AlmedaCheyne: improved structure further and fixed typos

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improved structure further and fixed typos

81.111.15.81: 1. Replace the pejorative "claims" with "reports"; 2. Shorten & clarify very long and confusing sentence.

2021-06-23T18:52:22Z

1. Replace the pejorative "claims" with "reports"; 2. Shorten & clarify very long and confusing sentence.

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{{Short description|A large igneous province located on the Deccan Plateau}}
{{Use Indian English|date=January 2016}}
{{Use dmy dates|date=October 2020}}

[[File:Western-Ghats-Matheran.jpg|thumb|right|The [[Western Ghats]] at [[Matheran]] in Maharashtra]]
[[File:Deccan Traps Maharashtra India 22Mar2018 SkySat.jpg|thumb|right|Oblique satellite view of the Deccan Traps]]

The '''Deccan Traps''' is a [[large igneous province]] of west-central [[India]] (17–24°N, 73–74°E). They are one of the largest [[volcanic]] features on Earth. They consist of multiple layers of solidified [[flood basalt]] that together are more than {{convert|2000|m|ft|abbr=on|sigfig=2}} thick, cover an area of {{circa}} {{Convert|500000|km2|abbr=on|sigfig=1}},<ref name="Singh_and_Gupta94">{{cite journal |title=Workshop yields new insight into volcanism at Deccan Traps, India |first1=R. N. |last1=Singh |first2=K. R. |last2=Gupta |journal=Eos |year=1994 |volume=75 |issue= 31 |pages=356 |doi=10.1029/94EO01005 |bibcode=1994EOSTr..75..356S}}</ref> and have a volume of {{circa}} {{Convert|1000000|km3|abbr=on|sigfig=1}}.<ref name="Dessert2001">{{cite journal |title=Erosion of Deccan Traps determined by river geochemistry: impact on the global climate and the 87Sr/86Sr ratio of seawater |first1=Céline |last1=Dessert |first2=Bernard |last2=Dupréa |first3=Louis M. |last3=Françoisa |first4=Jacques |last4=Schotta |first5=Jérôme |last5=Gaillardet |first6=Govind |last6=Chakrapani |first7=Sujit |last7=Bajpai |journal=Earth and Planetary Science Letters |year=2001 |volume=188 |issue=3–4 |pages=459–474 |doi=10.1016/S0012-821X(01)00317-X |bibcode=2001E&PSL.188..459D}}</ref> Originally, the Deccan Traps may have covered {{circa}} {{Convert|1500000|km2|abbr=on|sigfig=1}},<ref name="MIT-Chu2014">[https://news.mit.edu/2014/volcanic-eruption-dinosaur-extinction-1211 "What really killed the dinosaurs?"] Jennifer Chu, MIT News Office, 11 December 2014</ref> with a correspondingly larger original volume.

==Etymology==
The term "[[Trap rock|trap]]" has been used in [[geology]] since 1785–1795 for such [[rock formation]]s. It is derived from the Swedish word for stairs ("trapp") and refers to the step-like hills forming the landscape of the region.<ref>[https://www.dictionary.com/browse/trap Trap] at dictionary.reference.com</ref>

==History==
[[File:Ajanta caves 1.JPG|thumb|Deccan Traps at [[Ajanta Caves]]]]
{{see also | Gondwana#Opening_of_western_Indian_Ocean | l1= Gondwana and opening of western Indian Ocean | Geology of India}}

The Deccan Traps began forming 66.25 [[geologic timescale|million years ago]],<ref name="MIT-Chu2014"/> at the end of the [[Cretaceous]] period. The bulk of the volcanic eruption occurred at the [[Western Ghats]] some 66 million years ago. This series of eruptions may have lasted fewer than 30,000 years.<ref>"[https://www.sciencedaily.com/releases/2005/08/050810130729.htm India's Smoking Gun: Dino-killing Eruptions]." ''ScienceDaily,'' 10 August 2005.</ref>

The original area covered by the [[lava flow]]s is estimated to have been as large as {{convert|1.5|e6km2||abbr=unit||}}, approximately half the size of modern [[India]]. The Deccan Traps region was reduced to its current size by [[erosion]] and plate tectonics; the present area of directly observable lava flows is around {{convert|500000|km2|sigfig=1|abbr=on}}.

