Xiapotou Fm
Type Locality and Naming
Xiong Jiayong and Liu Shirong named in 1983. The named section is located in the Xiapotou Village, Yunxian Township, Huangzhulin District, Simao County, Yunnan Province. ["Lower Potou" = Xia Potou].
Synonym: The original Xiapotou Formation represents the Middle Triassic Anisian sediments dominated by clastic rocks and carbonate rocks in the Choushui area, Simao County, Yunnan Province. In 1990, Yunnan Geology and Mineral Bureau combined this formation with the overlying Dashuijingshan Fm, also called Huangzhulin Fm, and dated in Middle Triassic Anisian. In 1992, the Chengdu Institute of Geology and Mineral Resources of the Chinese Academy of Geological Sciences and the Sichuan regional survey team still used the name, Xiapotou Fm, which was dated to the early Early of the Middle Triassic.
Lithology and Thickness
Mainly composed of clastic rocks and carbonate rocks. Two cycles, the bottom of which is composed of compound basal conglomerate, and the upper part is composed of grey purple lithic sandstone, grey purple siltstone and grey thin-medium layered silt limestone and marl limestone. Thickness is 376 m.
Relationships and Distribution
Lower contact
It is unconformable to underlying Lower Permian of the Upper Carboniferous
Upper contact
It is conformable to the overlying Dashuijingshan Fm
Regional extent
Located in Choushui, Simao County, Yunnan Province, Ganlanba, Dehua, Puer County, Xiangheping Township, Jinggu County. The thickness of this formation is the largest at the named site, extending southward to Ganlanba and eastwards to Dehua County. The thickness of this formation is obviously thinner, while the clastic rocks increase and the carbonate rocks decrease. It is 179 m in the Ganlanba area and 156m in the Dehua County.
GeoJSON
Fossils
Bivalve: Costatoria goldfussi mansuyi, C. cf. radiata hsuei, C. cf. proharpa multiformis, Entolium discites, Plagiostoma beyrichii, Hoernesia cf. socialis, and brachiopods, gastropods, corals, ammonoids and crinoids.
Age
Depositional setting
The formation is of coastal facies shallow sea sediments.
Additional Information