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Bawdwin Volcanic Formation
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Bawdwin Volcanic Fm base reconstruction

Bawdwin Volcanic Fm

Period: 
Cambrian

Age Interval: 
Late Cambrian


Province: 
Myanmar Shan Region

Type Locality and Naming

Bawdwin area, Namtu township, Shan State North. Kyaukme–Longtawkno area in

Shan State North, 80 km ENE of Myitkyina, Kachin State. This unit was named the Bawdwin Grit and Rhyolite or Bawdwin Volcanic Stage by La Touche (e.g., 1913), and the term Bawdwin Volcanic Fm was used by Brinckmann & Hinze (1981). [Original Publication: Barber, A. J., Khin Zaw & Crow, M. J. (eds) 2017. Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs, 48, 317-342]


Lithology and Thickness

Volcanics. The unit is composed solely of massive, hard, grey and red, dense, rhyolite tuff and volcanoclastic sediments. Its thickness is variable: up to 2000 m according to Brinckmann & Hinze (1981), but only 1000 m according to Bender (1983).


Lithology Pattern: 
Volcanics


Relationships and Distribution

Lower contact

Unconformable with Chaung Magyi Gr

Upper contact

Conformable with Lokepyin Fm

Regional extent

The Bawdwin Volcanic Fm is known to be intercalated with the Pangyun Fm. From its lithology and stratigraphical position, the Bawdwin Volcanic Fm may be in part correlateable with the Late Cambrian Tarutao Gr of Thailand and Machinchang Fm of Malaysia.


GeoJSON

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Fossils

No fauna has been found in it; Brinckmann & Hinze (1981)


Age 

Late Cambrian, La Touche (1913).[Figure: Stratigraphical correlation of the Cambrian–Devonian rocks of Myanmar Shan region with those of northern Thailand and NW Malaysia. Asterisks indicate the levels at which fossils useful in correlation were found (after Aung&Cocks, 2017)]

Age Span: 

    Beginning stage: 
Drumian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
504.50

    Ending stage: 
Cambrian Stage 10

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
486.85

Depositional setting

The rhyolitic volcaniclastic sediments, which are typical of continental margin origin, show intermittent volcanic activity near the depositional basin.


Depositional pattern:  


Additional Information


Compiler:  

Aye Ko Aung and L. Robin M. Cocks (Aung & Cocks, Cambrian–Devonian stratigraphy of the Shan Plateau, Myanmar (Burma), Chapter 14 in Barber, A. J., Khin Zaw & Crow, M. J. (eds) 2017. Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs, 48, 317-342).