==Effect on mass extinctions and climate==
The release of [[volcanic gas]]es, particularly [[sulfur dioxide]], during the formation of the traps may have contributed to [[Climate variability and change|climate change]]. Data points to an average drop in temperature of about {{convert|2|C-change|F-change}} in this period.<ref>{{cite journal|author=Royer, D. L.|author2=Berner, R. A.|author3=Montañez, I. P.|author4=Tabor, N. J.|author5=Beerling, D. J. |author5-link=David Beerling |year=2004 |title=CO<sub>2</sub> as a primary driver of Phanerozoic climate|journal=GSA Today|volume=14|issue=3|pages=4–10|issn=1052-5173|doi=10.1130/1052-5173(2004)014<4:CAAPDO>2.0.CO;2|doi-access=free}}</ref>

Because of its magnitude, scientists have speculated that the gases released during the formation of the Deccan Traps played a major role in the [[Cretaceous–Paleogene extinction event|Cretaceous–Paleogene (K–Pg) extinction event]] (also known as the Cretaceous–Tertiary or K–T extinction).<ref>{{cite journal|title= A Volcanic Eruption|last= Courtillot|first= Vincent|date= 1990|journal= Scientific American|doi= 10.1038/scientificamerican1090-85|pmid= 11536474|issue= 4|volume= 263|pages= 85–92|bibcode= 1990SciAm.263d..85C}}</ref> It has been theorized that sudden cooling due to sulfurous volcanic gases released by the formation of the traps and toxic gas emissions may have contributed significantly to the K–Pg, as well as other, mass extinctions.<ref>{{cite journal|title= Star-Struck?|last= Beardsley|first= Tim|date= 1988|journal= Scientific American|doi= 10.1038/scientificamerican0488-37b|volume= 258|issue= 4|pages= 37–40|bibcode= 1988SciAm.258d..37B}}</ref> However, the current consensus among the scientific community is that the extinction was primarily triggered by the [[Chicxulub crater|Chicxulub impact event]] in North America, which would have produced a sunlight-blocking dust cloud that killed much of the plant life and reduced global temperature (this cooling is called an [[impact winter]]).<ref name="science">{{cite journal|last=Schulte|first=Peter|date=5 March 2010|title=The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary|journal=Science|volume=327|issue=5970|pages=1214–1218|issn=1095-9203 |doi=10.1126/science.1177265|pmid=20203042|bibcode=2010Sci...327.1214S|s2cid=2659741|display-authors=etal|url=http://doc.rero.ch/record/210367/files/PAL_E4389.pdf}}</ref>

Work published in 2014 by geologist [[Gerta Keller]] and others on the timing of the Deccan volcanism suggests the extinction may have been caused by both the volcanism and the impact event.<ref>Keller, G., ''Deccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?,'' in ''Volcanism, Impacts, and Mass Extinctions: Causes and Effects,'' GSA Special Paper 505, pp. 29–55, 2014 [http://specialpapers.gsapubs.org/content/early/2014/06/10/2014.2505_03.1.abstract abstract] {{Webarchive|url=https://web.archive.org/web/20170618024315/http://specialpapers.gsapubs.org/content/early/2014/06/10/2014.2505_03.1.abstract |date=18 June 2017}}</ref><ref>{{cite journal |last1=Schoene |first1=B. |last2=Samperton |first2=K. M. |last3=Eddy |first3=M. P. |last4=Keller |first4=G. |last5=Adatte |first5=T. |last6=Bowring |first6=S. A. |last7=Khadri |first7=S. F. R. |last8=Gertsch |first8=B. |title=U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction |journal=Science |date=11 December 2014 |volume=347 |issue=6218 |pages=182–184 |doi=10.1126/science.aaa0118 |bibcode=2015Sci...347..182S |pmid=25502315|s2cid=206632431 }}</ref> This was followed by a similar study in 2015, both of which consider the hypothesis that the impact exacerbated or induced the Deccan volcanism, since the events occur at [[antipodes]].<ref>{{cite journal |title=State shift in Deccan volcanism at the Cretaceous-Paleogene boundary, possibly induced by impact |date=2 October 2015 |journal=Science |volume=350 |issue=6256 |pages=76–78 |doi=10.1126/science.aac7549 |pmid=26430116 |last1=Renne |first1=P. R. |last2=Sprain |first2=C. J. |last3=Richards |first3=M. A. |last4=Self |first4=S. |last5=Vanderkluysen |first5=L. |last6=Pande |first6=K. |bibcode=2015Sci...350...76R|doi-access=free }}</ref><ref>{{cite web |title=Asteroid that killed dinosaurs also intensified volcanic eruptions - study |url=https://www.theguardian.com/science/2015/oct/01/asteroid-that-killed-dinosaurs-also-intensified-volcanic-eruptions-study |date=2 October 2015 |work=The Guardian |access-date=2 October 2015}}</ref>

