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Khoraidi Formation
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Khoraidi Fm base reconstruction

Khoraidi Fm

Period: 
Calymmian

Age Interval: 
early Calymmian


Province: 
Nepal Lesser Himalaya

Type Locality and Naming

Tansen and lower Kali Gandaki region


Lithology and Thickness

"This formation consists predominantly (more than 80%) of stromatolitic dolomites. Apart from them, there also occur a few strata made up of oolites and others, represented by quartzites, and rhythmites. Its thickness at the type locality is about 350 m (Sakai 1985, p. 356). … Subspherical to domed stromatolites predominate, and they are generally followed up-section by tabular bodies. The stromatolites are laterally linked to yield 0.5–1 m thick biostromes."


Lithology Pattern: 
Reef limestone


Relationships and Distribution

Lower contact

The Khoraidi Fm begins with a large stromatolite-bearing dolomite bed, resting over the quartzites of the underlying Chappani Fm.

Upper contact

Regional extent


GeoJSON

{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[80.69,29.05],[80.69,28.99],[82.16,28.29],[83.81,27.82],[85.31,27.01],[86.61,26.7],[87.8,26.7],[87.49,26.98],[85.91,27.2],[84.91,27.97],[84.24,28.17],[83.63,28.35],[82.48,28.63],[81.57,28.92],[80.69,29.05]]]]}}

Fossils

Stromatolites


Age 

Martin (2017) schematically suggests early Calymmian (ca. 1580 Ma)

Age Span: 

    Beginning stage: 
Calymmian

    Fraction up in beginning stage: 
0.1

    Beginning date (Ma): 
1,580.00

    Ending stage: 
Calymmian

    Fraction up in the ending stage: 
0.15

    Ending date (Ma):  
1,570.00

Depositional setting

"Khoraidi Formation was deposited in intertidal sandy flats, algal flats, sandy beaches, tidal channels, and lagoons in an arid shoreline environment (Sakai 1985, p. 361)."


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.