Lujiaping Fm
Type Locality and Naming
The type section of the Lujiaping Formation is located between Lujiaping and Chazaicun villages, lying 3 km south of the Wamiao Town, Ziyang, Shaanxi Province (108°09’30”E, 32°23’15”N). It was measured by Shaanxi Regional Geological Survey Team in 1989. The Lujiaping Formation was named by Shaanxi Regional Geological Survey Team (1966b). The name is derived from Lujiaping Village in Wamiao Township, Ziyang County, southern Shaanxi Province. Originally it was used by the Qinling Regional Survey Team in 1959 during geological surveying in the Qinling Mountains.
Synonym:
Lithology and Thickness
The Lujiaping Formation is a clastic sequence. In the type section, the formation is divided into three parts. Lower part consists of siltstone, carbonaceous shale and crystalline limestone (147 m thick); Middle part consists of siliceous rock, siliceous slate and minor carbonaceous slate (221 m); Upper part consists of carbonaceous slate, carbonic siltstone and siliceous rock with shale at its top (333 m). In the type section, the Lujiaping Formation is 701 m thick.
The upper part of the formation is comparatively stable in lithology and facies, while the middle and lower parts are rather variable in lithology. For example, along the banks of Renhe River, 15 km northwest of type area at Lujiaping Village, the middle part becomes siliceous rock intercalated with dolomite, dolomitic limestone, crystalline limestone and carbonaceous slate, and the lower part is composed of limestone and marlstone with minor siliceous rock and carbonaceous slate. In the west of Zhenping County, about 100 km southeast of Lujiaping, the middle part consists of siliceous rock intercalated with minor carbonaceous slate, while the upper interval of the lower part consists of siliceous limestone, and the lower interval of the lower part consists of siliceous slate, micritic limestone and carbonaceous slate.
Relationships and Distribution
Lower contact
The Lujiaping Fm rests either disconformably or unconformably on the underlying Yaolinghe Fm of Ediacaran System. The lower boundary of Lujiaping Fm is marked by the disconformable plane or unconformable plane.
Upper contact
It is conformably overlain by Jianzhuba Fm. The upper boundary of is defined by lithologic change from the slate or siltstone of Lujiaping Fm and to the marlstone at the base of the Jianzhuba Fm.
Regional extent
The formation is exposed in the Jiangbei Slope Area of South China Region, distributed in southern Shaanxi Province (Zhenba, Ziyang, Pingli, Langao, and Zhenping counties), northeastern Sichuan Province (Wanyuan County), and northwestern Chongqing Municipality (Chengkou County). The thickness of the Lujiaping Formation varies from 130 to 793 m.
GeoJSON
Fossils
No fossil was reported from the type section of the Lujiaping Formation. In a section at Guanyingchuhe of Zhenba County, small shelly fossils Condonmorfa, Punclatus, Protosphaerites, Scleritids, and circothecids are yielded at a level 137 m above the base of the Lujiaping Formation. In other sections, the formation yields additional small shelly fossils Archaeooides sp., Chancelloria sp., and Protohertzina? sp.
Age
Depositional setting
Additional Information