Jianzhuba Fm
Type Locality and Naming
The type section is the Jianzhuba（Shiziya Precipice） section, located at Lianfeng Village (Jianzhuba) in Longtian Township, Chengkou County, Chongqing Municipality. The section lies about 14 km north of Gecheng Town, the seat of Chengkou County (108°41’50” E, 32°13’20” N), In this section, the Jianzhuba Formation is 176.0 m thick. The Jianzhuba Formation was first published by Shaanxi Regional Geological Survey Team (1966b). The name is derived from Jianzhuba (now Lianfeng) Village, Longtian Township, Chengkou County, northwestern Chongqing Municipality, and was originally used by the Qinling Regional Survey Team in 1959 during regional survey in the Qinling Mountain Area.
Synonym: （箭竹坝组）
Lithology and Thickness
The Jianzhuba Formation is mainly a carbonate sequence, and in the type section, it is divided into five lithologic beds, from bottom up: 1, marlstone (40 m thick); 2, thin-bedded argillaceous striped limestone (30 m); 3, thin-bedded, limestone (60 m); 4, thin-bedded argillaceous striped limestone (12 m); 5, grey, thin-bedded limestone (34 m). In the Pujiaba section in Wanyuan County northeastern Sichuan Province, 35 km northwest of Jianzhuba, a number of tempestite beds are developed, which is characterized by well-devoloped tempestite succession, hummocky cross-stratification, horizontal lamination and convolute bedding, demonstrating the features of near-depositional tempestite.
Relationships and Distribution
Lower contact
The Jianzhuba Fm is conformably rests conformably on the underlying greyish black phyllite of Lujiaping Fm
Upper contact
It is conformably overlain by Maobaguan Fm with carbonaceous slate interbedded bone coal at the base.
Regional extent
The Jianzhuba Formation is exposed in the Jiangbei Slope Area of South China Region, distributed in southern Shaanxi (Wamiao, Lujiaping, Shaba and Shanjiazhuang of Ziyang County; Minzhuba, Xigou and Xiaodonggou of Langao County; Haofang, Huhe and Zhichang of Pingli County; Xiangjianghe and Shibangou of Zhenping County), northern Chongqing Municipality (Lianfeng of Chengkou) and northeastern Sichuan (Pujiaba of Wanyuan County). The thickness of the formation varies from 110 to 540 m. The Formation decreases thickness and weakens the tempestitic features eastward and westward from Pujiaba, whereas argillaceous content is correspondingly increased.
GeoJSON
Fossils
No fossil was reported from the type and almost all other sections of the Jianzhuba Formation. The only trilobite Kootenia yui was found in the middle part of the formation near Pujiaba in Wanyuan County, Sichuan Province.
Age
Depositional setting
Additional Information