However, the impact theory is still the best supported and has been determined by various reviews to be the consensus view.<ref>{{cite news|url=https://www.bbc.co.uk/news/science-environment-51150001|title=Dinosaur extinction: 'Asteroid strike was real culprit'|work=BBC NEWS|date=17 January 2020}}</ref>

==Petrology==
[[File:World geologic provinces.jpg|thumb|right|The Deccan Traps shown as a dark purple spot on the geologic map of India]]
[[File:Epistilbite-Calcite-170550.jpg|thumb|Crystals of [[epistilbite]] and [[calcite]] in a [[vug]] in Deccan Traps basalt lava from Jalgaon District, Maharashtra]]Within the Deccan Traps at least 95% of the lavas are [[tholeiitic basalt]]s.<ref>{{cite journal|last1=Aramaki|first1=S.|last2=Fukuoka|first2=T.|last3=Deshmukh|first3=S. S.|last4=Fujii|first4=T.|last5=Sano|first5=T.|date=2001-12-01|title=Differentiation Processes of Deccan Trap Basalts: Contribution from Geochemistry and Experimental Petrology|journal=Journal of Petrology|language=en|volume=42|issue=12|pages=2175–2195|doi=10.1093/petrology/42.12.2175|issn=0022-3530|doi-access=free}}</ref> Other rock types present include: [[alkali basalt]], [[nephelinite]], [[lamprophyre]], and [[carbonatite]].

Mantle [[xenolith]]s have been described from [[Kachchh]] (northwestern India) and elsewhere in the western Deccan.<ref>{{cite journal|last1=Dessai|first1=A.G.|last2=Vaselli|first2=O.|date=October 1999|title=Petrology and geochemistry of xenoliths in lamprophyres from the Deccan Traps: implications for the nature of the deep crust boundary in western India|url=https://rruff.info/doclib/MinMag/Volume_63/63-5-703.pdf|journal=Mineralogical Magazine|volume=63|issue=5|pages=703–722|doi=10.1180/minmag.1999.063.5.08}}</ref>

==Fossils==
The Deccan Traps are famous for the beds of fossils that have been found between layers of lava. Particularly well known species include the frog ''[[Oxyglossus]] pusillus'' (Owen) of the [[Eocene]] of [[India]] and the toothed frog ''[[Indobatrachus]]'', an early lineage of modern frogs, which is now placed in the Australian family [[Myobatrachidae]].<ref>{{cite journal |last1= Noble |first1= Gladwyn Kingsley |author-link= Gladwyn Kingsley Noble |year= 1930 |title= The Fossil Frogs of the Intertrappean Beds of Bombay, India |journal= American Museum of Natural History |volume= 401 |page= 1930 |hdl= 2246/3061}}</ref><ref>{{cite web |url=http://tolweb.org/Myobatrachinae/16946 |title=Myobatrachinae}}</ref> The [[Infratrappean Beds]] (Lameta Formation) and [[Intertrappean Beds]] also contain fossil freshwater [[molluscs]].<ref>Hartman, J.H., Mohabey, D.M., Bingle, M., Scholz, H., Bajpai, S., and Sharma, R., 2006, Initial survivorship of nonmarine molluscan faunas in end-Cretaceous Deccan intertrappean strata, India: Geological Society of America (annual meeting, Philadelphia) Abstracts with Programs, v. 38, no. 7, p. 143.</ref>

==Theories of formation==
It is postulated that the Deccan Traps eruption was associated with a deep [[mantle plume]]. The area of long-term eruption (the [[hotspot (geology)|hotspot]]), known as the [[Réunion hotspot]], is suspected of both causing the Deccan Traps eruption and opening the [[rift]] that once separated the [[Mascarene Plateau|Seychelles plateau]] from India. [[Seafloor spreading]] at the boundary between the Indian and [[African Plate]]s subsequently pushed India north over the plume, which now lies under [[Réunion]] island in the [[Indian Ocean]], southwest of India. The mantle plume model has, however, been challenged.<ref name="mantleplumes">Sheth, Hetu C. "[http://www.mantleplumes.org/Deccan.html The Deccan Beyond the Plume Hypothesis]." ''MantlePlumes.org,'' 2006.</ref>

