Liujiagou Fm
Type Locality and Naming
The type section is located at Liujiagou, Huabeitun, Ningwu, Shanxi and the reference section is located at Peijiashan, Jiaocheng, Shanxi. It was named by the Shanxi Stratigraphy Team of Chinese Academy of Sciences in 1959.
Synonym: The Liujiagou Formation originally refers to a set of purple-red fine-grained feldspar sandstone in the middle section of the Upper Permian "Shiqianfeng Group" with multiple thin layers of purple-red siltstone and sandy shale. In the mid-1970s, the Shanxi District Survey Team and the North China Institute of Geology and Mineral Research (now Tianjin Institute of Geology and Mineral Resources) discovered the Pleuromeia flora in the Liujiagou Fm and Heshanggou Fm in the "Qinshui Basin" of Shanxi, and so assigned the Liujiagou Fm as the Early Triassic. In addition, the former Dingjiagou Fm in Hebei was assigned to the Liujiagou Formation.
Lithology and Thickness
It is dominated by a set of gray-red, gray-purple, light-purple, and purple-red medium-thin fine-grained feldspar sandstones, mixed with unstable purple-red siltstones, sandy shales, conglomerates, gray-white quartz sandstone and gray, Gray-green feldspar sandstone, shale. It also contains calcareous "sand balls" and magnetite bands. Its thickness can be up to 600.2 m.
Relationships and Distribution
Lower contact
Its bottom is gray-red thin layer of fine-grained feldspar sandstone, which is in conformable contact with the underlying purple-red mudstone of the Upper Permian Sunjiagou Fm
Upper contact
Conformable contact with the overlying Heshanggou Fm
Regional extent
Coeval with the Qishan Fm of Ordos Basin. This Liujiagou Fm is widely distributed in Shanxi, Shaanxi, Gansu, Inner Mongolia, Shandong, Hebei and other regions. In Shanxi Ningwu-Jingle and Xingxian-Baode areas, sandstones are relatively coarse in grain size, mainly medium-medium-coarse feldspar sandstones; in the south of Shanxi's Jixian, Anze, and Qinxian areas, the sandstone has a finer grain size, it is mainly composed of fine-grained feldspar sandstone and siltstone intercalated with mudstone and shale. The thickness of this formation varies greatly, generally between 250 and 630 m, gradually becoming thinner from east to west and from north to south in North China.
GeoJSON
Fossils
Plants: Pleuromeia jiaochengensis, Crematopteris circinalis, Willsistrobus hongyantouensis. Fossil spores and pollens: Lundbladispora-Cycadopites-Taeniaesporites assemblage; Conchostracan fossils.
Age
Depositional setting
It is interpreted as the inland fluvial face deposits under a hot dry climate.
Additional Information