Tsanglangpu Fm
Type Locality and Naming
The type section of the Tsanglangpu Formation is located between Canglongpu and Huangtupo (Hongjunshao-Wulongqing) villages, about 6.5 km southwest of the seat of Malong District, Qujing City (103°31’E, 25°23’N). It was remeasured by Zhang Wentang, Ren Xian and others in 1962 (Zhang et al., 1979, p. 73). In this section, the Tsanglangpu Formation is 299 m thick. The Tsanglangpu Formation was named by Ding and Wang (1937). The name is derived from Tsanglangpu (spelled Canglangpu in Hanyu Pinyin)Village, Malong District, Qujing City, eastern Yunnan Province. The name was originally appeared in a 1914 manuscript by Ding Wenjiang and Wang Yuelunm and was formally published as Tsanglangpu series by themselves (Ding and Wang, 1937). Afterwards this unit was renamed as Tsanglangpu Formation by Lu (1941). Subsequently the unit was adopted as a Chinese standard Cambrian chronostratigraphic unit, the Tsanglangpuan Stage (Xiang et al., 1981; Zhang, 1985; Compiling Committee for Chinese Stratigraphic Lexicon et al., 1999), and had been used for a long time until a new four-fold chronostratigraphic subdivision was introduced (Peng, 2000a, b).
Synonym: （沧浪铺组）; It is divided into two lithologic members, the Hongjingshao Member below and the Wulongqing Member above.
Lithology and Thickness
The Tsanglangpu Formation is a fine clastic sequence. The lower Hongjingshao Member is 186 m thick, consisting of greyish yellow and yellowish green sandy shale, siltstone and shale, intercalated with purplish red, thin- to medium-bedded sandstone. The upper Wulongqing Member is 113 m thick, consisting of yellowish green, micaceous silty shale, siltstone, and micaceous quartzose sandstone, and usually with fossil tube traces on the surfaces.
Relationships and Distribution
Lower contact
The Tsanglangpu Fm rests conformably on the underlying Chiungchussu Fm. The lower boundary of Tsanglangpu Fm is marked by the disappearance of the black shale of the underlying Chiungchussu Fm.
Upper contact
It is conformably overlain by the Lungwangmiao Fm. The upper boundary is defined by the appearance of limestone at the base of overlying Lungwangmiao Fm
Regional extent
The Tsanglangpu Formation is exposed in the western part of Yangtze Area of South China Region, distributed in eastern and northeastern Yunnan Province and eastern Sichuan Province. The formation is stable in lithology. In Yunnan, the Hongjingshao Member increases its thickness eastward, ranging between 83.5 and 206 m, usually it is about 90 m thick; In general, Wulongqing Member also increases its thickness northeastward, ranging between 38 and 277.5 m. In Sichuan, the thickness of the formation decreases northward, ranging between 64 and 180 m.
GeoJSON
Fossils
The Tsanglangpu Formation yields trilobites Drepanuroides, Drepanopyge, Eoptychoparia, Longduia, Malungia, Mayiella, Palaeolenus, Paramalungia, Redlichia (Redlichia), R. (Pteroredlichia), Syndianella, Yiliangella, Yiliangellina, Yinites, Yuehsienszella, Yunnanaspis, and Yunnanaspidella; brachiopods Diandongia, Lingulepis, Lingullena, and Westonia; hyolithids Ambrolinevirtus and Malungtheca; trace fossils Hamipes, Helicodromites, Helminthoida, Monomorphychnus, Palaeophycus, Planolites, Polycampton, and Taphrheliminthopsis.
Age
Depositional setting
The formation represents deposits in subtidal flat environment.
Additional Information