Data continues to emerge that support the plume model. The motion of the Indian tectonic plate and the eruptive history of the Deccan traps show strong correlations. Based on data from marine magnetic profiles, a pulse of unusually rapid plate motion began at the same time as the first pulse of Deccan flood basalts, which is dated at 67 million years ago. The spreading rate rapidly increased and reached a maximum at the same time as the peak basaltic eruptions. The spreading rate then dropped off, with the decrease occurring around 63 million years ago, by which time the main phase of Deccan volcanism ended. This correlation is seen as driven by plume dynamics.<ref name=Cande>{{cite journal | last1 = Cande | first1 = S.C. | last2 = Stegman | first2 = D.R. | year = 2011| title = Indian and African plate motions driven by the push force of the Réunion plume head | journal = Nature | volume = 475 | issue = 7354| pages = 47–52 | doi = 10.1038/nature10174 | pmid = 21734702 | s2cid = 205225348 }}</ref>

The motions of the Indian and African plates have also been shown to be coupled, the common element being the position of these plates relative to the location of the Réunion plume head. The onset of accelerated motion of India coincides with a large slowing of the rate of counterclockwise rotation of Africa. The close correlations between the plate motions suggest that they were both driven by the force of the Réunion plume.<ref name=Cande/>

==Suggested link to impact events==

===Chicxulub crater===
There is some evidence to link the Deccan Traps eruption to the contemporaneous asteroid impact that created the nearly [[Antipodes|antipodal]] [[Chicxulub crater]] in the Mexican state of [[Yucatán]]. Although the Deccan Traps began erupting well before the impact, [[argon–argon dating]] suggests that the impact may have caused an increase in permeability that allowed magma to reach the surface and produced the most voluminous flows, accounting for around 70% of the volume.<ref name=Richards2015>{{cite journal |last1=Richards|first1=Mark A. |last2=Alvarez|first2=Walter |last3=Self|first3=Stephen |last4=Karlstrom|first4=Leif |last5=Renne|first5=Paul R. |last6=Manga|first6=Michael |last7=Sprain|first7=Courtney J. |last8=Smit|first8=Jan |last9=Vanderkluysen|first9=Loÿc |last10=Gibson|first10=Sally A. |author-link2=Walter Alvarez |author-link5=Paul Renne |author-link6=Michael Manga |title=Triggering of the largest Deccan eruptions by the Chicxulub impact|journal=Geological Society of America Bulletin |volume=127|issue=11–12|pages=1507–1520 |doi=10.1130/B31167.1 |year=2015|bibcode=2015GSAB..127.1507R |url= http://eprints.esc.cam.ac.uk/3289/1/Gibson%20bul%20gsa.pdf}}</ref> The combination of the asteroid impact and the resulting increase in eruptive volume may have been responsible for the mass extinctions that occurred at the time that separates the Cretaceous and [[Paleogene]] periods, known as the [[K–Pg boundary]].<ref>{{cite journal |title=State shift in Deccan volcanism at the Cretaceous-Paleogene boundary, possibly induced by impact |last1=Renne |first1=P. R. |display-authors=etal |date=2015 |journal=Science |doi=10.1126/science.aac7549 |pmid= 26430116|volume=350 |issue=6256 |pages=76–78|bibcode=2015Sci...350...76R|doi-access=free }}</ref><ref>{{cite journal |last1=Sprain |first1=Courtney J. |last2=Renne |first2=Paul R. |last3=Vanderkluysen |first3=Loÿc |last4=Pande |first4=Kanchan |last5=Self |first5=Stephen |last6=Mittal |first6=Tushar |title=The eruptive tempo of Deccan volcanism in relation to the Cretaceous-Paleogene boundary |journal=Science |date=21 February 2019 |volume=363 |issue=6429 |pages=866–870 |doi=10.1126/science.aav1446 |pmid=30792301 |bibcode=2019Sci...363..866S|s2cid=67876911 |doi-access=free }}</ref>

A more recent discovery appears to demonstrate the scope of the destruction from the impact alone, however. In a March 2019 article in the [[Proceedings of the National Academy of Sciences]], an international team of twelve scientists revealed the contents of the [[Tanis (fossil site)|Tanis fossil site]] discovered near [[Bowman, North Dakota]], that appeared to show a devastating mass destruction of an ancient lake and its inhabitants at the time of the Chicxulub impact. In the paper, the group reports that the geology of the site is strewn with [[fossil]]ized trees and remains of fish and other animals. The lead researcher, Robert A. DePalma of the [[University of Kansas]], was quoted in the New York Times as stating that "You would be blind to miss the carcasses sticking out... It is impossible to miss when you see the outcrop". Evidence correlating this find to the Chicxulub impact included [[tektites]] bearing "the unique chemical signature of other tektites associated with the Chicxulub event" found in the gills of fish fossils and embedded in [[amber]], an [[iridium]]-rich top layer that is considered another signature of the event, and an atypical lack of evidence for scavenging perhaps suggesting that there were few survivors. The exact mechanism of the site's destruction has been debated as either an impact-caused [[tsunami]] or lake and river [[seiche]] activity triggered by post-impact earthquakes, though there has yet been no firm conclusion upon which researchers have settled.<ref>{{Cite web|url=https://news.ku.edu/2019/03/29/stunning-discovery-offers-glimpse-minutes-following-%E2%80%98dinosaur-killer%E2%80%99-chicxulub-impact|title=Stunning discovery offers glimpse of minutes following 'dinosaur-killer' Chicxulub impact|date=29 March 2019|access-date=10 April 2019}}</ref><ref>{{Cite news|url=https://www.nytimes.com/2019/03/29/science/dinosaurs-extinction-asteroid.html|title=Fossil Site Reveals Day That Meteor Hit Earth and, Maybe, Wiped Out Dinosaurs|date=29 March 2019|newspaper=The New York Times|last1=Broad|first1=William J.|last2=Chang|first2=Kenneth}}</ref>

