Dashuijingshan Fm

Named by Xiong Jiayong and Shirong Liu at Dashuijingshan, Yunxian Township, Huangzhulin District, Simao County, Yunnan.

Synonym: The original Dashuijingshan Fm represents the early Ladinian early Middle Triassic deposits dominated by carbonate rocks in the Xiushui area of Simao County, Yunnan. In 1990, the Yunnan Bureau of Geology and Mineral Resources merged this formation with its underlying Lower Potou Formation [= Xiapotou Fm] and called it the Huangzhulin Fm and determined its age as the Middle Triassic Anisian. In 1992, the Chengdu Institute of Geology and Mineral Resources of the Chinese Academy of Geological Sciences and the Sichuan Geology and Mineral Bureau continued to use the Dashuijingshan Fm, and their age was set as the Anisian, late Middle Triassic. This lexicon follows it.

It is dominated by a huge set of marine carbonate rocks. Lower part is gray-light gray silty crystalline granular limestone, which is characterized by siliceous nodules and bands. Middle part is light gray-grey-white massive silty crystalline granular ash. Upper part is pale gray-gray limestone with dolomitic agglomerates, and a small amount of gray thin calcareous mudstone is often interposed on the top. It is 893 m thick.

Bivalve fossils include: Asoella cf. illyrica, Daonella boeckhi, D. reticulata, Posidonia cf. ussurica etc. Ammonoids for example, Anolcites sp. and brachiopods and corals.