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Harza Formation
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Harza Fm base reconstruction

Harza Fm

Period: 
Devonian

Age Interval: 
D3 (17), Late Devonian


Province: 
Qinghai

Type Locality and Naming

The type section is located at Harza on the northern slope of Qimantage, Qinghai Province. It was named by No.8 Branch Team of Qinghai Team of Petroleum Reconnaissance Survey in 1958 and was quoted by Qinghai Team of Regional Geological Survey (1965, 1969).


Lithology and Thickness

Volcanics, Sandstone. This formation has mixed lithologies of volcanics interbedded in clastic to carbonate sediments. It is 1316 m in total thickness.

Lower part is composed of grayish-green slate, feldspathic quartz sandstone and grayish-green andesite, grayish-white rhyolite, grayish purple andesitic agglomerate, etc. Middle part is gray thick-bedded pebble-bearing sandy limestone intercalated with siltstone, grayish-purple conglomerate and pebble-bearing sandstone. Upper part consists of gray dacite, fine volcanic breccia, tuff, and silty slate intercalated with light-grayish purple rhyolitic andesite, etc.


Lithology Pattern: 
Volcanics


Relationships and Distribution

Lower contact

It is in an intrusive contact with the underlying Variscan granite. Regionally, the next older formation is the Qigaisu Gr (also volcanics)

Upper contact

It is in a disconformable contact with the overlying Wulonggou Fm of Lower Carboniferous.

Regional extent


GeoJSON

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Fossils

The middle part yields brachiopods Cyrtospirifer sinensis, C. chaoi, Daralenlodon sp., Tenticospirifer sp.


Age 

Late Devonian

Age Span: 

    Beginning stage: 
Frasnian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
378.90

    Ending stage: 
Famennian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
359.30

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

(Wang Shitao)