Zhiluo Fm
Type Locality and Naming
Ordos Basin. It was named by Li Desheng in 1951, and was first cited publicly by Pan Zhongxiang in 1954. The naming section is located in the vicinity of Zhiluo Town of Fuxian County, Sha’anxi Province, with the section along the Xixingzi River of Yan’an City serving as its reference section.
Lithology and Thickness
Lower part is composed of yellow-green and grey-green fine-grained sandstones, siltstones and mudstones, with its basal part with a 34 m-thick layer of yellow-green medium-grained sandstones and conglomerates. Upper part is composed largely of purple, brown and grey-green mudstones and siltstones. The total thickness of the formation is of 135 m.
Relationships and Distribution
Lower contact
It is in conformable contact with the underlying Yan'an Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Anding Fm
Regional extent
The formation is distributed extensively in the Ordos Basin. It is changeable in both lithology and thickness greatly from region to region, yet with a general tendency being characterized by the predominance of fine clastic rocks and mudstones in the central part of the basin, and of more coarse clastic rocks on the margins of the basin.
GeoJSON
Fossils
It yields bivalves as represented by Ferganoconcha sp. In the area of the Xixingzi River of Yan’an City the formation yields plants such as Coniopteris hymenophylloides; bivalves such as Sibireconcha anodontoides, as well as spore-pollen fossils.
Age
Depositional setting
Additional Information