===Shiva crater===
A geological structure that exists in the sea floor off the west coast of India has been suggested as a possible impact crater, in this context called the [[Shiva crater]]. It has also been dated at approximately 66 million years ago, potentially matching the Deccan traps. The researchers claiming that this feature is an impact crater suggest that the impact may have been the triggering event for the Deccan Traps as well as contributing to the acceleration of the Indian plate in the early [[Paleogene]].<ref>[[Sankar Chatterjee|Chatterjee, Sankar]]. "[https://gsa.confex.com/gsa/2003AM/finalprogram/abstract_58126.htm The Shiva Crater: Implications for Deccan Volcanism, India-Seychelles Rifting, Dinosaur Extinction, and Petroleum Entrapment at the KT Boundary] {{Webarchive|url=https://web.archive.org/web/20161202220808/https://gsa.confex.com/gsa/2003AM/finalprogram/abstract_58126.htm |date=2 December 2016 }}." Paper No. 60-8, Seattle Annual Meeting, November 2003.</ref> However, the current consensus in the Earth science community is that this feature is unlikely to be an actual impact crater.<ref name="Leslie2008a">{{cite web|author=Mullen, Leslie|date=2 November 2004|url=http://www.spacedaily.com/news/deepimpact-04r.html|title=Shiva: Another K–Pg Impact?|work=Spacedaily.com|access-date=20 February 2008}} - original article at [http://www.astrobio.net/news/article1281.html source]</ref><ref>{{cite web |url=http://www.space.com/scienceastronomy/091018-dinosaur-crater.html |title=New Dino-destroying Theory Fuels Hot Debate |first=Clara |last=Moskowitz |publisher=space.com |date=18 October 2009}}</ref>

==See also==
*[[Columbia River Basalt Group]]
*[[Emeishan Traps]]
*[[Geology of India]]
*[[Krishna Godavari Basin]]
*[[Lameta Formation]]
*[[List of flood basalt provinces]]
*[[List of volcanoes in India]]
*[[Siberian Traps]]
*[[Verneshot]]
*[[Late Devonian extinction#Magmatism|Viluy Traps]]

==References==
{{Reflist}}

==External links==
{{Commons category}}
*{{cite web |url=http://www.geodynamics.no/indexOld.htm |title=Animated simulation by the Geodynamics group at the Geological Survey of Norway illustrating the Indian plate moving through the Indian Ocean |url-status=dead |archive-url=https://web.archive.org/web/20110723122146/http://www.geodynamics.no/indexOld.htm |archive-date=23 July 2011}}
*[http://www.nbcnews.com/id/50119631/ns/technology_and_science-science/ Scientist argues that volcanoes, not meteorite, killed dinosaurs]
*[https://hoopermuseum.carleton.ca/saleem/volcanism.htm The Deccan Traps/Volcanism Theory]

{{coord|18|51|N|73|43|E|region:IN_type:landmark_scale:2500000|display=title}}
{{Large igneous provinces}}

[[Category:Cretaceous paleontological sites of Asia]]
[[Category:Cretaceous volcanism]]
[[Category:Events that forced the climate]]
[[Category:Geology of India]]
[[Category:Geology of Maharashtra]]
[[Category:Large igneous provinces]]
[[Category:Paleocene volcanism]]
[[Category:Plate tectonics]]
[[Category:Volcanism of India]]

Deccan Traps - Revision history

AlmedaCheyne: improved structure further and fixed typos

UpdateBot: robot: Update article

81.111.15.81: 1. Replace the pejorative "claims" with "reports"; 2. Shorten & clarify very long and confusing sentence.