka, Madhya Pradesh and Andhra Pradesh marginally. During its journey northward after breaking off from the rest of Gondwana, the Indian Plate passed over a geologic hotspot, the Réunion hotspot, which caused extensive melting underneath the Indian Craton. The melting broke through the surface of the craton in a massive flood basalt event, creating the Deccan Traps. It is also thought that the Reunion hotspot caused the separation of Madagascar and India.
The
The
Plate tectonics
The Indian
Tectonic evolution
The earliest phase of tectonic evolution was marked by the cooling and solidification of the upper
Minor igneous intrusions, deformation (folding and faulting) and subsequent metamorphism of the Aravalli Mountains represent the main phase of orogenesis. The erosion of the mountains, and further deformation of the sediments of the Dharwarian group (Bijawars) marks the second phase. The volcanic activities and intrusions, associated with this second phase are recorded in the composition of these sediments.
Early to Late Proterozoic(2.5 to 0.54 billion years) calcareous and arenaceous deposits, which correspond to humid and semi-arid climatic regimes, were deposited the Cuddapah and Vindhyan basins. These basins which border or lie within the existing crystalline basement, were uplifted during the Cambrian (500 Ma (ICS 2004)). The sediments are generally undeformed and have in many places preserved their original horizontal stratification. The Vindhyans consist of a lower Supergroup that was deposited sometime between ~1800-1600 Ma. The lower Vindhyan rocks were slightly deformed (tilted) and the Upper Vindhyan sequence lies unconformably over the Lower Vindhyan. The age of Upper Vindhyan (Kaimur, Rewa and Bhander) sedimentation is contentious. Kaimur rocks were intruded by the 1073 Ma Majhgawan kimberlite (Gregory et al., 2006) and are therefore older than 1073 Ma. The Rewa contains diamondiferous conglomerates suggesting that they formed after the Kaimur. The Rewa is conformably overlain by the Bhander Group. Indirect evidence for the age of the Upper Vindhyan was discussed by Meert and Pandit (2015) who noted the similarity in paleomagnetic directions from the 1073 Ma Majhgawan kimberlite, the 1.1 Ga Mahoba dyke and sediments of the Bhander and Rewa Groups. In addition, multiple detrital zircon studies failed to isolate any ages younger than ~1000 Ma from Upper Vindhyan rocks. A recent claim of the iconic Ediacaran fossil "Dickinsonia" located in the Upper Bhander (Retallack et al., 2021) required an Ediacaran age for that Group; however, Meert et al. (2023) demonstrated that the fossil was misidentified and therefore the age of the Upper Vindhyan is still debated.
Early
In the Late Paleozoic,
The late Paleozoic coincided with the deformation and drift of the Gondwana supercontinent. To this drift, the uplift of the Vindhyan sediments and the deposition of northern peripheral sediments in the Himalayan Sea, can be attributed.
During the Jurassic, as Pangea began to rift apart, large grabens formed in central India filling with Upper Jurassic and Lower Cretaceous sandstones and conglomerates.
By the Late Cretaceous India had separated from Australia and Africa and was moving northward towards Asia. At this time, prior to the Deccan eruptions, uplift in southern India resulted in sedimentation in the adjacent nascent Indian Ocean. Exposures of these rocks occur along the south Indian coast at Pondicherry and in Tamil Nadu.
At the close of the Mesozoic one of the greatest volcanic eruptions in earth's history occurred, the Deccan lava flows. Covering more than 500,000 square kilometres (193,051 sq mi) area, these mark the final break from Gondwana.
In the early Tertiary, the first phase of the Himalayan orogeny, the Karakoram phase occurred. The Himalayan orogeny has continued to the present day.
Greater India
Greater India or the Greater India Basin means the
The
Major rock groups
Precambrian super-eon
A considerable area of peninsular India, the
The rocks of the Dharwar system are mainly sedimentary in origin, are believed to be of the same age as the Dharwar system.
