Fangcheng Fm
Type Locality and Naming
It was named by Zhang Jiefang in 1959. The type section is at Pingwang in Fangcheng County, Guangxi Zhuang Zizhiqu. The reference section is at Fuwei, Qinzhou, Guangxi Zhuangzu Zizhiqu.
Synonym: (防城组)
Lithology and Thickness
Lower part, 948 m thick, consists of brown yellow, purplish red and grayish black thin-to-medium-bedded micritic sandstone, shale, pelitic siltstone intercalated with medium-to-fine-grained quartzose sandstone. Upper part, 496 m in thickness, is composed of grey green, grey black shale, silty shale intercalated with medium-to-fine-grained quartzose sandstone.
Relationships and Distribution
Lower contact
It is conformably contacted with the underlying Hepu Gr
Upper contact
It is conformably contacted with the overlying Qinzhou Gr of the early Devonian.
Regional extent
The lithology varies rather considerably. In the area of Fangcheng and Qinzhou of southern Guangxi it consists of micritic arkosic sandstone and micritic siltstone intercalated with shale, partly with limestone lenses, and accounts 1593 m in thickness. In Lingshan and Hefu, it shows black shale and siltstone of 204-267 m in thickness. In the area of Yulin it is dominated by shale, 180 m thick. In southeast Guangxi the exposures are restricted merely at Mingle of Beiliu County and Nuotong of Cenxi County, and the thickness varies from 20 m to 100 m.
GeoJSON
Fossils
There are three graptolite zones in the lower part, namely being in ascending order: the Pristiograptus nilssoni zone, the Cucullograptus scanicus zone, and the Pristiograptus tumescens zone; there are also three graptolite zones in the upper part, such as in ascending order: the Pristiograptus ultimus zone, the Monograptus ex gr. similis zone and the Pristiograptus transgrediens proximus zone. In addition to the graptolite fossils, the formation bears brachiopods, trilobites, etc.
Age
Depositional setting
The formation belongs to clastic sediments of littoral-neritic facies with very developed flysch-flyschoid rhythmites.
Additional Information