Fenfanghe Fm
Type Locality and Naming
Ordos Basin. The type section is located at Fenfang River in the vicinity of Caobi Town, Qianyang County, Sha’anxi Province. It was named by the Geological Prospecting Party of No. 186 Coalfield, Sha’anxi Province in 1973, and was first cited publicly by the Compiler
Jingeng Sha (coordinator) Group for the Regional Stratigraphic Chart of Sha’anxi Province in the 1983.
Synonym: （芬芳河组）
Lithology and Thickness
Composed mainly of brown-red, violet-grey conglomerates and boulder conglomerate, intercalated with brown-red sandstone and a small amount of argillaceous siltstone. In the Tianshuipu area it still represents conglomerate, with a thickness of 121 m. In the area of Ruqigou it is composed of calcareous siltstone and mudstone, intercalated with sandstone, with a thickness of 977 m. Its thickness is of 1174 m.
Relationships and Distribution
Lower contact
It conformably underlies the Anding Fm
Regional extent
It is distributed in the area of Qianyang County, Sha’anxi Province, and with its occurrence being found also at the Lijia River of Fengyang County in the southwestern part of the Ordos Basin, Tianshuipu of Huanxian County in the western part of the above-mentioned basin, as well as in the area of Ruqi Gully of Pingluo County, Ningxia Hui Autonomous Region.
GeoJSON
Fossils
It yields plant fossils as represented by Coniopteris hymenophylloides when approaching to its basal part in the Tianshuipu area.
Age
Depositional setting
The formation belongs to basin-margin foothill fluvial and alluvial-fan deposits.
Additional Information
Age:
At present there are multiple opinions about the age of the formation: one opinion was to assign it to the Middle Jurassic (as used in previous "red" Chinese-language lexicon), and another opinion was to assign it to the Late Jurassic. In the earlier version of this stratigraphic lexicon, the author had assigned it to the Middle Jurassic in accordance with the plant fossils gained, as well as with its regional correlation. However, Diying Huang (2019; Jurassic integrative stratigraphy and timescale of China. Science China: Earth Sciences, v. 62) re-assigns this Fenfanghe Fm as Berriasian (used here) and the Cretaceous had assigned the overlying Yijun Fm as late-Berriasian.
Age span:
Beginning stage: Berriasian
Fraction up in beginning stage: 0.0
Beginning date (Ma):
Ending stage: Berriasian
Fraction up in ending stage: 0.4
Ending date (Ma):
Depositional setting:
The formation belongs to basin-margin foothill fluvial and alluvial-fan deposits.
Depositional-pattern:
Additional Information
Compiler
Jingeng Sha (coordinator)