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

Okhmintaung Fm

Period: 
Paleogene

Age Interval: 
Late Oligocene


Province: 
Myanmar Central Basins

Type Locality and Naming

Minbu-Salin Basin, Okhmintaung 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

Sandstone. This Fm is composed mainly of sandstones, interbedded with very few shale beds. Sandstones are grey to dark grey, hard, bedded to thickly bedded, fine- to medium-grained; fining-upwards sequences are common, composed of quartz, feldspar, mica, lithic clasts and carbonaceous material. Shales are dark grey, soft, laminated, carbonaceous and micaceous. Thickness in the Okhmintaung area was measured as c. 1246 m (4000 ft), with sand 70% and shale 30%.


Lithology Pattern: 
Sandstone


Relationships and Distribution

Lower contact

Conformable with Padaung Fm

Upper contact

Unconformable with Pyawbwe 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

Contains the fossils Lepidocyclina sp. and Heterostegina (reef facies), the microfossils Globigerina venezuelana (shallow marine) and numerous burrows (Skolithos and Glossifungites).


Age 

Late Oligocene

Age Span: 

    Beginning stage: 
Chattian

    Fraction up in beginning stage: 
0.3

    Beginning date (Ma): 
26.01

    Ending stage: 
Chattian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
23.04

Depositional setting

This Fm was deposited under tidal zone and fore-reefal to neritic zones.


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)