Naocangjiangou Fm
Type Locality and Naming
The named section is located in Naocangjian Gou, Huashixia Township, Maduo County, Qinghai Province. The former Naocangjiangou Fm represents the Middle Triassic Anisian marine deposits on the southern slope of East Kunlun Mountains in Qinghai Province. Xu Xian et al. (1982) divided the formation into arenaceous conglomerate, arenaceous slate, and carbonate from bottom to top, and attributed the age to the Middle Triassic. This book maintains the original meaning of Naocangjiangou Fm.
Synonym:
Lithology and Thickness
It is mainly composed of clastic rocks and carbonate rocks. Lower part is mainly composed of hard sandstone, feldspar sandstone, siltstone, slate and limestone, and its lithofacies and thickness vary significantly with the thickness of 236 to 1207 m. Upper part is mainly limestone with relatively stable lithofacies and a thickness of 37 to 1380 m.
Relationships and Distribution
Lower contact
At the bottom, the clastic rocks are in conformable contact with the carbonate rocks at the top of the underlying Hongshuichuan Gr
Upper contact
The top is delimited with the overlying Babaoshan Gr by a pseudo-conformable surface.
Regional extent
The formation is distributed on the southern slope of Kunlun Mountain in Qinghai Province. The lithology and thickness of the formation vary greatly, and the biota contained in the formation also varies from place to place. On the north bank of Hongshuichuan, the formation is composed of limestone, sandstone and SLATE, and the difference between the upper and lower parts is not obvious, with a thickness of 2845 m. In the upper reaches of Nuomuhong River, there is tuff, clastic black limestone, and a set of clastic rocks and carbonate strata from Xiugou to the north of Kunlun River, interbedded with volcanic rocks and coal lines, with a total thickness of more than 4393 m.
GeoJSON
Fossils
Fossils include ammonoids, brachiopods and bivalves. The lower part of the zone can be formed into the Lenotropites-Japonites zone, which can be divided into the lower Lenotropites qinghaiensis subzone and the upper Japonites meridianus subzone. The upper part can be built into the Beyrichites-Hollandites zone. Brachiopods can be called Diholkorhynchia sinensis- Pseudospiriferina tsinghaiensis assemblage; Bivalves are characterized by Leptochondria and Neomorphotis abundance.
Age
Depositional setting
Transgressive deposits
Additional Information