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Ranaghat Formation
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Ranaghat Fm base reconstruction

Ranaghat Fm

Period: 
Neogene

Age Interval: 
Pliocene


Province: 
NE.India West Bengal Basin

Type Locality and Naming

Type section is in the well Ranaghat – 1, Interval is 171-2705 m according to original definition Chandra et al. (1993) revised the top and bottom to be between 1000-3016 m respectively. [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

Sandstone. The Ranaghat Formation represents the sand equivalent of the Debagram Fm. In type section, it comprises fine- to very fine-grained, grey to greyish white, white sandstone. Minor silt and shale are also present. The Ranaghat Formation, wherever present, includes considerable sedimentary thickness. It is of the order of 2500 – 3000 m in Deganga - Bodra - shallow marine Miocene prospect area.

[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: 
Sandstone


Relationships and Distribution

Lower contact

Lower boundary is unconformable with the Pandua Fm and conformable with the Matla Fm.

Upper contact

Upper contact is unconformable with the Bengal Alluvium Fm.

Regional extent

West Bengal basin – more basinal facies (coeval with Debagam Fm)


GeoJSON

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Fossils

The formation mainly consists of smaller benthic foraminifera such as Brizalina, Ammonia beccarii, Bolivina, Cibicides etc, besides Chiloguembelina globigesina and few globigerines.


Age 

Pliocene

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

Deltaic to shallow-marine environment of deposition.

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


Depositional pattern:  


Additional Information


Compiler:  

D.S.N Raju