Puchanghe Fm
Type Locality and Naming
Chuxiong Basin. The Puchanghe Formation was erected by the Yunnan First Regional Geological Survey Team under the Yunnan Bureau of Geology and Mineral Resources in 1965. The section for the designation is at the Puchanghe Village of Pupeng township of the Xiangyun County, Yunnan.
Lithology and Thickness
The Puchanghe Formation is mainly represented by purple red mudstone with variegated marl and sandstone bands, which is roughly divided into three parts. Lower part is represented by purple red mudstone and sandy mudstone, with yellow green fine bands or lumps. Middle part is purple red and yellow green mudstone with multiple layers of gray marl, forming variegated bands. Upper part is purple red medium and thin-bedded fine-grained clayey sandstone interbedded with mudstone. It is 1311 m thick.
Relationships and Distribution
Lower contact
The base of the formation is a conformity marked by purple red thick-bedded mudstone and sandy mudstone, with yellow green sandy mudstone bands is distinguished from the underlying Gaofengsi Fm marked by gray thick-bedded fine-grained quartz sandstone.
Upper contact
The top is a disconformity bounded by the appearance of gray white clay and gray purple thick-bedded quartz sandstone at the base of the Matoushan Fm.
Regional extent
The formation is persistent in lithology and is generally 200-500 m in thickness, 1232 m thick in Yongren and Tuanshan. It is widespread to the east of Ailaoshan and to the west of Yuanmo-Luzijiang major fault in central Yunnan. It is 362 m and 488 m thick in Longjie of Dayao and Liuju respectively, 692 m and 394 m in Yejiachong of Yaoan and Houmafang of Chuxiong, respectively, and 268 m in Nijing of Lanhan of Shuangbai. It is continuous contact with the underlying Gaofengsi Formation in different parts of central Yunnan and is in disconformable contact with the overlying Matoushan Formation in many places but in unconformable contact in Shuangbai.
GeoJSON
Fossils
It yields bivalves Nakamuranaia elongata, Yunnanococha khoratensis, Y. pupengensis, Sphaerium yanbiense, S. dayaoense; ostracods Ziziphocypris simakovi, Rhinocypris jurassica, Cypridea minevensis, C. paulsgrovensis, C. cf. inversa, C. suboblonga, Monosulcocypris pupengensis, N. reticulata; estherias Orthestheriopsis dayaoensis, O. dajingensis, O. puchangheensis; Charophytes Nodosoclavator puchangheensis, Flabellochara grovensis; and in Tuanshan, Liuju of Dayao and Longjie, it also yields bivalves Nakamuranaia chingshanensis, Brachidontes yunnanensis; ostracods Cypridea dayaoensis; and in Mixichong-Houmafang of Chuxiong, bivalves Peregeinoconcha yunnanensis.
Age
Depositional setting
It is mainly of shallow lacustrine deposition.
Additional Information