The metamorphic basement consists of gneisses which are further classified into the
Phanerozoic
Palaeozoic
Lower Paleozoic
Rocks of the earliest part of the Cambrian Period are found in the Salt range in
.Upper Paleozoic
Mesozoic
In the Triassic the Ceratite beds, named after the ammonite
Cenozoic
Tertiary period
In this period the
Quaternary period
The
Earthquakes
The Indian subcontinent has a history of devastating earthquakes. The Assam earthquake of 1950 registered a magnitude of 8.6; it is one of the most powerful earthquakes to have ever been recorded.[9] A similar earthquake in a densely populated area today would kill hundreds of thousands if not millions. This is why the Himalayan range is believed to be one of the most dangerous places to build large dams. The major reason for the high frequency and intensity of the earthquakes is that the Indian plate is driving into Asia at a rate of approximately 47 mm/year.[10] Geographical statistics of India show that almost 54% of the land is vulnerable to earthquakes. A World Bank & United Nations report shows estimates that around 200 million city dwellers in India will be exposed to storms and earthquakes by 2050.[11] National Disaster Management Authority says that 60% of Indian landmass is prone to earthquake and 8% susceptible to cyclone risks.
See also
References
- ^ "National Geological Monument, from Geological Survey of India website". Archived from the original on 12 July 2017. Retrieved 21 January 2019.
- ^ "Geo-Heritage Sites". pib.nic.in. Press Information Bureau. 9 March 2016. Retrieved 15 September 2018.
- ^ national geo-heritage of India Archived 11 January 2017 at the Wayback Machine, INTACH
- ^ Briggs, John C. (2003) The biogeographic and tectonic history of India. Journal of Biogeography 30:381–388
- .
- ^ Argand, E., 1924. La tectonique de l' Asie. Proc. 13th Int. Geol. Cong. 7 (1924), 171–372.
- ^ "The Greater India Basin hypothesis" (PDF). University of Oslo. Retrieved 20 December 2016.
- ISBN 9789351343578.
- JSTOR 1790893.
- ^ "Earthquake Hazards and the Collision between India and Asia". Archived from the original on 19 September 2006. Retrieved 13 May 2006.
- ^ "Indian cities under threat of storms & earthquakes by 2050: World Bank & United Nations". The Times Of India. 9 December 2011.
Further reading
- Gregory, L. C., Meert, J. G., Pradhan, V., Pandit, M. K., Tamrat, E., & Malone, S. J., 2006. A paleomagnetic and geochronologic study of the Majhgawan kimberlite, India: implications for the age of the Upper Vindhyan Supergroup. Precambrian Research, 149, 65-75.
- Grout, Andrew. "Geology and India, 1775-1805: an episode in colonial science." South Asia Research 10.1 (1990): 1-18.
- Jain, A.K., D.M. Banerjee, et al. eds. Tectonics of the Indian Subcontinent (Society of Earth Scientists Series) (2020). excerpt
- Medlicott, Henry Benedict, and William Thomas Blanford. A Manual of the Geology of India: Chiefly Compiled from the Observations of the Geological Survey (2nd ed. 1892) reprinted by Cambridge University Press, 2011.
- Meert, J.G. and Pandit, M.K., 2015. The Archaean and Proterozoic history of Peninsular India: tectonic framework for Precambrian sedimentary basins in India. Geological Society, London, Memoirs, 43, 29-54.
- Meert, J.G., Pandit, M.K, Kwafo, S., Singha, A., 2023. Stinging News: ‘Dickinsonia’ discovered in the Upper Vindhyan of India not worth the buzz, Gondwana Research, doi:10.1016/j.gr.2023.01.003.
- Raju, D. S. N. "Paleogene Stratigraphy of India: An Overview." The Indian Paleogene. (Springer, Cham, 2018). 1-89.
- Ramakrishnan, Moni, and Rajagopala Vaidyanadhan. Geology of India (2 vol. GSI Publications 2.1 (2010).
- Retallack, G.J., Matthews, N.A., Master, S., Khangar, R.G. and Khan, M., 2021. Dickinsonia discovered in India and late Ediacaran biogeography. Gondwana Research, 90, 165-170.
- Saikia, Arupjyoti. "Earthquakes and the Environmental Transformation of a Floodplain Landscape: The Brahmaputra Valley and the Earthquakes of 1897 and 1950." Environment and History 26.1 (2020): 51-77.
- Wadia, Darashaw Nosherwan. Geology of India (Macmillan, 1939).
- Wadia, Darashaw Nosherwan. Geology of India: For Students (Macmillan, 1919) online.