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Variegated Formation
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Variegated Fm base reconstruction

Variegated Fm

Period: 
Silurian

Age Interval: 
?Early to Late Silurian (?433-419 Ma)


Province: 
NW Himalaya Kumaun-Garhwal Tethyan Himalaya

Type Locality and Naming

Type section is in Bamras (Untabhura pass) Shiala pass, Kuti-Yangte Valley. [Original Publication: Kumar, S., Singh, I.B., and Singh, S.K. 1977. Lithostratigraphy, structure, depositional environment, palaeocurrent and trace fossils of the Tethyan sediments of Malla Johar area, Pithoragarh-Chamoli districts, Uttar Pradesh, India. Jour Pal Soc. India, 20, 396-435; Heim, A. and Gansser, A. 1939. Central Himalaya: Geological observations of Swiss expedition 1936; Reprinted Delhi Hind. Publ. Co. 246]

Synonyms: Bamras Fm (Jamwal and Kacker, 1989)

[Figure 1: Location of the Kumaun-Garhwal region (from Celerier et al., GSA Bull 2009)]

[Figure 2: Geologic map of the Kumaun-Garhwal region (from Celerier et al., GSA Bull 2009)]


Lithology and Thickness

Claystone and Dolomite. Comprised of shale alternating with chocolate brown micrite dolomite and siliceous limestone, carbonaceous shale. Very variable thickness from 100 to 1000 m.


Lithology Pattern: 
Continental marl


Relationships and Distribution

Lower contact

Conformably overlies the Young Fm.

Upper contact

Conformably overlain by the Muth Fm. In the Young Valley section it has angular unconformable contact with overlying Muth Fm. [Note: The Muth Fm is usually assigned as middle Devonian, but the Variegated Fm is assigned as Silurian.]

Regional extent

Kumaun to Garhwal regions


GeoJSON

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Fossils

Atrypa reticularis; Strophonella sp; Orthis basalis. Leptaena rhomboidalis, favosites sp. (Khana et al., 1985) Orthis (Dalmanella) bouchardi; Orthis (Dalmanella) basalis; var. muthensis (Valdiya and Gupta, 1972); Trace Fossils are Chondrites sp. Volkichrium sp.; (Tandon and Bhatia, 1978)


Age 

late Early Silurian-Late Silurian.

Age Span: 

    Beginning stage: 
Telychian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
438.59

    Ending stage: 
Ludfordian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
422.73

Depositional setting

Marine shallow-water environment.


Depositional pattern:  


Additional Information


Compiler:  

Birendra Singh & O.N. Bhargava.