Jianghe Fm
Type Locality and Naming
The type section is located at Caodigou and Dajialiangou, Xiahuancang Village, Tianjun County, Qinghai Province. It was named by Conference on the Fault of Marine Triassic and Jurassic Stratigraphy in Northwest China in 1976. And Yang Zunyi et al. publicly cited in 1983 at first time.
Synonym: The original Jianghe Fm represented the upper layer of the Yangkang Gr in the southern Qilian Mountains of Qinghai Province. After its name was founded, it was cited by Yang Zunyi et al. in 1983, and it was divided into two lithological sections. See the Xiahuancang Fm for details.
Lithology and Thickness
The section mainly consists of clastic rock and limestone, it can be divided into Lower clastic rock section and Upper limestone section. Lower clastic rock section is composed of purple, light gray, gray-green quartz sandstone, siltstone, sandy shale and thin limestone, with a thickness of 22-59 m. Upper limestone section is mainly medium- to thick-bedded bioclastic limestone with mud(?) band limestone, oolitic limestone, nodular limestone. 84-144 m thick.
Relationships and Distribution
Lower contact
Conformable contact with the Lower Triassic Xiahuancanggou Fm (= Xiahuancang Fm in this Lexicon usage). The bottom boundary onto the is marked by the appearance of purple-red sandstone
Upper contact
The top boundary to the overlying Junzihe Fm is marked by the disappearance of bioclastic limestone in the argillaceous zone.
Regional extent
This formation is mainly distributed in the South Qilian Mountains of Qinghai Province, especially in the middle reaches of Junyu River and Xiariha River.
GeoJSON
Fossils
Bivalves: Bakevellia exporrecta, Leptochondria minima, L. minima lavis, Promyalina intermedia, P. putiatinensis, Leptochondria albertii, Entolium discites, Eumorphotis huancangensis, E. rwanawi, E. cf. tellen, Pleuronecites difformis, Brachiopods and gastropods.
Age
Depositional setting
It is interpreted as shallow water deposits.
Additional Information