Home Multi-Country Search About Admin Login
Cenozoic
Mesozoic
Paleozoic
Neoproterozoic
Mesoproterozoic
Paleoproterozoic

Search by
Select Region(s) to search
Hold Ctrl (Windows/Linux) or Command (Mac) to select multiple
Yaw Formation
Click to display on map of the Ancient World at:
Yaw Fm base reconstruction

Yaw Fm

Period: 
Paleogene

Age Interval: 
Late Eocene- Early Oligocene


Province: 
Myanmar Central Basins

Type Locality and Naming

Chindwin Basin, Gangaw area in Minbu-Salin Basin. [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

Claystone. Mainly composed of blue-grey carbonaceous clays, interbedded with thick coal beds and sandstone beds. In the Yaw River section, they are a belt of soft blue shales, without much interbedded sandstones, and occupying long valleys or areas of low relief. Thick: In general, its thickness is 1200 m. In Minbu-Salin Basin and Pyay Embayment, it is Clayey sandstone. The Yaw Fm consists mainly of shale and clay beds, interbedded with a few sandstone beds and fairly thick coal beds in the upper part. Shales are blue-grey, moderately hard, thinly laminated to laminated, micaceous and highly carbonaceous.

[Figure: Stratigraphic succession of the Chindwin Basin (after Than Htut, 2017)]


Lithology Pattern: 
Sandy claystone


Relationships and Distribution

Lower contact

Unconformable with Pondaung Fm

Upper contact

Conformable with Tonhe Fm, Conformable with Shwezetaw Fm in Minbu-Salin Basin and Pyay Embayment.

Regional extent

This Fm is developed in Chindwin Basin, Minbu-Salin Basin and 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

In Minbu-Salin Basin and Pyay Embayment, Nummulities yawensis, Discocyclinasella, Discocyclina omphalus, D. (Aslericyclina) stellaris, Operculina cf. canalifera and Biplanispira spp., the planktonic foraminifera Hantkenina alabemensis and Globorotalia cerro-azuensis, and a rich molluscan fauna with Velates schmideliana.


Age 

Late Eocene. [Note: But the Latkhat Fm is assigned as Late Oligocene => if conformable, then extends into Early Oligocene; which is as it shown in schematic strat column in the ONGC Bull. 44]

Age Span: 

    Beginning stage: 
Priabonian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
37.71

    Ending stage: 
Rupelian

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
30.60

Depositional setting

Deposited under pro-delta to floodplain swamp conditions in Chindwin Basin, deposited in marsh and lagoonal environments in Minbu-Salin Basin and Pyay Embayment.


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)