Changtanzi Fm
Type Locality and Naming
The type section is located at the Changtanzi lime kiln, east of Shawozi Village in Ganxi of Beichuan County, Sichuan Province. It was named by Fan Yingnian in 1980.
Lithology and Thickness
Limestone. It is dominated by gray to dark-gray lumpy and pellet limestone, intercalated with micritic sandy limestone, algal-laminated limestone and bioclastic micritic limestone. The formation is 121 m in thickness.
Relationships and Distribution
Lower contact
Conformably on the oolitic limestone of Maoba Fm.
Upper contact
Conformably overlain by the dolomite of Majiaoba Fm (earliest Carboniferous; map-column 41) or the Heiyanwao Fm (revised Longmenshan column by Hongfei Hou, 5Apr2021)
Regional extent
GeoJSON
Fossils
The fossils are characterized by abundant solitary coral that can be divided into a Lower Siphonophyllia stereoseptata-Caninia cornucopiae zone and an Upper Beichuanophyllum pachysepataum-Neobeichuanophyllum multiseptatum zone; by stromatopora of Cystostrorau, Rosenella, Pachyshylostroma, Beichuanostroma; and by conodonts of Polygnathus znepolensis-P. changtanziensis assemblage zone.
NOTE: Compilation by Fan Yingnian (for basal Carboniferous) stated that: bottom contains Coral Guerichiphyllum elegantum, Conodonts Apatognathus geminus and Polygnathus znepolenses. Middle part: Corals Siphonophylloides stereoseptata, S. shawozensis and Caninia cornucopiae ateles, Foraminifera Stylostroma sublobosum, Conodonts Polygnathus znepolenses, Apatognathus geminus and A. extenata. Upper part: Corals Cystophrentis kolaohoensis, Beichuanophyllum pachyseptatum and Neobeichuanophyllum multiseptatum, and Conodont Drepanodus sp.
Age
Depositional setting
Carbonate platform.
Additional Information