Editing Paleogene (section)

==== Himalayan orogeny ====
[[File:India 71-0 Ma.gif|alt=Map showing the outline of the Indian continent as it drifted north from close to Madagascar to its present day position. |thumb|Map showing the northwards drift of the Indian continent between 71 and 0 Ma. The leading edge of Greater India (not shown on the map) collided with the Eurasian plate c. 55 Ma, whilst India itself still lay to the south. (From: Dèzes, 1999)]]
The Indian continent rifted from [[Madagascar]] at c. 83 Ma and drifted rapidly (c. 18 cm/yr in the Paleocene) northwards towards the southern margin of Eurasia. A rapid decrease in velocity to c. 5 cm/yr in the early Eocene records the collision of the Tethyan (Tibetan) [[Himalayas]], the leading edge of Greater India, with the [[Lhasa terrane]] of [[Tibet]] (southern Eurasian margin), along the [[Indus-Yarlung suture zone|Indus-Yarling-Zangbo suture zone]].<ref name=":1" /><ref>{{Cite journal |last=Metcalfe |first=Ian |date=2021-12-01 |title=Multiple Tethyan ocean basins and orogenic belts in Asia |url=https://www.sciencedirect.com/science/article/abs/pii/S1342937X21000307 |journal=Gondwana Research |series=SPECIAL ISSUE: GR-100 |volume=100 |pages=87–130 |doi=10.1016/j.gr.2021.01.012 |bibcode=2021GondR.100...87M |issn=1342-937X}}</ref> To the south of this zone, the Himalaya are composed of [[Metasedimentary rock|metasedimentary]] rocks scraped off the now subducted Indian continental crust and [[Mantle (geology)|mantle]] lithosphere as the collision progressed.<ref name=":1" />

[[Paleomagnetism|Palaeomagnetic]] data place the present day Indian continent further south at the time of collision and decrease in plate velocity, indicating the presence of a large region to the north of India that has now been subducted beneath the Eurasian plate or incorporated into the mountain belt. This region, known as Greater India, formed by [[Extensional tectonics|extension]] along the northern margin of India during the opening of the Neotethys. The Tethyan Himalaya block lay along its northern edge, with the Neotethys Ocean lying between it and southern Eurasia.<ref name=":1" /><ref name=":8">{{Cite journal |last1=Martin |first1=Craig R. |last2=Jagoutz |first2=Oliver |last3=Upadhyay |first3=Rajeev |last4=Royden |first4=Leigh H. |last5=Eddy |first5=Michael P. |last6=Bailey |first6=Elizabeth |last7=Nichols |first7=Claire I. O. |last8=Weiss |first8=Benjamin P. |date=2020-11-24 |title=Paleocene latitude of the Kohistan–Ladakh arc indicates multistage India–Eurasia collision |journal=Proceedings of the National Academy of Sciences |language=en |volume=117 |issue=47 |pages=29487–29494 |doi=10.1073/pnas.2009039117 |doi-access=free |issn=0027-8424 |pmc=7703637 |pmid=33148806|bibcode=2020PNAS..11729487M }}</ref>

Debate about the amount of deformation seen in the geological record in the India–Eurasia collision zone versus the size of Greater India, the timing and nature of the collision relative to the decrease in plate velocity, and explanations for the unusually high velocity of the Indian plate have led to several models for Greater India: 1) A Late Cretaceous to early Paleocene subduction zone may have lain between India and Eurasia in the Neotethys, dividing the region into two plates, subduction was followed by collision of India with Eurasia in the middle Eocene. In this model Greater India would have been less than 900 km wide;<ref name=":8" /> 2) Greater India may have formed a single plate, several thousand kilometres wide, with the Tethyan Himalaya microcontinent separated from the Indian continent by an [[oceanic basin]]. The microcontinent collided with southern Eurasia c. 58 Ma (late Paleocene), whilst the velocity of the plate did not decrease until c. 50 Ma when subduction rates dropped as young, oceanic crust entered the subduction zone;<ref>{{Cite journal |last1=van Hinsbergen |first1=Douwe J. J. |last2=Lippert |first2=Peter C. |last3=Li |first3=Shihu |last4=Huang |first4=Wentao |last5=Advokaat |first5=Eldert L. |last6=Spakman |first6=Wim |date=2019-06-05 |title=Reconstructing Greater India: Paleogeographic, kinematic, and geodynamic perspectives |url=https://www.sciencedirect.com/science/article/abs/pii/S0040195118301331 |journal=Tectonophysics |series=Linking Plate Tectonics and Volcanism to Deep Earth Dynamics – a tribute to Trond H. Torsvik |volume=760 |pages=69–94 |doi=10.1016/j.tecto.2018.04.006 |bibcode=2019Tectp.760...69V |hdl=1874/380963 |issn=0040-1951 |hdl-access=free |access-date=2024-08-19 |archive-date=2024-04-15 |archive-url=https://web.archive.org/web/20240415030023/https://www.sciencedirect.com/science/article/abs/pii/S0040195118301331 |url-status=live }}</ref> 3) This model assigns older dates to parts of Greater India, which changes its paleogeographic position relative to Eurasia and creates a Greater India formed of extended continental crust 2000–3000 km wide.<ref>{{Cite journal |last1=Meng |first1=Jun |last2=Gilder |first2=Stuart A. |last3=Tan |first3=Xiaodong |last4=Li |first4=Xin |last5=Li |first5=Yalin |last6=Luo |first6=Hui |last7=Suzuki |first7=Noritoshi |last8=Wang |first8=Zihao |last9=Chi |first9=Yuchen |last10=Zhang |first10=Chunyang |last11=Wang |first11=Chengshan |date=2023-08-15 |title=Strengthening the argument for a large Greater India |journal=Proceedings of the National Academy of Sciences |language=en |volume=120 |issue=33 |pages=e2305928120 |doi=10.1073/pnas.2305928120 |issn=0027-8424 |pmc=10433724 |pmid=37552758|bibcode=2023PNAS..12005928M }}</ref>