Yongdingzhuang Fm
Type Locality and Naming
It was named by the Compiler
Jingeng Sha (coordinator) Group for the Regional Stratigraphic Chart of Shanxi Province in 1979. The naming section is located in the Yongdingzhuang area of the Huayuan Temple, Kouquan Region, Datong City.
Synonym: （永定庄组）
Lithology and Thickness
Lower member is composed mainly of grey-white and grey-yellow pebble-bearing sandstones and sandy conglomerates, intercalated with a small amount of siltstones. Upper member is largely of violet, yellow, grey and green siltstones and silty mudstones, intercalated with sandstones and sandy conglomerates, with a total thickness commonly of about 100 m, and with a maximum thickness being of 170 m.
Relationships and Distribution
Lower contact
It is in an unconformable contact with the underlying Permian Shiqianfeng Gr, or overlies directly on the Shihezi Fm, the Shanxi Fm, the Taiyuan Fm or the Zhangxia Fm.
Upper contact
It is in a conformable contact with the overlying Datong Fm.
Regional extent
It is distributed only in a restricted region, including Qingciyao, Meiyukou, Tuopigou, Huayuan Temple and Qifeng Mts areas in the Datong Coalfield Domain, as well as the Makou and Yangjuangou areas of Huairen County, and Shimen and Madaotou areas of Zuoyun County. The strata of the formation are changeable greatly in a crosswise direction. In the Tuopigou and Yongdingzhuang areas of Datong City the formation is composed of white and light-grey-yellow pebble-bearing sandstone or sandy conglomerate, while in the Qingciyao, Shichang and Madaotou areas of Zuoyun County the formation represents variegated alluvial-slope clays.
GeoJSON
Fossils
It yields abundant plant fossils such as Coniopteris hymenophylloides, C. tatungensis, C. szeiana, Czekanowskia rigida, Cladophlebis shansiensis, C. gracilis, Ctenopteris sp., Podozamites lanceolatus, Pterophyllum angustum, P. decurrens, Anomozamites minor, Neocalamites hoerensis, Eboracia lobifolia and Baiera gracilis. In addition, there are found to occur also bivalve fossils as represented by Ferganoconcha and Utschamiella, as well as insect fossils.
Age
Depositional setting
The formation is interpreted as represents alluvial-proluvial deposits.
Additional Information
Age:
Schematic strat column suggests late-Early Jurassic age
Age span:
Beginning stage: Pliensbachian
Fraction up in beginning stage: 0.0
Beginning date (Ma):
Ending stage: Toarcian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
The formation is interpreted as represents alluvial-proluvial deposits.
Depositional-pattern:
Additional Information
Compiler
Jingeng Sha (coordinator)