Zhongcao Fm
Type Locality and Naming
It was proposed by the Compiling Group of Regional Stratigraphical Scale, Sichuan Province in 1978. The type section is located at Zhongcao, about 10 km northwest of Shuhe Township, Yanyuan County, Sichuan Province.
Synonym: (中槽组) . The Goukou Fm is used in recent studies on the Baizitian section, Yanbian County. The authors considered rock series of the Goukou Fm is the facies change of Zhongcao Fm. Thus the name of Goukou Fm is treated as a synonym of Zhongcao Fm herein.
Lithology and Thickness
The formation, 325 m in thickness, is dominated by dark gray, grayish black crystalline limestone, limestone, chert with argillaceous limestone partings, sandy pelite; with pelitic siltstone and sandy pelite at the top and with thin-bedded pelite intercalated with fine-grained quartzose sandstone at the base.
Relationships and Distribution
Lower contact
It rests conformably on the underlying Baizitian Fm.
Upper contact
The formation is in fault contact relation with the overlying Devonian strata.
Regional extent
It belongs to neritic carbonate facies and is distributed in the areas south of Kuangshanliangzi in Yanyuan County, Baizitian and Yangpaixi of Yanbian County, Sichuan Province; Xiapangluo and Alencu of Lijiang County, Yunnan Province. It consists of dark gray, blackish gray marl with chert partings in Dapingzi area in thickness ranging from 140-200 m; it is composed of marl, argillaceous limestone with siltstone partings in thickness of 144 m. The formation, stretching to the border area of Yunnan Province, is facies-changed into purplish red quartzose sandstone and siltstone and is 150 m in thickness in Lijiang, Yunnan Province.
GeoJSON
Fossils
The lower part of the formation bears graptolites Pristiograptus bohemicus, P. nilssoni, Monograptus scanicus, and also anthozoa, trilobite, brachiopod, bivalve, etc.
Age
Depositional setting
Additional Information