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

Debagram Fm

Period: 
Neogene

Age Interval: 
Pliocene


Province: 
NE.India West Bengal Basin, Bangladesh NW

Type Locality and Naming

Type section is in the well Debagram – 1, Interval is 117-986 m and thickness is 869 m. [Original Publication: Biswas, B. (1963) Results of exploration for Petroleum in the Western part of Bengal Basin, India. Proc. 2nd Symp. Dev. Petrol Res. ECAFE Mins. Res. DeVol. Ser No. 18, pt 1, pp. 241-250.]

[Figure 1: Location map showing tectonic elements and drilled wells (after R.N Dwivedi in Raju and Misra, 2009)]


Lithology and Thickness

Shallow-marine marl. In the type section, it consists of feebly calcareous silty clay, shale and claystone in the lower part and alternation of calcareous shale and siltstone in the upper part. Its minimum thickness is observed in Bolpur-1 well. In Golf Green-1, Jaguli-1 and in its east it is more than 1700 m thick.

[Figure 1: West Bengal Basin lithostratigraphy (after R.N. Dwivedi in Raju and Misra, 2009) with red-arrow showing position of this formation]


Lithology Pattern: 
Shallow-marine marl


Relationships and Distribution

Lower contact

Lower boundary is unconformable with the Pandua Fm.

Upper contact

Upper contact is unconformable with the Bengal Alluvium Fm.

Regional extent

West Bengal basin – more shelf-slope facies (coeval with Ranaghat Fm). Regional West Bengal Basin, and NW Bangladesh (on Precambrian platform region)


GeoJSON

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Fossils

The Debagram Formation shows sporadic faunal occurrence. No age indicative foraminiferal assemblage is recorded.


Age 

Pliocene age is assigned based on its stratigraphic position.

Age Span: 

    Beginning stage: 
Zanclean

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
5.34

    Ending stage: 
Gelasian

    Fraction up in the ending stage: 
0.4

    Ending date (Ma):  
2.27

Depositional setting

It comprises mainly marginal deltaic facies.

[Figure: Environments of Deposition of West Bengal Basin (from dghindia.gov.in)]


Depositional pattern:  


Additional Information


Compiler:  

D.S.N Raju