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

Obogon Fm

Period: 
Neogene

Age Interval: 
Late Miocene


Province: 
Myanmar Central Basins

Type Locality and Naming

Minbu-Salin Basin, Obogon area in Minbu Township. [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 sandstone. Sandstones are light grey, soft, moderately hard, thinly bedded, fine- to medium-grained, consisting of quartz, feldspar, mica and lithic clasts, interbedded with thinly laminated shales. Shales are olive-grey to dark grey, soft, laminated, micaceous and carbonaceous. Thickness measured in the Obogon area in Minbu Township is c. 1308 m (4200 ft), with sand 50% and shale 50%.


Lithology Pattern: 
Clayey sandstone


Relationships and Distribution

Lower contact

Conformable with Kyaukkok Fm

Upper contact

Unconformable with Irrawaddy Fm

Regional extent

The Obogon Fm is developed in in the Minbu-Salin basin, Pyay embayment, and Gulf of Martaban Basin. The Obogon Fm is only found where the erosion associated with the Irrawaddy-Pegu unconformity has been comparatively small.

[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

Macrofauna is relatively sparse.


Age 

Late Miocene

Age Span: 

    Beginning stage: 
Tortonian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
11.63

    Ending stage: 
Messinian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
5.34

Depositional setting

This Fm was deposited under oscillating brackish and shallow-marine conditions.


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)