Dapingzhang Fm
Type Locality and Naming
The type section is located in Dazhangping Village, Jingu County, Yunnan Province, which was named by Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences in 1973. Originally, the Dapingzhang Fm represented the clastic around Simao, Yunnan Province, which was stratigraphically between the Weiyuanjiang Formation of Upper Triassic and Hepingxiang Fm of Middle Jurassic and was suggestive of late Late Triassic. Later, 7-9 beds of Middle-Lower part of Dapingzhang Fm (equal to 7-10 beds in type section) were ascribed to the newly proposed Taozishu Fm by Jiayong Liu and Shirong Liu in 1983. The revised Dapingzhang Fm only included the tenth bed of type section and was interpretive of early Norian of Late Triassic.
Synonym:
Lithology and Thickness
It is dominated by fuchsia-colored mudstone or grey-green mudstone, calcareous mudstone, sandstone interbedded with lithic sandstone. Thickness ranges from 7.9 to 100 m.
Relationships and Distribution
Lower contact
The base of this formation is dominated by purple-red and grey-greenish shale where shows conformable relationship with underlying Taozishu Fm. However, the formation is conformable in contact to the Changxing Fm, upper Permian unconformity in Simao dazhai; or on the Longtan Fm of upper Permian in eastern Simaoling, Mashuli area.
Upper contact
Disconformity with overlying Xiaohongqiao Fm, which belongs to middle Jurassic; or with Zhangkezhai Fm of Early Jurassic (Pu'er region).
Regional extent
This formation is distributed in Maosi, Jinggu and Pu'er in Yunnan Province where was coastal marine setting. Bed packages extend in a long distance in lateral, but thickness varies. The thickness of this formation, for example, 7.9 m at Simao dazhai, 15.9 m at both Jinggu and Pingxiang, 21.3 m in Pu'er dehua but the sediment grains here coarser than other area; part of outcrops of this formation, about 100 m thick, distributed sporadically at Simao dazhai, eastern part of Waling, Malishu etc.
GeoJSON
Fossils
Bivalves include: Halobia cf. plicosa, Posidonia bittneri, Unionites minimus, U. griesbachi, U.? cardiiformis, U.? cf. manmuensis, Yunnanophorus cf. boulei, Y. cf. gracilis etc.; Ammonoids: Thisbites cf. agricolae, Choristoceras sp. etc.
Age
Depositional setting
Coastal marine setting
Additional Information