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Shwezetaw Formation
Click to display on map of the Ancient World at:
Shwezetaw Fm base reconstruction

Shwezetaw Fm

Period: 
Paleogene

Age Interval: 
Early Oligocene


Province: 
Myanmar Central Basins

Type Locality and Naming

Minbu-Salin Basin, lower Mann Chaung area. [Original Publication: Barber, A. J., Khin Zaw & Crow, M. J. (eds) 2017. Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs, 48, 219–260]

[Figure: Map showing location of sub-basins of the Central Myanmar Basin (after Myint Thein and M. Maung 2017)]


Lithology and Thickness

Sandy claystone. This Fm contains an Upper Sandstone Member, c. 243 m (800 ft) thick, and a Lower Alternation Member c. 732 m (2400 ft) thick. The sandstone beds are yellow-brown to light grey, hard, bedded to cross-bedded, fine to medium grained, composed of quartz, feldspar, mica and lithic clasts set in a silty matrix. Calcareous and fossiliferous hard beds with carbonaceous materials are common in the upper part. The Lower Member contains dark grey, silty shales, thinly laminated, interbedded with dark grey carbonaceous clay beds. A thickness of c. 996 m (3200 ft) has been recorded in the lower Mann Chaung area, with sand 70% and shale 30%.


Lithology Pattern: 
Sandy claystone


Relationships and Distribution

Lower contact

Unconformable with Yaw Fm

Upper contact

Conformable with Padaung Fm

Regional extent

This Fm is developed in Minbu-Salin basin, Pyay embayment.

[Figure: a) Composite stratigraphic correlation of Myanmar Central Basins (after Than et al., 2017)]


GeoJSON

{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[97.36,26.84],[95.62,26.11],[94.83,24.64],[94.19,22.39],[94.3,20.38],[95.11,17.51],[96.41,17.81],[95.95,20.52],[95.51,22.18],[96.28,24.52],[96.96,24.26],[97.82,25.42],[97.36,26.84]]]]}}

Fossils

Bathysiphon sp., Ammobaculites sp., Trochonnmina sp. and Haplophragmoides sp.


Age 

Early Oligocene

Age Span: 

    Beginning stage: 
Rupelian

    Fraction up in beginning stage: 
0.2

    Beginning date (Ma): 
32.58

    Ending stage: 
Rupelian

    Fraction up in the ending stage: 
0.7

    Ending date (Ma):  
29.27

Depositional setting

This Fm was deposited in fluvial to littoral Environments.


Depositional pattern:  


Additional Information


Compiler:  

Than Htut, Kapesa Lokho, D.S.N.Raju and Ravi Misra (Than Htut, Myanmar petroleum systems, including the offshore area, Chapter 11 in Barber, A. J., Khin Zaw & Crow, M. J. (eds) 2017. Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs, 48, 219–260)