Madi Fm
Type Locality and Naming
Central-north Yunnan (border with southernmost Sichuan). The Madi Fm was named by Li Gongju in 1964, and published by Zhang Weicha et al. in 1972. The type locality is Madi village, Dongchuan, Yunnan Province. The reference section is at Xiaoheiqing Puduhe, Dongchuan Ore District, Yunnan Province. The Madi Fm is the upper formation-level stratigraphic unit of the Kunyang Gr in the Dongchuan area.
Synonym:
Lithology and Thickness
The Madi Fm is dominated by carbonates of greyish, grey-white dolomite, limestone, stromatolite-bearing limestone and sandy limestone, sandwiched with calcareous sandstone, and calcareous quartzite. The limestone in the lower part is intercalated with metamorphosed basic volcanic rock (spilite), volcanic tuff and tuffaceous phyllite. The thickness varies from 465 m to 1400 m.
Relationships and Distribution
Lower contact
It is in conformable contact with the underlying Xiaohekou Fm.
Upper contact
Disconformably overlain by the Liubangtang Fm of Qingbaikouan (Tonian) according to the schematic stratigraphic column.
Regional extent
Central-north Yunnan (border with southernmost Sichuan).
GeoJSON
Fossils
It has diverse stromatolites and microplants. The main stromatolite taxa are Conophyton f., Colonnella cf. discreta, Schancharia tenuiseptata. The major microplant taxa are: Trematosphaeridium, Laminarites, Polyporata etc.
Age
Depositional setting
Additional Information