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Ramdighar Formation
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Ramdighar Fm base reconstruction

Ramdighar Fm

Period: 
Calymmian

Age Interval: 
early Calymmian


Province: 
Nepal Lesser Himalaya

Type Locality and Naming

Tansen and lower Kali Gandaki region


Lithology and Thickness

The Ramdighat Formation is dominated by calcareous claystone, with a minor proportion of thin limestone. "Coarse-grained terrigenous rocks are characteristically absent in this formation. It attains a thickness of about 750 m in its reference section of the Nisti Khola and is subdivided into three members." A thin Lower of black slate; a thick Middle of red-purple and green calcareous slate, and a medium-thick Upper of alternating slate and limestone.


Lithology Pattern: 
Shallow-marine marl


Relationships and Distribution

Lower contact

Overlies the Saidi Khola Fm sandstones and shales at the top of the Middle Kali Gandaki Gr.

Upper contact

Conformably below the Kerabari Fm dolomite.

Regional extent


GeoJSON

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Fossils


Age 

Martin (2017) schematically suggests early-middle Calymmian (ca. 1570 Ma)

Age Span: 

    Beginning stage: 
Calymmian

    Fraction up in beginning stage: 
0.2

    Beginning date (Ma): 
1,560.00

    Ending stage: 
Calymmian

    Fraction up in the ending stage: 
0.3

    Ending date (Ma):  
1,540.00

Depositional setting

"The Ramdighat Formation was deposited in a lagoon or a large bay that bordered an intertidal flat with an algal marsh zone."


Depositional pattern:  


Additional Information


Compiler:  

Descriptions from Megh Raj Dhital (2015, Geology of Nepal: Regional Perspective of the Classic Collided Orogen, Springer Publ., 499 pp.). Age spans estimated from correlation diagrams in Martin, A.J. (2017, "A review of Himalayan stratigraphy, magmatism, and structure", Gondwana Research, 49: 42-80; http://dx.doi.org/10.1016/j.gr.2017.04.031), but these are often controversial.