Nanshimenzi Fm
Type Locality and Naming
The type section is at Nanshimenzigou in Dongdayao, Yumen, Gansu. The Nanshimenzi Fm is derived from the Nanshimenzi Series proposed by Yin Zanxun (T.H.Yin) in 1957. In 1964, Mu Enzhi et al. renamed it the Nanshimenzi Gr which was in turn redefined the Nanshimenzi Fm.
Synonym: (南石门子组）
Lithology and Thickness
The Nanshimenzi Fm has a Lower part composed of black shale, crystalline limestone and sandy limestone, and an Upper part of volcanic rock, diabase, calcirudite, limestone and tuff. In the type area, the formation is recorded an incomplete thickness of 570 m.
Relationships and Distribution
Lower contact
It rests conformably on the limestone of the Yaomoshan Fm
Upper contact
With a covered upper boundary.
Regional extent
The lithology and thickness of the Nanshimenzi Fm vary considerably along the length of its outcrop. At Changma in Yumen, Gansu, it recorded a thickness of 330 m respectively, and is composed of sandstone, siliceous slate and tuffaceous sandstone. In Dahaizi, Sunan County, it is up to 1665 m thick, and contains increasing volcanic rock; the limestone in its upper part yields corals of Favositella-Wormsipora-Agetolites assemblage. Southeastward to Sidalong, its exposure is 926 m thick; at Lijiahe in Qin'an, it is composed of volcanic rock, clastic rock and marble, and is 463 m thick. In western segment of Daban Mountain and on the south slope of the east segment of Tuolai Mountain in Qinghai, the Nanshimenzi Fm is characterized by basic volcanic rock intercalated with limestone; at Honggou, Menyuan, it recorded an incomplete thickness of 2542 m (Qinghai Bureau of Geology and Mineral Resources, 1991).
GeoJSON
Fossils
This stratigraphic unit yields graptolites Climacograptus putillus, C. yumenensis, Pseudoclimacograptus scharenbergi and trilobite Corrugatagnostus sp.
Age
Depositional setting
Additional Information