Indo-Burman Ranges
{{short description|Mountain range between India and Myanmar (Burma)}}
{{Infobox mountain
| fetchwikidata = ALL
| name = Indo-Burman Ranges
| map_image = Indo Burman Ranges.jpg
| map_size = 280
| other_name = Indo-Myanmar Ranges
| country = {{hlist|{{flag|India}}|{{flag|Myanmar}}}}
| subdivision2_type = States/Regions
| subdivision2 = {{hlist|Nagaland|Manipur|Mizoram|Sagaing|Chin|Rakhine}}
| parent =
| geology =
| age =
| orogeny =
| highest = Mount Saramati[https://books.google.com/books?id=hHKiJGzJ5ewC&q=%22patkai+range%22+%22mt.+saramati%22 The new encyclopaedia Britannica]
| elevation_m= 3826
| elevation =
| elevation_ref =
| length_ref =
| coordinates =
| range_coordinates = {{coord|23|40|N|94|10|E|type:mountain_dim:2000000|display=inline,title}}
| length_mi =
| length_km = 1200
| area_km2 =
| area_mi2 =
| area_ref =
}}
The Indo-Burman Ranges (IBR), also known as the Indo-Myanmar Ranges,{{cite journal|url=https://www.lyellcollection.org/doi/full/10.1144/jgs2022-091|title=Age, depositional history and tectonics of the Indo-Myanmar Ranges, Myanmar|journal=Journal of the Geological Society|volume=180|date=August 2023|doi=10.1144/jgs2022-091|first1=Tin Tin|last1=Naing|first2=Stuart A.|last2=Robinson|first3=Mike P.|last3=Searle|hdl=2434/970119|hdl-access=free}}{{cite journal|title=Petrogenesis of neo-Tethyan ophiolites from the Indo-Myanmar ranges: a review|url=https://www.tandfonline.com/doi/full/10.1080/00206814.2020.1775137|first1=Thungyani N|last1=Ovung|first2=Biswajit|last2=Ghosh|first3=Jyotisankar|last3=Rayare|date=15 June 2020|doi=10.1080/00206814.2020.1775137|journal=International Geology Review}} is a mountain chain that forms the boundary between the Indian subcontinent and the Indochinese peninsula. This geological feature sits at the convergent boundary of the Indian Plate and the Burma Plate. The Indo-Burman Range merged with Eastern Himalayan Syntaxis further north, submerged into the Andaman Sea, and resurfaced as Andaman Islands further south.{{Cite journal|last1=Mukhopadhyay|first1=Manoj|last2=Dasgupta|first2=Sujit|date=1988-06-01|title=Deep structure and tectonics of the burmese arc: constraints from earthquake and gravity data|bibcode=1988Tectp.149..299M|journal=Tectonophysics|volume=149|issue=3|pages=299–322|doi=10.1016/0040-1951(88)90180-1|s2cid=129288739 |issn=0040-1951}}
The mountain belt comprises the following ranges from north to south: the Patkai Bum, the Naga Hills, the Mikir Hills, the Mizo Hills and the Arakan Mountains.{{Cite journal|last1=Wang|first1=Yu|last2=Sieh|first2=Kerry|last3=Tun|first3=Soe Thura|last4=Lai|first4=Kuang-Yin|last5=Myint|first5=Than|date=2014-04-01|title=Active tectonics and earthquake potential of the Myanmar region|journal=Journal of Geophysical Research: Solid Earth|language=en|volume=119|issue=4|pages=2013JB010762|doi=10.1002/2013JB010762|issn=2169-9356|doi-access=free|hdl=10220/19774|hdl-access=free}} The first four are often grouped into the Purvanchal Range, and comprise the northern half of the Indo-Burman mountain system.
