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Shedwindu Formation
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Shedwindu Fm base reconstruction

Shedwindu Fm

Period: 
Cretaceous

Age Interval: 
Late Cretaceous


Province: 
Myanmar Central Basins

Type Locality and Naming

Irrawaddy River Delta, its type locality is Shwedwindu village in the eastern foothills of the Rakhine-Yoma (16° 41′ N, 94° 35′ E). [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

Clayey limestone. The Shwedwindu Fm is an alternating sequence of hard, greenish-grey shales with Globotruncana, together with milky white limestone blocks and very hard, greenish-grey sandstone associated with igneous bodies of various sizes, exposed in the neighbourhood of Shwedwindu village.


Lithology Pattern: 
Clayey limestone


Relationships and Distribution

Lower contact

This is the oldest unit in the Irrawaddy River Delta.

Upper contact

It is unconformable with Kwingu Fm

Regional extent

It is developed in Irrawaddy River Delta.

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


GeoJSON

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Fossils

The Fm contains Globotruncana lapparenti, Ammodiscus, Haplophragmoides, Glomospira, Globigerina triloculinoides, Amphifenestrella and Textulariella sp.,


Age 

Late Cretaceous. In a joint study byMOGE and JNOC, a block of dark grey, very hard, argillaceous chert was found to be composed of abundant radiolarian fossils of Early Cretaceous age (Barremian to Hauterivian) (Yaguchi et al. 1984–1985).

Age Span: 

    Beginning stage: 
Campanian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
83.65

    Ending stage: 
Maastrichtian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
66.04

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Than Htut, (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)