Yongping Fm
Type Locality and Naming
Mesozoic and Cenozoic Stratigraphy Conference in Northwest China, named in 1976. The Shaanxi Branch of Regional Stratigraphic Tables of Northwest China (1983) was quoted publicly for the first time. The named section is located in Yongping, Yanchuan County, Shaanxi Province. The reference section is located at Qishui River, Tongchuan, Shaanxi. Middle formation of Yanchang Gr.
Synonym: (See Additional Information below; and for the Yanchang Gr.)
Lithology and Thickness
It is a set of medium-fine sandstone and siltstone interbedded with gray-black and blue-gray mudstone. It includes an important oil-bearing horizon, and the sandstone contains pyrite nodules. Its thickness is 99 m.
Relationships and Distribution
Lower contact
It is in conformable contact with the underlying Tongchuan Fm
Upper contact
It is in conformable contact with the overlying Wayaobao Fm
Regional extent
GeoJSON
Fossils
Plants: Danaeopsis fecunda, Neocalamites carcinoides, Cladophlebis ichunensis, Otozamites, Podozamites. And bivalve fossils and Ostracoda and leaf pod, sporopollen and other fossils.
Age
Depositional setting
Additional Information
Lithology and Thickness:
It is a set of medium-fine sandstone and siltstone interbedded with gray-black and blue-gray mudstone. It includes an important oil-bearing horizon, and the sandstone contains pyrite nodules. Its thickness is 99 m.
Lithology-pattern: Fine-grained sandstone
Relationships and Distribution:
Lower contact:
It is in conformable contact with the underlying Tongchuan Fm
Upper contact:
It is in conformable contact with the overlying Wayaobao Fm
Regional extent:
GeoJSON:
Fossils:
Plants: Danaeopsis fecunda, Neocalamites carcinoides, Cladophlebis ichunensis, Otozamites, Podozamites. And bivalve fossils and Ostracoda and leaf pod, sporopollen and other fossils.
Age:
Tong et al. (2019; Triassic integrative stratigraphy and timescale of China; Science China: Earth Sciences, 82: 189-222) indicate that it as middle Carnian through Norian
Age span:
Beginning stage: Carnian
Fraction up in beginning stage: 0.15
Beginning date (Ma):
Ending stage: Norian
Fraction up in ending stage: 1.0
Ending date (Ma):
Depositional setting:
Depositional-pattern:
Additional Information
The former Yongping Fm refers to the fourth member of Yanchang Group (T3Y4). The Institute of Geology, Chinese Academy of Geological Sciences (1980) classified the strata as the middle section of the "Yanchang Formation"; Regional Stratigraphic Table of Northwest China (1983) and Regional Geology of Shaanxi Province (1989) adopted the division scheme of Yongping Fm in Yanchang Gr. The National Multiple Stratigraphic Division and Contrastive Study on the Lithostratigraphy of Shaanxi Province (1994) combined the former Hujiacun Fm (T3Y3) and the former Yongping Fm (T3Y4) to be collectively known as the Yongping Fm, which belongs to the Yanchang Gr.