Geology
The subduction between the Indian Plate and the Burma Plate resulted in the development of accretionary wedges, in order to accommodate the EW shortening along the convergent boundary. Later, thrusting, folding and uplifting formed the Indo-Burman Ranges.{{Cite journal|last1=Sikder|first1=Arif Mohiuddin|last2=Alam|first2=M.Mustafa|title=2-D modelling of the anticlinal structures and structural development of the eastern fold belt of the Bengal Basin, Bangladesh|journal=Sedimentary Geology|volume=155|issue=3–4|pages=209–226|doi=10.1016/s0037-0738(02)00181-1|year=2003}}
The Indo-Burman Range bulges towards the west at the center (about 22°N), forming an arc-shaped structure. This arc-shaped structure implies restriction on the convergent motion along the Indian-Burma boundary, therefore the collision intensity varies along the range.
The collision is at a maximum at the center of the Indo-Burman Range around 24°N, which is presented with a broad, high range (up to 20 km wide) and evolves to narrow, low hills in the south (16°N). The collision strikes in NW-SE at the northern part of the Indo-Burman Range (Naga Domain).{{Cite journal|last1=Maurin|first1=Thomas|last2=Rangin|first2=Claude|date=2009-04-01|title=Structure and kinematics of the Indo-Burmese Wedge: Recent and fast growth of the outer wedge|journal=Tectonics|language=en|volume=28|issue=2|pages=TC2010|doi=10.1029/2008TC002276|issn=1944-9194|doi-access=free}}
Lithology
The Indo-Burman Range is a sedimentary belt mainly consisted of Cenozoic flysch sediments{{Cite journal|last=Brunel|first=Maurice|title=Late Cretaceous to Eocene metamorphism of internal zones of the Indo-Burma range (western Myanmar): geodynamic implications. About the paper by Anne Socquet et al.|journal=Comptes Rendus Geoscience|volume=334|issue=12|pages=875–876|doi=10.1016/s1631-0713(02)01824-2|year=2002|url=https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.1016/S1631-0713(02)01824-2/ }} and a core of Mesozoic ophiolites dated back to late Jurassic overlain on a thick Mesozoic sequence. All the above unconformity lies on a metamorphic basement dated back to pre-Triassic.{{Cite web|url=http://www.schweizerbart.de/publications/detail/isbn/9783443110161/#|title=Geology of Burma|last=Bender|first=Friedrich|editor1-last=Bannert|editor1-first=Dietrich|editor2-last=Brinckmann|editor2-first=Jörn u.a.|date=1983-02-14|website=www.schweizerbart.de|language=en|access-date=2017-11-16}}
The core Mesozoic ophiolites consists of serpentinite peridotites, pillow basalts and red cherts etc. The obduction of ophiolites is interpreted as the closure of several Neo-Tethys between the Shan-Thai block, Burma microplate and Indian Plate.{{Cite journal|last1=Rangin|first1=Claude|last2=Maurin|first2=Thomas|last3=Masson|first3=Frederic|title=Combined effects of Eurasia/Sunda oblique convergence and East-Tibetan crustal flow on the active tectonics of Burma|journal=Journal of Asian Earth Sciences|volume=76|pages=185–194|doi=10.1016/j.jseaes.2013.05.018|year=2013}}
The sedimentary sequence overlain by the ophiolites ranges from Late Triassic to Orbitoides-bearing Late Cretaceous carbonates and shales, where part of the sedimentary sequence has undergone high pressure/low temperature blue-schist metamorphism.
The pre-Triassic metamorphic basement composed of Kampetlet schist and gneisses were exposed in the Mount Victoria area in Myanmar. The flysch type sediments in the western flank of the Indo-Burman Range are relatively younger than the folded and thrusted eastern flank.{{Cite journal|last=Mitchell|first=A. H. G.|date=1993-12-01|title=Cretaceous–Cenozoic tectonic events in the western Myanmar (Burma)–Assam region|url=http://jgs.lyellcollection.org/content/150/6/1089|journal=Journal of the Geological Society|language=en|volume=150|issue=6|pages=1089–1102|doi=10.1144/gsjgs.150.6.1089|s2cid=129830325 |issn=0016-7649}}