Leidashu Fm
Type Locality and Naming
Named by No. 508 Geological Party, Southwest Bureau of Geology in 1954 and formally published in the Stratigraphic Table of Sichuan Province in 1978. The naming section is located at Leidashu, Zhangguan 20 km south of Huili, Sichuan.
Lithology and Thickness
Lower Member is arkosic sandstone with siltstone and mudstone, 347 m thick. Middle Member is alternating calcareous siltstone and sandstone, with minor mudstone 651 m thick. Upper Member is calcareous mudstone, containing thin-bedded or lenticular gypsum bodies, 450 m thick.
Relationships and Distribution
Lower contact
The base has a disconformable contact with the underlying Cretaceous Xiaoba Fm.
Upper contact
The top is undefined and covered by the Quaternary
Regional extent
This formation is of restricted distribution. It mostly occurs in the Mishi and Jiangzhou basins, being 1453 m thick; it is 1015 m thick in the Tong’an area, ~200 m thick in the Luchang area and 85 m thick in the Xidehongma area. The depocenter lies in the Liangshan Mountains area, displaying a nearly N-S-trending zone.
GeoJSON
Fossils
The Lower Member, no fossil being found; the Middle Member, containing the biotic assemblage represented by the ostracods Limnocyhere-Sinocypris-Ilyocypris assemblage; the Upper Member, containing the charophytes Obtusochara sp. and the ostracods Pinnocypridea-Limnocythere assemblage.
Age
Depositional setting
Additional Information